Adding upstream version 3.1.2.upstream/3.1.2upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

32 files changed, 14456 insertions, 0 deletions

diff --git a/src/Jinja2.egg-info/PKG-INFO b/src/Jinja2.egg-info/PKG-INFO
new file mode 100644
index 0000000..7b92c21
--- /dev/null
+++ b/src/Jinja2.egg-info/PKG-INFO
@@ -0,0 +1,111 @@
+Metadata-Version: 2.1
+Name: Jinja2
+Version: 3.1.2
+Summary: A very fast and expressive template engine.
+Home-page: https://palletsprojects.com/p/jinja/
+Author: Armin Ronacher
+Author-email: armin.ronacher@active-4.com
+Maintainer: Pallets
+Maintainer-email: contact@palletsprojects.com
+License: BSD-3-Clause
+Project-URL: Donate, https://palletsprojects.com/donate
+Project-URL: Documentation, https://jinja.palletsprojects.com/
+Project-URL: Changes, https://jinja.palletsprojects.com/changes/
+Project-URL: Source Code, https://github.com/pallets/jinja/
+Project-URL: Issue Tracker, https://github.com/pallets/jinja/issues/
+Project-URL: Twitter, https://twitter.com/PalletsTeam
+Project-URL: Chat, https://discord.gg/pallets
+Platform: UNKNOWN
+Classifier: Development Status :: 5 - Production/Stable
+Classifier: Environment :: Web Environment
+Classifier: Intended Audience :: Developers
+Classifier: License :: OSI Approved :: BSD License
+Classifier: Operating System :: OS Independent
+Classifier: Programming Language :: Python
+Classifier: Topic :: Internet :: WWW/HTTP :: Dynamic Content
+Classifier: Topic :: Text Processing :: Markup :: HTML
+Requires-Python: >=3.7
+Description-Content-Type: text/x-rst
+Provides-Extra: i18n
+License-File: LICENSE.rst
+
+Jinja
+=====
+
+Jinja is a fast, expressive, extensible templating engine. Special
+placeholders in the template allow writing code similar to Python
+syntax. Then the template is passed data to render the final document.
+
+It includes:
+
+-   Template inheritance and inclusion.
+-   Define and import macros within templates.
+-   HTML templates can use autoescaping to prevent XSS from untrusted
+    user input.
+-   A sandboxed environment can safely render untrusted templates.
+-   AsyncIO support for generating templates and calling async
+    functions.
+-   I18N support with Babel.
+-   Templates are compiled to optimized Python code just-in-time and
+    cached, or can be compiled ahead-of-time.
+-   Exceptions point to the correct line in templates to make debugging
+    easier.
+-   Extensible filters, tests, functions, and even syntax.
+
+Jinja's philosophy is that while application logic belongs in Python if
+possible, it shouldn't make the template designer's job difficult by
+restricting functionality too much.
+
+
+Installing
+----------
+
+Install and update using `pip`_:
+
+.. code-block:: text
+
+    $ pip install -U Jinja2
+
+.. _pip: https://pip.pypa.io/en/stable/getting-started/
+
+
+In A Nutshell
+-------------
+
+.. code-block:: jinja
+
+    {% extends "base.html" %}
+    {% block title %}Members{% endblock %}
+    {% block content %}
+      <ul>
+      {% for user in users %}
+        <li><a href="{{ user.url }}">{{ user.username }}</a></li>
+      {% endfor %}
+      </ul>
+    {% endblock %}
+
+
+Donate
+------
+
+The Pallets organization develops and supports Jinja and other popular
+packages. In order to grow the community of contributors and users, and
+allow the maintainers to devote more time to the projects, `please
+donate today`_.
+
+.. _please donate today: https://palletsprojects.com/donate
+
+
+Links
+-----
+
+-   Documentation: https://jinja.palletsprojects.com/
+-   Changes: https://jinja.palletsprojects.com/changes/
+-   PyPI Releases: https://pypi.org/project/Jinja2/
+-   Source Code: https://github.com/pallets/jinja/
+-   Issue Tracker: https://github.com/pallets/jinja/issues/
+-   Website: https://palletsprojects.com/p/jinja/
+-   Twitter: https://twitter.com/PalletsTeam
+-   Chat: https://discord.gg/pallets
+
+
diff --git a/src/Jinja2.egg-info/SOURCES.txt b/src/Jinja2.egg-info/SOURCES.txt
new file mode 100644
index 0000000..7f7a21f
--- /dev/null
+++ b/src/Jinja2.egg-info/SOURCES.txt
@@ -0,0 +1,104 @@
+CHANGES.rst
+LICENSE.rst
+MANIFEST.in
+README.rst
+setup.cfg
+setup.py
+tox.ini
+artwork/jinjalogo.svg
+docs/Makefile
+docs/api.rst
+docs/changes.rst
+docs/conf.py
+docs/extensions.rst
+docs/faq.rst
+docs/index.rst
+docs/integration.rst
+docs/intro.rst
+docs/license.rst
+docs/make.bat
+docs/nativetypes.rst
+docs/sandbox.rst
+docs/switching.rst
+docs/templates.rst
+docs/tricks.rst
+docs/_static/jinja-logo-sidebar.png
+docs/_static/jinja-logo.png
+docs/examples/cache_extension.py
+docs/examples/inline_gettext_extension.py
+examples/basic/cycle.py
+examples/basic/debugger.py
+examples/basic/inheritance.py
+examples/basic/test.py
+examples/basic/test_filter_and_linestatements.py
+examples/basic/test_loop_filter.py
+examples/basic/translate.py
+examples/basic/templates/broken.html
+examples/basic/templates/subbroken.html
+requirements/dev.txt
+requirements/docs.txt
+requirements/tests.txt
+requirements/typing.txt
+src/Jinja2.egg-info/PKG-INFO
+src/Jinja2.egg-info/SOURCES.txt
+src/Jinja2.egg-info/dependency_links.txt
+src/Jinja2.egg-info/entry_points.txt
+src/Jinja2.egg-info/requires.txt
+src/Jinja2.egg-info/top_level.txt
+src/jinja2/__init__.py
+src/jinja2/_identifier.py
+src/jinja2/async_utils.py
+src/jinja2/bccache.py
+src/jinja2/compiler.py
+src/jinja2/constants.py
+src/jinja2/debug.py
+src/jinja2/defaults.py
+src/jinja2/environment.py
+src/jinja2/exceptions.py
+src/jinja2/ext.py
+src/jinja2/filters.py
+src/jinja2/idtracking.py
+src/jinja2/lexer.py
+src/jinja2/loaders.py
+src/jinja2/meta.py
+src/jinja2/nativetypes.py
+src/jinja2/nodes.py
+src/jinja2/optimizer.py
+src/jinja2/parser.py
+src/jinja2/py.typed
+src/jinja2/runtime.py
+src/jinja2/sandbox.py
+src/jinja2/tests.py
+src/jinja2/utils.py
+src/jinja2/visitor.py
+tests/conftest.py
+tests/test_api.py
+tests/test_async.py
+tests/test_async_filters.py
+tests/test_bytecode_cache.py
+tests/test_compile.py
+tests/test_core_tags.py
+tests/test_debug.py
+tests/test_ext.py
+tests/test_filters.py
+tests/test_idtracking.py
+tests/test_imports.py
+tests/test_inheritance.py
+tests/test_lexnparse.py
+tests/test_loader.py
+tests/test_nativetypes.py
+tests/test_nodes.py
+tests/test_pickle.py
+tests/test_regression.py
+tests/test_runtime.py
+tests/test_security.py
+tests/test_tests.py
+tests/test_utils.py
+tests/res/__init__.py
+tests/res/package.zip
+tests/res/templates/broken.html
+tests/res/templates/mojibake.txt
+tests/res/templates/syntaxerror.html
+tests/res/templates/test.html
+tests/res/templates/foo/test.html
+tests/res/templates2/foo
\ No newline at end of file
diff --git a/src/Jinja2.egg-info/dependency_links.txt b/src/Jinja2.egg-info/dependency_links.txt
new file mode 100644
index 0000000..8b13789
--- /dev/null
+++ b/src/Jinja2.egg-info/dependency_links.txt
@@ -0,0 +1 @@
+
diff --git a/src/Jinja2.egg-info/entry_points.txt b/src/Jinja2.egg-info/entry_points.txt
new file mode 100644
index 0000000..7b9666c
--- /dev/null
+++ b/src/Jinja2.egg-info/entry_points.txt
@@ -0,0 +1,2 @@
+[babel.extractors]
+jinja2 = jinja2.ext:babel_extract[i18n]
diff --git a/src/Jinja2.egg-info/requires.txt b/src/Jinja2.egg-info/requires.txt
new file mode 100644
index 0000000..fbc43b7
--- /dev/null
+++ b/src/Jinja2.egg-info/requires.txt
@@ -0,0 +1,4 @@
+MarkupSafe>=2.0
+
+[i18n]
+Babel>=2.7
diff --git a/src/Jinja2.egg-info/top_level.txt b/src/Jinja2.egg-info/top_level.txt
new file mode 100644
index 0000000..7f7afbf
--- /dev/null
+++ b/src/Jinja2.egg-info/top_level.txt
@@ -0,0 +1 @@
+jinja2
diff --git a/src/jinja2/__init__.py b/src/jinja2/__init__.py
new file mode 100644
index 0000000..e323926
--- /dev/null
+++ b/src/jinja2/__init__.py
@@ -0,0 +1,37 @@
+"""Jinja is a template engine written in pure Python. It provides a
+non-XML syntax that supports inline expressions and an optional
+sandboxed environment.
+"""
+from .bccache import BytecodeCache as BytecodeCache
+from .bccache import FileSystemBytecodeCache as FileSystemBytecodeCache
+from .bccache import MemcachedBytecodeCache as MemcachedBytecodeCache
+from .environment import Environment as Environment
+from .environment import Template as Template
+from .exceptions import TemplateAssertionError as TemplateAssertionError
+from .exceptions import TemplateError as TemplateError
+from .exceptions import TemplateNotFound as TemplateNotFound
+from .exceptions import TemplateRuntimeError as TemplateRuntimeError
+from .exceptions import TemplatesNotFound as TemplatesNotFound
+from .exceptions import TemplateSyntaxError as TemplateSyntaxError
+from .exceptions import UndefinedError as UndefinedError
+from .loaders import BaseLoader as BaseLoader
+from .loaders import ChoiceLoader as ChoiceLoader
+from .loaders import DictLoader as DictLoader
+from .loaders import FileSystemLoader as FileSystemLoader
+from .loaders import FunctionLoader as FunctionLoader
+from .loaders import ModuleLoader as ModuleLoader
+from .loaders import PackageLoader as PackageLoader
+from .loaders import PrefixLoader as PrefixLoader
+from .runtime import ChainableUndefined as ChainableUndefined
+from .runtime import DebugUndefined as DebugUndefined
+from .runtime import make_logging_undefined as make_logging_undefined
+from .runtime import StrictUndefined as StrictUndefined
+from .runtime import Undefined as Undefined
+from .utils import clear_caches as clear_caches
+from .utils import is_undefined as is_undefined
+from .utils import pass_context as pass_context
+from .utils import pass_environment as pass_environment
+from .utils import pass_eval_context as pass_eval_context
+from .utils import select_autoescape as select_autoescape
+
+__version__ = "3.1.2"
diff --git a/src/jinja2/_identifier.py b/src/jinja2/_identifier.py
new file mode 100644
index 0000000..928c150
--- /dev/null
+++ b/src/jinja2/_identifier.py
@@ -0,0 +1,6 @@
+import re
+
+# generated by scripts/generate_identifier_pattern.py
+pattern = re.compile(
+    r"[\w·̀-ͯ·҃-֑҇-ׇֽֿׁׂׅׄؐ-ًؚ-ٰٟۖ-ۜ۟-۪ۤۧۨ-ܑۭܰ-݊ަ-ް߫-߽߳ࠖ-࠙ࠛ-ࠣࠥ-ࠧࠩ-࡙࠭-࡛࣓-ࣣ࣡-ःऺ-़ा-ॏ॑-ॗॢॣঁ-ঃ়া-ৄেৈো-্ৗৢৣ৾ਁ-ਃ਼ਾ-ੂੇੈੋ-੍ੑੰੱੵઁ-ઃ઼ા-ૅે-ૉો-્ૢૣૺ-૿ଁ-ଃ଼ା-ୄେୈୋ-୍ୖୗୢୣஂா-ூெ-ைொ-்ௗఀ-ఄా-ౄె-ైొ-్ౕౖౢౣಁ-ಃ಼ಾ-ೄೆ-ೈೊ-್ೕೖೢೣഀ-ഃ഻഼ാ-ൄെ-ൈൊ-്ൗൢൣංඃ්ා-ුූෘ-ෟෲෳัิ-ฺ็-๎ັິ-ູົຼ່-ໍ༹༘༙༵༷༾༿ཱ-྄྆྇ྍ-ྗྙ-ྼ࿆ါ-ှၖ-ၙၞ-ၠၢ-ၤၧ-ၭၱ-ၴႂ-ႍႏႚ-ႝ፝-፟ᜒ-᜔ᜲ-᜴ᝒᝓᝲᝳ឴-៓៝᠋-᠍ᢅᢆᢩᤠ-ᤫᤰ-᤻ᨗ-ᨛᩕ-ᩞ᩠-᩿᩼᪰-᪽ᬀ-ᬄ᬴-᭄᭫-᭳ᮀ-ᮂᮡ-ᮭ᯦-᯳ᰤ-᰷᳐-᳔᳒-᳨᳭ᳲ-᳴᳷-᳹᷀-᷹᷻-᷿‿⁀⁔⃐-⃥⃜⃡-⃰℘℮⳯-⵿⳱ⷠ-〪ⷿ-゙゚〯꙯ꙴ-꙽ꚞꚟ꛰꛱ꠂ꠆ꠋꠣ-ꠧꢀꢁꢴ-ꣅ꣠-꣱ꣿꤦ-꤭ꥇ-꥓ꦀ-ꦃ꦳-꧀ꧥꨩ-ꨶꩃꩌꩍꩻ-ꩽꪰꪲ-ꪴꪷꪸꪾ꪿꫁ꫫ-ꫯꫵ꫶ꯣ-ꯪ꯬꯭ﬞ︀-️︠-︯︳︴﹍-﹏＿𐇽𐋠𐍶-𐍺𐨁-𐨃𐨅𐨆𐨌-𐨏𐨸-𐨿𐨺𐫦𐫥𐴤-𐽆𐴧-𐽐𑀀-𑀂𑀸-𑁆𑁿-𑂂𑂰-𑂺𑄀-𑄂𑄧-𑄴𑅅𑅆𑅳𑆀-𑆂𑆳-𑇀𑇉-𑇌𑈬-𑈷𑈾𑋟-𑋪𑌀-𑌃𑌻𑌼𑌾-𑍄𑍇𑍈𑍋-𑍍𑍗𑍢𑍣𑍦-𑍬𑍰-𑍴𑐵-𑑆𑑞𑒰-𑓃𑖯-𑖵𑖸-𑗀𑗜𑗝𑘰-𑙀𑚫-𑚷𑜝-𑜫𑠬-𑠺𑨁-𑨊𑨳-𑨹𑨻-𑨾𑩇𑩑-𑩛𑪊-𑪙𑰯-𑰶𑰸-𑰿𑲒-𑲧𑲩-𑲶𑴱-𑴶𑴺𑴼𑴽𑴿-𑵅𑵇𑶊-𑶎𑶐𑶑𑶓-𑶗𑻳-𑻶𖫰-𖫴𖬰-𖬶𖽑-𖽾𖾏-𖾒𛲝𛲞𝅥-𝅩𝅭-𝅲𝅻-𝆂𝆅-𝆋𝆪-𝆭𝉂-𝉄𝨀-𝨶𝨻-𝩬𝩵𝪄𝪛-𝪟𝪡-𝪯𞀀-𞀆𞀈-𞀘𞀛-𞀡𞀣𞀤𞀦-𞣐𞀪-𞣖𞥄-𞥊󠄀-󠇯]+"  # noqa: B950
+)
diff --git a/src/jinja2/async_utils.py b/src/jinja2/async_utils.py
new file mode 100644
index 0000000..1a4f389
--- /dev/null
+++ b/src/jinja2/async_utils.py
@@ -0,0 +1,84 @@
+import inspect
+import typing as t
+from functools import WRAPPER_ASSIGNMENTS
+from functools import wraps
+
+from .utils import _PassArg
+from .utils import pass_eval_context
+
+V = t.TypeVar("V")
+
+
+def async_variant(normal_func):  # type: ignore
+    def decorator(async_func):  # type: ignore
+        pass_arg = _PassArg.from_obj(normal_func)
+        need_eval_context = pass_arg is None
+
+        if pass_arg is _PassArg.environment:
+
+            def is_async(args: t.Any) -> bool:
+                return t.cast(bool, args[0].is_async)
+
+        else:
+
+            def is_async(args: t.Any) -> bool:
+                return t.cast(bool, args[0].environment.is_async)
+
+        # Take the doc and annotations from the sync function, but the
+        # name from the async function. Pallets-Sphinx-Themes
+        # build_function_directive expects __wrapped__ to point to the
+        # sync function.
+        async_func_attrs = ("__module__", "__name__", "__qualname__")
+        normal_func_attrs = tuple(set(WRAPPER_ASSIGNMENTS).difference(async_func_attrs))
+
+        @wraps(normal_func, assigned=normal_func_attrs)
+        @wraps(async_func, assigned=async_func_attrs, updated=())
+        def wrapper(*args, **kwargs):  # type: ignore
+            b = is_async(args)
+
+            if need_eval_context:
+                args = args[1:]
+
+            if b:
+                return async_func(*args, **kwargs)
+
+            return normal_func(*args, **kwargs)
+
+        if need_eval_context:
+            wrapper = pass_eval_context(wrapper)
+
+        wrapper.jinja_async_variant = True
+        return wrapper
+
+    return decorator
+
+
+_common_primitives = {int, float, bool, str, list, dict, tuple, type(None)}
+
+
+async def auto_await(value: t.Union[t.Awaitable["V"], "V"]) -> "V":
+    # Avoid a costly call to isawaitable
+    if type(value) in _common_primitives:
+        return t.cast("V", value)
+
+    if inspect.isawaitable(value):
+        return await t.cast("t.Awaitable[V]", value)
+
+    return t.cast("V", value)
+
+
+async def auto_aiter(
+    iterable: "t.Union[t.AsyncIterable[V], t.Iterable[V]]",
+) -> "t.AsyncIterator[V]":
+    if hasattr(iterable, "__aiter__"):
+        async for item in t.cast("t.AsyncIterable[V]", iterable):
+            yield item
+    else:
+        for item in t.cast("t.Iterable[V]", iterable):
+            yield item
+
+
+async def auto_to_list(
+    value: "t.Union[t.AsyncIterable[V], t.Iterable[V]]",
+) -> t.List["V"]:
+    return [x async for x in auto_aiter(value)]
diff --git a/src/jinja2/bccache.py b/src/jinja2/bccache.py
new file mode 100644
index 0000000..d0ddf56
--- /dev/null
+++ b/src/jinja2/bccache.py
@@ -0,0 +1,406 @@
+"""The optional bytecode cache system. This is useful if you have very
+complex template situations and the compilation of all those templates
+slows down your application too much.
+
+Situations where this is useful are often forking web applications that
+are initialized on the first request.
+"""
+import errno
+import fnmatch
+import marshal
+import os
+import pickle
+import stat
+import sys
+import tempfile
+import typing as t
+from hashlib import sha1
+from io import BytesIO
+from types import CodeType
+
+if t.TYPE_CHECKING:
+    import typing_extensions as te
+    from .environment import Environment
+
+    class _MemcachedClient(te.Protocol):
+        def get(self, key: str) -> bytes:
+            ...
+
+        def set(self, key: str, value: bytes, timeout: t.Optional[int] = None) -> None:
+            ...
+
+
+bc_version = 5
+# Magic bytes to identify Jinja bytecode cache files. Contains the
+# Python major and minor version to avoid loading incompatible bytecode
+# if a project upgrades its Python version.
+bc_magic = (
+    b"j2"
+    + pickle.dumps(bc_version, 2)
+    + pickle.dumps((sys.version_info[0] << 24) | sys.version_info[1], 2)
+)
+
+
+class Bucket:
+    """Buckets are used to store the bytecode for one template.  It's created
+    and initialized by the bytecode cache and passed to the loading functions.
+
+    The buckets get an internal checksum from the cache assigned and use this
+    to automatically reject outdated cache material.  Individual bytecode
+    cache subclasses don't have to care about cache invalidation.
+    """
+
+    def __init__(self, environment: "Environment", key: str, checksum: str) -> None:
+        self.environment = environment
+        self.key = key
+        self.checksum = checksum
+        self.reset()
+
+    def reset(self) -> None:
+        """Resets the bucket (unloads the bytecode)."""
+        self.code: t.Optional[CodeType] = None
+
+    def load_bytecode(self, f: t.BinaryIO) -> None:
+        """Loads bytecode from a file or file like object."""
+        # make sure the magic header is correct
+        magic = f.read(len(bc_magic))
+        if magic != bc_magic:
+            self.reset()
+            return
+        # the source code of the file changed, we need to reload
+        checksum = pickle.load(f)
+        if self.checksum != checksum:
+            self.reset()
+            return
+        # if marshal_load fails then we need to reload
+        try:
+            self.code = marshal.load(f)
+        except (EOFError, ValueError, TypeError):
+            self.reset()
+            return
+
+    def write_bytecode(self, f: t.IO[bytes]) -> None:
+        """Dump the bytecode into the file or file like object passed."""
+        if self.code is None:
+            raise TypeError("can't write empty bucket")
+        f.write(bc_magic)
+        pickle.dump(self.checksum, f, 2)
+        marshal.dump(self.code, f)
+
+    def bytecode_from_string(self, string: bytes) -> None:
+        """Load bytecode from bytes."""
+        self.load_bytecode(BytesIO(string))
+
+    def bytecode_to_string(self) -> bytes:
+        """Return the bytecode as bytes."""
+        out = BytesIO()
+        self.write_bytecode(out)
+        return out.getvalue()
+
+
+class BytecodeCache:
+    """To implement your own bytecode cache you have to subclass this class
+    and override :meth:`load_bytecode` and :meth:`dump_bytecode`.  Both of
+    these methods are passed a :class:`~jinja2.bccache.Bucket`.
+
+    A very basic bytecode cache that saves the bytecode on the file system::
+
+        from os import path
+
+        class MyCache(BytecodeCache):
+
+            def __init__(self, directory):
+                self.directory = directory
+
+            def load_bytecode(self, bucket):
+                filename = path.join(self.directory, bucket.key)
+                if path.exists(filename):
+                    with open(filename, 'rb') as f:
+                        bucket.load_bytecode(f)
+
+            def dump_bytecode(self, bucket):
+                filename = path.join(self.directory, bucket.key)
+                with open(filename, 'wb') as f:
+                    bucket.write_bytecode(f)
+
+    A more advanced version of a filesystem based bytecode cache is part of
+    Jinja.
+    """
+
+    def load_bytecode(self, bucket: Bucket) -> None:
+        """Subclasses have to override this method to load bytecode into a
+        bucket.  If they are not able to find code in the cache for the
+        bucket, it must not do anything.
+        """
+        raise NotImplementedError()
+
+    def dump_bytecode(self, bucket: Bucket) -> None:
+        """Subclasses have to override this method to write the bytecode
+        from a bucket back to the cache.  If it unable to do so it must not
+        fail silently but raise an exception.
+        """
+        raise NotImplementedError()
+
+    def clear(self) -> None:
+        """Clears the cache.  This method is not used by Jinja but should be
+        implemented to allow applications to clear the bytecode cache used
+        by a particular environment.
+        """
+
+    def get_cache_key(
+        self, name: str, filename: t.Optional[t.Union[str]] = None
+    ) -> str:
+        """Returns the unique hash key for this template name."""
+        hash = sha1(name.encode("utf-8"))
+
+        if filename is not None:
+            hash.update(f"|{filename}".encode())
+
+        return hash.hexdigest()
+
+    def get_source_checksum(self, source: str) -> str:
+        """Returns a checksum for the source."""
+        return sha1(source.encode("utf-8")).hexdigest()
+
+    def get_bucket(
+        self,
+        environment: "Environment",
+        name: str,
+        filename: t.Optional[str],
+        source: str,
+    ) -> Bucket:
+        """Return a cache bucket for the given template.  All arguments are
+        mandatory but filename may be `None`.
+        """
+        key = self.get_cache_key(name, filename)
+        checksum = self.get_source_checksum(source)
+        bucket = Bucket(environment, key, checksum)
+        self.load_bytecode(bucket)
+        return bucket
+
+    def set_bucket(self, bucket: Bucket) -> None:
+        """Put the bucket into the cache."""
+        self.dump_bytecode(bucket)
+
+
+class FileSystemBytecodeCache(BytecodeCache):
+    """A bytecode cache that stores bytecode on the filesystem.  It accepts
+    two arguments: The directory where the cache items are stored and a
+    pattern string that is used to build the filename.
+
+    If no directory is specified a default cache directory is selected.  On
+    Windows the user's temp directory is used, on UNIX systems a directory
+    is created for the user in the system temp directory.
+
+    The pattern can be used to have multiple separate caches operate on the
+    same directory.  The default pattern is ``'__jinja2_%s.cache'``.  ``%s``
+    is replaced with the cache key.
+
+    >>> bcc = FileSystemBytecodeCache('/tmp/jinja_cache', '%s.cache')
+
+    This bytecode cache supports clearing of the cache using the clear method.
+    """
+
+    def __init__(
+        self, directory: t.Optional[str] = None, pattern: str = "__jinja2_%s.cache"
+    ) -> None:
+        if directory is None:
+            directory = self._get_default_cache_dir()
+        self.directory = directory
+        self.pattern = pattern
+
+    def _get_default_cache_dir(self) -> str:
+        def _unsafe_dir() -> "te.NoReturn":
+            raise RuntimeError(
+                "Cannot determine safe temp directory.  You "
+                "need to explicitly provide one."
+            )
+
+        tmpdir = tempfile.gettempdir()
+
+        # On windows the temporary directory is used specific unless
+        # explicitly forced otherwise.  We can just use that.
+        if os.name == "nt":
+            return tmpdir
+        if not hasattr(os, "getuid"):
+            _unsafe_dir()
+
+        dirname = f"_jinja2-cache-{os.getuid()}"
+        actual_dir = os.path.join(tmpdir, dirname)
+
+        try:
+            os.mkdir(actual_dir, stat.S_IRWXU)
+        except OSError as e:
+            if e.errno != errno.EEXIST:
+                raise
+        try:
+            os.chmod(actual_dir, stat.S_IRWXU)
+            actual_dir_stat = os.lstat(actual_dir)
+            if (
+                actual_dir_stat.st_uid != os.getuid()
+                or not stat.S_ISDIR(actual_dir_stat.st_mode)
+                or stat.S_IMODE(actual_dir_stat.st_mode) != stat.S_IRWXU
+            ):
+                _unsafe_dir()
+        except OSError as e:
+            if e.errno != errno.EEXIST:
+                raise
+
+        actual_dir_stat = os.lstat(actual_dir)
+        if (
+            actual_dir_stat.st_uid != os.getuid()
+            or not stat.S_ISDIR(actual_dir_stat.st_mode)
+            or stat.S_IMODE(actual_dir_stat.st_mode) != stat.S_IRWXU
+        ):
+            _unsafe_dir()
+
+        return actual_dir
+
+    def _get_cache_filename(self, bucket: Bucket) -> str:
+        return os.path.join(self.directory, self.pattern % (bucket.key,))
+
+    def load_bytecode(self, bucket: Bucket) -> None:
+        filename = self._get_cache_filename(bucket)
+
+        # Don't test for existence before opening the file, since the
+        # file could disappear after the test before the open.
+        try:
+            f = open(filename, "rb")
+        except (FileNotFoundError, IsADirectoryError, PermissionError):
+            # PermissionError can occur on Windows when an operation is
+            # in progress, such as calling clear().
+            return
+
+        with f:
+            bucket.load_bytecode(f)
+
+    def dump_bytecode(self, bucket: Bucket) -> None:
+        # Write to a temporary file, then rename to the real name after
+        # writing. This avoids another process reading the file before
+        # it is fully written.
+        name = self._get_cache_filename(bucket)
+        f = tempfile.NamedTemporaryFile(
+            mode="wb",
+            dir=os.path.dirname(name),
+            prefix=os.path.basename(name),
+            suffix=".tmp",
+            delete=False,
+        )
+
+        def remove_silent() -> None:
+            try:
+                os.remove(f.name)
+            except OSError:
+                # Another process may have called clear(). On Windows,
+                # another program may be holding the file open.
+                pass
+
+        try:
+            with f:
+                bucket.write_bytecode(f)
+        except BaseException:
+            remove_silent()
+            raise
+
+        try:
+            os.replace(f.name, name)
+        except OSError:
+            # Another process may have called clear(). On Windows,
+            # another program may be holding the file open.
+            remove_silent()
+        except BaseException:
+            remove_silent()
+            raise
+
+    def clear(self) -> None:
+        # imported lazily here because google app-engine doesn't support
+        # write access on the file system and the function does not exist
+        # normally.
+        from os import remove
+
+        files = fnmatch.filter(os.listdir(self.directory), self.pattern % ("*",))
+        for filename in files:
+            try:
+                remove(os.path.join(self.directory, filename))
+            except OSError:
+                pass
+
+
+class MemcachedBytecodeCache(BytecodeCache):
+    """This class implements a bytecode cache that uses a memcache cache for
+    storing the information.  It does not enforce a specific memcache library
+    (tummy's memcache or cmemcache) but will accept any class that provides
+    the minimal interface required.
+
+    Libraries compatible with this class:
+
+    -   `cachelib <https://github.com/pallets/cachelib>`_
+    -   `python-memcached <https://pypi.org/project/python-memcached/>`_
+
+    (Unfortunately the django cache interface is not compatible because it
+    does not support storing binary data, only text. You can however pass
+    the underlying cache client to the bytecode cache which is available
+    as `django.core.cache.cache._client`.)
+
+    The minimal interface for the client passed to the constructor is this:
+
+    .. class:: MinimalClientInterface
+
+        .. method:: set(key, value[, timeout])
+
+            Stores the bytecode in the cache.  `value` is a string and
+            `timeout` the timeout of the key.  If timeout is not provided
+            a default timeout or no timeout should be assumed, if it's
+            provided it's an integer with the number of seconds the cache
+            item should exist.
+
+        .. method:: get(key)
+
+            Returns the value for the cache key.  If the item does not
+            exist in the cache the return value must be `None`.
+
+    The other arguments to the constructor are the prefix for all keys that
+    is added before the actual cache key and the timeout for the bytecode in
+    the cache system.  We recommend a high (or no) timeout.
+
+    This bytecode cache does not support clearing of used items in the cache.
+    The clear method is a no-operation function.
+
+    .. versionadded:: 2.7
+       Added support for ignoring memcache errors through the
+       `ignore_memcache_errors` parameter.
+    """
+
+    def __init__(
+        self,
+        client: "_MemcachedClient",
+        prefix: str = "jinja2/bytecode/",
+        timeout: t.Optional[int] = None,
+        ignore_memcache_errors: bool = True,
+    ):
+        self.client = client
+        self.prefix = prefix
+        self.timeout = timeout
+        self.ignore_memcache_errors = ignore_memcache_errors
+
+    def load_bytecode(self, bucket: Bucket) -> None:
+        try:
+            code = self.client.get(self.prefix + bucket.key)
+        except Exception:
+            if not self.ignore_memcache_errors:
+                raise
+        else:
+            bucket.bytecode_from_string(code)
+
+    def dump_bytecode(self, bucket: Bucket) -> None:
+        key = self.prefix + bucket.key
+        value = bucket.bytecode_to_string()
+
+        try:
+            if self.timeout is not None:
+                self.client.set(key, value, self.timeout)
+            else:
+                self.client.set(key, value)
+        except Exception:
+            if not self.ignore_memcache_errors:
+                raise
diff --git a/src/jinja2/compiler.py b/src/jinja2/compiler.py
new file mode 100644
index 0000000..3458095
--- /dev/null
+++ b/src/jinja2/compiler.py
@@ -0,0 +1,1957 @@
+"""Compiles nodes from the parser into Python code."""
+import typing as t
+from contextlib import contextmanager
+from functools import update_wrapper
+from io import StringIO
+from itertools import chain
+from keyword import iskeyword as is_python_keyword
+
+from markupsafe import escape
+from markupsafe import Markup
+
+from . import nodes
+from .exceptions import TemplateAssertionError
+from .idtracking import Symbols
+from .idtracking import VAR_LOAD_ALIAS
+from .idtracking import VAR_LOAD_PARAMETER
+from .idtracking import VAR_LOAD_RESOLVE
+from .idtracking import VAR_LOAD_UNDEFINED
+from .nodes import EvalContext
+from .optimizer import Optimizer
+from .utils import _PassArg
+from .utils import concat
+from .visitor import NodeVisitor
+
+if t.TYPE_CHECKING:
+    import typing_extensions as te
+    from .environment import Environment
+
+F = t.TypeVar("F", bound=t.Callable[..., t.Any])
+
+operators = {
+    "eq": "==",
+    "ne": "!=",
+    "gt": ">",
+    "gteq": ">=",
+    "lt": "<",
+    "lteq": "<=",
+    "in": "in",
+    "notin": "not in",
+}
+
+
+def optimizeconst(f: F) -> F:
+    def new_func(
+        self: "CodeGenerator", node: nodes.Expr, frame: "Frame", **kwargs: t.Any
+    ) -> t.Any:
+        # Only optimize if the frame is not volatile
+        if self.optimizer is not None and not frame.eval_ctx.volatile:
+            new_node = self.optimizer.visit(node, frame.eval_ctx)
+
+            if new_node != node:
+                return self.visit(new_node, frame)
+
+        return f(self, node, frame, **kwargs)
+
+    return update_wrapper(t.cast(F, new_func), f)
+
+
+def _make_binop(op: str) -> t.Callable[["CodeGenerator", nodes.BinExpr, "Frame"], None]:
+    @optimizeconst
+    def visitor(self: "CodeGenerator", node: nodes.BinExpr, frame: Frame) -> None:
+        if (
+            self.environment.sandboxed
+            and op in self.environment.intercepted_binops  # type: ignore
+        ):
+            self.write(f"environment.call_binop(context, {op!r}, ")
+            self.visit(node.left, frame)
+            self.write(", ")
+            self.visit(node.right, frame)
+        else:
+            self.write("(")
+            self.visit(node.left, frame)
+            self.write(f" {op} ")
+            self.visit(node.right, frame)
+
+        self.write(")")
+
+    return visitor
+
+
+def _make_unop(
+    op: str,
+) -> t.Callable[["CodeGenerator", nodes.UnaryExpr, "Frame"], None]:
+    @optimizeconst
+    def visitor(self: "CodeGenerator", node: nodes.UnaryExpr, frame: Frame) -> None:
+        if (
+            self.environment.sandboxed
+            and op in self.environment.intercepted_unops  # type: ignore
+        ):
+            self.write(f"environment.call_unop(context, {op!r}, ")
+            self.visit(node.node, frame)
+        else:
+            self.write("(" + op)
+            self.visit(node.node, frame)
+
+        self.write(")")
+
+    return visitor
+
+
+def generate(
+    node: nodes.Template,
+    environment: "Environment",
+    name: t.Optional[str],
+    filename: t.Optional[str],
+    stream: t.Optional[t.TextIO] = None,
+    defer_init: bool = False,
+    optimized: bool = True,
+) -> t.Optional[str]:
+    """Generate the python source for a node tree."""
+    if not isinstance(node, nodes.Template):
+        raise TypeError("Can't compile non template nodes")
+
+    generator = environment.code_generator_class(
+        environment, name, filename, stream, defer_init, optimized
+    )
+    generator.visit(node)
+
+    if stream is None:
+        return generator.stream.getvalue()  # type: ignore
+
+    return None
+
+
+def has_safe_repr(value: t.Any) -> bool:
+    """Does the node have a safe representation?"""
+    if value is None or value is NotImplemented or value is Ellipsis:
+        return True
+
+    if type(value) in {bool, int, float, complex, range, str, Markup}:
+        return True
+
+    if type(value) in {tuple, list, set, frozenset}:
+        return all(has_safe_repr(v) for v in value)
+
+    if type(value) is dict:
+        return all(has_safe_repr(k) and has_safe_repr(v) for k, v in value.items())
+
+    return False
+
+
+def find_undeclared(
+    nodes: t.Iterable[nodes.Node], names: t.Iterable[str]
+) -> t.Set[str]:
+    """Check if the names passed are accessed undeclared.  The return value
+    is a set of all the undeclared names from the sequence of names found.
+    """
+    visitor = UndeclaredNameVisitor(names)
+    try:
+        for node in nodes:
+            visitor.visit(node)
+    except VisitorExit:
+        pass
+    return visitor.undeclared
+
+
+class MacroRef:
+    def __init__(self, node: t.Union[nodes.Macro, nodes.CallBlock]) -> None:
+        self.node = node
+        self.accesses_caller = False
+        self.accesses_kwargs = False
+        self.accesses_varargs = False
+
+
+class Frame:
+    """Holds compile time information for us."""
+
+    def __init__(
+        self,
+        eval_ctx: EvalContext,
+        parent: t.Optional["Frame"] = None,
+        level: t.Optional[int] = None,
+    ) -> None:
+        self.eval_ctx = eval_ctx
+
+        # the parent of this frame
+        self.parent = parent
+
+        if parent is None:
+            self.symbols = Symbols(level=level)
+
+            # in some dynamic inheritance situations the compiler needs to add
+            # write tests around output statements.
+            self.require_output_check = False
+
+            # inside some tags we are using a buffer rather than yield statements.
+            # this for example affects {% filter %} or {% macro %}.  If a frame
+            # is buffered this variable points to the name of the list used as
+            # buffer.
+            self.buffer: t.Optional[str] = None
+
+            # the name of the block we're in, otherwise None.
+            self.block: t.Optional[str] = None
+
+        else:
+            self.symbols = Symbols(parent.symbols, level=level)
+            self.require_output_check = parent.require_output_check
+            self.buffer = parent.buffer
+            self.block = parent.block
+
+        # a toplevel frame is the root + soft frames such as if conditions.
+        self.toplevel = False
+
+        # the root frame is basically just the outermost frame, so no if
+        # conditions.  This information is used to optimize inheritance
+        # situations.
+        self.rootlevel = False
+
+        # variables set inside of loops and blocks should not affect outer frames,
+        # but they still needs to be kept track of as part of the active context.
+        self.loop_frame = False
+        self.block_frame = False
+
+        # track whether the frame is being used in an if-statement or conditional
+        # expression as it determines which errors should be raised during runtime
+        # or compile time.
+        self.soft_frame = False
+
+    def copy(self) -> "Frame":
+        """Create a copy of the current one."""
+        rv = object.__new__(self.__class__)
+        rv.__dict__.update(self.__dict__)
+        rv.symbols = self.symbols.copy()
+        return rv
+
+    def inner(self, isolated: bool = False) -> "Frame":
+        """Return an inner frame."""
+        if isolated:
+            return Frame(self.eval_ctx, level=self.symbols.level + 1)
+        return Frame(self.eval_ctx, self)
+
+    def soft(self) -> "Frame":
+        """Return a soft frame.  A soft frame may not be modified as
+        standalone thing as it shares the resources with the frame it
+        was created of, but it's not a rootlevel frame any longer.
+
+        This is only used to implement if-statements and conditional
+        expressions.
+        """
+        rv = self.copy()
+        rv.rootlevel = False
+        rv.soft_frame = True
+        return rv
+
+    __copy__ = copy
+
+
+class VisitorExit(RuntimeError):
+    """Exception used by the `UndeclaredNameVisitor` to signal a stop."""
+
+
+class DependencyFinderVisitor(NodeVisitor):
+    """A visitor that collects filter and test calls."""
+
+    def __init__(self) -> None:
+        self.filters: t.Set[str] = set()
+        self.tests: t.Set[str] = set()
+
+    def visit_Filter(self, node: nodes.Filter) -> None:
+        self.generic_visit(node)
+        self.filters.add(node.name)
+
+    def visit_Test(self, node: nodes.Test) -> None:
+        self.generic_visit(node)
+        self.tests.add(node.name)
+
+    def visit_Block(self, node: nodes.Block) -> None:
+        """Stop visiting at blocks."""
+
+
+class UndeclaredNameVisitor(NodeVisitor):
+    """A visitor that checks if a name is accessed without being
+    declared.  This is different from the frame visitor as it will
+    not stop at closure frames.
+    """
+
+    def __init__(self, names: t.Iterable[str]) -> None:
+        self.names = set(names)
+        self.undeclared: t.Set[str] = set()
+
+    def visit_Name(self, node: nodes.Name) -> None:
+        if node.ctx == "load" and node.name in self.names:
+            self.undeclared.add(node.name)
+            if self.undeclared == self.names:
+                raise VisitorExit()
+        else:
+            self.names.discard(node.name)
+
+    def visit_Block(self, node: nodes.Block) -> None:
+        """Stop visiting a blocks."""
+
+
+class CompilerExit(Exception):
+    """Raised if the compiler encountered a situation where it just
+    doesn't make sense to further process the code.  Any block that
+    raises such an exception is not further processed.
+    """
+
+
+class CodeGenerator(NodeVisitor):
+    def __init__(
+        self,
+        environment: "Environment",
+        name: t.Optional[str],
+        filename: t.Optional[str],
+        stream: t.Optional[t.TextIO] = None,
+        defer_init: bool = False,
+        optimized: bool = True,
+    ) -> None:
+        if stream is None:
+            stream = StringIO()
+        self.environment = environment
+        self.name = name
+        self.filename = filename
+        self.stream = stream
+        self.created_block_context = False
+        self.defer_init = defer_init
+        self.optimizer: t.Optional[Optimizer] = None
+
+        if optimized:
+            self.optimizer = Optimizer(environment)
+
+        # aliases for imports
+        self.import_aliases: t.Dict[str, str] = {}
+
+        # a registry for all blocks.  Because blocks are moved out
+        # into the global python scope they are registered here
+        self.blocks: t.Dict[str, nodes.Block] = {}
+
+        # the number of extends statements so far
+        self.extends_so_far = 0
+
+        # some templates have a rootlevel extends.  In this case we
+        # can safely assume that we're a child template and do some
+        # more optimizations.
+        self.has_known_extends = False
+
+        # the current line number
+        self.code_lineno = 1
+
+        # registry of all filters and tests (global, not block local)
+        self.tests: t.Dict[str, str] = {}
+        self.filters: t.Dict[str, str] = {}
+
+        # the debug information
+        self.debug_info: t.List[t.Tuple[int, int]] = []
+        self._write_debug_info: t.Optional[int] = None
+
+        # the number of new lines before the next write()
+        self._new_lines = 0
+
+        # the line number of the last written statement
+        self._last_line = 0
+
+        # true if nothing was written so far.
+        self._first_write = True
+
+        # used by the `temporary_identifier` method to get new
+        # unique, temporary identifier
+        self._last_identifier = 0
+
+        # the current indentation
+        self._indentation = 0
+
+        # Tracks toplevel assignments
+        self._assign_stack: t.List[t.Set[str]] = []
+
+        # Tracks parameter definition blocks
+        self._param_def_block: t.List[t.Set[str]] = []
+
+        # Tracks the current context.
+        self._context_reference_stack = ["context"]
+
+    @property
+    def optimized(self) -> bool:
+        return self.optimizer is not None
+
+    # -- Various compilation helpers
+
+    def fail(self, msg: str, lineno: int) -> "te.NoReturn":
+        """Fail with a :exc:`TemplateAssertionError`."""
+        raise TemplateAssertionError(msg, lineno, self.name, self.filename)
+
+    def temporary_identifier(self) -> str:
+        """Get a new unique identifier."""
+        self._last_identifier += 1
+        return f"t_{self._last_identifier}"
+
+    def buffer(self, frame: Frame) -> None:
+        """Enable buffering for the frame from that point onwards."""
+        frame.buffer = self.temporary_identifier()
+        self.writeline(f"{frame.buffer} = []")
+
+    def return_buffer_contents(
+        self, frame: Frame, force_unescaped: bool = False
+    ) -> None:
+        """Return the buffer contents of the frame."""
+        if not force_unescaped:
+            if frame.eval_ctx.volatile:
+                self.writeline("if context.eval_ctx.autoescape:")
+                self.indent()
+                self.writeline(f"return Markup(concat({frame.buffer}))")
+                self.outdent()
+                self.writeline("else:")
+                self.indent()
+                self.writeline(f"return concat({frame.buffer})")
+                self.outdent()
+                return
+            elif frame.eval_ctx.autoescape:
+                self.writeline(f"return Markup(concat({frame.buffer}))")
+                return
+        self.writeline(f"return concat({frame.buffer})")
+
+    def indent(self) -> None:
+        """Indent by one."""
+        self._indentation += 1
+
+    def outdent(self, step: int = 1) -> None:
+        """Outdent by step."""
+        self._indentation -= step
+
+    def start_write(self, frame: Frame, node: t.Optional[nodes.Node] = None) -> None:
+        """Yield or write into the frame buffer."""
+        if frame.buffer is None:
+            self.writeline("yield ", node)
+        else:
+            self.writeline(f"{frame.buffer}.append(", node)
+
+    def end_write(self, frame: Frame) -> None:
+        """End the writing process started by `start_write`."""
+        if frame.buffer is not None:
+            self.write(")")
+
+    def simple_write(
+        self, s: str, frame: Frame, node: t.Optional[nodes.Node] = None
+    ) -> None:
+        """Simple shortcut for start_write + write + end_write."""
+        self.start_write(frame, node)
+        self.write(s)
+        self.end_write(frame)
+
+    def blockvisit(self, nodes: t.Iterable[nodes.Node], frame: Frame) -> None:
+        """Visit a list of nodes as block in a frame.  If the current frame
+        is no buffer a dummy ``if 0: yield None`` is written automatically.
+        """
+        try:
+            self.writeline("pass")
+            for node in nodes:
+                self.visit(node, frame)
+        except CompilerExit:
+            pass
+
+    def write(self, x: str) -> None:
+        """Write a string into the output stream."""
+        if self._new_lines:
+            if not self._first_write:
+                self.stream.write("\n" * self._new_lines)
+                self.code_lineno += self._new_lines
+                if self._write_debug_info is not None:
+                    self.debug_info.append((self._write_debug_info, self.code_lineno))
+                    self._write_debug_info = None
+            self._first_write = False
+            self.stream.write("    " * self._indentation)
+            self._new_lines = 0
+        self.stream.write(x)
+
+    def writeline(
+        self, x: str, node: t.Optional[nodes.Node] = None, extra: int = 0
+    ) -> None:
+        """Combination of newline and write."""
+        self.newline(node, extra)
+        self.write(x)
+
+    def newline(self, node: t.Optional[nodes.Node] = None, extra: int = 0) -> None:
+        """Add one or more newlines before the next write."""
+        self._new_lines = max(self._new_lines, 1 + extra)
+        if node is not None and node.lineno != self._last_line:
+            self._write_debug_info = node.lineno
+            self._last_line = node.lineno
+
+    def signature(
+        self,
+        node: t.Union[nodes.Call, nodes.Filter, nodes.Test],
+        frame: Frame,
+        extra_kwargs: t.Optional[t.Mapping[str, t.Any]] = None,
+    ) -> None:
+        """Writes a function call to the stream for the current node.
+        A leading comma is added automatically.  The extra keyword
+        arguments may not include python keywords otherwise a syntax
+        error could occur.  The extra keyword arguments should be given
+        as python dict.
+        """
+        # if any of the given keyword arguments is a python keyword
+        # we have to make sure that no invalid call is created.
+        kwarg_workaround = any(
+            is_python_keyword(t.cast(str, k))
+            for k in chain((x.key for x in node.kwargs), extra_kwargs or ())
+        )
+
+        for arg in node.args:
+            self.write(", ")
+            self.visit(arg, frame)
+
+        if not kwarg_workaround:
+            for kwarg in node.kwargs:
+                self.write(", ")
+                self.visit(kwarg, frame)
+            if extra_kwargs is not None:
+                for key, value in extra_kwargs.items():
+                    self.write(f", {key}={value}")
+        if node.dyn_args:
+            self.write(", *")
+            self.visit(node.dyn_args, frame)
+
+        if kwarg_workaround:
+            if node.dyn_kwargs is not None:
+                self.write(", **dict({")
+            else:
+                self.write(", **{")
+            for kwarg in node.kwargs:
+                self.write(f"{kwarg.key!r}: ")
+                self.visit(kwarg.value, frame)
+                self.write(", ")
+            if extra_kwargs is not None:
+                for key, value in extra_kwargs.items():
+                    self.write(f"{key!r}: {value}, ")
+            if node.dyn_kwargs is not None:
+                self.write("}, **")
+                self.visit(node.dyn_kwargs, frame)
+                self.write(")")
+            else:
+                self.write("}")
+
+        elif node.dyn_kwargs is not None:
+            self.write(", **")
+            self.visit(node.dyn_kwargs, frame)
+
+    def pull_dependencies(self, nodes: t.Iterable[nodes.Node]) -> None:
+        """Find all filter and test names used in the template and
+        assign them to variables in the compiled namespace. Checking
+        that the names are registered with the environment is done when
+        compiling the Filter and Test nodes. If the node is in an If or
+        CondExpr node, the check is done at runtime instead.
+
+        .. versionchanged:: 3.0
+            Filters and tests in If and CondExpr nodes are checked at
+            runtime instead of compile time.
+        """
+        visitor = DependencyFinderVisitor()
+
+        for node in nodes:
+            visitor.visit(node)
+
+        for id_map, names, dependency in (self.filters, visitor.filters, "filters"), (
+            self.tests,
+            visitor.tests,
+            "tests",
+        ):
+            for name in sorted(names):
+                if name not in id_map:
+                    id_map[name] = self.temporary_identifier()
+
+                # add check during runtime that dependencies used inside of executed
+                # blocks are defined, as this step may be skipped during compile time
+                self.writeline("try:")
+                self.indent()
+                self.writeline(f"{id_map[name]} = environment.{dependency}[{name!r}]")
+                self.outdent()
+                self.writeline("except KeyError:")
+                self.indent()
+                self.writeline("@internalcode")
+                self.writeline(f"def {id_map[name]}(*unused):")
+                self.indent()
+                self.writeline(
+                    f'raise TemplateRuntimeError("No {dependency[:-1]}'
+                    f' named {name!r} found.")'
+                )
+                self.outdent()
+                self.outdent()
+
+    def enter_frame(self, frame: Frame) -> None:
+        undefs = []
+        for target, (action, param) in frame.symbols.loads.items():
+            if action == VAR_LOAD_PARAMETER:
+                pass
+            elif action == VAR_LOAD_RESOLVE:
+                self.writeline(f"{target} = {self.get_resolve_func()}({param!r})")
+            elif action == VAR_LOAD_ALIAS:
+                self.writeline(f"{target} = {param}")
+            elif action == VAR_LOAD_UNDEFINED:
+                undefs.append(target)
+            else:
+                raise NotImplementedError("unknown load instruction")
+        if undefs:
+            self.writeline(f"{' = '.join(undefs)} = missing")
+
+    def leave_frame(self, frame: Frame, with_python_scope: bool = False) -> None:
+        if not with_python_scope:
+            undefs = []
+            for target in frame.symbols.loads:
+                undefs.append(target)
+            if undefs:
+                self.writeline(f"{' = '.join(undefs)} = missing")
+
+    def choose_async(self, async_value: str = "async ", sync_value: str = "") -> str:
+        return async_value if self.environment.is_async else sync_value
+
+    def func(self, name: str) -> str:
+        return f"{self.choose_async()}def {name}"
+
+    def macro_body(
+        self, node: t.Union[nodes.Macro, nodes.CallBlock], frame: Frame
+    ) -> t.Tuple[Frame, MacroRef]:
+        """Dump the function def of a macro or call block."""
+        frame = frame.inner()
+        frame.symbols.analyze_node(node)
+        macro_ref = MacroRef(node)
+
+        explicit_caller = None
+        skip_special_params = set()
+        args = []
+
+        for idx, arg in enumerate(node.args):
+            if arg.name == "caller":
+                explicit_caller = idx
+            if arg.name in ("kwargs", "varargs"):
+                skip_special_params.add(arg.name)
+            args.append(frame.symbols.ref(arg.name))
+
+        undeclared = find_undeclared(node.body, ("caller", "kwargs", "varargs"))
+
+        if "caller" in undeclared:
+            # In older Jinja versions there was a bug that allowed caller
+            # to retain the special behavior even if it was mentioned in
+            # the argument list.  However thankfully this was only really
+            # working if it was the last argument.  So we are explicitly
+            # checking this now and error out if it is anywhere else in
+            # the argument list.
+            if explicit_caller is not None:
+                try:
+                    node.defaults[explicit_caller - len(node.args)]
+                except IndexError:
+                    self.fail(
+                        "When defining macros or call blocks the "
+                        'special "caller" argument must be omitted '
+                        "or be given a default.",
+                        node.lineno,
+                    )
+            else:
+                args.append(frame.symbols.declare_parameter("caller"))
+            macro_ref.accesses_caller = True
+        if "kwargs" in undeclared and "kwargs" not in skip_special_params:
+            args.append(frame.symbols.declare_parameter("kwargs"))
+            macro_ref.accesses_kwargs = True
+        if "varargs" in undeclared and "varargs" not in skip_special_params:
+            args.append(frame.symbols.declare_parameter("varargs"))
+            macro_ref.accesses_varargs = True
+
+        # macros are delayed, they never require output checks
+        frame.require_output_check = False
+        frame.symbols.analyze_node(node)
+        self.writeline(f"{self.func('macro')}({', '.join(args)}):", node)
+        self.indent()
+
+        self.buffer(frame)
+        self.enter_frame(frame)
+
+        self.push_parameter_definitions(frame)
+        for idx, arg in enumerate(node.args):
+            ref = frame.symbols.ref(arg.name)
+            self.writeline(f"if {ref} is missing:")
+            self.indent()
+            try:
+                default = node.defaults[idx - len(node.args)]
+            except IndexError:
+                self.writeline(
+                    f'{ref} = undefined("parameter {arg.name!r} was not provided",'
+                    f" name={arg.name!r})"
+                )
+            else:
+                self.writeline(f"{ref} = ")
+                self.visit(default, frame)
+            self.mark_parameter_stored(ref)
+            self.outdent()
+        self.pop_parameter_definitions()
+
+        self.blockvisit(node.body, frame)
+        self.return_buffer_contents(frame, force_unescaped=True)
+        self.leave_frame(frame, with_python_scope=True)
+        self.outdent()
+
+        return frame, macro_ref
+
+    def macro_def(self, macro_ref: MacroRef, frame: Frame) -> None:
+        """Dump the macro definition for the def created by macro_body."""
+        arg_tuple = ", ".join(repr(x.name) for x in macro_ref.node.args)
+        name = getattr(macro_ref.node, "name", None)
+        if len(macro_ref.node.args) == 1:
+            arg_tuple += ","
+        self.write(
+            f"Macro(environment, macro, {name!r}, ({arg_tuple}),"
+            f" {macro_ref.accesses_kwargs!r}, {macro_ref.accesses_varargs!r},"
+            f" {macro_ref.accesses_caller!r}, context.eval_ctx.autoescape)"
+        )
+
+    def position(self, node: nodes.Node) -> str:
+        """Return a human readable position for the node."""
+        rv = f"line {node.lineno}"
+        if self.name is not None:
+            rv = f"{rv} in {self.name!r}"
+        return rv
+
+    def dump_local_context(self, frame: Frame) -> str:
+        items_kv = ", ".join(
+            f"{name!r}: {target}"
+            for name, target in frame.symbols.dump_stores().items()
+        )
+        return f"{{{items_kv}}}"
+
+    def write_commons(self) -> None:
+        """Writes a common preamble that is used by root and block functions.
+        Primarily this sets up common local helpers and enforces a generator
+        through a dead branch.
+        """
+        self.writeline("resolve = context.resolve_or_missing")
+        self.writeline("undefined = environment.undefined")
+        self.writeline("concat = environment.concat")
+        # always use the standard Undefined class for the implicit else of
+        # conditional expressions
+        self.writeline("cond_expr_undefined = Undefined")
+        self.writeline("if 0: yield None")
+
+    def push_parameter_definitions(self, frame: Frame) -> None:
+        """Pushes all parameter targets from the given frame into a local
+        stack that permits tracking of yet to be assigned parameters.  In
+        particular this enables the optimization from `visit_Name` to skip
+        undefined expressions for parameters in macros as macros can reference
+        otherwise unbound parameters.
+        """
+        self._param_def_block.append(frame.symbols.dump_param_targets())
+
+    def pop_parameter_definitions(self) -> None:
+        """Pops the current parameter definitions set."""
+        self._param_def_block.pop()
+
+    def mark_parameter_stored(self, target: str) -> None:
+        """Marks a parameter in the current parameter definitions as stored.
+        This will skip the enforced undefined checks.
+        """
+        if self._param_def_block:
+            self._param_def_block[-1].discard(target)
+
+    def push_context_reference(self, target: str) -> None:
+        self._context_reference_stack.append(target)
+
+    def pop_context_reference(self) -> None:
+        self._context_reference_stack.pop()
+
+    def get_context_ref(self) -> str:
+        return self._context_reference_stack[-1]
+
+    def get_resolve_func(self) -> str:
+        target = self._context_reference_stack[-1]
+        if target == "context":
+            return "resolve"
+        return f"{target}.resolve"
+
+    def derive_context(self, frame: Frame) -> str:
+        return f"{self.get_context_ref()}.derived({self.dump_local_context(frame)})"
+
+    def parameter_is_undeclared(self, target: str) -> bool:
+        """Checks if a given target is an undeclared parameter."""
+        if not self._param_def_block:
+            return False
+        return target in self._param_def_block[-1]
+
+    def push_assign_tracking(self) -> None:
+        """Pushes a new layer for assignment tracking."""
+        self._assign_stack.append(set())
+
+    def pop_assign_tracking(self, frame: Frame) -> None:
+        """Pops the topmost level for assignment tracking and updates the
+        context variables if necessary.
+        """
+        vars = self._assign_stack.pop()
+        if (
+            not frame.block_frame
+            and not frame.loop_frame
+            and not frame.toplevel
+            or not vars
+        ):
+            return
+        public_names = [x for x in vars if x[:1] != "_"]
+        if len(vars) == 1:
+            name = next(iter(vars))
+            ref = frame.symbols.ref(name)
+            if frame.loop_frame:
+                self.writeline(f"_loop_vars[{name!r}] = {ref}")
+                return
+            if frame.block_frame:
+                self.writeline(f"_block_vars[{name!r}] = {ref}")
+                return
+            self.writeline(f"context.vars[{name!r}] = {ref}")
+        else:
+            if frame.loop_frame:
+                self.writeline("_loop_vars.update({")
+            elif frame.block_frame:
+                self.writeline("_block_vars.update({")
+            else:
+                self.writeline("context.vars.update({")
+            for idx, name in enumerate(vars):
+                if idx:
+                    self.write(", ")
+                ref = frame.symbols.ref(name)
+                self.write(f"{name!r}: {ref}")
+            self.write("})")
+        if not frame.block_frame and not frame.loop_frame and public_names:
+            if len(public_names) == 1:
+                self.writeline(f"context.exported_vars.add({public_names[0]!r})")
+            else:
+                names_str = ", ".join(map(repr, public_names))
+                self.writeline(f"context.exported_vars.update(({names_str}))")
+
+    # -- Statement Visitors
+
+    def visit_Template(
+        self, node: nodes.Template, frame: t.Optional[Frame] = None
+    ) -> None:
+        assert frame is None, "no root frame allowed"
+        eval_ctx = EvalContext(self.environment, self.name)
+
+        from .runtime import exported, async_exported
+
+        if self.environment.is_async:
+            exported_names = sorted(exported + async_exported)
+        else:
+            exported_names = sorted(exported)
+
+        self.writeline("from jinja2.runtime import " + ", ".join(exported_names))
+
+        # if we want a deferred initialization we cannot move the
+        # environment into a local name
+        envenv = "" if self.defer_init else ", environment=environment"
+
+        # do we have an extends tag at all?  If not, we can save some
+        # overhead by just not processing any inheritance code.
+        have_extends = node.find(nodes.Extends) is not None
+
+        # find all blocks
+        for block in node.find_all(nodes.Block):
+            if block.name in self.blocks:
+                self.fail(f"block {block.name!r} defined twice", block.lineno)
+            self.blocks[block.name] = block
+
+        # find all imports and import them
+        for import_ in node.find_all(nodes.ImportedName):
+            if import_.importname not in self.import_aliases:
+                imp = import_.importname
+                self.import_aliases[imp] = alias = self.temporary_identifier()
+                if "." in imp:
+                    module, obj = imp.rsplit(".", 1)
+                    self.writeline(f"from {module} import {obj} as {alias}")
+                else:
+                    self.writeline(f"import {imp} as {alias}")
+
+        # add the load name
+        self.writeline(f"name = {self.name!r}")
+
+        # generate the root render function.
+        self.writeline(
+            f"{self.func('root')}(context, missing=missing{envenv}):", extra=1
+        )
+        self.indent()
+        self.write_commons()
+
+        # process the root
+        frame = Frame(eval_ctx)
+        if "self" in find_undeclared(node.body, ("self",)):
+            ref = frame.symbols.declare_parameter("self")
+            self.writeline(f"{ref} = TemplateReference(context)")
+        frame.symbols.analyze_node(node)
+        frame.toplevel = frame.rootlevel = True
+        frame.require_output_check = have_extends and not self.has_known_extends
+        if have_extends:
+            self.writeline("parent_template = None")
+        self.enter_frame(frame)
+        self.pull_dependencies(node.body)
+        self.blockvisit(node.body, frame)
+        self.leave_frame(frame, with_python_scope=True)
+        self.outdent()
+
+        # make sure that the parent root is called.
+        if have_extends:
+            if not self.has_known_extends:
+                self.indent()
+                self.writeline("if parent_template is not None:")
+            self.indent()
+            if not self.environment.is_async:
+                self.writeline("yield from parent_template.root_render_func(context)")
+            else:
+                self.writeline(
+                    "async for event in parent_template.root_render_func(context):"
+                )
+                self.indent()
+                self.writeline("yield event")
+                self.outdent()
+            self.outdent(1 + (not self.has_known_extends))
+
+        # at this point we now have the blocks collected and can visit them too.
+        for name, block in self.blocks.items():
+            self.writeline(
+                f"{self.func('block_' + name)}(context, missing=missing{envenv}):",
+                block,
+                1,
+            )
+            self.indent()
+            self.write_commons()
+            # It's important that we do not make this frame a child of the
+            # toplevel template.  This would cause a variety of
+            # interesting issues with identifier tracking.
+            block_frame = Frame(eval_ctx)
+            block_frame.block_frame = True
+            undeclared = find_undeclared(block.body, ("self", "super"))
+            if "self" in undeclared:
+                ref = block_frame.symbols.declare_parameter("self")
+                self.writeline(f"{ref} = TemplateReference(context)")
+            if "super" in undeclared:
+                ref = block_frame.symbols.declare_parameter("super")
+                self.writeline(f"{ref} = context.super({name!r}, block_{name})")
+            block_frame.symbols.analyze_node(block)
+            block_frame.block = name
+            self.writeline("_block_vars = {}")
+            self.enter_frame(block_frame)
+            self.pull_dependencies(block.body)
+            self.blockvisit(block.body, block_frame)
+            self.leave_frame(block_frame, with_python_scope=True)
+            self.outdent()
+
+        blocks_kv_str = ", ".join(f"{x!r}: block_{x}" for x in self.blocks)
+        self.writeline(f"blocks = {{{blocks_kv_str}}}", extra=1)
+        debug_kv_str = "&".join(f"{k}={v}" for k, v in self.debug_info)
+        self.writeline(f"debug_info = {debug_kv_str!r}")
+
+    def visit_Block(self, node: nodes.Block, frame: Frame) -> None:
+        """Call a block and register it for the template."""
+        level = 0
+        if frame.toplevel:
+            # if we know that we are a child template, there is no need to
+            # check if we are one
+            if self.has_known_extends:
+                return
+            if self.extends_so_far > 0:
+                self.writeline("if parent_template is None:")
+                self.indent()
+                level += 1
+
+        if node.scoped:
+            context = self.derive_context(frame)
+        else:
+            context = self.get_context_ref()
+
+        if node.required:
+            self.writeline(f"if len(context.blocks[{node.name!r}]) <= 1:", node)
+            self.indent()
+            self.writeline(
+                f'raise TemplateRuntimeError("Required block {node.name!r} not found")',
+                node,
+            )
+            self.outdent()
+
+        if not self.environment.is_async and frame.buffer is None:
+            self.writeline(
+                f"yield from context.blocks[{node.name!r}][0]({context})", node
+            )
+        else:
+            self.writeline(
+                f"{self.choose_async()}for event in"
+                f" context.blocks[{node.name!r}][0]({context}):",
+                node,
+            )
+            self.indent()
+            self.simple_write("event", frame)
+            self.outdent()
+
+        self.outdent(level)
+
+    def visit_Extends(self, node: nodes.Extends, frame: Frame) -> None:
+        """Calls the extender."""
+        if not frame.toplevel:
+            self.fail("cannot use extend from a non top-level scope", node.lineno)
+
+        # if the number of extends statements in general is zero so
+        # far, we don't have to add a check if something extended
+        # the template before this one.
+        if self.extends_so_far > 0:
+
+            # if we have a known extends we just add a template runtime
+            # error into the generated code.  We could catch that at compile
+            # time too, but i welcome it not to confuse users by throwing the
+            # same error at different times just "because we can".
+            if not self.has_known_extends:
+                self.writeline("if parent_template is not None:")
+                self.indent()
+            self.writeline('raise TemplateRuntimeError("extended multiple times")')
+
+            # if we have a known extends already we don't need that code here
+            # as we know that the template execution will end here.
+            if self.has_known_extends:
+                raise CompilerExit()
+            else:
+                self.outdent()
+
+        self.writeline("parent_template = environment.get_template(", node)
+        self.visit(node.template, frame)
+        self.write(f", {self.name!r})")
+        self.writeline("for name, parent_block in parent_template.blocks.items():")
+        self.indent()
+        self.writeline("context.blocks.setdefault(name, []).append(parent_block)")
+        self.outdent()
+
+        # if this extends statement was in the root level we can take
+        # advantage of that information and simplify the generated code
+        # in the top level from this point onwards
+        if frame.rootlevel:
+            self.has_known_extends = True
+
+        # and now we have one more
+        self.extends_so_far += 1
+
+    def visit_Include(self, node: nodes.Include, frame: Frame) -> None:
+        """Handles includes."""
+        if node.ignore_missing:
+            self.writeline("try:")
+            self.indent()
+
+        func_name = "get_or_select_template"
+        if isinstance(node.template, nodes.Const):
+            if isinstance(node.template.value, str):
+                func_name = "get_template"
+            elif isinstance(node.template.value, (tuple, list)):
+                func_name = "select_template"
+        elif isinstance(node.template, (nodes.Tuple, nodes.List)):
+            func_name = "select_template"
+
+        self.writeline(f"template = environment.{func_name}(", node)
+        self.visit(node.template, frame)
+        self.write(f", {self.name!r})")
+        if node.ignore_missing:
+            self.outdent()
+            self.writeline("except TemplateNotFound:")
+            self.indent()
+            self.writeline("pass")
+            self.outdent()
+            self.writeline("else:")
+            self.indent()
+
+        skip_event_yield = False
+        if node.with_context:
+            self.writeline(
+                f"{self.choose_async()}for event in template.root_render_func("
+                "template.new_context(context.get_all(), True,"
+                f" {self.dump_local_context(frame)})):"
+            )
+        elif self.environment.is_async:
+            self.writeline(
+                "for event in (await template._get_default_module_async())"
+                "._body_stream:"
+            )
+        else:
+            self.writeline("yield from template._get_default_module()._body_stream")
+            skip_event_yield = True
+
+        if not skip_event_yield:
+            self.indent()
+            self.simple_write("event", frame)
+            self.outdent()
+
+        if node.ignore_missing:
+            self.outdent()
+
+    def _import_common(
+        self, node: t.Union[nodes.Import, nodes.FromImport], frame: Frame
+    ) -> None:
+        self.write(f"{self.choose_async('await ')}environment.get_template(")
+        self.visit(node.template, frame)
+        self.write(f", {self.name!r}).")
+
+        if node.with_context:
+            f_name = f"make_module{self.choose_async('_async')}"
+            self.write(
+                f"{f_name}(context.get_all(), True, {self.dump_local_context(frame)})"
+            )
+        else:
+            self.write(f"_get_default_module{self.choose_async('_async')}(context)")
+
+    def visit_Import(self, node: nodes.Import, frame: Frame) -> None:
+        """Visit regular imports."""
+        self.writeline(f"{frame.symbols.ref(node.target)} = ", node)
+        if frame.toplevel:
+            self.write(f"context.vars[{node.target!r}] = ")
+
+        self._import_common(node, frame)
+
+        if frame.toplevel and not node.target.startswith("_"):
+            self.writeline(f"context.exported_vars.discard({node.target!r})")
+
+    def visit_FromImport(self, node: nodes.FromImport, frame: Frame) -> None:
+        """Visit named imports."""
+        self.newline(node)
+        self.write("included_template = ")
+        self._import_common(node, frame)
+        var_names = []
+        discarded_names = []
+        for name in node.names:
+            if isinstance(name, tuple):
+                name, alias = name
+            else:
+                alias = name
+            self.writeline(
+                f"{frame.symbols.ref(alias)} ="
+                f" getattr(included_template, {name!r}, missing)"
+            )
+            self.writeline(f"if {frame.symbols.ref(alias)} is missing:")
+            self.indent()
+            message = (
+                "the template {included_template.__name__!r}"
+                f" (imported on {self.position(node)})"
+                f" does not export the requested name {name!r}"
+            )
+            self.writeline(
+                f"{frame.symbols.ref(alias)} = undefined(f{message!r}, name={name!r})"
+            )
+            self.outdent()
+            if frame.toplevel:
+                var_names.append(alias)
+                if not alias.startswith("_"):
+                    discarded_names.append(alias)
+
+        if var_names:
+            if len(var_names) == 1:
+                name = var_names[0]
+                self.writeline(f"context.vars[{name!r}] = {frame.symbols.ref(name)}")
+            else:
+                names_kv = ", ".join(
+                    f"{name!r}: {frame.symbols.ref(name)}" for name in var_names
+                )
+                self.writeline(f"context.vars.update({{{names_kv}}})")
+        if discarded_names:
+            if len(discarded_names) == 1:
+                self.writeline(f"context.exported_vars.discard({discarded_names[0]!r})")
+            else:
+                names_str = ", ".join(map(repr, discarded_names))
+                self.writeline(
+                    f"context.exported_vars.difference_update(({names_str}))"
+                )
+
+    def visit_For(self, node: nodes.For, frame: Frame) -> None:
+        loop_frame = frame.inner()
+        loop_frame.loop_frame = True
+        test_frame = frame.inner()
+        else_frame = frame.inner()
+
+        # try to figure out if we have an extended loop.  An extended loop
+        # is necessary if the loop is in recursive mode if the special loop
+        # variable is accessed in the body if the body is a scoped block.
+        extended_loop = (
+            node.recursive
+            or "loop"
+            in find_undeclared(node.iter_child_nodes(only=("body",)), ("loop",))
+            or any(block.scoped for block in node.find_all(nodes.Block))
+        )
+
+        loop_ref = None
+        if extended_loop:
+            loop_ref = loop_frame.symbols.declare_parameter("loop")
+
+        loop_frame.symbols.analyze_node(node, for_branch="body")
+        if node.else_:
+            else_frame.symbols.analyze_node(node, for_branch="else")
+
+        if node.test:
+            loop_filter_func = self.temporary_identifier()
+            test_frame.symbols.analyze_node(node, for_branch="test")
+            self.writeline(f"{self.func(loop_filter_func)}(fiter):", node.test)
+            self.indent()
+            self.enter_frame(test_frame)
+            self.writeline(self.choose_async("async for ", "for "))
+            self.visit(node.target, loop_frame)
+            self.write(" in ")
+            self.write(self.choose_async("auto_aiter(fiter)", "fiter"))
+            self.write(":")
+            self.indent()
+            self.writeline("if ", node.test)
+            self.visit(node.test, test_frame)
+            self.write(":")
+            self.indent()
+            self.writeline("yield ")
+            self.visit(node.target, loop_frame)
+            self.outdent(3)
+            self.leave_frame(test_frame, with_python_scope=True)
+
+        # if we don't have an recursive loop we have to find the shadowed
+        # variables at that point.  Because loops can be nested but the loop
+        # variable is a special one we have to enforce aliasing for it.
+        if node.recursive:
+            self.writeline(
+                f"{self.func('loop')}(reciter, loop_render_func, depth=0):", node
+            )
+            self.indent()
+            self.buffer(loop_frame)
+
+            # Use the same buffer for the else frame
+            else_frame.buffer = loop_frame.buffer
+
+        # make sure the loop variable is a special one and raise a template
+        # assertion error if a loop tries to write to loop
+        if extended_loop:
+            self.writeline(f"{loop_ref} = missing")
+
+        for name in node.find_all(nodes.Name):
+            if name.ctx == "store" and name.name == "loop":
+                self.fail(
+                    "Can't assign to special loop variable in for-loop target",
+                    name.lineno,
+                )
+
+        if node.else_:
+            iteration_indicator = self.temporary_identifier()
+            self.writeline(f"{iteration_indicator} = 1")
+
+        self.writeline(self.choose_async("async for ", "for "), node)
+        self.visit(node.target, loop_frame)
+        if extended_loop:
+            self.write(f", {loop_ref} in {self.choose_async('Async')}LoopContext(")
+        else:
+            self.write(" in ")
+
+        if node.test:
+            self.write(f"{loop_filter_func}(")
+        if node.recursive:
+            self.write("reciter")
+        else:
+            if self.environment.is_async and not extended_loop:
+                self.write("auto_aiter(")
+            self.visit(node.iter, frame)
+            if self.environment.is_async and not extended_loop:
+                self.write(")")
+        if node.test:
+            self.write(")")
+
+        if node.recursive:
+            self.write(", undefined, loop_render_func, depth):")
+        else:
+            self.write(", undefined):" if extended_loop else ":")
+
+        self.indent()
+        self.enter_frame(loop_frame)
+
+        self.writeline("_loop_vars = {}")
+        self.blockvisit(node.body, loop_frame)
+        if node.else_:
+            self.writeline(f"{iteration_indicator} = 0")
+        self.outdent()
+        self.leave_frame(
+            loop_frame, with_python_scope=node.recursive and not node.else_
+        )
+
+        if node.else_:
+            self.writeline(f"if {iteration_indicator}:")
+            self.indent()
+            self.enter_frame(else_frame)
+            self.blockvisit(node.else_, else_frame)
+            self.leave_frame(else_frame)
+            self.outdent()
+
+        # if the node was recursive we have to return the buffer contents
+        # and start the iteration code
+        if node.recursive:
+            self.return_buffer_contents(loop_frame)
+            self.outdent()
+            self.start_write(frame, node)
+            self.write(f"{self.choose_async('await ')}loop(")
+            if self.environment.is_async:
+                self.write("auto_aiter(")
+            self.visit(node.iter, frame)
+            if self.environment.is_async:
+                self.write(")")
+            self.write(", loop)")
+            self.end_write(frame)
+
+        # at the end of the iteration, clear any assignments made in the
+        # loop from the top level
+        if self._assign_stack:
+            self._assign_stack[-1].difference_update(loop_frame.symbols.stores)
+
+    def visit_If(self, node: nodes.If, frame: Frame) -> None:
+        if_frame = frame.soft()
+        self.writeline("if ", node)
+        self.visit(node.test, if_frame)
+        self.write(":")
+        self.indent()
+        self.blockvisit(node.body, if_frame)
+        self.outdent()
+        for elif_ in node.elif_:
+            self.writeline("elif ", elif_)
+            self.visit(elif_.test, if_frame)
+            self.write(":")
+            self.indent()
+            self.blockvisit(elif_.body, if_frame)
+            self.outdent()
+        if node.else_:
+            self.writeline("else:")
+            self.indent()
+            self.blockvisit(node.else_, if_frame)
+            self.outdent()
+
+    def visit_Macro(self, node: nodes.Macro, frame: Frame) -> None:
+        macro_frame, macro_ref = self.macro_body(node, frame)
+        self.newline()
+        if frame.toplevel:
+            if not node.name.startswith("_"):
+                self.write(f"context.exported_vars.add({node.name!r})")
+            self.writeline(f"context.vars[{node.name!r}] = ")
+        self.write(f"{frame.symbols.ref(node.name)} = ")
+        self.macro_def(macro_ref, macro_frame)
+
+    def visit_CallBlock(self, node: nodes.CallBlock, frame: Frame) -> None:
+        call_frame, macro_ref = self.macro_body(node, frame)
+        self.writeline("caller = ")
+        self.macro_def(macro_ref, call_frame)
+        self.start_write(frame, node)
+        self.visit_Call(node.call, frame, forward_caller=True)
+        self.end_write(frame)
+
+    def visit_FilterBlock(self, node: nodes.FilterBlock, frame: Frame) -> None:
+        filter_frame = frame.inner()
+        filter_frame.symbols.analyze_node(node)
+        self.enter_frame(filter_frame)
+        self.buffer(filter_frame)
+        self.blockvisit(node.body, filter_frame)
+        self.start_write(frame, node)
+        self.visit_Filter(node.filter, filter_frame)
+        self.end_write(frame)
+        self.leave_frame(filter_frame)
+
+    def visit_With(self, node: nodes.With, frame: Frame) -> None:
+        with_frame = frame.inner()
+        with_frame.symbols.analyze_node(node)
+        self.enter_frame(with_frame)
+        for target, expr in zip(node.targets, node.values):
+            self.newline()
+            self.visit(target, with_frame)
+            self.write(" = ")
+            self.visit(expr, frame)
+        self.blockvisit(node.body, with_frame)
+        self.leave_frame(with_frame)
+
+    def visit_ExprStmt(self, node: nodes.ExprStmt, frame: Frame) -> None:
+        self.newline(node)
+        self.visit(node.node, frame)
+
+    class _FinalizeInfo(t.NamedTuple):
+        const: t.Optional[t.Callable[..., str]]
+        src: t.Optional[str]
+
+    @staticmethod
+    def _default_finalize(value: t.Any) -> t.Any:
+        """The default finalize function if the environment isn't
+        configured with one. Or, if the environment has one, this is
+        called on that function's output for constants.
+        """
+        return str(value)
+
+    _finalize: t.Optional[_FinalizeInfo] = None
+
+    def _make_finalize(self) -> _FinalizeInfo:
+        """Build the finalize function to be used on constants and at
+        runtime. Cached so it's only created once for all output nodes.
+
+        Returns a ``namedtuple`` with the following attributes:
+
+        ``const``
+            A function to finalize constant data at compile time.
+
+        ``src``
+            Source code to output around nodes to be evaluated at
+            runtime.
+        """
+        if self._finalize is not None:
+            return self._finalize
+
+        finalize: t.Optional[t.Callable[..., t.Any]]
+        finalize = default = self._default_finalize
+        src = None
+
+        if self.environment.finalize:
+            src = "environment.finalize("
+            env_finalize = self.environment.finalize
+            pass_arg = {
+                _PassArg.context: "context",
+                _PassArg.eval_context: "context.eval_ctx",
+                _PassArg.environment: "environment",
+            }.get(
+                _PassArg.from_obj(env_finalize)  # type: ignore
+            )
+            finalize = None
+
+            if pass_arg is None:
+
+                def finalize(value: t.Any) -> t.Any:
+                    return default(env_finalize(value))
+
+            else:
+                src = f"{src}{pass_arg}, "
+
+                if pass_arg == "environment":
+
+                    def finalize(value: t.Any) -> t.Any:
+                        return default(env_finalize(self.environment, value))
+
+        self._finalize = self._FinalizeInfo(finalize, src)
+        return self._finalize
+
+    def _output_const_repr(self, group: t.Iterable[t.Any]) -> str:
+        """Given a group of constant values converted from ``Output``
+        child nodes, produce a string to write to the template module
+        source.
+        """
+        return repr(concat(group))
+
+    def _output_child_to_const(
+        self, node: nodes.Expr, frame: Frame, finalize: _FinalizeInfo
+    ) -> str:
+        """Try to optimize a child of an ``Output`` node by trying to
+        convert it to constant, finalized data at compile time.
+
+        If :exc:`Impossible` is raised, the node is not constant and
+        will be evaluated at runtime. Any other exception will also be
+        evaluated at runtime for easier debugging.
+        """
+        const = node.as_const(frame.eval_ctx)
+
+        if frame.eval_ctx.autoescape:
+            const = escape(const)
+
+        # Template data doesn't go through finalize.
+        if isinstance(node, nodes.TemplateData):
+            return str(const)
+
+        return finalize.const(const)  # type: ignore
+
+    def _output_child_pre(
+        self, node: nodes.Expr, frame: Frame, finalize: _FinalizeInfo
+    ) -> None:
+        """Output extra source code before visiting a child of an
+        ``Output`` node.
+        """
+        if frame.eval_ctx.volatile:
+            self.write("(escape if context.eval_ctx.autoescape else str)(")
+        elif frame.eval_ctx.autoescape:
+            self.write("escape(")
+        else:
+            self.write("str(")
+
+        if finalize.src is not None:
+            self.write(finalize.src)
+
+    def _output_child_post(
+        self, node: nodes.Expr, frame: Frame, finalize: _FinalizeInfo
+    ) -> None:
+        """Output extra source code after visiting a child of an
+        ``Output`` node.
+        """
+        self.write(")")
+
+        if finalize.src is not None:
+            self.write(")")
+
+    def visit_Output(self, node: nodes.Output, frame: Frame) -> None:
+        # If an extends is active, don't render outside a block.
+        if frame.require_output_check:
+            # A top-level extends is known to exist at compile time.
+            if self.has_known_extends:
+                return
+
+            self.writeline("if parent_template is None:")
+            self.indent()
+
+        finalize = self._make_finalize()
+        body: t.List[t.Union[t.List[t.Any], nodes.Expr]] = []
+
+        # Evaluate constants at compile time if possible. Each item in
+        # body will be either a list of static data or a node to be
+        # evaluated at runtime.
+        for child in node.nodes:
+            try:
+                if not (
+                    # If the finalize function requires runtime context,
+                    # constants can't be evaluated at compile time.
+                    finalize.const
+                    # Unless it's basic template data that won't be
+                    # finalized anyway.
+                    or isinstance(child, nodes.TemplateData)
+                ):
+                    raise nodes.Impossible()
+
+                const = self._output_child_to_const(child, frame, finalize)
+            except (nodes.Impossible, Exception):
+                # The node was not constant and needs to be evaluated at
+                # runtime. Or another error was raised, which is easier
+                # to debug at runtime.
+                body.append(child)
+                continue
+
+            if body and isinstance(body[-1], list):
+                body[-1].append(const)
+            else:
+                body.append([const])
+
+        if frame.buffer is not None:
+            if len(body) == 1:
+                self.writeline(f"{frame.buffer}.append(")
+            else:
+                self.writeline(f"{frame.buffer}.extend((")
+
+            self.indent()
+
+        for item in body:
+            if isinstance(item, list):
+                # A group of constant data to join and output.
+                val = self._output_const_repr(item)
+
+                if frame.buffer is None:
+                    self.writeline("yield " + val)
+                else:
+                    self.writeline(val + ",")
+            else:
+                if frame.buffer is None:
+                    self.writeline("yield ", item)
+                else:
+                    self.newline(item)
+
+                # A node to be evaluated at runtime.
+                self._output_child_pre(item, frame, finalize)
+                self.visit(item, frame)
+                self._output_child_post(item, frame, finalize)
+
+                if frame.buffer is not None:
+                    self.write(",")
+
+        if frame.buffer is not None:
+            self.outdent()
+            self.writeline(")" if len(body) == 1 else "))")
+
+        if frame.require_output_check:
+            self.outdent()
+
+    def visit_Assign(self, node: nodes.Assign, frame: Frame) -> None:
+        self.push_assign_tracking()
+        self.newline(node)
+        self.visit(node.target, frame)
+        self.write(" = ")
+        self.visit(node.node, frame)
+        self.pop_assign_tracking(frame)
+
+    def visit_AssignBlock(self, node: nodes.AssignBlock, frame: Frame) -> None:
+        self.push_assign_tracking()
+        block_frame = frame.inner()
+        # This is a special case.  Since a set block always captures we
+        # will disable output checks.  This way one can use set blocks
+        # toplevel even in extended templates.
+        block_frame.require_output_check = False
+        block_frame.symbols.analyze_node(node)
+        self.enter_frame(block_frame)
+        self.buffer(block_frame)
+        self.blockvisit(node.body, block_frame)
+        self.newline(node)
+        self.visit(node.target, frame)
+        self.write(" = (Markup if context.eval_ctx.autoescape else identity)(")
+        if node.filter is not None:
+            self.visit_Filter(node.filter, block_frame)
+        else:
+            self.write(f"concat({block_frame.buffer})")
+        self.write(")")
+        self.pop_assign_tracking(frame)
+        self.leave_frame(block_frame)
+
+    # -- Expression Visitors
+
+    def visit_Name(self, node: nodes.Name, frame: Frame) -> None:
+        if node.ctx == "store" and (
+            frame.toplevel or frame.loop_frame or frame.block_frame
+        ):
+            if self._assign_stack:
+                self._assign_stack[-1].add(node.name)
+        ref = frame.symbols.ref(node.name)
+
+        # If we are looking up a variable we might have to deal with the
+        # case where it's undefined.  We can skip that case if the load
+        # instruction indicates a parameter which are always defined.
+        if node.ctx == "load":
+            load = frame.symbols.find_load(ref)
+            if not (
+                load is not None
+                and load[0] == VAR_LOAD_PARAMETER
+                and not self.parameter_is_undeclared(ref)
+            ):
+                self.write(
+                    f"(undefined(name={node.name!r}) if {ref} is missing else {ref})"
+                )
+                return
+
+        self.write(ref)
+
+    def visit_NSRef(self, node: nodes.NSRef, frame: Frame) -> None:
+        # NSRefs can only be used to store values; since they use the normal
+        # `foo.bar` notation they will be parsed as a normal attribute access
+        # when used anywhere but in a `set` context
+        ref = frame.symbols.ref(node.name)
+        self.writeline(f"if not isinstance({ref}, Namespace):")
+        self.indent()
+        self.writeline(
+            "raise TemplateRuntimeError"
+            '("cannot assign attribute on non-namespace object")'
+        )
+        self.outdent()
+        self.writeline(f"{ref}[{node.attr!r}]")
+
+    def visit_Const(self, node: nodes.Const, frame: Frame) -> None:
+        val = node.as_const(frame.eval_ctx)
+        if isinstance(val, float):
+            self.write(str(val))
+        else:
+            self.write(repr(val))
+
+    def visit_TemplateData(self, node: nodes.TemplateData, frame: Frame) -> None:
+        try:
+            self.write(repr(node.as_const(frame.eval_ctx)))
+        except nodes.Impossible:
+            self.write(
+                f"(Markup if context.eval_ctx.autoescape else identity)({node.data!r})"
+            )
+
+    def visit_Tuple(self, node: nodes.Tuple, frame: Frame) -> None:
+        self.write("(")
+        idx = -1
+        for idx, item in enumerate(node.items):
+            if idx:
+                self.write(", ")
+            self.visit(item, frame)
+        self.write(",)" if idx == 0 else ")")
+
+    def visit_List(self, node: nodes.List, frame: Frame) -> None:
+        self.write("[")
+        for idx, item in enumerate(node.items):
+            if idx:
+                self.write(", ")
+            self.visit(item, frame)
+        self.write("]")
+
+    def visit_Dict(self, node: nodes.Dict, frame: Frame) -> None:
+        self.write("{")
+        for idx, item in enumerate(node.items):
+            if idx:
+                self.write(", ")
+            self.visit(item.key, frame)
+            self.write(": ")
+            self.visit(item.value, frame)
+        self.write("}")
+
+    visit_Add = _make_binop("+")
+    visit_Sub = _make_binop("-")
+    visit_Mul = _make_binop("*")
+    visit_Div = _make_binop("/")
+    visit_FloorDiv = _make_binop("//")
+    visit_Pow = _make_binop("**")
+    visit_Mod = _make_binop("%")
+    visit_And = _make_binop("and")
+    visit_Or = _make_binop("or")
+    visit_Pos = _make_unop("+")
+    visit_Neg = _make_unop("-")
+    visit_Not = _make_unop("not ")
+
+    @optimizeconst
+    def visit_Concat(self, node: nodes.Concat, frame: Frame) -> None:
+        if frame.eval_ctx.volatile:
+            func_name = "(markup_join if context.eval_ctx.volatile else str_join)"
+        elif frame.eval_ctx.autoescape:
+            func_name = "markup_join"
+        else:
+            func_name = "str_join"
+        self.write(f"{func_name}((")
+        for arg in node.nodes:
+            self.visit(arg, frame)
+            self.write(", ")
+        self.write("))")
+
+    @optimizeconst
+    def visit_Compare(self, node: nodes.Compare, frame: Frame) -> None:
+        self.write("(")
+        self.visit(node.expr, frame)
+        for op in node.ops:
+            self.visit(op, frame)
+        self.write(")")
+
+    def visit_Operand(self, node: nodes.Operand, frame: Frame) -> None:
+        self.write(f" {operators[node.op]} ")
+        self.visit(node.expr, frame)
+
+    @optimizeconst
+    def visit_Getattr(self, node: nodes.Getattr, frame: Frame) -> None:
+        if self.environment.is_async:
+            self.write("(await auto_await(")
+
+        self.write("environment.getattr(")
+        self.visit(node.node, frame)
+        self.write(f", {node.attr!r})")
+
+        if self.environment.is_async:
+            self.write("))")
+
+    @optimizeconst
+    def visit_Getitem(self, node: nodes.Getitem, frame: Frame) -> None:
+        # slices bypass the environment getitem method.
+        if isinstance(node.arg, nodes.Slice):
+            self.visit(node.node, frame)
+            self.write("[")
+            self.visit(node.arg, frame)
+            self.write("]")
+        else:
+            if self.environment.is_async:
+                self.write("(await auto_await(")
+
+            self.write("environment.getitem(")
+            self.visit(node.node, frame)
+            self.write(", ")
+            self.visit(node.arg, frame)
+            self.write(")")
+
+            if self.environment.is_async:
+                self.write("))")
+
+    def visit_Slice(self, node: nodes.Slice, frame: Frame) -> None:
+        if node.start is not None:
+            self.visit(node.start, frame)
+        self.write(":")
+        if node.stop is not None:
+            self.visit(node.stop, frame)
+        if node.step is not None:
+            self.write(":")
+            self.visit(node.step, frame)
+
+    @contextmanager
+    def _filter_test_common(
+        self, node: t.Union[nodes.Filter, nodes.Test], frame: Frame, is_filter: bool
+    ) -> t.Iterator[None]:
+        if self.environment.is_async:
+            self.write("(await auto_await(")
+
+        if is_filter:
+            self.write(f"{self.filters[node.name]}(")
+            func = self.environment.filters.get(node.name)
+        else:
+            self.write(f"{self.tests[node.name]}(")
+            func = self.environment.tests.get(node.name)
+
+        # When inside an If or CondExpr frame, allow the filter to be
+        # undefined at compile time and only raise an error if it's
+        # actually called at runtime. See pull_dependencies.
+        if func is None and not frame.soft_frame:
+            type_name = "filter" if is_filter else "test"
+            self.fail(f"No {type_name} named {node.name!r}.", node.lineno)
+
+        pass_arg = {
+            _PassArg.context: "context",
+            _PassArg.eval_context: "context.eval_ctx",
+            _PassArg.environment: "environment",
+        }.get(
+            _PassArg.from_obj(func)  # type: ignore
+        )
+
+        if pass_arg is not None:
+            self.write(f"{pass_arg}, ")
+
+        # Back to the visitor function to handle visiting the target of
+        # the filter or test.
+        yield
+
+        self.signature(node, frame)
+        self.write(")")
+
+        if self.environment.is_async:
+            self.write("))")
+
+    @optimizeconst
+    def visit_Filter(self, node: nodes.Filter, frame: Frame) -> None:
+        with self._filter_test_common(node, frame, True):
+            # if the filter node is None we are inside a filter block
+            # and want to write to the current buffer
+            if node.node is not None:
+                self.visit(node.node, frame)
+            elif frame.eval_ctx.volatile:
+                self.write(
+                    f"(Markup(concat({frame.buffer}))"
+                    f" if context.eval_ctx.autoescape else concat({frame.buffer}))"
+                )
+            elif frame.eval_ctx.autoescape:
+                self.write(f"Markup(concat({frame.buffer}))")
+            else:
+                self.write(f"concat({frame.buffer})")
+
+    @optimizeconst
+    def visit_Test(self, node: nodes.Test, frame: Frame) -> None:
+        with self._filter_test_common(node, frame, False):
+            self.visit(node.node, frame)
+
+    @optimizeconst
+    def visit_CondExpr(self, node: nodes.CondExpr, frame: Frame) -> None:
+        frame = frame.soft()
+
+        def write_expr2() -> None:
+            if node.expr2 is not None:
+                self.visit(node.expr2, frame)
+                return
+
+            self.write(
+                f'cond_expr_undefined("the inline if-expression on'
+                f" {self.position(node)} evaluated to false and no else"
+                f' section was defined.")'
+            )
+
+        self.write("(")
+        self.visit(node.expr1, frame)
+        self.write(" if ")
+        self.visit(node.test, frame)
+        self.write(" else ")
+        write_expr2()
+        self.write(")")
+
+    @optimizeconst
+    def visit_Call(
+        self, node: nodes.Call, frame: Frame, forward_caller: bool = False
+    ) -> None:
+        if self.environment.is_async:
+            self.write("(await auto_await(")
+        if self.environment.sandboxed:
+            self.write("environment.call(context, ")
+        else:
+            self.write("context.call(")
+        self.visit(node.node, frame)
+        extra_kwargs = {"caller": "caller"} if forward_caller else None
+        loop_kwargs = {"_loop_vars": "_loop_vars"} if frame.loop_frame else {}
+        block_kwargs = {"_block_vars": "_block_vars"} if frame.block_frame else {}
+        if extra_kwargs:
+            extra_kwargs.update(loop_kwargs, **block_kwargs)
+        elif loop_kwargs or block_kwargs:
+            extra_kwargs = dict(loop_kwargs, **block_kwargs)
+        self.signature(node, frame, extra_kwargs)
+        self.write(")")
+        if self.environment.is_async:
+            self.write("))")
+
+    def visit_Keyword(self, node: nodes.Keyword, frame: Frame) -> None:
+        self.write(node.key + "=")
+        self.visit(node.value, frame)
+
+    # -- Unused nodes for extensions
+
+    def visit_MarkSafe(self, node: nodes.MarkSafe, frame: Frame) -> None:
+        self.write("Markup(")
+        self.visit(node.expr, frame)
+        self.write(")")
+
+    def visit_MarkSafeIfAutoescape(
+        self, node: nodes.MarkSafeIfAutoescape, frame: Frame
+    ) -> None:
+        self.write("(Markup if context.eval_ctx.autoescape else identity)(")
+        self.visit(node.expr, frame)
+        self.write(")")
+
+    def visit_EnvironmentAttribute(
+        self, node: nodes.EnvironmentAttribute, frame: Frame
+    ) -> None:
+        self.write("environment." + node.name)
+
+    def visit_ExtensionAttribute(
+        self, node: nodes.ExtensionAttribute, frame: Frame
+    ) -> None:
+        self.write(f"environment.extensions[{node.identifier!r}].{node.name}")
+
+    def visit_ImportedName(self, node: nodes.ImportedName, frame: Frame) -> None:
+        self.write(self.import_aliases[node.importname])
+
+    def visit_InternalName(self, node: nodes.InternalName, frame: Frame) -> None:
+        self.write(node.name)
+
+    def visit_ContextReference(
+        self, node: nodes.ContextReference, frame: Frame
+    ) -> None:
+        self.write("context")
+
+    def visit_DerivedContextReference(
+        self, node: nodes.DerivedContextReference, frame: Frame
+    ) -> None:
+        self.write(self.derive_context(frame))
+
+    def visit_Continue(self, node: nodes.Continue, frame: Frame) -> None:
+        self.writeline("continue", node)
+
+    def visit_Break(self, node: nodes.Break, frame: Frame) -> None:
+        self.writeline("break", node)
+
+    def visit_Scope(self, node: nodes.Scope, frame: Frame) -> None:
+        scope_frame = frame.inner()
+        scope_frame.symbols.analyze_node(node)
+        self.enter_frame(scope_frame)
+        self.blockvisit(node.body, scope_frame)
+        self.leave_frame(scope_frame)
+
+    def visit_OverlayScope(self, node: nodes.OverlayScope, frame: Frame) -> None:
+        ctx = self.temporary_identifier()
+        self.writeline(f"{ctx} = {self.derive_context(frame)}")
+        self.writeline(f"{ctx}.vars = ")
+        self.visit(node.context, frame)
+        self.push_context_reference(ctx)
+
+        scope_frame = frame.inner(isolated=True)
+        scope_frame.symbols.analyze_node(node)
+        self.enter_frame(scope_frame)
+        self.blockvisit(node.body, scope_frame)
+        self.leave_frame(scope_frame)
+        self.pop_context_reference()
+
+    def visit_EvalContextModifier(
+        self, node: nodes.EvalContextModifier, frame: Frame
+    ) -> None:
+        for keyword in node.options:
+            self.writeline(f"context.eval_ctx.{keyword.key} = ")
+            self.visit(keyword.value, frame)
+            try:
+                val = keyword.value.as_const(frame.eval_ctx)
+            except nodes.Impossible:
+                frame.eval_ctx.volatile = True
+            else:
+                setattr(frame.eval_ctx, keyword.key, val)
+
+    def visit_ScopedEvalContextModifier(
+        self, node: nodes.ScopedEvalContextModifier, frame: Frame
+    ) -> None:
+        old_ctx_name = self.temporary_identifier()
+        saved_ctx = frame.eval_ctx.save()
+        self.writeline(f"{old_ctx_name} = context.eval_ctx.save()")
+        self.visit_EvalContextModifier(node, frame)
+        for child in node.body:
+            self.visit(child, frame)
+        frame.eval_ctx.revert(saved_ctx)
+        self.writeline(f"context.eval_ctx.revert({old_ctx_name})")
diff --git a/src/jinja2/constants.py b/src/jinja2/constants.py
new file mode 100644
index 0000000..41a1c23
--- /dev/null
+++ b/src/jinja2/constants.py
@@ -0,0 +1,20 @@
+#: list of lorem ipsum words used by the lipsum() helper function
+LOREM_IPSUM_WORDS = """\
+a ac accumsan ad adipiscing aenean aliquam aliquet amet ante aptent arcu at
+auctor augue bibendum blandit class commodo condimentum congue consectetuer
+consequat conubia convallis cras cubilia cum curabitur curae cursus dapibus
+diam dictum dictumst dignissim dis dolor donec dui duis egestas eget eleifend
+elementum elit enim erat eros est et etiam eu euismod facilisi facilisis fames
+faucibus felis fermentum feugiat fringilla fusce gravida habitant habitasse hac
+hendrerit hymenaeos iaculis id imperdiet in inceptos integer interdum ipsum
+justo lacinia lacus laoreet lectus leo libero ligula litora lobortis lorem
+luctus maecenas magna magnis malesuada massa mattis mauris metus mi molestie
+mollis montes morbi mus nam nascetur natoque nec neque netus nibh nisi nisl non
+nonummy nostra nulla nullam nunc odio orci ornare parturient pede pellentesque
+penatibus per pharetra phasellus placerat platea porta porttitor posuere
+potenti praesent pretium primis proin pulvinar purus quam quis quisque rhoncus
+ridiculus risus rutrum sagittis sapien scelerisque sed sem semper senectus sit
+sociis sociosqu sodales sollicitudin suscipit suspendisse taciti tellus tempor
+tempus tincidunt torquent tortor tristique turpis ullamcorper ultrices
+ultricies urna ut varius vehicula vel velit venenatis vestibulum vitae vivamus
+viverra volutpat vulputate"""
diff --git a/src/jinja2/debug.py b/src/jinja2/debug.py
new file mode 100644
index 0000000..7ed7e92
--- /dev/null
+++ b/src/jinja2/debug.py
@@ -0,0 +1,191 @@
+import sys
+import typing as t
+from types import CodeType
+from types import TracebackType
+
+from .exceptions import TemplateSyntaxError
+from .utils import internal_code
+from .utils import missing
+
+if t.TYPE_CHECKING:
+    from .runtime import Context
+
+
+def rewrite_traceback_stack(source: t.Optional[str] = None) -> BaseException:
+    """Rewrite the current exception to replace any tracebacks from
+    within compiled template code with tracebacks that look like they
+    came from the template source.
+
+    This must be called within an ``except`` block.
+
+    :param source: For ``TemplateSyntaxError``, the original source if
+        known.
+    :return: The original exception with the rewritten traceback.
+    """
+    _, exc_value, tb = sys.exc_info()
+    exc_value = t.cast(BaseException, exc_value)
+    tb = t.cast(TracebackType, tb)
+
+    if isinstance(exc_value, TemplateSyntaxError) and not exc_value.translated:
+        exc_value.translated = True
+        exc_value.source = source
+        # Remove the old traceback, otherwise the frames from the
+        # compiler still show up.
+        exc_value.with_traceback(None)
+        # Outside of runtime, so the frame isn't executing template
+        # code, but it still needs to point at the template.
+        tb = fake_traceback(
+            exc_value, None, exc_value.filename or "<unknown>", exc_value.lineno
+        )
+    else:
+        # Skip the frame for the render function.
+        tb = tb.tb_next
+
+    stack = []
+
+    # Build the stack of traceback object, replacing any in template
+    # code with the source file and line information.
+    while tb is not None:
+        # Skip frames decorated with @internalcode. These are internal
+        # calls that aren't useful in template debugging output.
+        if tb.tb_frame.f_code in internal_code:
+            tb = tb.tb_next
+            continue
+
+        template = tb.tb_frame.f_globals.get("__jinja_template__")
+
+        if template is not None:
+            lineno = template.get_corresponding_lineno(tb.tb_lineno)
+            fake_tb = fake_traceback(exc_value, tb, template.filename, lineno)
+            stack.append(fake_tb)
+        else:
+            stack.append(tb)
+
+        tb = tb.tb_next
+
+    tb_next = None
+
+    # Assign tb_next in reverse to avoid circular references.
+    for tb in reversed(stack):
+        tb.tb_next = tb_next
+        tb_next = tb
+
+    return exc_value.with_traceback(tb_next)
+
+
+def fake_traceback(  # type: ignore
+    exc_value: BaseException, tb: t.Optional[TracebackType], filename: str, lineno: int
+) -> TracebackType:
+    """Produce a new traceback object that looks like it came from the
+    template source instead of the compiled code. The filename, line
+    number, and location name will point to the template, and the local
+    variables will be the current template context.
+
+    :param exc_value: The original exception to be re-raised to create
+        the new traceback.
+    :param tb: The original traceback to get the local variables and
+        code info from.
+    :param filename: The template filename.
+    :param lineno: The line number in the template source.
+    """
+    if tb is not None:
+        # Replace the real locals with the context that would be
+        # available at that point in the template.
+        locals = get_template_locals(tb.tb_frame.f_locals)
+        locals.pop("__jinja_exception__", None)
+    else:
+        locals = {}
+
+    globals = {
+        "__name__": filename,
+        "__file__": filename,
+        "__jinja_exception__": exc_value,
+    }
+    # Raise an exception at the correct line number.
+    code: CodeType = compile(
+        "\n" * (lineno - 1) + "raise __jinja_exception__", filename, "exec"
+    )
+
+    # Build a new code object that points to the template file and
+    # replaces the location with a block name.
+    location = "template"
+
+    if tb is not None:
+        function = tb.tb_frame.f_code.co_name
+
+        if function == "root":
+            location = "top-level template code"
+        elif function.startswith("block_"):
+            location = f"block {function[6:]!r}"
+
+    if sys.version_info >= (3, 8):
+        code = code.replace(co_name=location)
+    else:
+        code = CodeType(
+            code.co_argcount,
+            code.co_kwonlyargcount,
+            code.co_nlocals,
+            code.co_stacksize,
+            code.co_flags,
+            code.co_code,
+            code.co_consts,
+            code.co_names,
+            code.co_varnames,
+            code.co_filename,
+            location,
+            code.co_firstlineno,
+            code.co_lnotab,
+            code.co_freevars,
+            code.co_cellvars,
+        )
+
+    # Execute the new code, which is guaranteed to raise, and return
+    # the new traceback without this frame.
+    try:
+        exec(code, globals, locals)
+    except BaseException:
+        return sys.exc_info()[2].tb_next  # type: ignore
+
+
+def get_template_locals(real_locals: t.Mapping[str, t.Any]) -> t.Dict[str, t.Any]:
+    """Based on the runtime locals, get the context that would be
+    available at that point in the template.
+    """
+    # Start with the current template context.
+    ctx: "t.Optional[Context]" = real_locals.get("context")
+
+    if ctx is not None:
+        data: t.Dict[str, t.Any] = ctx.get_all().copy()
+    else:
+        data = {}
+
+    # Might be in a derived context that only sets local variables
+    # rather than pushing a context. Local variables follow the scheme
+    # l_depth_name. Find the highest-depth local that has a value for
+    # each name.
+    local_overrides: t.Dict[str, t.Tuple[int, t.Any]] = {}
+
+    for name, value in real_locals.items():
+        if not name.startswith("l_") or value is missing:
+            # Not a template variable, or no longer relevant.
+            continue
+
+        try:
+            _, depth_str, name = name.split("_", 2)
+            depth = int(depth_str)
+        except ValueError:
+            continue
+
+        cur_depth = local_overrides.get(name, (-1,))[0]
+
+        if cur_depth < depth:
+            local_overrides[name] = (depth, value)
+
+    # Modify the context with any derived context.
+    for name, (_, value) in local_overrides.items():
+        if value is missing:
+            data.pop(name, None)
+        else:
+            data[name] = value
+
+    return data
diff --git a/src/jinja2/defaults.py b/src/jinja2/defaults.py
new file mode 100644
index 0000000..638cad3
--- /dev/null
+++ b/src/jinja2/defaults.py
@@ -0,0 +1,48 @@
+import typing as t
+
+from .filters import FILTERS as DEFAULT_FILTERS  # noqa: F401
+from .tests import TESTS as DEFAULT_TESTS  # noqa: F401
+from .utils import Cycler
+from .utils import generate_lorem_ipsum
+from .utils import Joiner
+from .utils import Namespace
+
+if t.TYPE_CHECKING:
+    import typing_extensions as te
+
+# defaults for the parser / lexer
+BLOCK_START_STRING = "{%"
+BLOCK_END_STRING = "%}"
+VARIABLE_START_STRING = "{{"
+VARIABLE_END_STRING = "}}"
+COMMENT_START_STRING = "{#"
+COMMENT_END_STRING = "#}"
+LINE_STATEMENT_PREFIX: t.Optional[str] = None
+LINE_COMMENT_PREFIX: t.Optional[str] = None
+TRIM_BLOCKS = False
+LSTRIP_BLOCKS = False
+NEWLINE_SEQUENCE: "te.Literal['\\n', '\\r\\n', '\\r']" = "\n"
+KEEP_TRAILING_NEWLINE = False
+
+# default filters, tests and namespace
+
+DEFAULT_NAMESPACE = {
+    "range": range,
+    "dict": dict,
+    "lipsum": generate_lorem_ipsum,
+    "cycler": Cycler,
+    "joiner": Joiner,
+    "namespace": Namespace,
+}
+
+# default policies
+DEFAULT_POLICIES: t.Dict[str, t.Any] = {
+    "compiler.ascii_str": True,
+    "urlize.rel": "noopener",
+    "urlize.target": None,
+    "urlize.extra_schemes": None,
+    "truncate.leeway": 5,
+    "json.dumps_function": None,
+    "json.dumps_kwargs": {"sort_keys": True},
+    "ext.i18n.trimmed": False,
+}
diff --git a/src/jinja2/environment.py b/src/jinja2/environment.py
new file mode 100644
index 0000000..ea04e8b
--- /dev/null
+++ b/src/jinja2/environment.py
@@ -0,0 +1,1667 @@
+"""Classes for managing templates and their runtime and compile time
+options.
+"""
+import os
+import typing
+import typing as t
+import weakref
+from collections import ChainMap
+from functools import lru_cache
+from functools import partial
+from functools import reduce
+from types import CodeType
+
+from markupsafe import Markup
+
+from . import nodes
+from .compiler import CodeGenerator
+from .compiler import generate
+from .defaults import BLOCK_END_STRING
+from .defaults import BLOCK_START_STRING
+from .defaults import COMMENT_END_STRING
+from .defaults import COMMENT_START_STRING
+from .defaults import DEFAULT_FILTERS
+from .defaults import DEFAULT_NAMESPACE
+from .defaults import DEFAULT_POLICIES
+from .defaults import DEFAULT_TESTS
+from .defaults import KEEP_TRAILING_NEWLINE
+from .defaults import LINE_COMMENT_PREFIX
+from .defaults import LINE_STATEMENT_PREFIX
+from .defaults import LSTRIP_BLOCKS
+from .defaults import NEWLINE_SEQUENCE
+from .defaults import TRIM_BLOCKS
+from .defaults import VARIABLE_END_STRING
+from .defaults import VARIABLE_START_STRING
+from .exceptions import TemplateNotFound
+from .exceptions import TemplateRuntimeError
+from .exceptions import TemplatesNotFound
+from .exceptions import TemplateSyntaxError
+from .exceptions import UndefinedError
+from .lexer import get_lexer
+from .lexer import Lexer
+from .lexer import TokenStream
+from .nodes import EvalContext
+from .parser import Parser
+from .runtime import Context
+from .runtime import new_context
+from .runtime import Undefined
+from .utils import _PassArg
+from .utils import concat
+from .utils import consume
+from .utils import import_string
+from .utils import internalcode
+from .utils import LRUCache
+from .utils import missing
+
+if t.TYPE_CHECKING:
+    import typing_extensions as te
+    from .bccache import BytecodeCache
+    from .ext import Extension
+    from .loaders import BaseLoader
+
+_env_bound = t.TypeVar("_env_bound", bound="Environment")
+
+
+# for direct template usage we have up to ten living environments
+@lru_cache(maxsize=10)
+def get_spontaneous_environment(cls: t.Type[_env_bound], *args: t.Any) -> _env_bound:
+    """Return a new spontaneous environment. A spontaneous environment
+    is used for templates created directly rather than through an
+    existing environment.
+
+    :param cls: Environment class to create.
+    :param args: Positional arguments passed to environment.
+    """
+    env = cls(*args)
+    env.shared = True
+    return env
+
+
+def create_cache(
+    size: int,
+) -> t.Optional[t.MutableMapping[t.Tuple[weakref.ref, str], "Template"]]:
+    """Return the cache class for the given size."""
+    if size == 0:
+        return None
+
+    if size < 0:
+        return {}
+
+    return LRUCache(size)  # type: ignore
+
+
+def copy_cache(
+    cache: t.Optional[t.MutableMapping],
+) -> t.Optional[t.MutableMapping[t.Tuple[weakref.ref, str], "Template"]]:
+    """Create an empty copy of the given cache."""
+    if cache is None:
+        return None
+
+    if type(cache) is dict:
+        return {}
+
+    return LRUCache(cache.capacity)  # type: ignore
+
+
+def load_extensions(
+    environment: "Environment",
+    extensions: t.Sequence[t.Union[str, t.Type["Extension"]]],
+) -> t.Dict[str, "Extension"]:
+    """Load the extensions from the list and bind it to the environment.
+    Returns a dict of instantiated extensions.
+    """
+    result = {}
+
+    for extension in extensions:
+        if isinstance(extension, str):
+            extension = t.cast(t.Type["Extension"], import_string(extension))
+
+        result[extension.identifier] = extension(environment)
+
+    return result
+
+
+def _environment_config_check(environment: "Environment") -> "Environment":
+    """Perform a sanity check on the environment."""
+    assert issubclass(
+        environment.undefined, Undefined
+    ), "'undefined' must be a subclass of 'jinja2.Undefined'."
+    assert (
+        environment.block_start_string
+        != environment.variable_start_string
+        != environment.comment_start_string
+    ), "block, variable and comment start strings must be different."
+    assert environment.newline_sequence in {
+        "\r",
+        "\r\n",
+        "\n",
+    }, "'newline_sequence' must be one of '\\n', '\\r\\n', or '\\r'."
+    return environment
+
+
+class Environment:
+    r"""The core component of Jinja is the `Environment`.  It contains
+    important shared variables like configuration, filters, tests,
+    globals and others.  Instances of this class may be modified if
+    they are not shared and if no template was loaded so far.
+    Modifications on environments after the first template was loaded
+    will lead to surprising effects and undefined behavior.
+
+    Here are the possible initialization parameters:
+
+        `block_start_string`
+            The string marking the beginning of a block.  Defaults to ``'{%'``.
+
+        `block_end_string`
+            The string marking the end of a block.  Defaults to ``'%}'``.
+
+        `variable_start_string`
+            The string marking the beginning of a print statement.
+            Defaults to ``'{{'``.
+
+        `variable_end_string`
+            The string marking the end of a print statement.  Defaults to
+            ``'}}'``.
+
+        `comment_start_string`
+            The string marking the beginning of a comment.  Defaults to ``'{#'``.
+
+        `comment_end_string`
+            The string marking the end of a comment.  Defaults to ``'#}'``.
+
+        `line_statement_prefix`
+            If given and a string, this will be used as prefix for line based
+            statements.  See also :ref:`line-statements`.
+
+        `line_comment_prefix`
+            If given and a string, this will be used as prefix for line based
+            comments.  See also :ref:`line-statements`.
+
+            .. versionadded:: 2.2
+
+        `trim_blocks`
+            If this is set to ``True`` the first newline after a block is
+            removed (block, not variable tag!).  Defaults to `False`.
+
+        `lstrip_blocks`
+            If this is set to ``True`` leading spaces and tabs are stripped
+            from the start of a line to a block.  Defaults to `False`.
+
+        `newline_sequence`
+            The sequence that starts a newline.  Must be one of ``'\r'``,
+            ``'\n'`` or ``'\r\n'``.  The default is ``'\n'`` which is a
+            useful default for Linux and OS X systems as well as web
+            applications.
+
+        `keep_trailing_newline`
+            Preserve the trailing newline when rendering templates.
+            The default is ``False``, which causes a single newline,
+            if present, to be stripped from the end of the template.
+
+            .. versionadded:: 2.7
+
+        `extensions`
+            List of Jinja extensions to use.  This can either be import paths
+            as strings or extension classes.  For more information have a
+            look at :ref:`the extensions documentation <jinja-extensions>`.
+
+        `optimized`
+            should the optimizer be enabled?  Default is ``True``.
+
+        `undefined`
+            :class:`Undefined` or a subclass of it that is used to represent
+            undefined values in the template.
+
+        `finalize`
+            A callable that can be used to process the result of a variable
+            expression before it is output.  For example one can convert
+            ``None`` implicitly into an empty string here.
+
+        `autoescape`
+            If set to ``True`` the XML/HTML autoescaping feature is enabled by
+            default.  For more details about autoescaping see
+            :class:`~markupsafe.Markup`.  As of Jinja 2.4 this can also
+            be a callable that is passed the template name and has to
+            return ``True`` or ``False`` depending on autoescape should be
+            enabled by default.
+
+            .. versionchanged:: 2.4
+               `autoescape` can now be a function
+
+        `loader`
+            The template loader for this environment.
+
+        `cache_size`
+            The size of the cache.  Per default this is ``400`` which means
+            that if more than 400 templates are loaded the loader will clean
+            out the least recently used template.  If the cache size is set to
+            ``0`` templates are recompiled all the time, if the cache size is
+            ``-1`` the cache will not be cleaned.
+
+            .. versionchanged:: 2.8
+               The cache size was increased to 400 from a low 50.
+
+        `auto_reload`
+            Some loaders load templates from locations where the template
+            sources may change (ie: file system or database).  If
+            ``auto_reload`` is set to ``True`` (default) every time a template is
+            requested the loader checks if the source changed and if yes, it
+            will reload the template.  For higher performance it's possible to
+            disable that.
+
+        `bytecode_cache`
+            If set to a bytecode cache object, this object will provide a
+            cache for the internal Jinja bytecode so that templates don't
+            have to be parsed if they were not changed.
+
+            See :ref:`bytecode-cache` for more information.
+
+        `enable_async`
+            If set to true this enables async template execution which
+            allows using async functions and generators.
+    """
+
+    #: if this environment is sandboxed.  Modifying this variable won't make
+    #: the environment sandboxed though.  For a real sandboxed environment
+    #: have a look at jinja2.sandbox.  This flag alone controls the code
+    #: generation by the compiler.
+    sandboxed = False
+
+    #: True if the environment is just an overlay
+    overlayed = False
+
+    #: the environment this environment is linked to if it is an overlay
+    linked_to: t.Optional["Environment"] = None
+
+    #: shared environments have this set to `True`.  A shared environment
+    #: must not be modified
+    shared = False
+
+    #: the class that is used for code generation.  See
+    #: :class:`~jinja2.compiler.CodeGenerator` for more information.
+    code_generator_class: t.Type["CodeGenerator"] = CodeGenerator
+
+    concat = "".join
+
+    #: the context class that is used for templates.  See
+    #: :class:`~jinja2.runtime.Context` for more information.
+    context_class: t.Type[Context] = Context
+
+    template_class: t.Type["Template"]
+
+    def __init__(
+        self,
+        block_start_string: str = BLOCK_START_STRING,
+        block_end_string: str = BLOCK_END_STRING,
+        variable_start_string: str = VARIABLE_START_STRING,
+        variable_end_string: str = VARIABLE_END_STRING,
+        comment_start_string: str = COMMENT_START_STRING,
+        comment_end_string: str = COMMENT_END_STRING,
+        line_statement_prefix: t.Optional[str] = LINE_STATEMENT_PREFIX,
+        line_comment_prefix: t.Optional[str] = LINE_COMMENT_PREFIX,
+        trim_blocks: bool = TRIM_BLOCKS,
+        lstrip_blocks: bool = LSTRIP_BLOCKS,
+        newline_sequence: "te.Literal['\\n', '\\r\\n', '\\r']" = NEWLINE_SEQUENCE,
+        keep_trailing_newline: bool = KEEP_TRAILING_NEWLINE,
+        extensions: t.Sequence[t.Union[str, t.Type["Extension"]]] = (),
+        optimized: bool = True,
+        undefined: t.Type[Undefined] = Undefined,
+        finalize: t.Optional[t.Callable[..., t.Any]] = None,
+        autoescape: t.Union[bool, t.Callable[[t.Optional[str]], bool]] = False,
+        loader: t.Optional["BaseLoader"] = None,
+        cache_size: int = 400,
+        auto_reload: bool = True,
+        bytecode_cache: t.Optional["BytecodeCache"] = None,
+        enable_async: bool = False,
+    ):
+        # !!Important notice!!
+        #   The constructor accepts quite a few arguments that should be
+        #   passed by keyword rather than position.  However it's important to
+        #   not change the order of arguments because it's used at least
+        #   internally in those cases:
+        #       -   spontaneous environments (i18n extension and Template)
+        #       -   unittests
+        #   If parameter changes are required only add parameters at the end
+        #   and don't change the arguments (or the defaults!) of the arguments
+        #   existing already.
+
+        # lexer / parser information
+        self.block_start_string = block_start_string
+        self.block_end_string = block_end_string
+        self.variable_start_string = variable_start_string
+        self.variable_end_string = variable_end_string
+        self.comment_start_string = comment_start_string
+        self.comment_end_string = comment_end_string
+        self.line_statement_prefix = line_statement_prefix
+        self.line_comment_prefix = line_comment_prefix
+        self.trim_blocks = trim_blocks
+        self.lstrip_blocks = lstrip_blocks
+        self.newline_sequence = newline_sequence
+        self.keep_trailing_newline = keep_trailing_newline
+
+        # runtime information
+        self.undefined: t.Type[Undefined] = undefined
+        self.optimized = optimized
+        self.finalize = finalize
+        self.autoescape = autoescape
+
+        # defaults
+        self.filters = DEFAULT_FILTERS.copy()
+        self.tests = DEFAULT_TESTS.copy()
+        self.globals = DEFAULT_NAMESPACE.copy()
+
+        # set the loader provided
+        self.loader = loader
+        self.cache = create_cache(cache_size)
+        self.bytecode_cache = bytecode_cache
+        self.auto_reload = auto_reload
+
+        # configurable policies
+        self.policies = DEFAULT_POLICIES.copy()
+
+        # load extensions
+        self.extensions = load_extensions(self, extensions)
+
+        self.is_async = enable_async
+        _environment_config_check(self)
+
+    def add_extension(self, extension: t.Union[str, t.Type["Extension"]]) -> None:
+        """Adds an extension after the environment was created.
+
+        .. versionadded:: 2.5
+        """
+        self.extensions.update(load_extensions(self, [extension]))
+
+    def extend(self, **attributes: t.Any) -> None:
+        """Add the items to the instance of the environment if they do not exist
+        yet.  This is used by :ref:`extensions <writing-extensions>` to register
+        callbacks and configuration values without breaking inheritance.
+        """
+        for key, value in attributes.items():
+            if not hasattr(self, key):
+                setattr(self, key, value)
+
+    def overlay(
+        self,
+        block_start_string: str = missing,
+        block_end_string: str = missing,
+        variable_start_string: str = missing,
+        variable_end_string: str = missing,
+        comment_start_string: str = missing,
+        comment_end_string: str = missing,
+        line_statement_prefix: t.Optional[str] = missing,
+        line_comment_prefix: t.Optional[str] = missing,
+        trim_blocks: bool = missing,
+        lstrip_blocks: bool = missing,
+        newline_sequence: "te.Literal['\\n', '\\r\\n', '\\r']" = missing,
+        keep_trailing_newline: bool = missing,
+        extensions: t.Sequence[t.Union[str, t.Type["Extension"]]] = missing,
+        optimized: bool = missing,
+        undefined: t.Type[Undefined] = missing,
+        finalize: t.Optional[t.Callable[..., t.Any]] = missing,
+        autoescape: t.Union[bool, t.Callable[[t.Optional[str]], bool]] = missing,
+        loader: t.Optional["BaseLoader"] = missing,
+        cache_size: int = missing,
+        auto_reload: bool = missing,
+        bytecode_cache: t.Optional["BytecodeCache"] = missing,
+        enable_async: bool = False,
+    ) -> "Environment":
+        """Create a new overlay environment that shares all the data with the
+        current environment except for cache and the overridden attributes.
+        Extensions cannot be removed for an overlayed environment.  An overlayed
+        environment automatically gets all the extensions of the environment it
+        is linked to plus optional extra extensions.
+
+        Creating overlays should happen after the initial environment was set
+        up completely.  Not all attributes are truly linked, some are just
+        copied over so modifications on the original environment may not shine
+        through.
+
+        .. versionchanged:: 3.1.2
+            Added the ``newline_sequence``,, ``keep_trailing_newline``,
+            and ``enable_async`` parameters to match ``__init__``.
+        """
+        args = dict(locals())
+        del args["self"], args["cache_size"], args["extensions"], args["enable_async"]
+
+        rv = object.__new__(self.__class__)
+        rv.__dict__.update(self.__dict__)
+        rv.overlayed = True
+        rv.linked_to = self
+
+        for key, value in args.items():
+            if value is not missing:
+                setattr(rv, key, value)
+
+        if cache_size is not missing:
+            rv.cache = create_cache(cache_size)
+        else:
+            rv.cache = copy_cache(self.cache)
+
+        rv.extensions = {}
+        for key, value in self.extensions.items():
+            rv.extensions[key] = value.bind(rv)
+        if extensions is not missing:
+            rv.extensions.update(load_extensions(rv, extensions))
+
+        if enable_async is not missing:
+            rv.is_async = enable_async
+
+        return _environment_config_check(rv)
+
+    @property
+    def lexer(self) -> Lexer:
+        """The lexer for this environment."""
+        return get_lexer(self)
+
+    def iter_extensions(self) -> t.Iterator["Extension"]:
+        """Iterates over the extensions by priority."""
+        return iter(sorted(self.extensions.values(), key=lambda x: x.priority))
+
+    def getitem(
+        self, obj: t.Any, argument: t.Union[str, t.Any]
+    ) -> t.Union[t.Any, Undefined]:
+        """Get an item or attribute of an object but prefer the item."""
+        try:
+            return obj[argument]
+        except (AttributeError, TypeError, LookupError):
+            if isinstance(argument, str):
+                try:
+                    attr = str(argument)
+                except Exception:
+                    pass
+                else:
+                    try:
+                        return getattr(obj, attr)
+                    except AttributeError:
+                        pass
+            return self.undefined(obj=obj, name=argument)
+
+    def getattr(self, obj: t.Any, attribute: str) -> t.Any:
+        """Get an item or attribute of an object but prefer the attribute.
+        Unlike :meth:`getitem` the attribute *must* be a string.
+        """
+        try:
+            return getattr(obj, attribute)
+        except AttributeError:
+            pass
+        try:
+            return obj[attribute]
+        except (TypeError, LookupError, AttributeError):
+            return self.undefined(obj=obj, name=attribute)
+
+    def _filter_test_common(
+        self,
+        name: t.Union[str, Undefined],
+        value: t.Any,
+        args: t.Optional[t.Sequence[t.Any]],
+        kwargs: t.Optional[t.Mapping[str, t.Any]],
+        context: t.Optional[Context],
+        eval_ctx: t.Optional[EvalContext],
+        is_filter: bool,
+    ) -> t.Any:
+        if is_filter:
+            env_map = self.filters
+            type_name = "filter"
+        else:
+            env_map = self.tests
+            type_name = "test"
+
+        func = env_map.get(name)  # type: ignore
+
+        if func is None:
+            msg = f"No {type_name} named {name!r}."
+
+            if isinstance(name, Undefined):
+                try:
+                    name._fail_with_undefined_error()
+                except Exception as e:
+                    msg = f"{msg} ({e}; did you forget to quote the callable name?)"
+
+            raise TemplateRuntimeError(msg)
+
+        args = [value, *(args if args is not None else ())]
+        kwargs = kwargs if kwargs is not None else {}
+        pass_arg = _PassArg.from_obj(func)
+
+        if pass_arg is _PassArg.context:
+            if context is None:
+                raise TemplateRuntimeError(
+                    f"Attempted to invoke a context {type_name} without context."
+                )
+
+            args.insert(0, context)
+        elif pass_arg is _PassArg.eval_context:
+            if eval_ctx is None:
+                if context is not None:
+                    eval_ctx = context.eval_ctx
+                else:
+                    eval_ctx = EvalContext(self)
+
+            args.insert(0, eval_ctx)
+        elif pass_arg is _PassArg.environment:
+            args.insert(0, self)
+
+        return func(*args, **kwargs)
+
+    def call_filter(
+        self,
+        name: str,
+        value: t.Any,
+        args: t.Optional[t.Sequence[t.Any]] = None,
+        kwargs: t.Optional[t.Mapping[str, t.Any]] = None,
+        context: t.Optional[Context] = None,
+        eval_ctx: t.Optional[EvalContext] = None,
+    ) -> t.Any:
+        """Invoke a filter on a value the same way the compiler does.
+
+        This might return a coroutine if the filter is running from an
+        environment in async mode and the filter supports async
+        execution. It's your responsibility to await this if needed.
+
+        .. versionadded:: 2.7
+        """
+        return self._filter_test_common(
+            name, value, args, kwargs, context, eval_ctx, True
+        )
+
+    def call_test(
+        self,
+        name: str,
+        value: t.Any,
+        args: t.Optional[t.Sequence[t.Any]] = None,
+        kwargs: t.Optional[t.Mapping[str, t.Any]] = None,
+        context: t.Optional[Context] = None,
+        eval_ctx: t.Optional[EvalContext] = None,
+    ) -> t.Any:
+        """Invoke a test on a value the same way the compiler does.
+
+        This might return a coroutine if the test is running from an
+        environment in async mode and the test supports async execution.
+        It's your responsibility to await this if needed.
+
+        .. versionchanged:: 3.0
+            Tests support ``@pass_context``, etc. decorators. Added
+            the ``context`` and ``eval_ctx`` parameters.
+
+        .. versionadded:: 2.7
+        """
+        return self._filter_test_common(
+            name, value, args, kwargs, context, eval_ctx, False
+        )
+
+    @internalcode
+    def parse(
+        self,
+        source: str,
+        name: t.Optional[str] = None,
+        filename: t.Optional[str] = None,
+    ) -> nodes.Template:
+        """Parse the sourcecode and return the abstract syntax tree.  This
+        tree of nodes is used by the compiler to convert the template into
+        executable source- or bytecode.  This is useful for debugging or to
+        extract information from templates.
+
+        If you are :ref:`developing Jinja extensions <writing-extensions>`
+        this gives you a good overview of the node tree generated.
+        """
+        try:
+            return self._parse(source, name, filename)
+        except TemplateSyntaxError:
+            self.handle_exception(source=source)
+
+    def _parse(
+        self, source: str, name: t.Optional[str], filename: t.Optional[str]
+    ) -> nodes.Template:
+        """Internal parsing function used by `parse` and `compile`."""
+        return Parser(self, source, name, filename).parse()
+
+    def lex(
+        self,
+        source: str,
+        name: t.Optional[str] = None,
+        filename: t.Optional[str] = None,
+    ) -> t.Iterator[t.Tuple[int, str, str]]:
+        """Lex the given sourcecode and return a generator that yields
+        tokens as tuples in the form ``(lineno, token_type, value)``.
+        This can be useful for :ref:`extension development <writing-extensions>`
+        and debugging templates.
+
+        This does not perform preprocessing.  If you want the preprocessing
+        of the extensions to be applied you have to filter source through
+        the :meth:`preprocess` method.
+        """
+        source = str(source)
+        try:
+            return self.lexer.tokeniter(source, name, filename)
+        except TemplateSyntaxError:
+            self.handle_exception(source=source)
+
+    def preprocess(
+        self,
+        source: str,
+        name: t.Optional[str] = None,
+        filename: t.Optional[str] = None,
+    ) -> str:
+        """Preprocesses the source with all extensions.  This is automatically
+        called for all parsing and compiling methods but *not* for :meth:`lex`
+        because there you usually only want the actual source tokenized.
+        """
+        return reduce(
+            lambda s, e: e.preprocess(s, name, filename),
+            self.iter_extensions(),
+            str(source),
+        )
+
+    def _tokenize(
+        self,
+        source: str,
+        name: t.Optional[str],
+        filename: t.Optional[str] = None,
+        state: t.Optional[str] = None,
+    ) -> TokenStream:
+        """Called by the parser to do the preprocessing and filtering
+        for all the extensions.  Returns a :class:`~jinja2.lexer.TokenStream`.
+        """
+        source = self.preprocess(source, name, filename)
+        stream = self.lexer.tokenize(source, name, filename, state)
+
+        for ext in self.iter_extensions():
+            stream = ext.filter_stream(stream)  # type: ignore
+
+            if not isinstance(stream, TokenStream):
+                stream = TokenStream(stream, name, filename)  # type: ignore
+
+        return stream
+
+    def _generate(
+        self,
+        source: nodes.Template,
+        name: t.Optional[str],
+        filename: t.Optional[str],
+        defer_init: bool = False,
+    ) -> str:
+        """Internal hook that can be overridden to hook a different generate
+        method in.
+
+        .. versionadded:: 2.5
+        """
+        return generate(  # type: ignore
+            source,
+            self,
+            name,
+            filename,
+            defer_init=defer_init,
+            optimized=self.optimized,
+        )
+
+    def _compile(self, source: str, filename: str) -> CodeType:
+        """Internal hook that can be overridden to hook a different compile
+        method in.
+
+        .. versionadded:: 2.5
+        """
+        return compile(source, filename, "exec")  # type: ignore
+
+    @typing.overload
+    def compile(  # type: ignore
+        self,
+        source: t.Union[str, nodes.Template],
+        name: t.Optional[str] = None,
+        filename: t.Optional[str] = None,
+        raw: "te.Literal[False]" = False,
+        defer_init: bool = False,
+    ) -> CodeType:
+        ...
+
+    @typing.overload
+    def compile(
+        self,
+        source: t.Union[str, nodes.Template],
+        name: t.Optional[str] = None,
+        filename: t.Optional[str] = None,
+        raw: "te.Literal[True]" = ...,
+        defer_init: bool = False,
+    ) -> str:
+        ...
+
+    @internalcode
+    def compile(
+        self,
+        source: t.Union[str, nodes.Template],
+        name: t.Optional[str] = None,
+        filename: t.Optional[str] = None,
+        raw: bool = False,
+        defer_init: bool = False,
+    ) -> t.Union[str, CodeType]:
+        """Compile a node or template source code.  The `name` parameter is
+        the load name of the template after it was joined using
+        :meth:`join_path` if necessary, not the filename on the file system.
+        the `filename` parameter is the estimated filename of the template on
+        the file system.  If the template came from a database or memory this
+        can be omitted.
+
+        The return value of this method is a python code object.  If the `raw`
+        parameter is `True` the return value will be a string with python
+        code equivalent to the bytecode returned otherwise.  This method is
+        mainly used internally.
+
+        `defer_init` is use internally to aid the module code generator.  This
+        causes the generated code to be able to import without the global
+        environment variable to be set.
+
+        .. versionadded:: 2.4
+           `defer_init` parameter added.
+        """
+        source_hint = None
+        try:
+            if isinstance(source, str):
+                source_hint = source
+                source = self._parse(source, name, filename)
+            source = self._generate(source, name, filename, defer_init=defer_init)
+            if raw:
+                return source
+            if filename is None:
+                filename = "<template>"
+            return self._compile(source, filename)
+        except TemplateSyntaxError:
+            self.handle_exception(source=source_hint)
+
+    def compile_expression(
+        self, source: str, undefined_to_none: bool = True
+    ) -> "TemplateExpression":
+        """A handy helper method that returns a callable that accepts keyword
+        arguments that appear as variables in the expression.  If called it
+        returns the result of the expression.
+
+        This is useful if applications want to use the same rules as Jinja
+        in template "configuration files" or similar situations.
+
+        Example usage:
+
+        >>> env = Environment()
+        >>> expr = env.compile_expression('foo == 42')
+        >>> expr(foo=23)
+        False
+        >>> expr(foo=42)
+        True
+
+        Per default the return value is converted to `None` if the
+        expression returns an undefined value.  This can be changed
+        by setting `undefined_to_none` to `False`.
+
+        >>> env.compile_expression('var')() is None
+        True
+        >>> env.compile_expression('var', undefined_to_none=False)()
+        Undefined
+
+        .. versionadded:: 2.1
+        """
+        parser = Parser(self, source, state="variable")
+        try:
+            expr = parser.parse_expression()
+            if not parser.stream.eos:
+                raise TemplateSyntaxError(
+                    "chunk after expression", parser.stream.current.lineno, None, None
+                )
+            expr.set_environment(self)
+        except TemplateSyntaxError:
+            self.handle_exception(source=source)
+
+        body = [nodes.Assign(nodes.Name("result", "store"), expr, lineno=1)]
+        template = self.from_string(nodes.Template(body, lineno=1))
+        return TemplateExpression(template, undefined_to_none)
+
+    def compile_templates(
+        self,
+        target: t.Union[str, os.PathLike],
+        extensions: t.Optional[t.Collection[str]] = None,
+        filter_func: t.Optional[t.Callable[[str], bool]] = None,
+        zip: t.Optional[str] = "deflated",
+        log_function: t.Optional[t.Callable[[str], None]] = None,
+        ignore_errors: bool = True,
+    ) -> None:
+        """Finds all the templates the loader can find, compiles them
+        and stores them in `target`.  If `zip` is `None`, instead of in a
+        zipfile, the templates will be stored in a directory.
+        By default a deflate zip algorithm is used. To switch to
+        the stored algorithm, `zip` can be set to ``'stored'``.
+
+        `extensions` and `filter_func` are passed to :meth:`list_templates`.
+        Each template returned will be compiled to the target folder or
+        zipfile.
+
+        By default template compilation errors are ignored.  In case a
+        log function is provided, errors are logged.  If you want template
+        syntax errors to abort the compilation you can set `ignore_errors`
+        to `False` and you will get an exception on syntax errors.
+
+        .. versionadded:: 2.4
+        """
+        from .loaders import ModuleLoader
+
+        if log_function is None:
+
+            def log_function(x: str) -> None:
+                pass
+
+        assert log_function is not None
+        assert self.loader is not None, "No loader configured."
+
+        def write_file(filename: str, data: str) -> None:
+            if zip:
+                info = ZipInfo(filename)
+                info.external_attr = 0o755 << 16
+                zip_file.writestr(info, data)
+            else:
+                with open(os.path.join(target, filename), "wb") as f:
+                    f.write(data.encode("utf8"))
+
+        if zip is not None:
+            from zipfile import ZipFile, ZipInfo, ZIP_DEFLATED, ZIP_STORED
+
+            zip_file = ZipFile(
+                target, "w", dict(deflated=ZIP_DEFLATED, stored=ZIP_STORED)[zip]
+            )
+            log_function(f"Compiling into Zip archive {target!r}")
+        else:
+            if not os.path.isdir(target):
+                os.makedirs(target)
+            log_function(f"Compiling into folder {target!r}")
+
+        try:
+            for name in self.list_templates(extensions, filter_func):
+                source, filename, _ = self.loader.get_source(self, name)
+                try:
+                    code = self.compile(source, name, filename, True, True)
+                except TemplateSyntaxError as e:
+                    if not ignore_errors:
+                        raise
+                    log_function(f'Could not compile "{name}": {e}')
+                    continue
+
+                filename = ModuleLoader.get_module_filename(name)
+
+                write_file(filename, code)
+                log_function(f'Compiled "{name}" as {filename}')
+        finally:
+            if zip:
+                zip_file.close()
+
+        log_function("Finished compiling templates")
+
+    def list_templates(
+        self,
+        extensions: t.Optional[t.Collection[str]] = None,
+        filter_func: t.Optional[t.Callable[[str], bool]] = None,
+    ) -> t.List[str]:
+        """Returns a list of templates for this environment.  This requires
+        that the loader supports the loader's
+        :meth:`~BaseLoader.list_templates` method.
+
+        If there are other files in the template folder besides the
+        actual templates, the returned list can be filtered.  There are two
+        ways: either `extensions` is set to a list of file extensions for
+        templates, or a `filter_func` can be provided which is a callable that
+        is passed a template name and should return `True` if it should end up
+        in the result list.
+
+        If the loader does not support that, a :exc:`TypeError` is raised.
+
+        .. versionadded:: 2.4
+        """
+        assert self.loader is not None, "No loader configured."
+        names = self.loader.list_templates()
+
+        if extensions is not None:
+            if filter_func is not None:
+                raise TypeError(
+                    "either extensions or filter_func can be passed, but not both"
+                )
+
+            def filter_func(x: str) -> bool:
+                return "." in x and x.rsplit(".", 1)[1] in extensions  # type: ignore
+
+        if filter_func is not None:
+            names = [name for name in names if filter_func(name)]
+
+        return names
+
+    def handle_exception(self, source: t.Optional[str] = None) -> "te.NoReturn":
+        """Exception handling helper.  This is used internally to either raise
+        rewritten exceptions or return a rendered traceback for the template.
+        """
+        from .debug import rewrite_traceback_stack
+
+        raise rewrite_traceback_stack(source=source)
+
+    def join_path(self, template: str, parent: str) -> str:
+        """Join a template with the parent.  By default all the lookups are
+        relative to the loader root so this method returns the `template`
+        parameter unchanged, but if the paths should be relative to the
+        parent template, this function can be used to calculate the real
+        template name.
+
+        Subclasses may override this method and implement template path
+        joining here.
+        """
+        return template
+
+    @internalcode
+    def _load_template(
+        self, name: str, globals: t.Optional[t.MutableMapping[str, t.Any]]
+    ) -> "Template":
+        if self.loader is None:
+            raise TypeError("no loader for this environment specified")
+        cache_key = (weakref.ref(self.loader), name)
+        if self.cache is not None:
+            template = self.cache.get(cache_key)
+            if template is not None and (
+                not self.auto_reload or template.is_up_to_date
+            ):
+                # template.globals is a ChainMap, modifying it will only
+                # affect the template, not the environment globals.
+                if globals:
+                    template.globals.update(globals)
+
+                return template
+
+        template = self.loader.load(self, name, self.make_globals(globals))
+
+        if self.cache is not None:
+            self.cache[cache_key] = template
+        return template
+
+    @internalcode
+    def get_template(
+        self,
+        name: t.Union[str, "Template"],
+        parent: t.Optional[str] = None,
+        globals: t.Optional[t.MutableMapping[str, t.Any]] = None,
+    ) -> "Template":
+        """Load a template by name with :attr:`loader` and return a
+        :class:`Template`. If the template does not exist a
+        :exc:`TemplateNotFound` exception is raised.
+
+        :param name: Name of the template to load. When loading
+            templates from the filesystem, "/" is used as the path
+            separator, even on Windows.
+        :param parent: The name of the parent template importing this
+            template. :meth:`join_path` can be used to implement name
+            transformations with this.
+        :param globals: Extend the environment :attr:`globals` with
+            these extra variables available for all renders of this
+            template. If the template has already been loaded and
+            cached, its globals are updated with any new items.
+
+        .. versionchanged:: 3.0
+            If a template is loaded from cache, ``globals`` will update
+            the template's globals instead of ignoring the new values.
+
+        .. versionchanged:: 2.4
+            If ``name`` is a :class:`Template` object it is returned
+            unchanged.
+        """
+        if isinstance(name, Template):
+            return name
+        if parent is not None:
+            name = self.join_path(name, parent)
+
+        return self._load_template(name, globals)
+
+    @internalcode
+    def select_template(
+        self,
+        names: t.Iterable[t.Union[str, "Template"]],
+        parent: t.Optional[str] = None,
+        globals: t.Optional[t.MutableMapping[str, t.Any]] = None,
+    ) -> "Template":
+        """Like :meth:`get_template`, but tries loading multiple names.
+        If none of the names can be loaded a :exc:`TemplatesNotFound`
+        exception is raised.
+
+        :param names: List of template names to try loading in order.
+        :param parent: The name of the parent template importing this
+            template. :meth:`join_path` can be used to implement name
+            transformations with this.
+        :param globals: Extend the environment :attr:`globals` with
+            these extra variables available for all renders of this
+            template. If the template has already been loaded and
+            cached, its globals are updated with any new items.
+
+        .. versionchanged:: 3.0
+            If a template is loaded from cache, ``globals`` will update
+            the template's globals instead of ignoring the new values.
+
+        .. versionchanged:: 2.11
+            If ``names`` is :class:`Undefined`, an :exc:`UndefinedError`
+            is raised instead. If no templates were found and ``names``
+            contains :class:`Undefined`, the message is more helpful.
+
+        .. versionchanged:: 2.4
+            If ``names`` contains a :class:`Template` object it is
+            returned unchanged.
+
+        .. versionadded:: 2.3
+        """
+        if isinstance(names, Undefined):
+            names._fail_with_undefined_error()
+
+        if not names:
+            raise TemplatesNotFound(
+                message="Tried to select from an empty list of templates."
+            )
+
+        for name in names:
+            if isinstance(name, Template):
+                return name
+            if parent is not None:
+                name = self.join_path(name, parent)
+            try:
+                return self._load_template(name, globals)
+            except (TemplateNotFound, UndefinedError):
+                pass
+        raise TemplatesNotFound(names)  # type: ignore
+
+    @internalcode
+    def get_or_select_template(
+        self,
+        template_name_or_list: t.Union[
+            str, "Template", t.List[t.Union[str, "Template"]]
+        ],
+        parent: t.Optional[str] = None,
+        globals: t.Optional[t.MutableMapping[str, t.Any]] = None,
+    ) -> "Template":
+        """Use :meth:`select_template` if an iterable of template names
+        is given, or :meth:`get_template` if one name is given.
+
+        .. versionadded:: 2.3
+        """
+        if isinstance(template_name_or_list, (str, Undefined)):
+            return self.get_template(template_name_or_list, parent, globals)
+        elif isinstance(template_name_or_list, Template):
+            return template_name_or_list
+        return self.select_template(template_name_or_list, parent, globals)
+
+    def from_string(
+        self,
+        source: t.Union[str, nodes.Template],
+        globals: t.Optional[t.MutableMapping[str, t.Any]] = None,
+        template_class: t.Optional[t.Type["Template"]] = None,
+    ) -> "Template":
+        """Load a template from a source string without using
+        :attr:`loader`.
+
+        :param source: Jinja source to compile into a template.
+        :param globals: Extend the environment :attr:`globals` with
+            these extra variables available for all renders of this
+            template. If the template has already been loaded and
+            cached, its globals are updated with any new items.
+        :param template_class: Return an instance of this
+            :class:`Template` class.
+        """
+        gs = self.make_globals(globals)
+        cls = template_class or self.template_class
+        return cls.from_code(self, self.compile(source), gs, None)
+
+    def make_globals(
+        self, d: t.Optional[t.MutableMapping[str, t.Any]]
+    ) -> t.MutableMapping[str, t.Any]:
+        """Make the globals map for a template. Any given template
+        globals overlay the environment :attr:`globals`.
+
+        Returns a :class:`collections.ChainMap`. This allows any changes
+        to a template's globals to only affect that template, while
+        changes to the environment's globals are still reflected.
+        However, avoid modifying any globals after a template is loaded.
+
+        :param d: Dict of template-specific globals.
+
+        .. versionchanged:: 3.0
+            Use :class:`collections.ChainMap` to always prevent mutating
+            environment globals.
+        """
+        if d is None:
+            d = {}
+
+        return ChainMap(d, self.globals)
+
+
+class Template:
+    """A compiled template that can be rendered.
+
+    Use the methods on :class:`Environment` to create or load templates.
+    The environment is used to configure how templates are compiled and
+    behave.
+
+    It is also possible to create a template object directly. This is
+    not usually recommended. The constructor takes most of the same
+    arguments as :class:`Environment`. All templates created with the
+    same environment arguments share the same ephemeral ``Environment``
+    instance behind the scenes.
+
+    A template object should be considered immutable. Modifications on
+    the object are not supported.
+    """
+
+    #: Type of environment to create when creating a template directly
+    #: rather than through an existing environment.
+    environment_class: t.Type[Environment] = Environment
+
+    environment: Environment
+    globals: t.MutableMapping[str, t.Any]
+    name: t.Optional[str]
+    filename: t.Optional[str]
+    blocks: t.Dict[str, t.Callable[[Context], t.Iterator[str]]]
+    root_render_func: t.Callable[[Context], t.Iterator[str]]
+    _module: t.Optional["TemplateModule"]
+    _debug_info: str
+    _uptodate: t.Optional[t.Callable[[], bool]]
+
+    def __new__(
+        cls,
+        source: t.Union[str, nodes.Template],
+        block_start_string: str = BLOCK_START_STRING,
+        block_end_string: str = BLOCK_END_STRING,
+        variable_start_string: str = VARIABLE_START_STRING,
+        variable_end_string: str = VARIABLE_END_STRING,
+        comment_start_string: str = COMMENT_START_STRING,
+        comment_end_string: str = COMMENT_END_STRING,
+        line_statement_prefix: t.Optional[str] = LINE_STATEMENT_PREFIX,
+        line_comment_prefix: t.Optional[str] = LINE_COMMENT_PREFIX,
+        trim_blocks: bool = TRIM_BLOCKS,
+        lstrip_blocks: bool = LSTRIP_BLOCKS,
+        newline_sequence: "te.Literal['\\n', '\\r\\n', '\\r']" = NEWLINE_SEQUENCE,
+        keep_trailing_newline: bool = KEEP_TRAILING_NEWLINE,
+        extensions: t.Sequence[t.Union[str, t.Type["Extension"]]] = (),
+        optimized: bool = True,
+        undefined: t.Type[Undefined] = Undefined,
+        finalize: t.Optional[t.Callable[..., t.Any]] = None,
+        autoescape: t.Union[bool, t.Callable[[t.Optional[str]], bool]] = False,
+        enable_async: bool = False,
+    ) -> t.Any:  # it returns a `Template`, but this breaks the sphinx build...
+        env = get_spontaneous_environment(
+            cls.environment_class,  # type: ignore
+            block_start_string,
+            block_end_string,
+            variable_start_string,
+            variable_end_string,
+            comment_start_string,
+            comment_end_string,
+            line_statement_prefix,
+            line_comment_prefix,
+            trim_blocks,
+            lstrip_blocks,
+            newline_sequence,
+            keep_trailing_newline,
+            frozenset(extensions),
+            optimized,
+            undefined,  # type: ignore
+            finalize,
+            autoescape,
+            None,
+            0,
+            False,
+            None,
+            enable_async,
+        )
+        return env.from_string(source, template_class=cls)
+
+    @classmethod
+    def from_code(
+        cls,
+        environment: Environment,
+        code: CodeType,
+        globals: t.MutableMapping[str, t.Any],
+        uptodate: t.Optional[t.Callable[[], bool]] = None,
+    ) -> "Template":
+        """Creates a template object from compiled code and the globals.  This
+        is used by the loaders and environment to create a template object.
+        """
+        namespace = {"environment": environment, "__file__": code.co_filename}
+        exec(code, namespace)
+        rv = cls._from_namespace(environment, namespace, globals)
+        rv._uptodate = uptodate
+        return rv
+
+    @classmethod
+    def from_module_dict(
+        cls,
+        environment: Environment,
+        module_dict: t.MutableMapping[str, t.Any],
+        globals: t.MutableMapping[str, t.Any],
+    ) -> "Template":
+        """Creates a template object from a module.  This is used by the
+        module loader to create a template object.
+
+        .. versionadded:: 2.4
+        """
+        return cls._from_namespace(environment, module_dict, globals)
+
+    @classmethod
+    def _from_namespace(
+        cls,
+        environment: Environment,
+        namespace: t.MutableMapping[str, t.Any],
+        globals: t.MutableMapping[str, t.Any],
+    ) -> "Template":
+        t: "Template" = object.__new__(cls)
+        t.environment = environment
+        t.globals = globals
+        t.name = namespace["name"]
+        t.filename = namespace["__file__"]
+        t.blocks = namespace["blocks"]
+
+        # render function and module
+        t.root_render_func = namespace["root"]  # type: ignore
+        t._module = None
+
+        # debug and loader helpers
+        t._debug_info = namespace["debug_info"]
+        t._uptodate = None
+
+        # store the reference
+        namespace["environment"] = environment
+        namespace["__jinja_template__"] = t
+
+        return t
+
+    def render(self, *args: t.Any, **kwargs: t.Any) -> str:
+        """This method accepts the same arguments as the `dict` constructor:
+        A dict, a dict subclass or some keyword arguments.  If no arguments
+        are given the context will be empty.  These two calls do the same::
+
+            template.render(knights='that say nih')
+            template.render({'knights': 'that say nih'})
+
+        This will return the rendered template as a string.
+        """
+        if self.environment.is_async:
+            import asyncio
+
+            close = False
+
+            try:
+                loop = asyncio.get_running_loop()
+            except RuntimeError:
+                loop = asyncio.new_event_loop()
+                close = True
+
+            try:
+                return loop.run_until_complete(self.render_async(*args, **kwargs))
+            finally:
+                if close:
+                    loop.close()
+
+        ctx = self.new_context(dict(*args, **kwargs))
+
+        try:
+            return self.environment.concat(self.root_render_func(ctx))  # type: ignore
+        except Exception:
+            self.environment.handle_exception()
+
+    async def render_async(self, *args: t.Any, **kwargs: t.Any) -> str:
+        """This works similar to :meth:`render` but returns a coroutine
+        that when awaited returns the entire rendered template string.  This
+        requires the async feature to be enabled.
+
+        Example usage::
+
+            await template.render_async(knights='that say nih; asynchronously')
+        """
+        if not self.environment.is_async:
+            raise RuntimeError(
+                "The environment was not created with async mode enabled."
+            )
+
+        ctx = self.new_context(dict(*args, **kwargs))
+
+        try:
+            return self.environment.concat(  # type: ignore
+                [n async for n in self.root_render_func(ctx)]  # type: ignore
+            )
+        except Exception:
+            return self.environment.handle_exception()
+
+    def stream(self, *args: t.Any, **kwargs: t.Any) -> "TemplateStream":
+        """Works exactly like :meth:`generate` but returns a
+        :class:`TemplateStream`.
+        """
+        return TemplateStream(self.generate(*args, **kwargs))
+
+    def generate(self, *args: t.Any, **kwargs: t.Any) -> t.Iterator[str]:
+        """For very large templates it can be useful to not render the whole
+        template at once but evaluate each statement after another and yield
+        piece for piece.  This method basically does exactly that and returns
+        a generator that yields one item after another as strings.
+
+        It accepts the same arguments as :meth:`render`.
+        """
+        if self.environment.is_async:
+            import asyncio
+
+            async def to_list() -> t.List[str]:
+                return [x async for x in self.generate_async(*args, **kwargs)]
+
+            yield from asyncio.run(to_list())
+            return
+
+        ctx = self.new_context(dict(*args, **kwargs))
+
+        try:
+            yield from self.root_render_func(ctx)  # type: ignore
+        except Exception:
+            yield self.environment.handle_exception()
+
+    async def generate_async(
+        self, *args: t.Any, **kwargs: t.Any
+    ) -> t.AsyncIterator[str]:
+        """An async version of :meth:`generate`.  Works very similarly but
+        returns an async iterator instead.
+        """
+        if not self.environment.is_async:
+            raise RuntimeError(
+                "The environment was not created with async mode enabled."
+            )
+
+        ctx = self.new_context(dict(*args, **kwargs))
+
+        try:
+            async for event in self.root_render_func(ctx):  # type: ignore
+                yield event
+        except Exception:
+            yield self.environment.handle_exception()
+
+    def new_context(
+        self,
+        vars: t.Optional[t.Dict[str, t.Any]] = None,
+        shared: bool = False,
+        locals: t.Optional[t.Mapping[str, t.Any]] = None,
+    ) -> Context:
+        """Create a new :class:`Context` for this template.  The vars
+        provided will be passed to the template.  Per default the globals
+        are added to the context.  If shared is set to `True` the data
+        is passed as is to the context without adding the globals.
+
+        `locals` can be a dict of local variables for internal usage.
+        """
+        return new_context(
+            self.environment, self.name, self.blocks, vars, shared, self.globals, locals
+        )
+
+    def make_module(
+        self,
+        vars: t.Optional[t.Dict[str, t.Any]] = None,
+        shared: bool = False,
+        locals: t.Optional[t.Mapping[str, t.Any]] = None,
+    ) -> "TemplateModule":
+        """This method works like the :attr:`module` attribute when called
+        without arguments but it will evaluate the template on every call
+        rather than caching it.  It's also possible to provide
+        a dict which is then used as context.  The arguments are the same
+        as for the :meth:`new_context` method.
+        """
+        ctx = self.new_context(vars, shared, locals)
+        return TemplateModule(self, ctx)
+
+    async def make_module_async(
+        self,
+        vars: t.Optional[t.Dict[str, t.Any]] = None,
+        shared: bool = False,
+        locals: t.Optional[t.Mapping[str, t.Any]] = None,
+    ) -> "TemplateModule":
+        """As template module creation can invoke template code for
+        asynchronous executions this method must be used instead of the
+        normal :meth:`make_module` one.  Likewise the module attribute
+        becomes unavailable in async mode.
+        """
+        ctx = self.new_context(vars, shared, locals)
+        return TemplateModule(
+            self, ctx, [x async for x in self.root_render_func(ctx)]  # type: ignore
+        )
+
+    @internalcode
+    def _get_default_module(self, ctx: t.Optional[Context] = None) -> "TemplateModule":
+        """If a context is passed in, this means that the template was
+        imported. Imported templates have access to the current
+        template's globals by default, but they can only be accessed via
+        the context during runtime.
+
+        If there are new globals, we need to create a new module because
+        the cached module is already rendered and will not have access
+        to globals from the current context. This new module is not
+        cached because the template can be imported elsewhere, and it
+        should have access to only the current template's globals.
+        """
+        if self.environment.is_async:
+            raise RuntimeError("Module is not available in async mode.")
+
+        if ctx is not None:
+            keys = ctx.globals_keys - self.globals.keys()
+
+            if keys:
+                return self.make_module({k: ctx.parent[k] for k in keys})
+
+        if self._module is None:
+            self._module = self.make_module()
+
+        return self._module
+
+    async def _get_default_module_async(
+        self, ctx: t.Optional[Context] = None
+    ) -> "TemplateModule":
+        if ctx is not None:
+            keys = ctx.globals_keys - self.globals.keys()
+
+            if keys:
+                return await self.make_module_async({k: ctx.parent[k] for k in keys})
+
+        if self._module is None:
+            self._module = await self.make_module_async()
+
+        return self._module
+
+    @property
+    def module(self) -> "TemplateModule":
+        """The template as module.  This is used for imports in the
+        template runtime but is also useful if one wants to access
+        exported template variables from the Python layer:
+
+        >>> t = Template('{% macro foo() %}42{% endmacro %}23')
+        >>> str(t.module)
+        '23'
+        >>> t.module.foo() == u'42'
+        True
+
+        This attribute is not available if async mode is enabled.
+        """
+        return self._get_default_module()
+
+    def get_corresponding_lineno(self, lineno: int) -> int:
+        """Return the source line number of a line number in the
+        generated bytecode as they are not in sync.
+        """
+        for template_line, code_line in reversed(self.debug_info):
+            if code_line <= lineno:
+                return template_line
+        return 1
+
+    @property
+    def is_up_to_date(self) -> bool:
+        """If this variable is `False` there is a newer version available."""
+        if self._uptodate is None:
+            return True
+        return self._uptodate()
+
+    @property
+    def debug_info(self) -> t.List[t.Tuple[int, int]]:
+        """The debug info mapping."""
+        if self._debug_info:
+            return [
+                tuple(map(int, x.split("=")))  # type: ignore
+                for x in self._debug_info.split("&")
+            ]
+
+        return []
+
+    def __repr__(self) -> str:
+        if self.name is None:
+            name = f"memory:{id(self):x}"
+        else:
+            name = repr(self.name)
+        return f"<{type(self).__name__} {name}>"
+
+
+class TemplateModule:
+    """Represents an imported template.  All the exported names of the
+    template are available as attributes on this object.  Additionally
+    converting it into a string renders the contents.
+    """
+
+    def __init__(
+        self,
+        template: Template,
+        context: Context,
+        body_stream: t.Optional[t.Iterable[str]] = None,
+    ) -> None:
+        if body_stream is None:
+            if context.environment.is_async:
+                raise RuntimeError(
+                    "Async mode requires a body stream to be passed to"
+                    " a template module. Use the async methods of the"
+                    " API you are using."
+                )
+
+            body_stream = list(template.root_render_func(context))  # type: ignore
+
+        self._body_stream = body_stream
+        self.__dict__.update(context.get_exported())
+        self.__name__ = template.name
+
+    def __html__(self) -> Markup:
+        return Markup(concat(self._body_stream))
+
+    def __str__(self) -> str:
+        return concat(self._body_stream)
+
+    def __repr__(self) -> str:
+        if self.__name__ is None:
+            name = f"memory:{id(self):x}"
+        else:
+            name = repr(self.__name__)
+        return f"<{type(self).__name__} {name}>"
+
+
+class TemplateExpression:
+    """The :meth:`jinja2.Environment.compile_expression` method returns an
+    instance of this object.  It encapsulates the expression-like access
+    to the template with an expression it wraps.
+    """
+
+    def __init__(self, template: Template, undefined_to_none: bool) -> None:
+        self._template = template
+        self._undefined_to_none = undefined_to_none
+
+    def __call__(self, *args: t.Any, **kwargs: t.Any) -> t.Optional[t.Any]:
+        context = self._template.new_context(dict(*args, **kwargs))
+        consume(self._template.root_render_func(context))  # type: ignore
+        rv = context.vars["result"]
+        if self._undefined_to_none and isinstance(rv, Undefined):
+            rv = None
+        return rv
+
+
+class TemplateStream:
+    """A template stream works pretty much like an ordinary python generator
+    but it can buffer multiple items to reduce the number of total iterations.
+    Per default the output is unbuffered which means that for every unbuffered
+    instruction in the template one string is yielded.
+
+    If buffering is enabled with a buffer size of 5, five items are combined
+    into a new string.  This is mainly useful if you are streaming
+    big templates to a client via WSGI which flushes after each iteration.
+    """
+
+    def __init__(self, gen: t.Iterator[str]) -> None:
+        self._gen = gen
+        self.disable_buffering()
+
+    def dump(
+        self,
+        fp: t.Union[str, t.IO],
+        encoding: t.Optional[str] = None,
+        errors: t.Optional[str] = "strict",
+    ) -> None:
+        """Dump the complete stream into a file or file-like object.
+        Per default strings are written, if you want to encode
+        before writing specify an `encoding`.
+
+        Example usage::
+
+            Template('Hello {{ name }}!').stream(name='foo').dump('hello.html')
+        """
+        close = False
+
+        if isinstance(fp, str):
+            if encoding is None:
+                encoding = "utf-8"
+
+            fp = open(fp, "wb")
+            close = True
+        try:
+            if encoding is not None:
+                iterable = (x.encode(encoding, errors) for x in self)  # type: ignore
+            else:
+                iterable = self  # type: ignore
+
+            if hasattr(fp, "writelines"):
+                fp.writelines(iterable)
+            else:
+                for item in iterable:
+                    fp.write(item)
+        finally:
+            if close:
+                fp.close()
+
+    def disable_buffering(self) -> None:
+        """Disable the output buffering."""
+        self._next = partial(next, self._gen)
+        self.buffered = False
+
+    def _buffered_generator(self, size: int) -> t.Iterator[str]:
+        buf: t.List[str] = []
+        c_size = 0
+        push = buf.append
+
+        while True:
+            try:
+                while c_size < size:
+                    c = next(self._gen)
+                    push(c)
+                    if c:
+                        c_size += 1
+            except StopIteration:
+                if not c_size:
+                    return
+            yield concat(buf)
+            del buf[:]
+            c_size = 0
+
+    def enable_buffering(self, size: int = 5) -> None:
+        """Enable buffering.  Buffer `size` items before yielding them."""
+        if size <= 1:
+            raise ValueError("buffer size too small")
+
+        self.buffered = True
+        self._next = partial(next, self._buffered_generator(size))
+
+    def __iter__(self) -> "TemplateStream":
+        return self
+
+    def __next__(self) -> str:
+        return self._next()  # type: ignore
+
+
+# hook in default template class.  if anyone reads this comment: ignore that
+# it's possible to use custom templates ;-)
+Environment.template_class = Template
diff --git a/src/jinja2/exceptions.py b/src/jinja2/exceptions.py
new file mode 100644
index 0000000..082ebe8
--- /dev/null
+++ b/src/jinja2/exceptions.py
@@ -0,0 +1,166 @@
+import typing as t
+
+if t.TYPE_CHECKING:
+    from .runtime import Undefined
+
+
+class TemplateError(Exception):
+    """Baseclass for all template errors."""
+
+    def __init__(self, message: t.Optional[str] = None) -> None:
+        super().__init__(message)
+
+    @property
+    def message(self) -> t.Optional[str]:
+        return self.args[0] if self.args else None
+
+
+class TemplateNotFound(IOError, LookupError, TemplateError):
+    """Raised if a template does not exist.
+
+    .. versionchanged:: 2.11
+        If the given name is :class:`Undefined` and no message was
+        provided, an :exc:`UndefinedError` is raised.
+    """
+
+    # Silence the Python warning about message being deprecated since
+    # it's not valid here.
+    message: t.Optional[str] = None
+
+    def __init__(
+        self,
+        name: t.Optional[t.Union[str, "Undefined"]],
+        message: t.Optional[str] = None,
+    ) -> None:
+        IOError.__init__(self, name)
+
+        if message is None:
+            from .runtime import Undefined
+
+            if isinstance(name, Undefined):
+                name._fail_with_undefined_error()
+
+            message = name
+
+        self.message = message
+        self.name = name
+        self.templates = [name]
+
+    def __str__(self) -> str:
+        return str(self.message)
+
+
+class TemplatesNotFound(TemplateNotFound):
+    """Like :class:`TemplateNotFound` but raised if multiple templates
+    are selected.  This is a subclass of :class:`TemplateNotFound`
+    exception, so just catching the base exception will catch both.
+
+    .. versionchanged:: 2.11
+        If a name in the list of names is :class:`Undefined`, a message
+        about it being undefined is shown rather than the empty string.
+
+    .. versionadded:: 2.2
+    """
+
+    def __init__(
+        self,
+        names: t.Sequence[t.Union[str, "Undefined"]] = (),
+        message: t.Optional[str] = None,
+    ) -> None:
+        if message is None:
+            from .runtime import Undefined
+
+            parts = []
+
+            for name in names:
+                if isinstance(name, Undefined):
+                    parts.append(name._undefined_message)
+                else:
+                    parts.append(name)
+
+            parts_str = ", ".join(map(str, parts))
+            message = f"none of the templates given were found: {parts_str}"
+
+        super().__init__(names[-1] if names else None, message)
+        self.templates = list(names)
+
+
+class TemplateSyntaxError(TemplateError):
+    """Raised to tell the user that there is a problem with the template."""
+
+    def __init__(
+        self,
+        message: str,
+        lineno: int,
+        name: t.Optional[str] = None,
+        filename: t.Optional[str] = None,
+    ) -> None:
+        super().__init__(message)
+        self.lineno = lineno
+        self.name = name
+        self.filename = filename
+        self.source: t.Optional[str] = None
+
+        # this is set to True if the debug.translate_syntax_error
+        # function translated the syntax error into a new traceback
+        self.translated = False
+
+    def __str__(self) -> str:
+        # for translated errors we only return the message
+        if self.translated:
+            return t.cast(str, self.message)
+
+        # otherwise attach some stuff
+        location = f"line {self.lineno}"
+        name = self.filename or self.name
+        if name:
+            location = f'File "{name}", {location}'
+        lines = [t.cast(str, self.message), "  " + location]
+
+        # if the source is set, add the line to the output
+        if self.source is not None:
+            try:
+                line = self.source.splitlines()[self.lineno - 1]
+            except IndexError:
+                pass
+            else:
+                lines.append("    " + line.strip())
+
+        return "\n".join(lines)
+
+    def __reduce__(self):  # type: ignore
+        # https://bugs.python.org/issue1692335 Exceptions that take
+        # multiple required arguments have problems with pickling.
+        # Without this, raises TypeError: __init__() missing 1 required
+        # positional argument: 'lineno'
+        return self.__class__, (self.message, self.lineno, self.name, self.filename)
+
+
+class TemplateAssertionError(TemplateSyntaxError):
+    """Like a template syntax error, but covers cases where something in the
+    template caused an error at compile time that wasn't necessarily caused
+    by a syntax error.  However it's a direct subclass of
+    :exc:`TemplateSyntaxError` and has the same attributes.
+    """
+
+
+class TemplateRuntimeError(TemplateError):
+    """A generic runtime error in the template engine.  Under some situations
+    Jinja may raise this exception.
+    """
+
+
+class UndefinedError(TemplateRuntimeError):
+    """Raised if a template tries to operate on :class:`Undefined`."""
+
+
+class SecurityError(TemplateRuntimeError):
+    """Raised if a template tries to do something insecure if the
+    sandbox is enabled.
+    """
+
+
+class FilterArgumentError(TemplateRuntimeError):
+    """This error is raised if a filter was called with inappropriate
+    arguments
+    """
diff --git a/src/jinja2/ext.py b/src/jinja2/ext.py
new file mode 100644
index 0000000..d555054
--- /dev/null
+++ b/src/jinja2/ext.py
@@ -0,0 +1,859 @@
+"""Extension API for adding custom tags and behavior."""
+import pprint
+import re
+import typing as t
+
+from markupsafe import Markup
+
+from . import defaults
+from . import nodes
+from .environment import Environment
+from .exceptions import TemplateAssertionError
+from .exceptions import TemplateSyntaxError
+from .runtime import concat  # type: ignore
+from .runtime import Context
+from .runtime import Undefined
+from .utils import import_string
+from .utils import pass_context
+
+if t.TYPE_CHECKING:
+    import typing_extensions as te
+    from .lexer import Token
+    from .lexer import TokenStream
+    from .parser import Parser
+
+    class _TranslationsBasic(te.Protocol):
+        def gettext(self, message: str) -> str:
+            ...
+
+        def ngettext(self, singular: str, plural: str, n: int) -> str:
+            pass
+
+    class _TranslationsContext(_TranslationsBasic):
+        def pgettext(self, context: str, message: str) -> str:
+            ...
+
+        def npgettext(self, context: str, singular: str, plural: str, n: int) -> str:
+            ...
+
+    _SupportedTranslations = t.Union[_TranslationsBasic, _TranslationsContext]
+
+
+# I18N functions available in Jinja templates. If the I18N library
+# provides ugettext, it will be assigned to gettext.
+GETTEXT_FUNCTIONS: t.Tuple[str, ...] = (
+    "_",
+    "gettext",
+    "ngettext",
+    "pgettext",
+    "npgettext",
+)
+_ws_re = re.compile(r"\s*\n\s*")
+
+
+class Extension:
+    """Extensions can be used to add extra functionality to the Jinja template
+    system at the parser level.  Custom extensions are bound to an environment
+    but may not store environment specific data on `self`.  The reason for
+    this is that an extension can be bound to another environment (for
+    overlays) by creating a copy and reassigning the `environment` attribute.
+
+    As extensions are created by the environment they cannot accept any
+    arguments for configuration.  One may want to work around that by using
+    a factory function, but that is not possible as extensions are identified
+    by their import name.  The correct way to configure the extension is
+    storing the configuration values on the environment.  Because this way the
+    environment ends up acting as central configuration storage the
+    attributes may clash which is why extensions have to ensure that the names
+    they choose for configuration are not too generic.  ``prefix`` for example
+    is a terrible name, ``fragment_cache_prefix`` on the other hand is a good
+    name as includes the name of the extension (fragment cache).
+    """
+
+    identifier: t.ClassVar[str]
+
+    def __init_subclass__(cls) -> None:
+        cls.identifier = f"{cls.__module__}.{cls.__name__}"
+
+    #: if this extension parses this is the list of tags it's listening to.
+    tags: t.Set[str] = set()
+
+    #: the priority of that extension.  This is especially useful for
+    #: extensions that preprocess values.  A lower value means higher
+    #: priority.
+    #:
+    #: .. versionadded:: 2.4
+    priority = 100
+
+    def __init__(self, environment: Environment) -> None:
+        self.environment = environment
+
+    def bind(self, environment: Environment) -> "Extension":
+        """Create a copy of this extension bound to another environment."""
+        rv = object.__new__(self.__class__)
+        rv.__dict__.update(self.__dict__)
+        rv.environment = environment
+        return rv
+
+    def preprocess(
+        self, source: str, name: t.Optional[str], filename: t.Optional[str] = None
+    ) -> str:
+        """This method is called before the actual lexing and can be used to
+        preprocess the source.  The `filename` is optional.  The return value
+        must be the preprocessed source.
+        """
+        return source
+
+    def filter_stream(
+        self, stream: "TokenStream"
+    ) -> t.Union["TokenStream", t.Iterable["Token"]]:
+        """It's passed a :class:`~jinja2.lexer.TokenStream` that can be used
+        to filter tokens returned.  This method has to return an iterable of
+        :class:`~jinja2.lexer.Token`\\s, but it doesn't have to return a
+        :class:`~jinja2.lexer.TokenStream`.
+        """
+        return stream
+
+    def parse(self, parser: "Parser") -> t.Union[nodes.Node, t.List[nodes.Node]]:
+        """If any of the :attr:`tags` matched this method is called with the
+        parser as first argument.  The token the parser stream is pointing at
+        is the name token that matched.  This method has to return one or a
+        list of multiple nodes.
+        """
+        raise NotImplementedError()
+
+    def attr(
+        self, name: str, lineno: t.Optional[int] = None
+    ) -> nodes.ExtensionAttribute:
+        """Return an attribute node for the current extension.  This is useful
+        to pass constants on extensions to generated template code.
+
+        ::
+
+            self.attr('_my_attribute', lineno=lineno)
+        """
+        return nodes.ExtensionAttribute(self.identifier, name, lineno=lineno)
+
+    def call_method(
+        self,
+        name: str,
+        args: t.Optional[t.List[nodes.Expr]] = None,
+        kwargs: t.Optional[t.List[nodes.Keyword]] = None,
+        dyn_args: t.Optional[nodes.Expr] = None,
+        dyn_kwargs: t.Optional[nodes.Expr] = None,
+        lineno: t.Optional[int] = None,
+    ) -> nodes.Call:
+        """Call a method of the extension.  This is a shortcut for
+        :meth:`attr` + :class:`jinja2.nodes.Call`.
+        """
+        if args is None:
+            args = []
+        if kwargs is None:
+            kwargs = []
+        return nodes.Call(
+            self.attr(name, lineno=lineno),
+            args,
+            kwargs,
+            dyn_args,
+            dyn_kwargs,
+            lineno=lineno,
+        )
+
+
+@pass_context
+def _gettext_alias(
+    __context: Context, *args: t.Any, **kwargs: t.Any
+) -> t.Union[t.Any, Undefined]:
+    return __context.call(__context.resolve("gettext"), *args, **kwargs)
+
+
+def _make_new_gettext(func: t.Callable[[str], str]) -> t.Callable[..., str]:
+    @pass_context
+    def gettext(__context: Context, __string: str, **variables: t.Any) -> str:
+        rv = __context.call(func, __string)
+        if __context.eval_ctx.autoescape:
+            rv = Markup(rv)
+        # Always treat as a format string, even if there are no
+        # variables. This makes translation strings more consistent
+        # and predictable. This requires escaping
+        return rv % variables  # type: ignore
+
+    return gettext
+
+
+def _make_new_ngettext(func: t.Callable[[str, str, int], str]) -> t.Callable[..., str]:
+    @pass_context
+    def ngettext(
+        __context: Context,
+        __singular: str,
+        __plural: str,
+        __num: int,
+        **variables: t.Any,
+    ) -> str:
+        variables.setdefault("num", __num)
+        rv = __context.call(func, __singular, __plural, __num)
+        if __context.eval_ctx.autoescape:
+            rv = Markup(rv)
+        # Always treat as a format string, see gettext comment above.
+        return rv % variables  # type: ignore
+
+    return ngettext
+
+
+def _make_new_pgettext(func: t.Callable[[str, str], str]) -> t.Callable[..., str]:
+    @pass_context
+    def pgettext(
+        __context: Context, __string_ctx: str, __string: str, **variables: t.Any
+    ) -> str:
+        variables.setdefault("context", __string_ctx)
+        rv = __context.call(func, __string_ctx, __string)
+
+        if __context.eval_ctx.autoescape:
+            rv = Markup(rv)
+
+        # Always treat as a format string, see gettext comment above.
+        return rv % variables  # type: ignore
+
+    return pgettext
+
+
+def _make_new_npgettext(
+    func: t.Callable[[str, str, str, int], str]
+) -> t.Callable[..., str]:
+    @pass_context
+    def npgettext(
+        __context: Context,
+        __string_ctx: str,
+        __singular: str,
+        __plural: str,
+        __num: int,
+        **variables: t.Any,
+    ) -> str:
+        variables.setdefault("context", __string_ctx)
+        variables.setdefault("num", __num)
+        rv = __context.call(func, __string_ctx, __singular, __plural, __num)
+
+        if __context.eval_ctx.autoescape:
+            rv = Markup(rv)
+
+        # Always treat as a format string, see gettext comment above.
+        return rv % variables  # type: ignore
+
+    return npgettext
+
+
+class InternationalizationExtension(Extension):
+    """This extension adds gettext support to Jinja."""
+
+    tags = {"trans"}
+
+    # TODO: the i18n extension is currently reevaluating values in a few
+    # situations.  Take this example:
+    #   {% trans count=something() %}{{ count }} foo{% pluralize
+    #     %}{{ count }} fooss{% endtrans %}
+    # something is called twice here.  One time for the gettext value and
+    # the other time for the n-parameter of the ngettext function.
+
+    def __init__(self, environment: Environment) -> None:
+        super().__init__(environment)
+        environment.globals["_"] = _gettext_alias
+        environment.extend(
+            install_gettext_translations=self._install,
+            install_null_translations=self._install_null,
+            install_gettext_callables=self._install_callables,
+            uninstall_gettext_translations=self._uninstall,
+            extract_translations=self._extract,
+            newstyle_gettext=False,
+        )
+
+    def _install(
+        self, translations: "_SupportedTranslations", newstyle: t.Optional[bool] = None
+    ) -> None:
+        # ugettext and ungettext are preferred in case the I18N library
+        # is providing compatibility with older Python versions.
+        gettext = getattr(translations, "ugettext", None)
+        if gettext is None:
+            gettext = translations.gettext
+        ngettext = getattr(translations, "ungettext", None)
+        if ngettext is None:
+            ngettext = translations.ngettext
+
+        pgettext = getattr(translations, "pgettext", None)
+        npgettext = getattr(translations, "npgettext", None)
+        self._install_callables(
+            gettext, ngettext, newstyle=newstyle, pgettext=pgettext, npgettext=npgettext
+        )
+
+    def _install_null(self, newstyle: t.Optional[bool] = None) -> None:
+        import gettext
+
+        translations = gettext.NullTranslations()
+
+        if hasattr(translations, "pgettext"):
+            # Python < 3.8
+            pgettext = translations.pgettext  # type: ignore
+        else:
+
+            def pgettext(c: str, s: str) -> str:
+                return s
+
+        if hasattr(translations, "npgettext"):
+            npgettext = translations.npgettext  # type: ignore
+        else:
+
+            def npgettext(c: str, s: str, p: str, n: int) -> str:
+                return s if n == 1 else p
+
+        self._install_callables(
+            gettext=translations.gettext,
+            ngettext=translations.ngettext,
+            newstyle=newstyle,
+            pgettext=pgettext,
+            npgettext=npgettext,
+        )
+
+    def _install_callables(
+        self,
+        gettext: t.Callable[[str], str],
+        ngettext: t.Callable[[str, str, int], str],
+        newstyle: t.Optional[bool] = None,
+        pgettext: t.Optional[t.Callable[[str, str], str]] = None,
+        npgettext: t.Optional[t.Callable[[str, str, str, int], str]] = None,
+    ) -> None:
+        if newstyle is not None:
+            self.environment.newstyle_gettext = newstyle  # type: ignore
+        if self.environment.newstyle_gettext:  # type: ignore
+            gettext = _make_new_gettext(gettext)
+            ngettext = _make_new_ngettext(ngettext)
+
+            if pgettext is not None:
+                pgettext = _make_new_pgettext(pgettext)
+
+            if npgettext is not None:
+                npgettext = _make_new_npgettext(npgettext)
+
+        self.environment.globals.update(
+            gettext=gettext, ngettext=ngettext, pgettext=pgettext, npgettext=npgettext
+        )
+
+    def _uninstall(self, translations: "_SupportedTranslations") -> None:
+        for key in ("gettext", "ngettext", "pgettext", "npgettext"):
+            self.environment.globals.pop(key, None)
+
+    def _extract(
+        self,
+        source: t.Union[str, nodes.Template],
+        gettext_functions: t.Sequence[str] = GETTEXT_FUNCTIONS,
+    ) -> t.Iterator[
+        t.Tuple[int, str, t.Union[t.Optional[str], t.Tuple[t.Optional[str], ...]]]
+    ]:
+        if isinstance(source, str):
+            source = self.environment.parse(source)
+        return extract_from_ast(source, gettext_functions)
+
+    def parse(self, parser: "Parser") -> t.Union[nodes.Node, t.List[nodes.Node]]:
+        """Parse a translatable tag."""
+        lineno = next(parser.stream).lineno
+
+        context = None
+        context_token = parser.stream.next_if("string")
+
+        if context_token is not None:
+            context = context_token.value
+
+        # find all the variables referenced.  Additionally a variable can be
+        # defined in the body of the trans block too, but this is checked at
+        # a later state.
+        plural_expr: t.Optional[nodes.Expr] = None
+        plural_expr_assignment: t.Optional[nodes.Assign] = None
+        num_called_num = False
+        variables: t.Dict[str, nodes.Expr] = {}
+        trimmed = None
+        while parser.stream.current.type != "block_end":
+            if variables:
+                parser.stream.expect("comma")
+
+            # skip colon for python compatibility
+            if parser.stream.skip_if("colon"):
+                break
+
+            token = parser.stream.expect("name")
+            if token.value in variables:
+                parser.fail(
+                    f"translatable variable {token.value!r} defined twice.",
+                    token.lineno,
+                    exc=TemplateAssertionError,
+                )
+
+            # expressions
+            if parser.stream.current.type == "assign":
+                next(parser.stream)
+                variables[token.value] = var = parser.parse_expression()
+            elif trimmed is None and token.value in ("trimmed", "notrimmed"):
+                trimmed = token.value == "trimmed"
+                continue
+            else:
+                variables[token.value] = var = nodes.Name(token.value, "load")
+
+            if plural_expr is None:
+                if isinstance(var, nodes.Call):
+                    plural_expr = nodes.Name("_trans", "load")
+                    variables[token.value] = plural_expr
+                    plural_expr_assignment = nodes.Assign(
+                        nodes.Name("_trans", "store"), var
+                    )
+                else:
+                    plural_expr = var
+                num_called_num = token.value == "num"
+
+        parser.stream.expect("block_end")
+
+        plural = None
+        have_plural = False
+        referenced = set()
+
+        # now parse until endtrans or pluralize
+        singular_names, singular = self._parse_block(parser, True)
+        if singular_names:
+            referenced.update(singular_names)
+            if plural_expr is None:
+                plural_expr = nodes.Name(singular_names[0], "load")
+                num_called_num = singular_names[0] == "num"
+
+        # if we have a pluralize block, we parse that too
+        if parser.stream.current.test("name:pluralize"):
+            have_plural = True
+            next(parser.stream)
+            if parser.stream.current.type != "block_end":
+                token = parser.stream.expect("name")
+                if token.value not in variables:
+                    parser.fail(
+                        f"unknown variable {token.value!r} for pluralization",
+                        token.lineno,
+                        exc=TemplateAssertionError,
+                    )
+                plural_expr = variables[token.value]
+                num_called_num = token.value == "num"
+            parser.stream.expect("block_end")
+            plural_names, plural = self._parse_block(parser, False)
+            next(parser.stream)
+            referenced.update(plural_names)
+        else:
+            next(parser.stream)
+
+        # register free names as simple name expressions
+        for name in referenced:
+            if name not in variables:
+                variables[name] = nodes.Name(name, "load")
+
+        if not have_plural:
+            plural_expr = None
+        elif plural_expr is None:
+            parser.fail("pluralize without variables", lineno)
+
+        if trimmed is None:
+            trimmed = self.environment.policies["ext.i18n.trimmed"]
+        if trimmed:
+            singular = self._trim_whitespace(singular)
+            if plural:
+                plural = self._trim_whitespace(plural)
+
+        node = self._make_node(
+            singular,
+            plural,
+            context,
+            variables,
+            plural_expr,
+            bool(referenced),
+            num_called_num and have_plural,
+        )
+        node.set_lineno(lineno)
+        if plural_expr_assignment is not None:
+            return [plural_expr_assignment, node]
+        else:
+            return node
+
+    def _trim_whitespace(self, string: str, _ws_re: t.Pattern[str] = _ws_re) -> str:
+        return _ws_re.sub(" ", string.strip())
+
+    def _parse_block(
+        self, parser: "Parser", allow_pluralize: bool
+    ) -> t.Tuple[t.List[str], str]:
+        """Parse until the next block tag with a given name."""
+        referenced = []
+        buf = []
+
+        while True:
+            if parser.stream.current.type == "data":
+                buf.append(parser.stream.current.value.replace("%", "%%"))
+                next(parser.stream)
+            elif parser.stream.current.type == "variable_begin":
+                next(parser.stream)
+                name = parser.stream.expect("name").value
+                referenced.append(name)
+                buf.append(f"%({name})s")
+                parser.stream.expect("variable_end")
+            elif parser.stream.current.type == "block_begin":
+                next(parser.stream)
+                if parser.stream.current.test("name:endtrans"):
+                    break
+                elif parser.stream.current.test("name:pluralize"):
+                    if allow_pluralize:
+                        break
+                    parser.fail(
+                        "a translatable section can have only one pluralize section"
+                    )
+                parser.fail(
+                    "control structures in translatable sections are not allowed"
+                )
+            elif parser.stream.eos:
+                parser.fail("unclosed translation block")
+            else:
+                raise RuntimeError("internal parser error")
+
+        return referenced, concat(buf)
+
+    def _make_node(
+        self,
+        singular: str,
+        plural: t.Optional[str],
+        context: t.Optional[str],
+        variables: t.Dict[str, nodes.Expr],
+        plural_expr: t.Optional[nodes.Expr],
+        vars_referenced: bool,
+        num_called_num: bool,
+    ) -> nodes.Output:
+        """Generates a useful node from the data provided."""
+        newstyle = self.environment.newstyle_gettext  # type: ignore
+        node: nodes.Expr
+
+        # no variables referenced?  no need to escape for old style
+        # gettext invocations only if there are vars.
+        if not vars_referenced and not newstyle:
+            singular = singular.replace("%%", "%")
+            if plural:
+                plural = plural.replace("%%", "%")
+
+        func_name = "gettext"
+        func_args: t.List[nodes.Expr] = [nodes.Const(singular)]
+
+        if context is not None:
+            func_args.insert(0, nodes.Const(context))
+            func_name = f"p{func_name}"
+
+        if plural_expr is not None:
+            func_name = f"n{func_name}"
+            func_args.extend((nodes.Const(plural), plural_expr))
+
+        node = nodes.Call(nodes.Name(func_name, "load"), func_args, [], None, None)
+
+        # in case newstyle gettext is used, the method is powerful
+        # enough to handle the variable expansion and autoescape
+        # handling itself
+        if newstyle:
+            for key, value in variables.items():
+                # the function adds that later anyways in case num was
+                # called num, so just skip it.
+                if num_called_num and key == "num":
+                    continue
+                node.kwargs.append(nodes.Keyword(key, value))
+
+        # otherwise do that here
+        else:
+            # mark the return value as safe if we are in an
+            # environment with autoescaping turned on
+            node = nodes.MarkSafeIfAutoescape(node)
+            if variables:
+                node = nodes.Mod(
+                    node,
+                    nodes.Dict(
+                        [
+                            nodes.Pair(nodes.Const(key), value)
+                            for key, value in variables.items()
+                        ]
+                    ),
+                )
+        return nodes.Output([node])
+
+
+class ExprStmtExtension(Extension):
+    """Adds a `do` tag to Jinja that works like the print statement just
+    that it doesn't print the return value.
+    """
+
+    tags = {"do"}
+
+    def parse(self, parser: "Parser") -> nodes.ExprStmt:
+        node = nodes.ExprStmt(lineno=next(parser.stream).lineno)
+        node.node = parser.parse_tuple()
+        return node
+
+
+class LoopControlExtension(Extension):
+    """Adds break and continue to the template engine."""
+
+    tags = {"break", "continue"}
+
+    def parse(self, parser: "Parser") -> t.Union[nodes.Break, nodes.Continue]:
+        token = next(parser.stream)
+        if token.value == "break":
+            return nodes.Break(lineno=token.lineno)
+        return nodes.Continue(lineno=token.lineno)
+
+
+class DebugExtension(Extension):
+    """A ``{% debug %}`` tag that dumps the available variables,
+    filters, and tests.
+
+    .. code-block:: html+jinja
+
+        <pre>{% debug %}</pre>
+
+    .. code-block:: text
+
+        {'context': {'cycler': <class 'jinja2.utils.Cycler'>,
+                     ...,
+                     'namespace': <class 'jinja2.utils.Namespace'>},
+         'filters': ['abs', 'attr', 'batch', 'capitalize', 'center', 'count', 'd',
+                     ..., 'urlencode', 'urlize', 'wordcount', 'wordwrap', 'xmlattr'],
+         'tests': ['!=', '<', '<=', '==', '>', '>=', 'callable', 'defined',
+                   ..., 'odd', 'sameas', 'sequence', 'string', 'undefined', 'upper']}
+
+    .. versionadded:: 2.11.0
+    """
+
+    tags = {"debug"}
+
+    def parse(self, parser: "Parser") -> nodes.Output:
+        lineno = parser.stream.expect("name:debug").lineno
+        context = nodes.ContextReference()
+        result = self.call_method("_render", [context], lineno=lineno)
+        return nodes.Output([result], lineno=lineno)
+
+    def _render(self, context: Context) -> str:
+        result = {
+            "context": context.get_all(),
+            "filters": sorted(self.environment.filters.keys()),
+            "tests": sorted(self.environment.tests.keys()),
+        }
+
+        # Set the depth since the intent is to show the top few names.
+        return pprint.pformat(result, depth=3, compact=True)
+
+
+def extract_from_ast(
+    ast: nodes.Template,
+    gettext_functions: t.Sequence[str] = GETTEXT_FUNCTIONS,
+    babel_style: bool = True,
+) -> t.Iterator[
+    t.Tuple[int, str, t.Union[t.Optional[str], t.Tuple[t.Optional[str], ...]]]
+]:
+    """Extract localizable strings from the given template node.  Per
+    default this function returns matches in babel style that means non string
+    parameters as well as keyword arguments are returned as `None`.  This
+    allows Babel to figure out what you really meant if you are using
+    gettext functions that allow keyword arguments for placeholder expansion.
+    If you don't want that behavior set the `babel_style` parameter to `False`
+    which causes only strings to be returned and parameters are always stored
+    in tuples.  As a consequence invalid gettext calls (calls without a single
+    string parameter or string parameters after non-string parameters) are
+    skipped.
+
+    This example explains the behavior:
+
+    >>> from jinja2 import Environment
+    >>> env = Environment()
+    >>> node = env.parse('{{ (_("foo"), _(), ngettext("foo", "bar", 42)) }}')
+    >>> list(extract_from_ast(node))
+    [(1, '_', 'foo'), (1, '_', ()), (1, 'ngettext', ('foo', 'bar', None))]
+    >>> list(extract_from_ast(node, babel_style=False))
+    [(1, '_', ('foo',)), (1, 'ngettext', ('foo', 'bar'))]
+
+    For every string found this function yields a ``(lineno, function,
+    message)`` tuple, where:
+
+    * ``lineno`` is the number of the line on which the string was found,
+    * ``function`` is the name of the ``gettext`` function used (if the
+      string was extracted from embedded Python code), and
+    *   ``message`` is the string, or a tuple of strings for functions
+         with multiple string arguments.
+
+    This extraction function operates on the AST and is because of that unable
+    to extract any comments.  For comment support you have to use the babel
+    extraction interface or extract comments yourself.
+    """
+    out: t.Union[t.Optional[str], t.Tuple[t.Optional[str], ...]]
+
+    for node in ast.find_all(nodes.Call):
+        if (
+            not isinstance(node.node, nodes.Name)
+            or node.node.name not in gettext_functions
+        ):
+            continue
+
+        strings: t.List[t.Optional[str]] = []
+
+        for arg in node.args:
+            if isinstance(arg, nodes.Const) and isinstance(arg.value, str):
+                strings.append(arg.value)
+            else:
+                strings.append(None)
+
+        for _ in node.kwargs:
+            strings.append(None)
+        if node.dyn_args is not None:
+            strings.append(None)
+        if node.dyn_kwargs is not None:
+            strings.append(None)
+
+        if not babel_style:
+            out = tuple(x for x in strings if x is not None)
+
+            if not out:
+                continue
+        else:
+            if len(strings) == 1:
+                out = strings[0]
+            else:
+                out = tuple(strings)
+
+        yield node.lineno, node.node.name, out
+
+
+class _CommentFinder:
+    """Helper class to find comments in a token stream.  Can only
+    find comments for gettext calls forwards.  Once the comment
+    from line 4 is found, a comment for line 1 will not return a
+    usable value.
+    """
+
+    def __init__(
+        self, tokens: t.Sequence[t.Tuple[int, str, str]], comment_tags: t.Sequence[str]
+    ) -> None:
+        self.tokens = tokens
+        self.comment_tags = comment_tags
+        self.offset = 0
+        self.last_lineno = 0
+
+    def find_backwards(self, offset: int) -> t.List[str]:
+        try:
+            for _, token_type, token_value in reversed(
+                self.tokens[self.offset : offset]
+            ):
+                if token_type in ("comment", "linecomment"):
+                    try:
+                        prefix, comment = token_value.split(None, 1)
+                    except ValueError:
+                        continue
+                    if prefix in self.comment_tags:
+                        return [comment.rstrip()]
+            return []
+        finally:
+            self.offset = offset
+
+    def find_comments(self, lineno: int) -> t.List[str]:
+        if not self.comment_tags or self.last_lineno > lineno:
+            return []
+        for idx, (token_lineno, _, _) in enumerate(self.tokens[self.offset :]):
+            if token_lineno > lineno:
+                return self.find_backwards(self.offset + idx)
+        return self.find_backwards(len(self.tokens))
+
+
+def babel_extract(
+    fileobj: t.BinaryIO,
+    keywords: t.Sequence[str],
+    comment_tags: t.Sequence[str],
+    options: t.Dict[str, t.Any],
+) -> t.Iterator[
+    t.Tuple[
+        int, str, t.Union[t.Optional[str], t.Tuple[t.Optional[str], ...]], t.List[str]
+    ]
+]:
+    """Babel extraction method for Jinja templates.
+
+    .. versionchanged:: 2.3
+       Basic support for translation comments was added.  If `comment_tags`
+       is now set to a list of keywords for extraction, the extractor will
+       try to find the best preceding comment that begins with one of the
+       keywords.  For best results, make sure to not have more than one
+       gettext call in one line of code and the matching comment in the
+       same line or the line before.
+
+    .. versionchanged:: 2.5.1
+       The `newstyle_gettext` flag can be set to `True` to enable newstyle
+       gettext calls.
+
+    .. versionchanged:: 2.7
+       A `silent` option can now be provided.  If set to `False` template
+       syntax errors are propagated instead of being ignored.
+
+    :param fileobj: the file-like object the messages should be extracted from
+    :param keywords: a list of keywords (i.e. function names) that should be
+                     recognized as translation functions
+    :param comment_tags: a list of translator tags to search for and include
+                         in the results.
+    :param options: a dictionary of additional options (optional)
+    :return: an iterator over ``(lineno, funcname, message, comments)`` tuples.
+             (comments will be empty currently)
+    """
+    extensions: t.Dict[t.Type[Extension], None] = {}
+
+    for extension_name in options.get("extensions", "").split(","):
+        extension_name = extension_name.strip()
+
+        if not extension_name:
+            continue
+
+        extensions[import_string(extension_name)] = None
+
+    if InternationalizationExtension not in extensions:
+        extensions[InternationalizationExtension] = None
+
+    def getbool(options: t.Mapping[str, str], key: str, default: bool = False) -> bool:
+        return options.get(key, str(default)).lower() in {"1", "on", "yes", "true"}
+
+    silent = getbool(options, "silent", True)
+    environment = Environment(
+        options.get("block_start_string", defaults.BLOCK_START_STRING),
+        options.get("block_end_string", defaults.BLOCK_END_STRING),
+        options.get("variable_start_string", defaults.VARIABLE_START_STRING),
+        options.get("variable_end_string", defaults.VARIABLE_END_STRING),
+        options.get("comment_start_string", defaults.COMMENT_START_STRING),
+        options.get("comment_end_string", defaults.COMMENT_END_STRING),
+        options.get("line_statement_prefix") or defaults.LINE_STATEMENT_PREFIX,
+        options.get("line_comment_prefix") or defaults.LINE_COMMENT_PREFIX,
+        getbool(options, "trim_blocks", defaults.TRIM_BLOCKS),
+        getbool(options, "lstrip_blocks", defaults.LSTRIP_BLOCKS),
+        defaults.NEWLINE_SEQUENCE,
+        getbool(options, "keep_trailing_newline", defaults.KEEP_TRAILING_NEWLINE),
+        tuple(extensions),
+        cache_size=0,
+        auto_reload=False,
+    )
+
+    if getbool(options, "trimmed"):
+        environment.policies["ext.i18n.trimmed"] = True
+    if getbool(options, "newstyle_gettext"):
+        environment.newstyle_gettext = True  # type: ignore
+
+    source = fileobj.read().decode(options.get("encoding", "utf-8"))
+    try:
+        node = environment.parse(source)
+        tokens = list(environment.lex(environment.preprocess(source)))
+    except TemplateSyntaxError:
+        if not silent:
+            raise
+        # skip templates with syntax errors
+        return
+
+    finder = _CommentFinder(tokens, comment_tags)
+    for lineno, func, message in extract_from_ast(node, keywords):
+        yield lineno, func, message, finder.find_comments(lineno)
+
+
+#: nicer import names
+i18n = InternationalizationExtension
+do = ExprStmtExtension
+loopcontrols = LoopControlExtension
+debug = DebugExtension
diff --git a/src/jinja2/filters.py b/src/jinja2/filters.py
new file mode 100644
index 0000000..ed07c4c
--- /dev/null
+++ b/src/jinja2/filters.py
@@ -0,0 +1,1840 @@
+"""Built-in template filters used with the ``|`` operator."""
+import math
+import random
+import re
+import typing
+import typing as t
+from collections import abc
+from itertools import chain
+from itertools import groupby
+
+from markupsafe import escape
+from markupsafe import Markup
+from markupsafe import soft_str
+
+from .async_utils import async_variant
+from .async_utils import auto_aiter
+from .async_utils import auto_await
+from .async_utils import auto_to_list
+from .exceptions import FilterArgumentError
+from .runtime import Undefined
+from .utils import htmlsafe_json_dumps
+from .utils import pass_context
+from .utils import pass_environment
+from .utils import pass_eval_context
+from .utils import pformat
+from .utils import url_quote
+from .utils import urlize
+
+if t.TYPE_CHECKING:
+    import typing_extensions as te
+    from .environment import Environment
+    from .nodes import EvalContext
+    from .runtime import Context
+    from .sandbox import SandboxedEnvironment  # noqa: F401
+
+    class HasHTML(te.Protocol):
+        def __html__(self) -> str:
+            pass
+
+
+F = t.TypeVar("F", bound=t.Callable[..., t.Any])
+K = t.TypeVar("K")
+V = t.TypeVar("V")
+
+
+def ignore_case(value: V) -> V:
+    """For use as a postprocessor for :func:`make_attrgetter`. Converts strings
+    to lowercase and returns other types as-is."""
+    if isinstance(value, str):
+        return t.cast(V, value.lower())
+
+    return value
+
+
+def make_attrgetter(
+    environment: "Environment",
+    attribute: t.Optional[t.Union[str, int]],
+    postprocess: t.Optional[t.Callable[[t.Any], t.Any]] = None,
+    default: t.Optional[t.Any] = None,
+) -> t.Callable[[t.Any], t.Any]:
+    """Returns a callable that looks up the given attribute from a
+    passed object with the rules of the environment.  Dots are allowed
+    to access attributes of attributes.  Integer parts in paths are
+    looked up as integers.
+    """
+    parts = _prepare_attribute_parts(attribute)
+
+    def attrgetter(item: t.Any) -> t.Any:
+        for part in parts:
+            item = environment.getitem(item, part)
+
+            if default is not None and isinstance(item, Undefined):
+                item = default
+
+        if postprocess is not None:
+            item = postprocess(item)
+
+        return item
+
+    return attrgetter
+
+
+def make_multi_attrgetter(
+    environment: "Environment",
+    attribute: t.Optional[t.Union[str, int]],
+    postprocess: t.Optional[t.Callable[[t.Any], t.Any]] = None,
+) -> t.Callable[[t.Any], t.List[t.Any]]:
+    """Returns a callable that looks up the given comma separated
+    attributes from a passed object with the rules of the environment.
+    Dots are allowed to access attributes of each attribute.  Integer
+    parts in paths are looked up as integers.
+
+    The value returned by the returned callable is a list of extracted
+    attribute values.
+
+    Examples of attribute: "attr1,attr2", "attr1.inner1.0,attr2.inner2.0", etc.
+    """
+    if isinstance(attribute, str):
+        split: t.Sequence[t.Union[str, int, None]] = attribute.split(",")
+    else:
+        split = [attribute]
+
+    parts = [_prepare_attribute_parts(item) for item in split]
+
+    def attrgetter(item: t.Any) -> t.List[t.Any]:
+        items = [None] * len(parts)
+
+        for i, attribute_part in enumerate(parts):
+            item_i = item
+
+            for part in attribute_part:
+                item_i = environment.getitem(item_i, part)
+
+            if postprocess is not None:
+                item_i = postprocess(item_i)
+
+            items[i] = item_i
+
+        return items
+
+    return attrgetter
+
+
+def _prepare_attribute_parts(
+    attr: t.Optional[t.Union[str, int]]
+) -> t.List[t.Union[str, int]]:
+    if attr is None:
+        return []
+
+    if isinstance(attr, str):
+        return [int(x) if x.isdigit() else x for x in attr.split(".")]
+
+    return [attr]
+
+
+def do_forceescape(value: "t.Union[str, HasHTML]") -> Markup:
+    """Enforce HTML escaping.  This will probably double escape variables."""
+    if hasattr(value, "__html__"):
+        value = t.cast("HasHTML", value).__html__()
+
+    return escape(str(value))
+
+
+def do_urlencode(
+    value: t.Union[str, t.Mapping[str, t.Any], t.Iterable[t.Tuple[str, t.Any]]]
+) -> str:
+    """Quote data for use in a URL path or query using UTF-8.
+
+    Basic wrapper around :func:`urllib.parse.quote` when given a
+    string, or :func:`urllib.parse.urlencode` for a dict or iterable.
+
+    :param value: Data to quote. A string will be quoted directly. A
+        dict or iterable of ``(key, value)`` pairs will be joined as a
+        query string.
+
+    When given a string, "/" is not quoted. HTTP servers treat "/" and
+    "%2F" equivalently in paths. If you need quoted slashes, use the
+    ``|replace("/", "%2F")`` filter.
+
+    .. versionadded:: 2.7
+    """
+    if isinstance(value, str) or not isinstance(value, abc.Iterable):
+        return url_quote(value)
+
+    if isinstance(value, dict):
+        items: t.Iterable[t.Tuple[str, t.Any]] = value.items()
+    else:
+        items = value  # type: ignore
+
+    return "&".join(
+        f"{url_quote(k, for_qs=True)}={url_quote(v, for_qs=True)}" for k, v in items
+    )
+
+
+@pass_eval_context
+def do_replace(
+    eval_ctx: "EvalContext", s: str, old: str, new: str, count: t.Optional[int] = None
+) -> str:
+    """Return a copy of the value with all occurrences of a substring
+    replaced with a new one. The first argument is the substring
+    that should be replaced, the second is the replacement string.
+    If the optional third argument ``count`` is given, only the first
+    ``count`` occurrences are replaced:
+
+    .. sourcecode:: jinja
+
+        {{ "Hello World"|replace("Hello", "Goodbye") }}
+            -> Goodbye World
+
+        {{ "aaaaargh"|replace("a", "d'oh, ", 2) }}
+            -> d'oh, d'oh, aaargh
+    """
+    if count is None:
+        count = -1
+
+    if not eval_ctx.autoescape:
+        return str(s).replace(str(old), str(new), count)
+
+    if (
+        hasattr(old, "__html__")
+        or hasattr(new, "__html__")
+        and not hasattr(s, "__html__")
+    ):
+        s = escape(s)
+    else:
+        s = soft_str(s)
+
+    return s.replace(soft_str(old), soft_str(new), count)
+
+
+def do_upper(s: str) -> str:
+    """Convert a value to uppercase."""
+    return soft_str(s).upper()
+
+
+def do_lower(s: str) -> str:
+    """Convert a value to lowercase."""
+    return soft_str(s).lower()
+
+
+def do_items(value: t.Union[t.Mapping[K, V], Undefined]) -> t.Iterator[t.Tuple[K, V]]:
+    """Return an iterator over the ``(key, value)`` items of a mapping.
+
+    ``x|items`` is the same as ``x.items()``, except if ``x`` is
+    undefined an empty iterator is returned.
+
+    This filter is useful if you expect the template to be rendered with
+    an implementation of Jinja in another programming language that does
+    not have a ``.items()`` method on its mapping type.
+
+    .. code-block:: html+jinja
+
+        <dl>
+        {% for key, value in my_dict|items %}
+            <dt>{{ key }}
+            <dd>{{ value }}
+        {% endfor %}
+        </dl>
+
+    .. versionadded:: 3.1
+    """
+    if isinstance(value, Undefined):
+        return
+
+    if not isinstance(value, abc.Mapping):
+        raise TypeError("Can only get item pairs from a mapping.")
+
+    yield from value.items()
+
+
+@pass_eval_context
+def do_xmlattr(
+    eval_ctx: "EvalContext", d: t.Mapping[str, t.Any], autospace: bool = True
+) -> str:
+    """Create an SGML/XML attribute string based on the items in a dict.
+    All values that are neither `none` nor `undefined` are automatically
+    escaped:
+
+    .. sourcecode:: html+jinja
+
+        <ul{{ {'class': 'my_list', 'missing': none,
+                'id': 'list-%d'|format(variable)}|xmlattr }}>
+        ...
+        </ul>
+
+    Results in something like this:
+
+    .. sourcecode:: html
+
+        <ul class="my_list" id="list-42">
+        ...
+        </ul>
+
+    As you can see it automatically prepends a space in front of the item
+    if the filter returned something unless the second parameter is false.
+    """
+    rv = " ".join(
+        f'{escape(key)}="{escape(value)}"'
+        for key, value in d.items()
+        if value is not None and not isinstance(value, Undefined)
+    )
+
+    if autospace and rv:
+        rv = " " + rv
+
+    if eval_ctx.autoescape:
+        rv = Markup(rv)
+
+    return rv
+
+
+def do_capitalize(s: str) -> str:
+    """Capitalize a value. The first character will be uppercase, all others
+    lowercase.
+    """
+    return soft_str(s).capitalize()
+
+
+_word_beginning_split_re = re.compile(r"([-\s({\[<]+)")
+
+
+def do_title(s: str) -> str:
+    """Return a titlecased version of the value. I.e. words will start with
+    uppercase letters, all remaining characters are lowercase.
+    """
+    return "".join(
+        [
+            item[0].upper() + item[1:].lower()
+            for item in _word_beginning_split_re.split(soft_str(s))
+            if item
+        ]
+    )
+
+
+def do_dictsort(
+    value: t.Mapping[K, V],
+    case_sensitive: bool = False,
+    by: 'te.Literal["key", "value"]' = "key",
+    reverse: bool = False,
+) -> t.List[t.Tuple[K, V]]:
+    """Sort a dict and yield (key, value) pairs. Python dicts may not
+    be in the order you want to display them in, so sort them first.
+
+    .. sourcecode:: jinja
+
+        {% for key, value in mydict|dictsort %}
+            sort the dict by key, case insensitive
+
+        {% for key, value in mydict|dictsort(reverse=true) %}
+            sort the dict by key, case insensitive, reverse order
+
+        {% for key, value in mydict|dictsort(true) %}
+            sort the dict by key, case sensitive
+
+        {% for key, value in mydict|dictsort(false, 'value') %}
+            sort the dict by value, case insensitive
+    """
+    if by == "key":
+        pos = 0
+    elif by == "value":
+        pos = 1
+    else:
+        raise FilterArgumentError('You can only sort by either "key" or "value"')
+
+    def sort_func(item: t.Tuple[t.Any, t.Any]) -> t.Any:
+        value = item[pos]
+
+        if not case_sensitive:
+            value = ignore_case(value)
+
+        return value
+
+    return sorted(value.items(), key=sort_func, reverse=reverse)
+
+
+@pass_environment
+def do_sort(
+    environment: "Environment",
+    value: "t.Iterable[V]",
+    reverse: bool = False,
+    case_sensitive: bool = False,
+    attribute: t.Optional[t.Union[str, int]] = None,
+) -> "t.List[V]":
+    """Sort an iterable using Python's :func:`sorted`.
+
+    .. sourcecode:: jinja
+
+        {% for city in cities|sort %}
+            ...
+        {% endfor %}
+
+    :param reverse: Sort descending instead of ascending.
+    :param case_sensitive: When sorting strings, sort upper and lower
+        case separately.
+    :param attribute: When sorting objects or dicts, an attribute or
+        key to sort by. Can use dot notation like ``"address.city"``.
+        Can be a list of attributes like ``"age,name"``.
+
+    The sort is stable, it does not change the relative order of
+    elements that compare equal. This makes it is possible to chain
+    sorts on different attributes and ordering.
+
+    .. sourcecode:: jinja
+
+        {% for user in users|sort(attribute="name")
+            |sort(reverse=true, attribute="age") %}
+            ...
+        {% endfor %}
+
+    As a shortcut to chaining when the direction is the same for all
+    attributes, pass a comma separate list of attributes.
+
+    .. sourcecode:: jinja
+
+        {% for user in users|sort(attribute="age,name") %}
+            ...
+        {% endfor %}
+
+    .. versionchanged:: 2.11.0
+        The ``attribute`` parameter can be a comma separated list of
+        attributes, e.g. ``"age,name"``.
+
+    .. versionchanged:: 2.6
+       The ``attribute`` parameter was added.
+    """
+    key_func = make_multi_attrgetter(
+        environment, attribute, postprocess=ignore_case if not case_sensitive else None
+    )
+    return sorted(value, key=key_func, reverse=reverse)
+
+
+@pass_environment
+def do_unique(
+    environment: "Environment",
+    value: "t.Iterable[V]",
+    case_sensitive: bool = False,
+    attribute: t.Optional[t.Union[str, int]] = None,
+) -> "t.Iterator[V]":
+    """Returns a list of unique items from the given iterable.
+
+    .. sourcecode:: jinja
+
+        {{ ['foo', 'bar', 'foobar', 'FooBar']|unique|list }}
+            -> ['foo', 'bar', 'foobar']
+
+    The unique items are yielded in the same order as their first occurrence in
+    the iterable passed to the filter.
+
+    :param case_sensitive: Treat upper and lower case strings as distinct.
+    :param attribute: Filter objects with unique values for this attribute.
+    """
+    getter = make_attrgetter(
+        environment, attribute, postprocess=ignore_case if not case_sensitive else None
+    )
+    seen = set()
+
+    for item in value:
+        key = getter(item)
+
+        if key not in seen:
+            seen.add(key)
+            yield item
+
+
+def _min_or_max(
+    environment: "Environment",
+    value: "t.Iterable[V]",
+    func: "t.Callable[..., V]",
+    case_sensitive: bool,
+    attribute: t.Optional[t.Union[str, int]],
+) -> "t.Union[V, Undefined]":
+    it = iter(value)
+
+    try:
+        first = next(it)
+    except StopIteration:
+        return environment.undefined("No aggregated item, sequence was empty.")
+
+    key_func = make_attrgetter(
+        environment, attribute, postprocess=ignore_case if not case_sensitive else None
+    )
+    return func(chain([first], it), key=key_func)
+
+
+@pass_environment
+def do_min(
+    environment: "Environment",
+    value: "t.Iterable[V]",
+    case_sensitive: bool = False,
+    attribute: t.Optional[t.Union[str, int]] = None,
+) -> "t.Union[V, Undefined]":
+    """Return the smallest item from the sequence.
+
+    .. sourcecode:: jinja
+
+        {{ [1, 2, 3]|min }}
+            -> 1
+
+    :param case_sensitive: Treat upper and lower case strings as distinct.
+    :param attribute: Get the object with the min value of this attribute.
+    """
+    return _min_or_max(environment, value, min, case_sensitive, attribute)
+
+
+@pass_environment
+def do_max(
+    environment: "Environment",
+    value: "t.Iterable[V]",
+    case_sensitive: bool = False,
+    attribute: t.Optional[t.Union[str, int]] = None,
+) -> "t.Union[V, Undefined]":
+    """Return the largest item from the sequence.
+
+    .. sourcecode:: jinja
+
+        {{ [1, 2, 3]|max }}
+            -> 3
+
+    :param case_sensitive: Treat upper and lower case strings as distinct.
+    :param attribute: Get the object with the max value of this attribute.
+    """
+    return _min_or_max(environment, value, max, case_sensitive, attribute)
+
+
+def do_default(
+    value: V,
+    default_value: V = "",  # type: ignore
+    boolean: bool = False,
+) -> V:
+    """If the value is undefined it will return the passed default value,
+    otherwise the value of the variable:
+
+    .. sourcecode:: jinja
+
+        {{ my_variable|default('my_variable is not defined') }}
+
+    This will output the value of ``my_variable`` if the variable was
+    defined, otherwise ``'my_variable is not defined'``. If you want
+    to use default with variables that evaluate to false you have to
+    set the second parameter to `true`:
+
+    .. sourcecode:: jinja
+
+        {{ ''|default('the string was empty', true) }}
+
+    .. versionchanged:: 2.11
+       It's now possible to configure the :class:`~jinja2.Environment` with
+       :class:`~jinja2.ChainableUndefined` to make the `default` filter work
+       on nested elements and attributes that may contain undefined values
+       in the chain without getting an :exc:`~jinja2.UndefinedError`.
+    """
+    if isinstance(value, Undefined) or (boolean and not value):
+        return default_value
+
+    return value
+
+
+@pass_eval_context
+def sync_do_join(
+    eval_ctx: "EvalContext",
+    value: t.Iterable,
+    d: str = "",
+    attribute: t.Optional[t.Union[str, int]] = None,
+) -> str:
+    """Return a string which is the concatenation of the strings in the
+    sequence. The separator between elements is an empty string per
+    default, you can define it with the optional parameter:
+
+    .. sourcecode:: jinja
+
+        {{ [1, 2, 3]|join('|') }}
+            -> 1|2|3
+
+        {{ [1, 2, 3]|join }}
+            -> 123
+
+    It is also possible to join certain attributes of an object:
+
+    .. sourcecode:: jinja
+
+        {{ users|join(', ', attribute='username') }}
+
+    .. versionadded:: 2.6
+       The `attribute` parameter was added.
+    """
+    if attribute is not None:
+        value = map(make_attrgetter(eval_ctx.environment, attribute), value)
+
+    # no automatic escaping?  joining is a lot easier then
+    if not eval_ctx.autoescape:
+        return str(d).join(map(str, value))
+
+    # if the delimiter doesn't have an html representation we check
+    # if any of the items has.  If yes we do a coercion to Markup
+    if not hasattr(d, "__html__"):
+        value = list(value)
+        do_escape = False
+
+        for idx, item in enumerate(value):
+            if hasattr(item, "__html__"):
+                do_escape = True
+            else:
+                value[idx] = str(item)
+
+        if do_escape:
+            d = escape(d)
+        else:
+            d = str(d)
+
+        return d.join(value)
+
+    # no html involved, to normal joining
+    return soft_str(d).join(map(soft_str, value))
+
+
+@async_variant(sync_do_join)  # type: ignore
+async def do_join(
+    eval_ctx: "EvalContext",
+    value: t.Union[t.AsyncIterable, t.Iterable],
+    d: str = "",
+    attribute: t.Optional[t.Union[str, int]] = None,
+) -> str:
+    return sync_do_join(eval_ctx, await auto_to_list(value), d, attribute)
+
+
+def do_center(value: str, width: int = 80) -> str:
+    """Centers the value in a field of a given width."""
+    return soft_str(value).center(width)
+
+
+@pass_environment
+def sync_do_first(
+    environment: "Environment", seq: "t.Iterable[V]"
+) -> "t.Union[V, Undefined]":
+    """Return the first item of a sequence."""
+    try:
+        return next(iter(seq))
+    except StopIteration:
+        return environment.undefined("No first item, sequence was empty.")
+
+
+@async_variant(sync_do_first)  # type: ignore
+async def do_first(
+    environment: "Environment", seq: "t.Union[t.AsyncIterable[V], t.Iterable[V]]"
+) -> "t.Union[V, Undefined]":
+    try:
+        return await auto_aiter(seq).__anext__()
+    except StopAsyncIteration:
+        return environment.undefined("No first item, sequence was empty.")
+
+
+@pass_environment
+def do_last(
+    environment: "Environment", seq: "t.Reversible[V]"
+) -> "t.Union[V, Undefined]":
+    """Return the last item of a sequence.
+
+    Note: Does not work with generators. You may want to explicitly
+    convert it to a list:
+
+    .. sourcecode:: jinja
+
+        {{ data | selectattr('name', '==', 'Jinja') | list | last }}
+    """
+    try:
+        return next(iter(reversed(seq)))
+    except StopIteration:
+        return environment.undefined("No last item, sequence was empty.")
+
+
+# No async do_last, it may not be safe in async mode.
+
+
+@pass_context
+def do_random(context: "Context", seq: "t.Sequence[V]") -> "t.Union[V, Undefined]":
+    """Return a random item from the sequence."""
+    try:
+        return random.choice(seq)
+    except IndexError:
+        return context.environment.undefined("No random item, sequence was empty.")
+
+
+def do_filesizeformat(value: t.Union[str, float, int], binary: bool = False) -> str:
+    """Format the value like a 'human-readable' file size (i.e. 13 kB,
+    4.1 MB, 102 Bytes, etc).  Per default decimal prefixes are used (Mega,
+    Giga, etc.), if the second parameter is set to `True` the binary
+    prefixes are used (Mebi, Gibi).
+    """
+    bytes = float(value)
+    base = 1024 if binary else 1000
+    prefixes = [
+        ("KiB" if binary else "kB"),
+        ("MiB" if binary else "MB"),
+        ("GiB" if binary else "GB"),
+        ("TiB" if binary else "TB"),
+        ("PiB" if binary else "PB"),
+        ("EiB" if binary else "EB"),
+        ("ZiB" if binary else "ZB"),
+        ("YiB" if binary else "YB"),
+    ]
+
+    if bytes == 1:
+        return "1 Byte"
+    elif bytes < base:
+        return f"{int(bytes)} Bytes"
+    else:
+        for i, prefix in enumerate(prefixes):
+            unit = base ** (i + 2)
+
+            if bytes < unit:
+                return f"{base * bytes / unit:.1f} {prefix}"
+
+        return f"{base * bytes / unit:.1f} {prefix}"
+
+
+def do_pprint(value: t.Any) -> str:
+    """Pretty print a variable. Useful for debugging."""
+    return pformat(value)
+
+
+_uri_scheme_re = re.compile(r"^([\w.+-]{2,}:(/){0,2})$")
+
+
+@pass_eval_context
+def do_urlize(
+    eval_ctx: "EvalContext",
+    value: str,
+    trim_url_limit: t.Optional[int] = None,
+    nofollow: bool = False,
+    target: t.Optional[str] = None,
+    rel: t.Optional[str] = None,
+    extra_schemes: t.Optional[t.Iterable[str]] = None,
+) -> str:
+    """Convert URLs in text into clickable links.
+
+    This may not recognize links in some situations. Usually, a more
+    comprehensive formatter, such as a Markdown library, is a better
+    choice.
+
+    Works on ``http://``, ``https://``, ``www.``, ``mailto:``, and email
+    addresses. Links with trailing punctuation (periods, commas, closing
+    parentheses) and leading punctuation (opening parentheses) are
+    recognized excluding the punctuation. Email addresses that include
+    header fields are not recognized (for example,
+    ``mailto:address@example.com?cc=copy@example.com``).
+
+    :param value: Original text containing URLs to link.
+    :param trim_url_limit: Shorten displayed URL values to this length.
+    :param nofollow: Add the ``rel=nofollow`` attribute to links.
+    :param target: Add the ``target`` attribute to links.
+    :param rel: Add the ``rel`` attribute to links.
+    :param extra_schemes: Recognize URLs that start with these schemes
+        in addition to the default behavior. Defaults to
+        ``env.policies["urlize.extra_schemes"]``, which defaults to no
+        extra schemes.
+
+    .. versionchanged:: 3.0
+        The ``extra_schemes`` parameter was added.
+
+    .. versionchanged:: 3.0
+        Generate ``https://`` links for URLs without a scheme.
+
+    .. versionchanged:: 3.0
+        The parsing rules were updated. Recognize email addresses with
+        or without the ``mailto:`` scheme. Validate IP addresses. Ignore
+        parentheses and brackets in more cases.
+
+    .. versionchanged:: 2.8
+       The ``target`` parameter was added.
+    """
+    policies = eval_ctx.environment.policies
+    rel_parts = set((rel or "").split())
+
+    if nofollow:
+        rel_parts.add("nofollow")
+
+    rel_parts.update((policies["urlize.rel"] or "").split())
+    rel = " ".join(sorted(rel_parts)) or None
+
+    if target is None:
+        target = policies["urlize.target"]
+
+    if extra_schemes is None:
+        extra_schemes = policies["urlize.extra_schemes"] or ()
+
+    for scheme in extra_schemes:
+        if _uri_scheme_re.fullmatch(scheme) is None:
+            raise FilterArgumentError(f"{scheme!r} is not a valid URI scheme prefix.")
+
+    rv = urlize(
+        value,
+        trim_url_limit=trim_url_limit,
+        rel=rel,
+        target=target,
+        extra_schemes=extra_schemes,
+    )
+
+    if eval_ctx.autoescape:
+        rv = Markup(rv)
+
+    return rv
+
+
+def do_indent(
+    s: str, width: t.Union[int, str] = 4, first: bool = False, blank: bool = False
+) -> str:
+    """Return a copy of the string with each line indented by 4 spaces. The
+    first line and blank lines are not indented by default.
+
+    :param width: Number of spaces, or a string, to indent by.
+    :param first: Don't skip indenting the first line.
+    :param blank: Don't skip indenting empty lines.
+
+    .. versionchanged:: 3.0
+        ``width`` can be a string.
+
+    .. versionchanged:: 2.10
+        Blank lines are not indented by default.
+
+        Rename the ``indentfirst`` argument to ``first``.
+    """
+    if isinstance(width, str):
+        indention = width
+    else:
+        indention = " " * width
+
+    newline = "\n"
+
+    if isinstance(s, Markup):
+        indention = Markup(indention)
+        newline = Markup(newline)
+
+    s += newline  # this quirk is necessary for splitlines method
+
+    if blank:
+        rv = (newline + indention).join(s.splitlines())
+    else:
+        lines = s.splitlines()
+        rv = lines.pop(0)
+
+        if lines:
+            rv += newline + newline.join(
+                indention + line if line else line for line in lines
+            )
+
+    if first:
+        rv = indention + rv
+
+    return rv
+
+
+@pass_environment
+def do_truncate(
+    env: "Environment",
+    s: str,
+    length: int = 255,
+    killwords: bool = False,
+    end: str = "...",
+    leeway: t.Optional[int] = None,
+) -> str:
+    """Return a truncated copy of the string. The length is specified
+    with the first parameter which defaults to ``255``. If the second
+    parameter is ``true`` the filter will cut the text at length. Otherwise
+    it will discard the last word. If the text was in fact
+    truncated it will append an ellipsis sign (``"..."``). If you want a
+    different ellipsis sign than ``"..."`` you can specify it using the
+    third parameter. Strings that only exceed the length by the tolerance
+    margin given in the fourth parameter will not be truncated.
+
+    .. sourcecode:: jinja
+
+        {{ "foo bar baz qux"|truncate(9) }}
+            -> "foo..."
+        {{ "foo bar baz qux"|truncate(9, True) }}
+            -> "foo ba..."
+        {{ "foo bar baz qux"|truncate(11) }}
+            -> "foo bar baz qux"
+        {{ "foo bar baz qux"|truncate(11, False, '...', 0) }}
+            -> "foo bar..."
+
+    The default leeway on newer Jinja versions is 5 and was 0 before but
+    can be reconfigured globally.
+    """
+    if leeway is None:
+        leeway = env.policies["truncate.leeway"]
+
+    assert length >= len(end), f"expected length >= {len(end)}, got {length}"
+    assert leeway >= 0, f"expected leeway >= 0, got {leeway}"
+
+    if len(s) <= length + leeway:
+        return s
+
+    if killwords:
+        return s[: length - len(end)] + end
+
+    result = s[: length - len(end)].rsplit(" ", 1)[0]
+    return result + end
+
+
+@pass_environment
+def do_wordwrap(
+    environment: "Environment",
+    s: str,
+    width: int = 79,
+    break_long_words: bool = True,
+    wrapstring: t.Optional[str] = None,
+    break_on_hyphens: bool = True,
+) -> str:
+    """Wrap a string to the given width. Existing newlines are treated
+    as paragraphs to be wrapped separately.
+
+    :param s: Original text to wrap.
+    :param width: Maximum length of wrapped lines.
+    :param break_long_words: If a word is longer than ``width``, break
+        it across lines.
+    :param break_on_hyphens: If a word contains hyphens, it may be split
+        across lines.
+    :param wrapstring: String to join each wrapped line. Defaults to
+        :attr:`Environment.newline_sequence`.
+
+    .. versionchanged:: 2.11
+        Existing newlines are treated as paragraphs wrapped separately.
+
+    .. versionchanged:: 2.11
+        Added the ``break_on_hyphens`` parameter.
+
+    .. versionchanged:: 2.7
+        Added the ``wrapstring`` parameter.
+    """
+    import textwrap
+
+    if wrapstring is None:
+        wrapstring = environment.newline_sequence
+
+    # textwrap.wrap doesn't consider existing newlines when wrapping.
+    # If the string has a newline before width, wrap will still insert
+    # a newline at width, resulting in a short line. Instead, split and
+    # wrap each paragraph individually.
+    return wrapstring.join(
+        [
+            wrapstring.join(
+                textwrap.wrap(
+                    line,
+                    width=width,
+                    expand_tabs=False,
+                    replace_whitespace=False,
+                    break_long_words=break_long_words,
+                    break_on_hyphens=break_on_hyphens,
+                )
+            )
+            for line in s.splitlines()
+        ]
+    )
+
+
+_word_re = re.compile(r"\w+")
+
+
+def do_wordcount(s: str) -> int:
+    """Count the words in that string."""
+    return len(_word_re.findall(soft_str(s)))
+
+
+def do_int(value: t.Any, default: int = 0, base: int = 10) -> int:
+    """Convert the value into an integer. If the
+    conversion doesn't work it will return ``0``. You can
+    override this default using the first parameter. You
+    can also override the default base (10) in the second
+    parameter, which handles input with prefixes such as
+    0b, 0o and 0x for bases 2, 8 and 16 respectively.
+    The base is ignored for decimal numbers and non-string values.
+    """
+    try:
+        if isinstance(value, str):
+            return int(value, base)
+
+        return int(value)
+    except (TypeError, ValueError):
+        # this quirk is necessary so that "42.23"|int gives 42.
+        try:
+            return int(float(value))
+        except (TypeError, ValueError):
+            return default
+
+
+def do_float(value: t.Any, default: float = 0.0) -> float:
+    """Convert the value into a floating point number. If the
+    conversion doesn't work it will return ``0.0``. You can
+    override this default using the first parameter.
+    """
+    try:
+        return float(value)
+    except (TypeError, ValueError):
+        return default
+
+
+def do_format(value: str, *args: t.Any, **kwargs: t.Any) -> str:
+    """Apply the given values to a `printf-style`_ format string, like
+    ``string % values``.
+
+    .. sourcecode:: jinja
+
+        {{ "%s, %s!"|format(greeting, name) }}
+        Hello, World!
+
+    In most cases it should be more convenient and efficient to use the
+    ``%`` operator or :meth:`str.format`.
+
+    .. code-block:: text
+
+        {{ "%s, %s!" % (greeting, name) }}
+        {{ "{}, {}!".format(greeting, name) }}
+
+    .. _printf-style: https://docs.python.org/library/stdtypes.html
+        #printf-style-string-formatting
+    """
+    if args and kwargs:
+        raise FilterArgumentError(
+            "can't handle positional and keyword arguments at the same time"
+        )
+
+    return soft_str(value) % (kwargs or args)
+
+
+def do_trim(value: str, chars: t.Optional[str] = None) -> str:
+    """Strip leading and trailing characters, by default whitespace."""
+    return soft_str(value).strip(chars)
+
+
+def do_striptags(value: "t.Union[str, HasHTML]") -> str:
+    """Strip SGML/XML tags and replace adjacent whitespace by one space."""
+    if hasattr(value, "__html__"):
+        value = t.cast("HasHTML", value).__html__()
+
+    return Markup(str(value)).striptags()
+
+
+def sync_do_slice(
+    value: "t.Collection[V]", slices: int, fill_with: "t.Optional[V]" = None
+) -> "t.Iterator[t.List[V]]":
+    """Slice an iterator and return a list of lists containing
+    those items. Useful if you want to create a div containing
+    three ul tags that represent columns:
+
+    .. sourcecode:: html+jinja
+
+        <div class="columnwrapper">
+          {%- for column in items|slice(3) %}
+            <ul class="column-{{ loop.index }}">
+            {%- for item in column %}
+              <li>{{ item }}</li>
+            {%- endfor %}
+            </ul>
+          {%- endfor %}
+        </div>
+
+    If you pass it a second argument it's used to fill missing
+    values on the last iteration.
+    """
+    seq = list(value)
+    length = len(seq)
+    items_per_slice = length // slices
+    slices_with_extra = length % slices
+    offset = 0
+
+    for slice_number in range(slices):
+        start = offset + slice_number * items_per_slice
+
+        if slice_number < slices_with_extra:
+            offset += 1
+
+        end = offset + (slice_number + 1) * items_per_slice
+        tmp = seq[start:end]
+
+        if fill_with is not None and slice_number >= slices_with_extra:
+            tmp.append(fill_with)
+
+        yield tmp
+
+
+@async_variant(sync_do_slice)  # type: ignore
+async def do_slice(
+    value: "t.Union[t.AsyncIterable[V], t.Iterable[V]]",
+    slices: int,
+    fill_with: t.Optional[t.Any] = None,
+) -> "t.Iterator[t.List[V]]":
+    return sync_do_slice(await auto_to_list(value), slices, fill_with)
+
+
+def do_batch(
+    value: "t.Iterable[V]", linecount: int, fill_with: "t.Optional[V]" = None
+) -> "t.Iterator[t.List[V]]":
+    """
+    A filter that batches items. It works pretty much like `slice`
+    just the other way round. It returns a list of lists with the
+    given number of items. If you provide a second parameter this
+    is used to fill up missing items. See this example:
+
+    .. sourcecode:: html+jinja
+
+        <table>
+        {%- for row in items|batch(3, '&nbsp;') %}
+          <tr>
+          {%- for column in row %}
+            <td>{{ column }}</td>
+          {%- endfor %}
+          </tr>
+        {%- endfor %}
+        </table>
+    """
+    tmp: "t.List[V]" = []
+
+    for item in value:
+        if len(tmp) == linecount:
+            yield tmp
+            tmp = []
+
+        tmp.append(item)
+
+    if tmp:
+        if fill_with is not None and len(tmp) < linecount:
+            tmp += [fill_with] * (linecount - len(tmp))
+
+        yield tmp
+
+
+def do_round(
+    value: float,
+    precision: int = 0,
+    method: 'te.Literal["common", "ceil", "floor"]' = "common",
+) -> float:
+    """Round the number to a given precision. The first
+    parameter specifies the precision (default is ``0``), the
+    second the rounding method:
+
+    - ``'common'`` rounds either up or down
+    - ``'ceil'`` always rounds up
+    - ``'floor'`` always rounds down
+
+    If you don't specify a method ``'common'`` is used.
+
+    .. sourcecode:: jinja
+
+        {{ 42.55|round }}
+            -> 43.0
+        {{ 42.55|round(1, 'floor') }}
+            -> 42.5
+
+    Note that even if rounded to 0 precision, a float is returned.  If
+    you need a real integer, pipe it through `int`:
+
+    .. sourcecode:: jinja
+
+        {{ 42.55|round|int }}
+            -> 43
+    """
+    if method not in {"common", "ceil", "floor"}:
+        raise FilterArgumentError("method must be common, ceil or floor")
+
+    if method == "common":
+        return round(value, precision)
+
+    func = getattr(math, method)
+    return t.cast(float, func(value * (10**precision)) / (10**precision))
+
+
+class _GroupTuple(t.NamedTuple):
+    grouper: t.Any
+    list: t.List
+
+    # Use the regular tuple repr to hide this subclass if users print
+    # out the value during debugging.
+    def __repr__(self) -> str:
+        return tuple.__repr__(self)
+
+    def __str__(self) -> str:
+        return tuple.__str__(self)
+
+
+@pass_environment
+def sync_do_groupby(
+    environment: "Environment",
+    value: "t.Iterable[V]",
+    attribute: t.Union[str, int],
+    default: t.Optional[t.Any] = None,
+    case_sensitive: bool = False,
+) -> "t.List[_GroupTuple]":
+    """Group a sequence of objects by an attribute using Python's
+    :func:`itertools.groupby`. The attribute can use dot notation for
+    nested access, like ``"address.city"``. Unlike Python's ``groupby``,
+    the values are sorted first so only one group is returned for each
+    unique value.
+
+    For example, a list of ``User`` objects with a ``city`` attribute
+    can be rendered in groups. In this example, ``grouper`` refers to
+    the ``city`` value of the group.
+
+    .. sourcecode:: html+jinja
+
+        <ul>{% for city, items in users|groupby("city") %}
+          <li>{{ city }}
+            <ul>{% for user in items %}
+              <li>{{ user.name }}
+            {% endfor %}</ul>
+          </li>
+        {% endfor %}</ul>
+
+    ``groupby`` yields namedtuples of ``(grouper, list)``, which
+    can be used instead of the tuple unpacking above. ``grouper`` is the
+    value of the attribute, and ``list`` is the items with that value.
+
+    .. sourcecode:: html+jinja
+
+        <ul>{% for group in users|groupby("city") %}
+          <li>{{ group.grouper }}: {{ group.list|join(", ") }}
+        {% endfor %}</ul>
+
+    You can specify a ``default`` value to use if an object in the list
+    does not have the given attribute.
+
+    .. sourcecode:: jinja
+
+        <ul>{% for city, items in users|groupby("city", default="NY") %}
+          <li>{{ city }}: {{ items|map(attribute="name")|join(", ") }}</li>
+        {% endfor %}</ul>
+
+    Like the :func:`~jinja-filters.sort` filter, sorting and grouping is
+    case-insensitive by default. The ``key`` for each group will have
+    the case of the first item in that group of values. For example, if
+    a list of users has cities ``["CA", "NY", "ca"]``, the "CA" group
+    will have two values. This can be disabled by passing
+    ``case_sensitive=True``.
+
+    .. versionchanged:: 3.1
+        Added the ``case_sensitive`` parameter. Sorting and grouping is
+        case-insensitive by default, matching other filters that do
+        comparisons.
+
+    .. versionchanged:: 3.0
+        Added the ``default`` parameter.
+
+    .. versionchanged:: 2.6
+        The attribute supports dot notation for nested access.
+    """
+    expr = make_attrgetter(
+        environment,
+        attribute,
+        postprocess=ignore_case if not case_sensitive else None,
+        default=default,
+    )
+    out = [
+        _GroupTuple(key, list(values))
+        for key, values in groupby(sorted(value, key=expr), expr)
+    ]
+
+    if not case_sensitive:
+        # Return the real key from the first value instead of the lowercase key.
+        output_expr = make_attrgetter(environment, attribute, default=default)
+        out = [_GroupTuple(output_expr(values[0]), values) for _, values in out]
+
+    return out
+
+
+@async_variant(sync_do_groupby)  # type: ignore
+async def do_groupby(
+    environment: "Environment",
+    value: "t.Union[t.AsyncIterable[V], t.Iterable[V]]",
+    attribute: t.Union[str, int],
+    default: t.Optional[t.Any] = None,
+    case_sensitive: bool = False,
+) -> "t.List[_GroupTuple]":
+    expr = make_attrgetter(
+        environment,
+        attribute,
+        postprocess=ignore_case if not case_sensitive else None,
+        default=default,
+    )
+    out = [
+        _GroupTuple(key, await auto_to_list(values))
+        for key, values in groupby(sorted(await auto_to_list(value), key=expr), expr)
+    ]
+
+    if not case_sensitive:
+        # Return the real key from the first value instead of the lowercase key.
+        output_expr = make_attrgetter(environment, attribute, default=default)
+        out = [_GroupTuple(output_expr(values[0]), values) for _, values in out]
+
+    return out
+
+
+@pass_environment
+def sync_do_sum(
+    environment: "Environment",
+    iterable: "t.Iterable[V]",
+    attribute: t.Optional[t.Union[str, int]] = None,
+    start: V = 0,  # type: ignore
+) -> V:
+    """Returns the sum of a sequence of numbers plus the value of parameter
+    'start' (which defaults to 0).  When the sequence is empty it returns
+    start.
+
+    It is also possible to sum up only certain attributes:
+
+    .. sourcecode:: jinja
+
+        Total: {{ items|sum(attribute='price') }}
+
+    .. versionchanged:: 2.6
+       The ``attribute`` parameter was added to allow summing up over
+       attributes.  Also the ``start`` parameter was moved on to the right.
+    """
+    if attribute is not None:
+        iterable = map(make_attrgetter(environment, attribute), iterable)
+
+    return sum(iterable, start)  # type: ignore[no-any-return, call-overload]
+
+
+@async_variant(sync_do_sum)  # type: ignore
+async def do_sum(
+    environment: "Environment",
+    iterable: "t.Union[t.AsyncIterable[V], t.Iterable[V]]",
+    attribute: t.Optional[t.Union[str, int]] = None,
+    start: V = 0,  # type: ignore
+) -> V:
+    rv = start
+
+    if attribute is not None:
+        func = make_attrgetter(environment, attribute)
+    else:
+
+        def func(x: V) -> V:
+            return x
+
+    async for item in auto_aiter(iterable):
+        rv += func(item)
+
+    return rv
+
+
+def sync_do_list(value: "t.Iterable[V]") -> "t.List[V]":
+    """Convert the value into a list.  If it was a string the returned list
+    will be a list of characters.
+    """
+    return list(value)
+
+
+@async_variant(sync_do_list)  # type: ignore
+async def do_list(value: "t.Union[t.AsyncIterable[V], t.Iterable[V]]") -> "t.List[V]":
+    return await auto_to_list(value)
+
+
+def do_mark_safe(value: str) -> Markup:
+    """Mark the value as safe which means that in an environment with automatic
+    escaping enabled this variable will not be escaped.
+    """
+    return Markup(value)
+
+
+def do_mark_unsafe(value: str) -> str:
+    """Mark a value as unsafe.  This is the reverse operation for :func:`safe`."""
+    return str(value)
+
+
+@typing.overload
+def do_reverse(value: str) -> str:
+    ...
+
+
+@typing.overload
+def do_reverse(value: "t.Iterable[V]") -> "t.Iterable[V]":
+    ...
+
+
+def do_reverse(value: t.Union[str, t.Iterable[V]]) -> t.Union[str, t.Iterable[V]]:
+    """Reverse the object or return an iterator that iterates over it the other
+    way round.
+    """
+    if isinstance(value, str):
+        return value[::-1]
+
+    try:
+        return reversed(value)  # type: ignore
+    except TypeError:
+        try:
+            rv = list(value)
+            rv.reverse()
+            return rv
+        except TypeError as e:
+            raise FilterArgumentError("argument must be iterable") from e
+
+
+@pass_environment
+def do_attr(
+    environment: "Environment", obj: t.Any, name: str
+) -> t.Union[Undefined, t.Any]:
+    """Get an attribute of an object.  ``foo|attr("bar")`` works like
+    ``foo.bar`` just that always an attribute is returned and items are not
+    looked up.
+
+    See :ref:`Notes on subscriptions <notes-on-subscriptions>` for more details.
+    """
+    try:
+        name = str(name)
+    except UnicodeError:
+        pass
+    else:
+        try:
+            value = getattr(obj, name)
+        except AttributeError:
+            pass
+        else:
+            if environment.sandboxed:
+                environment = t.cast("SandboxedEnvironment", environment)
+
+                if not environment.is_safe_attribute(obj, name, value):
+                    return environment.unsafe_undefined(obj, name)
+
+            return value
+
+    return environment.undefined(obj=obj, name=name)
+
+
+@typing.overload
+def sync_do_map(
+    context: "Context", value: t.Iterable, name: str, *args: t.Any, **kwargs: t.Any
+) -> t.Iterable:
+    ...
+
+
+@typing.overload
+def sync_do_map(
+    context: "Context",
+    value: t.Iterable,
+    *,
+    attribute: str = ...,
+    default: t.Optional[t.Any] = None,
+) -> t.Iterable:
+    ...
+
+
+@pass_context
+def sync_do_map(
+    context: "Context", value: t.Iterable, *args: t.Any, **kwargs: t.Any
+) -> t.Iterable:
+    """Applies a filter on a sequence of objects or looks up an attribute.
+    This is useful when dealing with lists of objects but you are really
+    only interested in a certain value of it.
+
+    The basic usage is mapping on an attribute.  Imagine you have a list
+    of users but you are only interested in a list of usernames:
+
+    .. sourcecode:: jinja
+
+        Users on this page: {{ users|map(attribute='username')|join(', ') }}
+
+    You can specify a ``default`` value to use if an object in the list
+    does not have the given attribute.
+
+    .. sourcecode:: jinja
+
+        {{ users|map(attribute="username", default="Anonymous")|join(", ") }}
+
+    Alternatively you can let it invoke a filter by passing the name of the
+    filter and the arguments afterwards.  A good example would be applying a
+    text conversion filter on a sequence:
+
+    .. sourcecode:: jinja
+
+        Users on this page: {{ titles|map('lower')|join(', ') }}
+
+    Similar to a generator comprehension such as:
+
+    .. code-block:: python
+
+        (u.username for u in users)
+        (getattr(u, "username", "Anonymous") for u in users)
+        (do_lower(x) for x in titles)
+
+    .. versionchanged:: 2.11.0
+        Added the ``default`` parameter.
+
+    .. versionadded:: 2.7
+    """
+    if value:
+        func = prepare_map(context, args, kwargs)
+
+        for item in value:
+            yield func(item)
+
+
+@typing.overload
+def do_map(
+    context: "Context",
+    value: t.Union[t.AsyncIterable, t.Iterable],
+    name: str,
+    *args: t.Any,
+    **kwargs: t.Any,
+) -> t.Iterable:
+    ...
+
+
+@typing.overload
+def do_map(
+    context: "Context",
+    value: t.Union[t.AsyncIterable, t.Iterable],
+    *,
+    attribute: str = ...,
+    default: t.Optional[t.Any] = None,
+) -> t.Iterable:
+    ...
+
+
+@async_variant(sync_do_map)  # type: ignore
+async def do_map(
+    context: "Context",
+    value: t.Union[t.AsyncIterable, t.Iterable],
+    *args: t.Any,
+    **kwargs: t.Any,
+) -> t.AsyncIterable:
+    if value:
+        func = prepare_map(context, args, kwargs)
+
+        async for item in auto_aiter(value):
+            yield await auto_await(func(item))
+
+
+@pass_context
+def sync_do_select(
+    context: "Context", value: "t.Iterable[V]", *args: t.Any, **kwargs: t.Any
+) -> "t.Iterator[V]":
+    """Filters a sequence of objects by applying a test to each object,
+    and only selecting the objects with the test succeeding.
+
+    If no test is specified, each object will be evaluated as a boolean.
+
+    Example usage:
+
+    .. sourcecode:: jinja
+
+        {{ numbers|select("odd") }}
+        {{ numbers|select("odd") }}
+        {{ numbers|select("divisibleby", 3) }}
+        {{ numbers|select("lessthan", 42) }}
+        {{ strings|select("equalto", "mystring") }}
+
+    Similar to a generator comprehension such as:
+
+    .. code-block:: python
+
+        (n for n in numbers if test_odd(n))
+        (n for n in numbers if test_divisibleby(n, 3))
+
+    .. versionadded:: 2.7
+    """
+    return select_or_reject(context, value, args, kwargs, lambda x: x, False)
+
+
+@async_variant(sync_do_select)  # type: ignore
+async def do_select(
+    context: "Context",
+    value: "t.Union[t.AsyncIterable[V], t.Iterable[V]]",
+    *args: t.Any,
+    **kwargs: t.Any,
+) -> "t.AsyncIterator[V]":
+    return async_select_or_reject(context, value, args, kwargs, lambda x: x, False)
+
+
+@pass_context
+def sync_do_reject(
+    context: "Context", value: "t.Iterable[V]", *args: t.Any, **kwargs: t.Any
+) -> "t.Iterator[V]":
+    """Filters a sequence of objects by applying a test to each object,
+    and rejecting the objects with the test succeeding.
+
+    If no test is specified, each object will be evaluated as a boolean.
+
+    Example usage:
+
+    .. sourcecode:: jinja
+
+        {{ numbers|reject("odd") }}
+
+    Similar to a generator comprehension such as:
+
+    .. code-block:: python
+
+        (n for n in numbers if not test_odd(n))
+
+    .. versionadded:: 2.7
+    """
+    return select_or_reject(context, value, args, kwargs, lambda x: not x, False)
+
+
+@async_variant(sync_do_reject)  # type: ignore
+async def do_reject(
+    context: "Context",
+    value: "t.Union[t.AsyncIterable[V], t.Iterable[V]]",
+    *args: t.Any,
+    **kwargs: t.Any,
+) -> "t.AsyncIterator[V]":
+    return async_select_or_reject(context, value, args, kwargs, lambda x: not x, False)
+
+
+@pass_context
+def sync_do_selectattr(
+    context: "Context", value: "t.Iterable[V]", *args: t.Any, **kwargs: t.Any
+) -> "t.Iterator[V]":
+    """Filters a sequence of objects by applying a test to the specified
+    attribute of each object, and only selecting the objects with the
+    test succeeding.
+
+    If no test is specified, the attribute's value will be evaluated as
+    a boolean.
+
+    Example usage:
+
+    .. sourcecode:: jinja
+
+        {{ users|selectattr("is_active") }}
+        {{ users|selectattr("email", "none") }}
+
+    Similar to a generator comprehension such as:
+
+    .. code-block:: python
+
+        (u for user in users if user.is_active)
+        (u for user in users if test_none(user.email))
+
+    .. versionadded:: 2.7
+    """
+    return select_or_reject(context, value, args, kwargs, lambda x: x, True)
+
+
+@async_variant(sync_do_selectattr)  # type: ignore
+async def do_selectattr(
+    context: "Context",
+    value: "t.Union[t.AsyncIterable[V], t.Iterable[V]]",
+    *args: t.Any,
+    **kwargs: t.Any,
+) -> "t.AsyncIterator[V]":
+    return async_select_or_reject(context, value, args, kwargs, lambda x: x, True)
+
+
+@pass_context
+def sync_do_rejectattr(
+    context: "Context", value: "t.Iterable[V]", *args: t.Any, **kwargs: t.Any
+) -> "t.Iterator[V]":
+    """Filters a sequence of objects by applying a test to the specified
+    attribute of each object, and rejecting the objects with the test
+    succeeding.
+
+    If no test is specified, the attribute's value will be evaluated as
+    a boolean.
+
+    .. sourcecode:: jinja
+
+        {{ users|rejectattr("is_active") }}
+        {{ users|rejectattr("email", "none") }}
+
+    Similar to a generator comprehension such as:
+
+    .. code-block:: python
+
+        (u for user in users if not user.is_active)
+        (u for user in users if not test_none(user.email))
+
+    .. versionadded:: 2.7
+    """
+    return select_or_reject(context, value, args, kwargs, lambda x: not x, True)
+
+
+@async_variant(sync_do_rejectattr)  # type: ignore
+async def do_rejectattr(
+    context: "Context",
+    value: "t.Union[t.AsyncIterable[V], t.Iterable[V]]",
+    *args: t.Any,
+    **kwargs: t.Any,
+) -> "t.AsyncIterator[V]":
+    return async_select_or_reject(context, value, args, kwargs, lambda x: not x, True)
+
+
+@pass_eval_context
+def do_tojson(
+    eval_ctx: "EvalContext", value: t.Any, indent: t.Optional[int] = None
+) -> Markup:
+    """Serialize an object to a string of JSON, and mark it safe to
+    render in HTML. This filter is only for use in HTML documents.
+
+    The returned string is safe to render in HTML documents and
+    ``<script>`` tags. The exception is in HTML attributes that are
+    double quoted; either use single quotes or the ``|forceescape``
+    filter.
+
+    :param value: The object to serialize to JSON.
+    :param indent: The ``indent`` parameter passed to ``dumps``, for
+        pretty-printing the value.
+
+    .. versionadded:: 2.9
+    """
+    policies = eval_ctx.environment.policies
+    dumps = policies["json.dumps_function"]
+    kwargs = policies["json.dumps_kwargs"]
+
+    if indent is not None:
+        kwargs = kwargs.copy()
+        kwargs["indent"] = indent
+
+    return htmlsafe_json_dumps(value, dumps=dumps, **kwargs)
+
+
+def prepare_map(
+    context: "Context", args: t.Tuple, kwargs: t.Dict[str, t.Any]
+) -> t.Callable[[t.Any], t.Any]:
+    if not args and "attribute" in kwargs:
+        attribute = kwargs.pop("attribute")
+        default = kwargs.pop("default", None)
+
+        if kwargs:
+            raise FilterArgumentError(
+                f"Unexpected keyword argument {next(iter(kwargs))!r}"
+            )
+
+        func = make_attrgetter(context.environment, attribute, default=default)
+    else:
+        try:
+            name = args[0]
+            args = args[1:]
+        except LookupError:
+            raise FilterArgumentError("map requires a filter argument") from None
+
+        def func(item: t.Any) -> t.Any:
+            return context.environment.call_filter(
+                name, item, args, kwargs, context=context
+            )
+
+    return func
+
+
+def prepare_select_or_reject(
+    context: "Context",
+    args: t.Tuple,
+    kwargs: t.Dict[str, t.Any],
+    modfunc: t.Callable[[t.Any], t.Any],
+    lookup_attr: bool,
+) -> t.Callable[[t.Any], t.Any]:
+    if lookup_attr:
+        try:
+            attr = args[0]
+        except LookupError:
+            raise FilterArgumentError("Missing parameter for attribute name") from None
+
+        transfunc = make_attrgetter(context.environment, attr)
+        off = 1
+    else:
+        off = 0
+
+        def transfunc(x: V) -> V:
+            return x
+
+    try:
+        name = args[off]
+        args = args[1 + off :]
+
+        def func(item: t.Any) -> t.Any:
+            return context.environment.call_test(name, item, args, kwargs)
+
+    except LookupError:
+        func = bool  # type: ignore
+
+    return lambda item: modfunc(func(transfunc(item)))
+
+
+def select_or_reject(
+    context: "Context",
+    value: "t.Iterable[V]",
+    args: t.Tuple,
+    kwargs: t.Dict[str, t.Any],
+    modfunc: t.Callable[[t.Any], t.Any],
+    lookup_attr: bool,
+) -> "t.Iterator[V]":
+    if value:
+        func = prepare_select_or_reject(context, args, kwargs, modfunc, lookup_attr)
+
+        for item in value:
+            if func(item):
+                yield item
+
+
+async def async_select_or_reject(
+    context: "Context",
+    value: "t.Union[t.AsyncIterable[V], t.Iterable[V]]",
+    args: t.Tuple,
+    kwargs: t.Dict[str, t.Any],
+    modfunc: t.Callable[[t.Any], t.Any],
+    lookup_attr: bool,
+) -> "t.AsyncIterator[V]":
+    if value:
+        func = prepare_select_or_reject(context, args, kwargs, modfunc, lookup_attr)
+
+        async for item in auto_aiter(value):
+            if func(item):
+                yield item
+
+
+FILTERS = {
+    "abs": abs,
+    "attr": do_attr,
+    "batch": do_batch,
+    "capitalize": do_capitalize,
+    "center": do_center,
+    "count": len,
+    "d": do_default,
+    "default": do_default,
+    "dictsort": do_dictsort,
+    "e": escape,
+    "escape": escape,
+    "filesizeformat": do_filesizeformat,
+    "first": do_first,
+    "float": do_float,
+    "forceescape": do_forceescape,
+    "format": do_format,
+    "groupby": do_groupby,
+    "indent": do_indent,
+    "int": do_int,
+    "join": do_join,
+    "last": do_last,
+    "length": len,
+    "list": do_list,
+    "lower": do_lower,
+    "items": do_items,
+    "map": do_map,
+    "min": do_min,
+    "max": do_max,
+    "pprint": do_pprint,
+    "random": do_random,
+    "reject": do_reject,
+    "rejectattr": do_rejectattr,
+    "replace": do_replace,
+    "reverse": do_reverse,
+    "round": do_round,
+    "safe": do_mark_safe,
+    "select": do_select,
+    "selectattr": do_selectattr,
+    "slice": do_slice,
+    "sort": do_sort,
+    "string": soft_str,
+    "striptags": do_striptags,
+    "sum": do_sum,
+    "title": do_title,
+    "trim": do_trim,
+    "truncate": do_truncate,
+    "unique": do_unique,
+    "upper": do_upper,
+    "urlencode": do_urlencode,
+    "urlize": do_urlize,
+    "wordcount": do_wordcount,
+    "wordwrap": do_wordwrap,
+    "xmlattr": do_xmlattr,
+    "tojson": do_tojson,
+}
diff --git a/src/jinja2/idtracking.py b/src/jinja2/idtracking.py
new file mode 100644
index 0000000..995ebaa
--- /dev/null
+++ b/src/jinja2/idtracking.py
@@ -0,0 +1,318 @@
+import typing as t
+
+from . import nodes
+from .visitor import NodeVisitor
+
+VAR_LOAD_PARAMETER = "param"
+VAR_LOAD_RESOLVE = "resolve"
+VAR_LOAD_ALIAS = "alias"
+VAR_LOAD_UNDEFINED = "undefined"
+
+
+def find_symbols(
+    nodes: t.Iterable[nodes.Node], parent_symbols: t.Optional["Symbols"] = None
+) -> "Symbols":
+    sym = Symbols(parent=parent_symbols)
+    visitor = FrameSymbolVisitor(sym)
+    for node in nodes:
+        visitor.visit(node)
+    return sym
+
+
+def symbols_for_node(
+    node: nodes.Node, parent_symbols: t.Optional["Symbols"] = None
+) -> "Symbols":
+    sym = Symbols(parent=parent_symbols)
+    sym.analyze_node(node)
+    return sym
+
+
+class Symbols:
+    def __init__(
+        self, parent: t.Optional["Symbols"] = None, level: t.Optional[int] = None
+    ) -> None:
+        if level is None:
+            if parent is None:
+                level = 0
+            else:
+                level = parent.level + 1
+
+        self.level: int = level
+        self.parent = parent
+        self.refs: t.Dict[str, str] = {}
+        self.loads: t.Dict[str, t.Any] = {}
+        self.stores: t.Set[str] = set()
+
+    def analyze_node(self, node: nodes.Node, **kwargs: t.Any) -> None:
+        visitor = RootVisitor(self)
+        visitor.visit(node, **kwargs)
+
+    def _define_ref(
+        self, name: str, load: t.Optional[t.Tuple[str, t.Optional[str]]] = None
+    ) -> str:
+        ident = f"l_{self.level}_{name}"
+        self.refs[name] = ident
+        if load is not None:
+            self.loads[ident] = load
+        return ident
+
+    def find_load(self, target: str) -> t.Optional[t.Any]:
+        if target in self.loads:
+            return self.loads[target]
+
+        if self.parent is not None:
+            return self.parent.find_load(target)
+
+        return None
+
+    def find_ref(self, name: str) -> t.Optional[str]:
+        if name in self.refs:
+            return self.refs[name]
+
+        if self.parent is not None:
+            return self.parent.find_ref(name)
+
+        return None
+
+    def ref(self, name: str) -> str:
+        rv = self.find_ref(name)
+        if rv is None:
+            raise AssertionError(
+                "Tried to resolve a name to a reference that was"
+                f" unknown to the frame ({name!r})"
+            )
+        return rv
+
+    def copy(self) -> "Symbols":
+        rv = object.__new__(self.__class__)
+        rv.__dict__.update(self.__dict__)
+        rv.refs = self.refs.copy()
+        rv.loads = self.loads.copy()
+        rv.stores = self.stores.copy()
+        return rv
+
+    def store(self, name: str) -> None:
+        self.stores.add(name)
+
+        # If we have not see the name referenced yet, we need to figure
+        # out what to set it to.
+        if name not in self.refs:
+            # If there is a parent scope we check if the name has a
+            # reference there.  If it does it means we might have to alias
+            # to a variable there.
+            if self.parent is not None:
+                outer_ref = self.parent.find_ref(name)
+                if outer_ref is not None:
+                    self._define_ref(name, load=(VAR_LOAD_ALIAS, outer_ref))
+                    return
+
+            # Otherwise we can just set it to undefined.
+            self._define_ref(name, load=(VAR_LOAD_UNDEFINED, None))
+
+    def declare_parameter(self, name: str) -> str:
+        self.stores.add(name)
+        return self._define_ref(name, load=(VAR_LOAD_PARAMETER, None))
+
+    def load(self, name: str) -> None:
+        if self.find_ref(name) is None:
+            self._define_ref(name, load=(VAR_LOAD_RESOLVE, name))
+
+    def branch_update(self, branch_symbols: t.Sequence["Symbols"]) -> None:
+        stores: t.Dict[str, int] = {}
+        for branch in branch_symbols:
+            for target in branch.stores:
+                if target in self.stores:
+                    continue
+                stores[target] = stores.get(target, 0) + 1
+
+        for sym in branch_symbols:
+            self.refs.update(sym.refs)
+            self.loads.update(sym.loads)
+            self.stores.update(sym.stores)
+
+        for name, branch_count in stores.items():
+            if branch_count == len(branch_symbols):
+                continue
+
+            target = self.find_ref(name)  # type: ignore
+            assert target is not None, "should not happen"
+
+            if self.parent is not None:
+                outer_target = self.parent.find_ref(name)
+                if outer_target is not None:
+                    self.loads[target] = (VAR_LOAD_ALIAS, outer_target)
+                    continue
+            self.loads[target] = (VAR_LOAD_RESOLVE, name)
+
+    def dump_stores(self) -> t.Dict[str, str]:
+        rv: t.Dict[str, str] = {}
+        node: t.Optional["Symbols"] = self
+
+        while node is not None:
+            for name in sorted(node.stores):
+                if name not in rv:
+                    rv[name] = self.find_ref(name)  # type: ignore
+
+            node = node.parent
+
+        return rv
+
+    def dump_param_targets(self) -> t.Set[str]:
+        rv = set()
+        node: t.Optional["Symbols"] = self
+
+        while node is not None:
+            for target, (instr, _) in self.loads.items():
+                if instr == VAR_LOAD_PARAMETER:
+                    rv.add(target)
+
+            node = node.parent
+
+        return rv
+
+
+class RootVisitor(NodeVisitor):
+    def __init__(self, symbols: "Symbols") -> None:
+        self.sym_visitor = FrameSymbolVisitor(symbols)
+
+    def _simple_visit(self, node: nodes.Node, **kwargs: t.Any) -> None:
+        for child in node.iter_child_nodes():
+            self.sym_visitor.visit(child)
+
+    visit_Template = _simple_visit
+    visit_Block = _simple_visit
+    visit_Macro = _simple_visit
+    visit_FilterBlock = _simple_visit
+    visit_Scope = _simple_visit
+    visit_If = _simple_visit
+    visit_ScopedEvalContextModifier = _simple_visit
+
+    def visit_AssignBlock(self, node: nodes.AssignBlock, **kwargs: t.Any) -> None:
+        for child in node.body:
+            self.sym_visitor.visit(child)
+
+    def visit_CallBlock(self, node: nodes.CallBlock, **kwargs: t.Any) -> None:
+        for child in node.iter_child_nodes(exclude=("call",)):
+            self.sym_visitor.visit(child)
+
+    def visit_OverlayScope(self, node: nodes.OverlayScope, **kwargs: t.Any) -> None:
+        for child in node.body:
+            self.sym_visitor.visit(child)
+
+    def visit_For(
+        self, node: nodes.For, for_branch: str = "body", **kwargs: t.Any
+    ) -> None:
+        if for_branch == "body":
+            self.sym_visitor.visit(node.target, store_as_param=True)
+            branch = node.body
+        elif for_branch == "else":
+            branch = node.else_
+        elif for_branch == "test":
+            self.sym_visitor.visit(node.target, store_as_param=True)
+            if node.test is not None:
+                self.sym_visitor.visit(node.test)
+            return
+        else:
+            raise RuntimeError("Unknown for branch")
+
+        if branch:
+            for item in branch:
+                self.sym_visitor.visit(item)
+
+    def visit_With(self, node: nodes.With, **kwargs: t.Any) -> None:
+        for target in node.targets:
+            self.sym_visitor.visit(target)
+        for child in node.body:
+            self.sym_visitor.visit(child)
+
+    def generic_visit(self, node: nodes.Node, *args: t.Any, **kwargs: t.Any) -> None:
+        raise NotImplementedError(f"Cannot find symbols for {type(node).__name__!r}")
+
+
+class FrameSymbolVisitor(NodeVisitor):
+    """A visitor for `Frame.inspect`."""
+
+    def __init__(self, symbols: "Symbols") -> None:
+        self.symbols = symbols
+
+    def visit_Name(
+        self, node: nodes.Name, store_as_param: bool = False, **kwargs: t.Any
+    ) -> None:
+        """All assignments to names go through this function."""
+        if store_as_param or node.ctx == "param":
+            self.symbols.declare_parameter(node.name)
+        elif node.ctx == "store":
+            self.symbols.store(node.name)
+        elif node.ctx == "load":
+            self.symbols.load(node.name)
+
+    def visit_NSRef(self, node: nodes.NSRef, **kwargs: t.Any) -> None:
+        self.symbols.load(node.name)
+
+    def visit_If(self, node: nodes.If, **kwargs: t.Any) -> None:
+        self.visit(node.test, **kwargs)
+        original_symbols = self.symbols
+
+        def inner_visit(nodes: t.Iterable[nodes.Node]) -> "Symbols":
+            self.symbols = rv = original_symbols.copy()
+
+            for subnode in nodes:
+                self.visit(subnode, **kwargs)
+
+            self.symbols = original_symbols
+            return rv
+
+        body_symbols = inner_visit(node.body)
+        elif_symbols = inner_visit(node.elif_)
+        else_symbols = inner_visit(node.else_ or ())
+        self.symbols.branch_update([body_symbols, elif_symbols, else_symbols])
+
+    def visit_Macro(self, node: nodes.Macro, **kwargs: t.Any) -> None:
+        self.symbols.store(node.name)
+
+    def visit_Import(self, node: nodes.Import, **kwargs: t.Any) -> None:
+        self.generic_visit(node, **kwargs)
+        self.symbols.store(node.target)
+
+    def visit_FromImport(self, node: nodes.FromImport, **kwargs: t.Any) -> None:
+        self.generic_visit(node, **kwargs)
+
+        for name in node.names:
+            if isinstance(name, tuple):
+                self.symbols.store(name[1])
+            else:
+                self.symbols.store(name)
+
+    def visit_Assign(self, node: nodes.Assign, **kwargs: t.Any) -> None:
+        """Visit assignments in the correct order."""
+        self.visit(node.node, **kwargs)
+        self.visit(node.target, **kwargs)
+
+    def visit_For(self, node: nodes.For, **kwargs: t.Any) -> None:
+        """Visiting stops at for blocks.  However the block sequence
+        is visited as part of the outer scope.
+        """
+        self.visit(node.iter, **kwargs)
+
+    def visit_CallBlock(self, node: nodes.CallBlock, **kwargs: t.Any) -> None:
+        self.visit(node.call, **kwargs)
+
+    def visit_FilterBlock(self, node: nodes.FilterBlock, **kwargs: t.Any) -> None:
+        self.visit(node.filter, **kwargs)
+
+    def visit_With(self, node: nodes.With, **kwargs: t.Any) -> None:
+        for target in node.values:
+            self.visit(target)
+
+    def visit_AssignBlock(self, node: nodes.AssignBlock, **kwargs: t.Any) -> None:
+        """Stop visiting at block assigns."""
+        self.visit(node.target, **kwargs)
+
+    def visit_Scope(self, node: nodes.Scope, **kwargs: t.Any) -> None:
+        """Stop visiting at scopes."""
+
+    def visit_Block(self, node: nodes.Block, **kwargs: t.Any) -> None:
+        """Stop visiting at blocks."""
+
+    def visit_OverlayScope(self, node: nodes.OverlayScope, **kwargs: t.Any) -> None:
+        """Do not visit into overlay scopes."""
diff --git a/src/jinja2/lexer.py b/src/jinja2/lexer.py
new file mode 100644
index 0000000..aff7e9f
--- /dev/null
+++ b/src/jinja2/lexer.py
@@ -0,0 +1,866 @@
+"""Implements a Jinja / Python combination lexer. The ``Lexer`` class
+is used to do some preprocessing. It filters out invalid operators like
+the bitshift operators we don't allow in templates. It separates
+template code and python code in expressions.
+"""
+import re
+import typing as t
+from ast import literal_eval
+from collections import deque
+from sys import intern
+
+from ._identifier import pattern as name_re
+from .exceptions import TemplateSyntaxError
+from .utils import LRUCache
+
+if t.TYPE_CHECKING:
+    import typing_extensions as te
+    from .environment import Environment
+
+# cache for the lexers. Exists in order to be able to have multiple
+# environments with the same lexer
+_lexer_cache: t.MutableMapping[t.Tuple, "Lexer"] = LRUCache(50)  # type: ignore
+
+# static regular expressions
+whitespace_re = re.compile(r"\s+")
+newline_re = re.compile(r"(\r\n|\r|\n)")
+string_re = re.compile(
+    r"('([^'\\]*(?:\\.[^'\\]*)*)'" r'|"([^"\\]*(?:\\.[^"\\]*)*)")', re.S
+)
+integer_re = re.compile(
+    r"""
+    (
+        0b(_?[0-1])+ # binary
+    |
+        0o(_?[0-7])+ # octal
+    |
+        0x(_?[\da-f])+ # hex
+    |
+        [1-9](_?\d)* # decimal
+    |
+        0(_?0)* # decimal zero
+    )
+    """,
+    re.IGNORECASE | re.VERBOSE,
+)
+float_re = re.compile(
+    r"""
+    (?<!\.)  # doesn't start with a .
+    (\d+_)*\d+  # digits, possibly _ separated
+    (
+        (\.(\d+_)*\d+)?  # optional fractional part
+        e[+\-]?(\d+_)*\d+  # exponent part
+    |
+        \.(\d+_)*\d+  # required fractional part
+    )
+    """,
+    re.IGNORECASE | re.VERBOSE,
+)
+
+# internal the tokens and keep references to them
+TOKEN_ADD = intern("add")
+TOKEN_ASSIGN = intern("assign")
+TOKEN_COLON = intern("colon")
+TOKEN_COMMA = intern("comma")
+TOKEN_DIV = intern("div")
+TOKEN_DOT = intern("dot")
+TOKEN_EQ = intern("eq")
+TOKEN_FLOORDIV = intern("floordiv")
+TOKEN_GT = intern("gt")
+TOKEN_GTEQ = intern("gteq")
+TOKEN_LBRACE = intern("lbrace")
+TOKEN_LBRACKET = intern("lbracket")
+TOKEN_LPAREN = intern("lparen")
+TOKEN_LT = intern("lt")
+TOKEN_LTEQ = intern("lteq")
+TOKEN_MOD = intern("mod")
+TOKEN_MUL = intern("mul")
+TOKEN_NE = intern("ne")
+TOKEN_PIPE = intern("pipe")
+TOKEN_POW = intern("pow")
+TOKEN_RBRACE = intern("rbrace")
+TOKEN_RBRACKET = intern("rbracket")
+TOKEN_RPAREN = intern("rparen")
+TOKEN_SEMICOLON = intern("semicolon")
+TOKEN_SUB = intern("sub")
+TOKEN_TILDE = intern("tilde")
+TOKEN_WHITESPACE = intern("whitespace")
+TOKEN_FLOAT = intern("float")
+TOKEN_INTEGER = intern("integer")
+TOKEN_NAME = intern("name")
+TOKEN_STRING = intern("string")
+TOKEN_OPERATOR = intern("operator")
+TOKEN_BLOCK_BEGIN = intern("block_begin")
+TOKEN_BLOCK_END = intern("block_end")
+TOKEN_VARIABLE_BEGIN = intern("variable_begin")
+TOKEN_VARIABLE_END = intern("variable_end")
+TOKEN_RAW_BEGIN = intern("raw_begin")
+TOKEN_RAW_END = intern("raw_end")
+TOKEN_COMMENT_BEGIN = intern("comment_begin")
+TOKEN_COMMENT_END = intern("comment_end")
+TOKEN_COMMENT = intern("comment")
+TOKEN_LINESTATEMENT_BEGIN = intern("linestatement_begin")
+TOKEN_LINESTATEMENT_END = intern("linestatement_end")
+TOKEN_LINECOMMENT_BEGIN = intern("linecomment_begin")
+TOKEN_LINECOMMENT_END = intern("linecomment_end")
+TOKEN_LINECOMMENT = intern("linecomment")
+TOKEN_DATA = intern("data")
+TOKEN_INITIAL = intern("initial")
+TOKEN_EOF = intern("eof")
+
+# bind operators to token types
+operators = {
+    "+": TOKEN_ADD,
+    "-": TOKEN_SUB,
+    "/": TOKEN_DIV,
+    "//": TOKEN_FLOORDIV,
+    "*": TOKEN_MUL,
+    "%": TOKEN_MOD,
+    "**": TOKEN_POW,
+    "~": TOKEN_TILDE,
+    "[": TOKEN_LBRACKET,
+    "]": TOKEN_RBRACKET,
+    "(": TOKEN_LPAREN,
+    ")": TOKEN_RPAREN,
+    "{": TOKEN_LBRACE,
+    "}": TOKEN_RBRACE,
+    "==": TOKEN_EQ,
+    "!=": TOKEN_NE,
+    ">": TOKEN_GT,
+    ">=": TOKEN_GTEQ,
+    "<": TOKEN_LT,
+    "<=": TOKEN_LTEQ,
+    "=": TOKEN_ASSIGN,
+    ".": TOKEN_DOT,
+    ":": TOKEN_COLON,
+    "|": TOKEN_PIPE,
+    ",": TOKEN_COMMA,
+    ";": TOKEN_SEMICOLON,
+}
+
+reverse_operators = {v: k for k, v in operators.items()}
+assert len(operators) == len(reverse_operators), "operators dropped"
+operator_re = re.compile(
+    f"({'|'.join(re.escape(x) for x in sorted(operators, key=lambda x: -len(x)))})"
+)
+
+ignored_tokens = frozenset(
+    [
+        TOKEN_COMMENT_BEGIN,
+        TOKEN_COMMENT,
+        TOKEN_COMMENT_END,
+        TOKEN_WHITESPACE,
+        TOKEN_LINECOMMENT_BEGIN,
+        TOKEN_LINECOMMENT_END,
+        TOKEN_LINECOMMENT,
+    ]
+)
+ignore_if_empty = frozenset(
+    [TOKEN_WHITESPACE, TOKEN_DATA, TOKEN_COMMENT, TOKEN_LINECOMMENT]
+)
+
+
+def _describe_token_type(token_type: str) -> str:
+    if token_type in reverse_operators:
+        return reverse_operators[token_type]
+
+    return {
+        TOKEN_COMMENT_BEGIN: "begin of comment",
+        TOKEN_COMMENT_END: "end of comment",
+        TOKEN_COMMENT: "comment",
+        TOKEN_LINECOMMENT: "comment",
+        TOKEN_BLOCK_BEGIN: "begin of statement block",
+        TOKEN_BLOCK_END: "end of statement block",
+        TOKEN_VARIABLE_BEGIN: "begin of print statement",
+        TOKEN_VARIABLE_END: "end of print statement",
+        TOKEN_LINESTATEMENT_BEGIN: "begin of line statement",
+        TOKEN_LINESTATEMENT_END: "end of line statement",
+        TOKEN_DATA: "template data / text",
+        TOKEN_EOF: "end of template",
+    }.get(token_type, token_type)
+
+
+def describe_token(token: "Token") -> str:
+    """Returns a description of the token."""
+    if token.type == TOKEN_NAME:
+        return token.value
+
+    return _describe_token_type(token.type)
+
+
+def describe_token_expr(expr: str) -> str:
+    """Like `describe_token` but for token expressions."""
+    if ":" in expr:
+        type, value = expr.split(":", 1)
+
+        if type == TOKEN_NAME:
+            return value
+    else:
+        type = expr
+
+    return _describe_token_type(type)
+
+
+def count_newlines(value: str) -> int:
+    """Count the number of newline characters in the string.  This is
+    useful for extensions that filter a stream.
+    """
+    return len(newline_re.findall(value))
+
+
+def compile_rules(environment: "Environment") -> t.List[t.Tuple[str, str]]:
+    """Compiles all the rules from the environment into a list of rules."""
+    e = re.escape
+    rules = [
+        (
+            len(environment.comment_start_string),
+            TOKEN_COMMENT_BEGIN,
+            e(environment.comment_start_string),
+        ),
+        (
+            len(environment.block_start_string),
+            TOKEN_BLOCK_BEGIN,
+            e(environment.block_start_string),
+        ),
+        (
+            len(environment.variable_start_string),
+            TOKEN_VARIABLE_BEGIN,
+            e(environment.variable_start_string),
+        ),
+    ]
+
+    if environment.line_statement_prefix is not None:
+        rules.append(
+            (
+                len(environment.line_statement_prefix),
+                TOKEN_LINESTATEMENT_BEGIN,
+                r"^[ \t\v]*" + e(environment.line_statement_prefix),
+            )
+        )
+    if environment.line_comment_prefix is not None:
+        rules.append(
+            (
+                len(environment.line_comment_prefix),
+                TOKEN_LINECOMMENT_BEGIN,
+                r"(?:^|(?<=\S))[^\S\r\n]*" + e(environment.line_comment_prefix),
+            )
+        )
+
+    return [x[1:] for x in sorted(rules, reverse=True)]
+
+
+class Failure:
+    """Class that raises a `TemplateSyntaxError` if called.
+    Used by the `Lexer` to specify known errors.
+    """
+
+    def __init__(
+        self, message: str, cls: t.Type[TemplateSyntaxError] = TemplateSyntaxError
+    ) -> None:
+        self.message = message
+        self.error_class = cls
+
+    def __call__(self, lineno: int, filename: str) -> "te.NoReturn":
+        raise self.error_class(self.message, lineno, filename)
+
+
+class Token(t.NamedTuple):
+    lineno: int
+    type: str
+    value: str
+
+    def __str__(self) -> str:
+        return describe_token(self)
+
+    def test(self, expr: str) -> bool:
+        """Test a token against a token expression.  This can either be a
+        token type or ``'token_type:token_value'``.  This can only test
+        against string values and types.
+        """
+        # here we do a regular string equality check as test_any is usually
+        # passed an iterable of not interned strings.
+        if self.type == expr:
+            return True
+
+        if ":" in expr:
+            return expr.split(":", 1) == [self.type, self.value]
+
+        return False
+
+    def test_any(self, *iterable: str) -> bool:
+        """Test against multiple token expressions."""
+        return any(self.test(expr) for expr in iterable)
+
+
+class TokenStreamIterator:
+    """The iterator for tokenstreams.  Iterate over the stream
+    until the eof token is reached.
+    """
+
+    def __init__(self, stream: "TokenStream") -> None:
+        self.stream = stream
+
+    def __iter__(self) -> "TokenStreamIterator":
+        return self
+
+    def __next__(self) -> Token:
+        token = self.stream.current
+
+        if token.type is TOKEN_EOF:
+            self.stream.close()
+            raise StopIteration
+
+        next(self.stream)
+        return token
+
+
+class TokenStream:
+    """A token stream is an iterable that yields :class:`Token`\\s.  The
+    parser however does not iterate over it but calls :meth:`next` to go
+    one token ahead.  The current active token is stored as :attr:`current`.
+    """
+
+    def __init__(
+        self,
+        generator: t.Iterable[Token],
+        name: t.Optional[str],
+        filename: t.Optional[str],
+    ):
+        self._iter = iter(generator)
+        self._pushed: "te.Deque[Token]" = deque()
+        self.name = name
+        self.filename = filename
+        self.closed = False
+        self.current = Token(1, TOKEN_INITIAL, "")
+        next(self)
+
+    def __iter__(self) -> TokenStreamIterator:
+        return TokenStreamIterator(self)
+
+    def __bool__(self) -> bool:
+        return bool(self._pushed) or self.current.type is not TOKEN_EOF
+
+    @property
+    def eos(self) -> bool:
+        """Are we at the end of the stream?"""
+        return not self
+
+    def push(self, token: Token) -> None:
+        """Push a token back to the stream."""
+        self._pushed.append(token)
+
+    def look(self) -> Token:
+        """Look at the next token."""
+        old_token = next(self)
+        result = self.current
+        self.push(result)
+        self.current = old_token
+        return result
+
+    def skip(self, n: int = 1) -> None:
+        """Got n tokens ahead."""
+        for _ in range(n):
+            next(self)
+
+    def next_if(self, expr: str) -> t.Optional[Token]:
+        """Perform the token test and return the token if it matched.
+        Otherwise the return value is `None`.
+        """
+        if self.current.test(expr):
+            return next(self)
+
+        return None
+
+    def skip_if(self, expr: str) -> bool:
+        """Like :meth:`next_if` but only returns `True` or `False`."""
+        return self.next_if(expr) is not None
+
+    def __next__(self) -> Token:
+        """Go one token ahead and return the old one.
+
+        Use the built-in :func:`next` instead of calling this directly.
+        """
+        rv = self.current
+
+        if self._pushed:
+            self.current = self._pushed.popleft()
+        elif self.current.type is not TOKEN_EOF:
+            try:
+                self.current = next(self._iter)
+            except StopIteration:
+                self.close()
+
+        return rv
+
+    def close(self) -> None:
+        """Close the stream."""
+        self.current = Token(self.current.lineno, TOKEN_EOF, "")
+        self._iter = iter(())
+        self.closed = True
+
+    def expect(self, expr: str) -> Token:
+        """Expect a given token type and return it.  This accepts the same
+        argument as :meth:`jinja2.lexer.Token.test`.
+        """
+        if not self.current.test(expr):
+            expr = describe_token_expr(expr)
+
+            if self.current.type is TOKEN_EOF:
+                raise TemplateSyntaxError(
+                    f"unexpected end of template, expected {expr!r}.",
+                    self.current.lineno,
+                    self.name,
+                    self.filename,
+                )
+
+            raise TemplateSyntaxError(
+                f"expected token {expr!r}, got {describe_token(self.current)!r}",
+                self.current.lineno,
+                self.name,
+                self.filename,
+            )
+
+        return next(self)
+
+
+def get_lexer(environment: "Environment") -> "Lexer":
+    """Return a lexer which is probably cached."""
+    key = (
+        environment.block_start_string,
+        environment.block_end_string,
+        environment.variable_start_string,
+        environment.variable_end_string,
+        environment.comment_start_string,
+        environment.comment_end_string,
+        environment.line_statement_prefix,
+        environment.line_comment_prefix,
+        environment.trim_blocks,
+        environment.lstrip_blocks,
+        environment.newline_sequence,
+        environment.keep_trailing_newline,
+    )
+    lexer = _lexer_cache.get(key)
+
+    if lexer is None:
+        _lexer_cache[key] = lexer = Lexer(environment)
+
+    return lexer
+
+
+class OptionalLStrip(tuple):
+    """A special tuple for marking a point in the state that can have
+    lstrip applied.
+    """
+
+    __slots__ = ()
+
+    # Even though it looks like a no-op, creating instances fails
+    # without this.
+    def __new__(cls, *members, **kwargs):  # type: ignore
+        return super().__new__(cls, members)
+
+
+class _Rule(t.NamedTuple):
+    pattern: t.Pattern[str]
+    tokens: t.Union[str, t.Tuple[str, ...], t.Tuple[Failure]]
+    command: t.Optional[str]
+
+
+class Lexer:
+    """Class that implements a lexer for a given environment. Automatically
+    created by the environment class, usually you don't have to do that.
+
+    Note that the lexer is not automatically bound to an environment.
+    Multiple environments can share the same lexer.
+    """
+
+    def __init__(self, environment: "Environment") -> None:
+        # shortcuts
+        e = re.escape
+
+        def c(x: str) -> t.Pattern[str]:
+            return re.compile(x, re.M | re.S)
+
+        # lexing rules for tags
+        tag_rules: t.List[_Rule] = [
+            _Rule(whitespace_re, TOKEN_WHITESPACE, None),
+            _Rule(float_re, TOKEN_FLOAT, None),
+            _Rule(integer_re, TOKEN_INTEGER, None),
+            _Rule(name_re, TOKEN_NAME, None),
+            _Rule(string_re, TOKEN_STRING, None),
+            _Rule(operator_re, TOKEN_OPERATOR, None),
+        ]
+
+        # assemble the root lexing rule. because "|" is ungreedy
+        # we have to sort by length so that the lexer continues working
+        # as expected when we have parsing rules like <% for block and
+        # <%= for variables. (if someone wants asp like syntax)
+        # variables are just part of the rules if variable processing
+        # is required.
+        root_tag_rules = compile_rules(environment)
+
+        block_start_re = e(environment.block_start_string)
+        block_end_re = e(environment.block_end_string)
+        comment_end_re = e(environment.comment_end_string)
+        variable_end_re = e(environment.variable_end_string)
+
+        # block suffix if trimming is enabled
+        block_suffix_re = "\\n?" if environment.trim_blocks else ""
+
+        self.lstrip_blocks = environment.lstrip_blocks
+
+        self.newline_sequence = environment.newline_sequence
+        self.keep_trailing_newline = environment.keep_trailing_newline
+
+        root_raw_re = (
+            rf"(?P<raw_begin>{block_start_re}(\-|\+|)\s*raw\s*"
+            rf"(?:\-{block_end_re}\s*|{block_end_re}))"
+        )
+        root_parts_re = "|".join(
+            [root_raw_re] + [rf"(?P<{n}>{r}(\-|\+|))" for n, r in root_tag_rules]
+        )
+
+        # global lexing rules
+        self.rules: t.Dict[str, t.List[_Rule]] = {
+            "root": [
+                # directives
+                _Rule(
+                    c(rf"(.*?)(?:{root_parts_re})"),
+                    OptionalLStrip(TOKEN_DATA, "#bygroup"),  # type: ignore
+                    "#bygroup",
+                ),
+                # data
+                _Rule(c(".+"), TOKEN_DATA, None),
+            ],
+            # comments
+            TOKEN_COMMENT_BEGIN: [
+                _Rule(
+                    c(
+                        rf"(.*?)((?:\+{comment_end_re}|\-{comment_end_re}\s*"
+                        rf"|{comment_end_re}{block_suffix_re}))"
+                    ),
+                    (TOKEN_COMMENT, TOKEN_COMMENT_END),
+                    "#pop",
+                ),
+                _Rule(c(r"(.)"), (Failure("Missing end of comment tag"),), None),
+            ],
+            # blocks
+            TOKEN_BLOCK_BEGIN: [
+                _Rule(
+                    c(
+                        rf"(?:\+{block_end_re}|\-{block_end_re}\s*"
+                        rf"|{block_end_re}{block_suffix_re})"
+                    ),
+                    TOKEN_BLOCK_END,
+                    "#pop",
+                ),
+            ]
+            + tag_rules,
+            # variables
+            TOKEN_VARIABLE_BEGIN: [
+                _Rule(
+                    c(rf"\-{variable_end_re}\s*|{variable_end_re}"),
+                    TOKEN_VARIABLE_END,
+                    "#pop",
+                )
+            ]
+            + tag_rules,
+            # raw block
+            TOKEN_RAW_BEGIN: [
+                _Rule(
+                    c(
+                        rf"(.*?)((?:{block_start_re}(\-|\+|))\s*endraw\s*"
+                        rf"(?:\+{block_end_re}|\-{block_end_re}\s*"
+                        rf"|{block_end_re}{block_suffix_re}))"
+                    ),
+                    OptionalLStrip(TOKEN_DATA, TOKEN_RAW_END),  # type: ignore
+                    "#pop",
+                ),
+                _Rule(c(r"(.)"), (Failure("Missing end of raw directive"),), None),
+            ],
+            # line statements
+            TOKEN_LINESTATEMENT_BEGIN: [
+                _Rule(c(r"\s*(\n|$)"), TOKEN_LINESTATEMENT_END, "#pop")
+            ]
+            + tag_rules,
+            # line comments
+            TOKEN_LINECOMMENT_BEGIN: [
+                _Rule(
+                    c(r"(.*?)()(?=\n|$)"),
+                    (TOKEN_LINECOMMENT, TOKEN_LINECOMMENT_END),
+                    "#pop",
+                )
+            ],
+        }
+
+    def _normalize_newlines(self, value: str) -> str:
+        """Replace all newlines with the configured sequence in strings
+        and template data.
+        """
+        return newline_re.sub(self.newline_sequence, value)
+
+    def tokenize(
+        self,
+        source: str,
+        name: t.Optional[str] = None,
+        filename: t.Optional[str] = None,
+        state: t.Optional[str] = None,
+    ) -> TokenStream:
+        """Calls tokeniter + tokenize and wraps it in a token stream."""
+        stream = self.tokeniter(source, name, filename, state)
+        return TokenStream(self.wrap(stream, name, filename), name, filename)
+
+    def wrap(
+        self,
+        stream: t.Iterable[t.Tuple[int, str, str]],
+        name: t.Optional[str] = None,
+        filename: t.Optional[str] = None,
+    ) -> t.Iterator[Token]:
+        """This is called with the stream as returned by `tokenize` and wraps
+        every token in a :class:`Token` and converts the value.
+        """
+        for lineno, token, value_str in stream:
+            if token in ignored_tokens:
+                continue
+
+            value: t.Any = value_str
+
+            if token == TOKEN_LINESTATEMENT_BEGIN:
+                token = TOKEN_BLOCK_BEGIN
+            elif token == TOKEN_LINESTATEMENT_END:
+                token = TOKEN_BLOCK_END
+            # we are not interested in those tokens in the parser
+            elif token in (TOKEN_RAW_BEGIN, TOKEN_RAW_END):
+                continue
+            elif token == TOKEN_DATA:
+                value = self._normalize_newlines(value_str)
+            elif token == "keyword":
+                token = value_str
+            elif token == TOKEN_NAME:
+                value = value_str
+
+                if not value.isidentifier():
+                    raise TemplateSyntaxError(
+                        "Invalid character in identifier", lineno, name, filename
+                    )
+            elif token == TOKEN_STRING:
+                # try to unescape string
+                try:
+                    value = (
+                        self._normalize_newlines(value_str[1:-1])
+                        .encode("ascii", "backslashreplace")
+                        .decode("unicode-escape")
+                    )
+                except Exception as e:
+                    msg = str(e).split(":")[-1].strip()
+                    raise TemplateSyntaxError(msg, lineno, name, filename) from e
+            elif token == TOKEN_INTEGER:
+                value = int(value_str.replace("_", ""), 0)
+            elif token == TOKEN_FLOAT:
+                # remove all "_" first to support more Python versions
+                value = literal_eval(value_str.replace("_", ""))
+            elif token == TOKEN_OPERATOR:
+                token = operators[value_str]
+
+            yield Token(lineno, token, value)
+
+    def tokeniter(
+        self,
+        source: str,
+        name: t.Optional[str],
+        filename: t.Optional[str] = None,
+        state: t.Optional[str] = None,
+    ) -> t.Iterator[t.Tuple[int, str, str]]:
+        """This method tokenizes the text and returns the tokens in a
+        generator. Use this method if you just want to tokenize a template.
+
+        .. versionchanged:: 3.0
+            Only ``\\n``, ``\\r\\n`` and ``\\r`` are treated as line
+            breaks.
+        """
+        lines = newline_re.split(source)[::2]
+
+        if not self.keep_trailing_newline and lines[-1] == "":
+            del lines[-1]
+
+        source = "\n".join(lines)
+        pos = 0
+        lineno = 1
+        stack = ["root"]
+
+        if state is not None and state != "root":
+            assert state in ("variable", "block"), "invalid state"
+            stack.append(state + "_begin")
+
+        statetokens = self.rules[stack[-1]]
+        source_length = len(source)
+        balancing_stack: t.List[str] = []
+        newlines_stripped = 0
+        line_starting = True
+
+        while True:
+            # tokenizer loop
+            for regex, tokens, new_state in statetokens:
+                m = regex.match(source, pos)
+
+                # if no match we try again with the next rule
+                if m is None:
+                    continue
+
+                # we only match blocks and variables if braces / parentheses
+                # are balanced. continue parsing with the lower rule which
+                # is the operator rule. do this only if the end tags look
+                # like operators
+                if balancing_stack and tokens in (
+                    TOKEN_VARIABLE_END,
+                    TOKEN_BLOCK_END,
+                    TOKEN_LINESTATEMENT_END,
+                ):
+                    continue
+
+                # tuples support more options
+                if isinstance(tokens, tuple):
+                    groups: t.Sequence[str] = m.groups()
+
+                    if isinstance(tokens, OptionalLStrip):
+                        # Rule supports lstrip. Match will look like
+                        # text, block type, whitespace control, type, control, ...
+                        text = groups[0]
+                        # Skipping the text and first type, every other group is the
+                        # whitespace control for each type. One of the groups will be
+                        # -, +, or empty string instead of None.
+                        strip_sign = next(g for g in groups[2::2] if g is not None)
+
+                        if strip_sign == "-":
+                            # Strip all whitespace between the text and the tag.
+                            stripped = text.rstrip()
+                            newlines_stripped = text[len(stripped) :].count("\n")
+                            groups = [stripped, *groups[1:]]
+                        elif (
+                            # Not marked for preserving whitespace.
+                            strip_sign != "+"
+                            # lstrip is enabled.
+                            and self.lstrip_blocks
+                            # Not a variable expression.
+                            and not m.groupdict().get(TOKEN_VARIABLE_BEGIN)
+                        ):
+                            # The start of text between the last newline and the tag.
+                            l_pos = text.rfind("\n") + 1
+
+                            if l_pos > 0 or line_starting:
+                                # If there's only whitespace between the newline and the
+                                # tag, strip it.
+                                if whitespace_re.fullmatch(text, l_pos):
+                                    groups = [text[:l_pos], *groups[1:]]
+
+                    for idx, token in enumerate(tokens):
+                        # failure group
+                        if token.__class__ is Failure:
+                            raise token(lineno, filename)
+                        # bygroup is a bit more complex, in that case we
+                        # yield for the current token the first named
+                        # group that matched
+                        elif token == "#bygroup":
+                            for key, value in m.groupdict().items():
+                                if value is not None:
+                                    yield lineno, key, value
+                                    lineno += value.count("\n")
+                                    break
+                            else:
+                                raise RuntimeError(
+                                    f"{regex!r} wanted to resolve the token dynamically"
+                                    " but no group matched"
+                                )
+                        # normal group
+                        else:
+                            data = groups[idx]
+
+                            if data or token not in ignore_if_empty:
+                                yield lineno, token, data
+
+                            lineno += data.count("\n") + newlines_stripped
+                            newlines_stripped = 0
+
+                # strings as token just are yielded as it.
+                else:
+                    data = m.group()
+
+                    # update brace/parentheses balance
+                    if tokens == TOKEN_OPERATOR:
+                        if data == "{":
+                            balancing_stack.append("}")
+                        elif data == "(":
+                            balancing_stack.append(")")
+                        elif data == "[":
+                            balancing_stack.append("]")
+                        elif data in ("}", ")", "]"):
+                            if not balancing_stack:
+                                raise TemplateSyntaxError(
+                                    f"unexpected '{data}'", lineno, name, filename
+                                )
+
+                            expected_op = balancing_stack.pop()
+
+                            if expected_op != data:
+                                raise TemplateSyntaxError(
+                                    f"unexpected '{data}', expected '{expected_op}'",
+                                    lineno,
+                                    name,
+                                    filename,
+                                )
+
+                    # yield items
+                    if data or tokens not in ignore_if_empty:
+                        yield lineno, tokens, data
+
+                    lineno += data.count("\n")
+
+                line_starting = m.group()[-1:] == "\n"
+                # fetch new position into new variable so that we can check
+                # if there is a internal parsing error which would result
+                # in an infinite loop
+                pos2 = m.end()
+
+                # handle state changes
+                if new_state is not None:
+                    # remove the uppermost state
+                    if new_state == "#pop":
+                        stack.pop()
+                    # resolve the new state by group checking
+                    elif new_state == "#bygroup":
+                        for key, value in m.groupdict().items():
+                            if value is not None:
+                                stack.append(key)
+                                break
+                        else:
+                            raise RuntimeError(
+                                f"{regex!r} wanted to resolve the new state dynamically"
+                                f" but no group matched"
+                            )
+                    # direct state name given
+                    else:
+                        stack.append(new_state)
+
+                    statetokens = self.rules[stack[-1]]
+                # we are still at the same position and no stack change.
+                # this means a loop without break condition, avoid that and
+                # raise error
+                elif pos2 == pos:
+                    raise RuntimeError(
+                        f"{regex!r} yielded empty string without stack change"
+                    )
+
+                # publish new function and start again
+                pos = pos2
+                break
+            # if loop terminated without break we haven't found a single match
+            # either we are at the end of the file or we have a problem
+            else:
+                # end of text
+                if pos >= source_length:
+                    return
+
+                # something went wrong
+                raise TemplateSyntaxError(
+                    f"unexpected char {source[pos]!r} at {pos}", lineno, name, filename
+                )
diff --git a/src/jinja2/loaders.py b/src/jinja2/loaders.py
new file mode 100644
index 0000000..d2f9809
--- /dev/null
+++ b/src/jinja2/loaders.py
@@ -0,0 +1,661 @@
+"""API and implementations for loading templates from different data
+sources.
+"""
+import importlib.util
+import os
+import posixpath
+import sys
+import typing as t
+import weakref
+import zipimport
+from collections import abc
+from hashlib import sha1
+from importlib import import_module
+from types import ModuleType
+
+from .exceptions import TemplateNotFound
+from .utils import internalcode
+from .utils import open_if_exists
+
+if t.TYPE_CHECKING:
+    from .environment import Environment
+    from .environment import Template
+
+
+def split_template_path(template: str) -> t.List[str]:
+    """Split a path into segments and perform a sanity check.  If it detects
+    '..' in the path it will raise a `TemplateNotFound` error.
+    """
+    pieces = []
+    for piece in template.split("/"):
+        if (
+            os.path.sep in piece
+            or (os.path.altsep and os.path.altsep in piece)
+            or piece == os.path.pardir
+        ):
+            raise TemplateNotFound(template)
+        elif piece and piece != ".":
+            pieces.append(piece)
+    return pieces
+
+
+class BaseLoader:
+    """Baseclass for all loaders.  Subclass this and override `get_source` to
+    implement a custom loading mechanism.  The environment provides a
+    `get_template` method that calls the loader's `load` method to get the
+    :class:`Template` object.
+
+    A very basic example for a loader that looks up templates on the file
+    system could look like this::
+
+        from jinja2 import BaseLoader, TemplateNotFound
+        from os.path import join, exists, getmtime
+
+        class MyLoader(BaseLoader):
+
+            def __init__(self, path):
+                self.path = path
+
+            def get_source(self, environment, template):
+                path = join(self.path, template)
+                if not exists(path):
+                    raise TemplateNotFound(template)
+                mtime = getmtime(path)
+                with open(path) as f:
+                    source = f.read()
+                return source, path, lambda: mtime == getmtime(path)
+    """
+
+    #: if set to `False` it indicates that the loader cannot provide access
+    #: to the source of templates.
+    #:
+    #: .. versionadded:: 2.4
+    has_source_access = True
+
+    def get_source(
+        self, environment: "Environment", template: str
+    ) -> t.Tuple[str, t.Optional[str], t.Optional[t.Callable[[], bool]]]:
+        """Get the template source, filename and reload helper for a template.
+        It's passed the environment and template name and has to return a
+        tuple in the form ``(source, filename, uptodate)`` or raise a
+        `TemplateNotFound` error if it can't locate the template.
+
+        The source part of the returned tuple must be the source of the
+        template as a string. The filename should be the name of the
+        file on the filesystem if it was loaded from there, otherwise
+        ``None``. The filename is used by Python for the tracebacks
+        if no loader extension is used.
+
+        The last item in the tuple is the `uptodate` function.  If auto
+        reloading is enabled it's always called to check if the template
+        changed.  No arguments are passed so the function must store the
+        old state somewhere (for example in a closure).  If it returns `False`
+        the template will be reloaded.
+        """
+        if not self.has_source_access:
+            raise RuntimeError(
+                f"{type(self).__name__} cannot provide access to the source"
+            )
+        raise TemplateNotFound(template)
+
+    def list_templates(self) -> t.List[str]:
+        """Iterates over all templates.  If the loader does not support that
+        it should raise a :exc:`TypeError` which is the default behavior.
+        """
+        raise TypeError("this loader cannot iterate over all templates")
+
+    @internalcode
+    def load(
+        self,
+        environment: "Environment",
+        name: str,
+        globals: t.Optional[t.MutableMapping[str, t.Any]] = None,
+    ) -> "Template":
+        """Loads a template.  This method looks up the template in the cache
+        or loads one by calling :meth:`get_source`.  Subclasses should not
+        override this method as loaders working on collections of other
+        loaders (such as :class:`PrefixLoader` or :class:`ChoiceLoader`)
+        will not call this method but `get_source` directly.
+        """
+        code = None
+        if globals is None:
+            globals = {}
+
+        # first we try to get the source for this template together
+        # with the filename and the uptodate function.
+        source, filename, uptodate = self.get_source(environment, name)
+
+        # try to load the code from the bytecode cache if there is a
+        # bytecode cache configured.
+        bcc = environment.bytecode_cache
+        if bcc is not None:
+            bucket = bcc.get_bucket(environment, name, filename, source)
+            code = bucket.code
+
+        # if we don't have code so far (not cached, no longer up to
+        # date) etc. we compile the template
+        if code is None:
+            code = environment.compile(source, name, filename)
+
+        # if the bytecode cache is available and the bucket doesn't
+        # have a code so far, we give the bucket the new code and put
+        # it back to the bytecode cache.
+        if bcc is not None and bucket.code is None:
+            bucket.code = code
+            bcc.set_bucket(bucket)
+
+        return environment.template_class.from_code(
+            environment, code, globals, uptodate
+        )
+
+
+class FileSystemLoader(BaseLoader):
+    """Load templates from a directory in the file system.
+
+    The path can be relative or absolute. Relative paths are relative to
+    the current working directory.
+
+    .. code-block:: python
+
+        loader = FileSystemLoader("templates")
+
+    A list of paths can be given. The directories will be searched in
+    order, stopping at the first matching template.
+
+    .. code-block:: python
+
+        loader = FileSystemLoader(["/override/templates", "/default/templates"])
+
+    :param searchpath: A path, or list of paths, to the directory that
+        contains the templates.
+    :param encoding: Use this encoding to read the text from template
+        files.
+    :param followlinks: Follow symbolic links in the path.
+
+    .. versionchanged:: 2.8
+        Added the ``followlinks`` parameter.
+    """
+
+    def __init__(
+        self,
+        searchpath: t.Union[str, os.PathLike, t.Sequence[t.Union[str, os.PathLike]]],
+        encoding: str = "utf-8",
+        followlinks: bool = False,
+    ) -> None:
+        if not isinstance(searchpath, abc.Iterable) or isinstance(searchpath, str):
+            searchpath = [searchpath]
+
+        self.searchpath = [os.fspath(p) for p in searchpath]
+        self.encoding = encoding
+        self.followlinks = followlinks
+
+    def get_source(
+        self, environment: "Environment", template: str
+    ) -> t.Tuple[str, str, t.Callable[[], bool]]:
+        pieces = split_template_path(template)
+        for searchpath in self.searchpath:
+            # Use posixpath even on Windows to avoid "drive:" or UNC
+            # segments breaking out of the search directory.
+            filename = posixpath.join(searchpath, *pieces)
+            f = open_if_exists(filename)
+            if f is None:
+                continue
+            try:
+                contents = f.read().decode(self.encoding)
+            finally:
+                f.close()
+
+            mtime = os.path.getmtime(filename)
+
+            def uptodate() -> bool:
+                try:
+                    return os.path.getmtime(filename) == mtime
+                except OSError:
+                    return False
+
+            # Use normpath to convert Windows altsep to sep.
+            return contents, os.path.normpath(filename), uptodate
+        raise TemplateNotFound(template)
+
+    def list_templates(self) -> t.List[str]:
+        found = set()
+        for searchpath in self.searchpath:
+            walk_dir = os.walk(searchpath, followlinks=self.followlinks)
+            for dirpath, _, filenames in walk_dir:
+                for filename in filenames:
+                    template = (
+                        os.path.join(dirpath, filename)[len(searchpath) :]
+                        .strip(os.path.sep)
+                        .replace(os.path.sep, "/")
+                    )
+                    if template[:2] == "./":
+                        template = template[2:]
+                    if template not in found:
+                        found.add(template)
+        return sorted(found)
+
+
+class PackageLoader(BaseLoader):
+    """Load templates from a directory in a Python package.
+
+    :param package_name: Import name of the package that contains the
+        template directory.
+    :param package_path: Directory within the imported package that
+        contains the templates.
+    :param encoding: Encoding of template files.
+
+    The following example looks up templates in the ``pages`` directory
+    within the ``project.ui`` package.
+
+    .. code-block:: python
+
+        loader = PackageLoader("project.ui", "pages")
+
+    Only packages installed as directories (standard pip behavior) or
+    zip/egg files (less common) are supported. The Python API for
+    introspecting data in packages is too limited to support other
+    installation methods the way this loader requires.
+
+    There is limited support for :pep:`420` namespace packages. The
+    template directory is assumed to only be in one namespace
+    contributor. Zip files contributing to a namespace are not
+    supported.
+
+    .. versionchanged:: 3.0
+        No longer uses ``setuptools`` as a dependency.
+
+    .. versionchanged:: 3.0
+        Limited PEP 420 namespace package support.
+    """
+
+    def __init__(
+        self,
+        package_name: str,
+        package_path: "str" = "templates",
+        encoding: str = "utf-8",
+    ) -> None:
+        package_path = os.path.normpath(package_path).rstrip(os.path.sep)
+
+        # normpath preserves ".", which isn't valid in zip paths.
+        if package_path == os.path.curdir:
+            package_path = ""
+        elif package_path[:2] == os.path.curdir + os.path.sep:
+            package_path = package_path[2:]
+
+        self.package_path = package_path
+        self.package_name = package_name
+        self.encoding = encoding
+
+        # Make sure the package exists. This also makes namespace
+        # packages work, otherwise get_loader returns None.
+        import_module(package_name)
+        spec = importlib.util.find_spec(package_name)
+        assert spec is not None, "An import spec was not found for the package."
+        loader = spec.loader
+        assert loader is not None, "A loader was not found for the package."
+        self._loader = loader
+        self._archive = None
+        template_root = None
+
+        if isinstance(loader, zipimport.zipimporter):
+            self._archive = loader.archive
+            pkgdir = next(iter(spec.submodule_search_locations))  # type: ignore
+            template_root = os.path.join(pkgdir, package_path).rstrip(os.path.sep)
+        else:
+            roots: t.List[str] = []
+
+            # One element for regular packages, multiple for namespace
+            # packages, or None for single module file.
+            if spec.submodule_search_locations:
+                roots.extend(spec.submodule_search_locations)
+            # A single module file, use the parent directory instead.
+            elif spec.origin is not None:
+                roots.append(os.path.dirname(spec.origin))
+
+            for root in roots:
+                root = os.path.join(root, package_path)
+
+                if os.path.isdir(root):
+                    template_root = root
+                    break
+
+        if template_root is None:
+            raise ValueError(
+                f"The {package_name!r} package was not installed in a"
+                " way that PackageLoader understands."
+            )
+
+        self._template_root = template_root
+
+    def get_source(
+        self, environment: "Environment", template: str
+    ) -> t.Tuple[str, str, t.Optional[t.Callable[[], bool]]]:
+        # Use posixpath even on Windows to avoid "drive:" or UNC
+        # segments breaking out of the search directory. Use normpath to
+        # convert Windows altsep to sep.
+        p = os.path.normpath(
+            posixpath.join(self._template_root, *split_template_path(template))
+        )
+        up_to_date: t.Optional[t.Callable[[], bool]]
+
+        if self._archive is None:
+            # Package is a directory.
+            if not os.path.isfile(p):
+                raise TemplateNotFound(template)
+
+            with open(p, "rb") as f:
+                source = f.read()
+
+            mtime = os.path.getmtime(p)
+
+            def up_to_date() -> bool:
+                return os.path.isfile(p) and os.path.getmtime(p) == mtime
+
+        else:
+            # Package is a zip file.
+            try:
+                source = self._loader.get_data(p)  # type: ignore
+            except OSError as e:
+                raise TemplateNotFound(template) from e
+
+            # Could use the zip's mtime for all template mtimes, but
+            # would need to safely reload the module if it's out of
+            # date, so just report it as always current.
+            up_to_date = None
+
+        return source.decode(self.encoding), p, up_to_date
+
+    def list_templates(self) -> t.List[str]:
+        results: t.List[str] = []
+
+        if self._archive is None:
+            # Package is a directory.
+            offset = len(self._template_root)
+
+            for dirpath, _, filenames in os.walk(self._template_root):
+                dirpath = dirpath[offset:].lstrip(os.path.sep)
+                results.extend(
+                    os.path.join(dirpath, name).replace(os.path.sep, "/")
+                    for name in filenames
+                )
+        else:
+            if not hasattr(self._loader, "_files"):
+                raise TypeError(
+                    "This zip import does not have the required"
+                    " metadata to list templates."
+                )
+
+            # Package is a zip file.
+            prefix = (
+                self._template_root[len(self._archive) :].lstrip(os.path.sep)
+                + os.path.sep
+            )
+            offset = len(prefix)
+
+            for name in self._loader._files.keys():  # type: ignore
+                # Find names under the templates directory that aren't directories.
+                if name.startswith(prefix) and name[-1] != os.path.sep:
+                    results.append(name[offset:].replace(os.path.sep, "/"))
+
+        results.sort()
+        return results
+
+
+class DictLoader(BaseLoader):
+    """Loads a template from a Python dict mapping template names to
+    template source.  This loader is useful for unittesting:
+
+    >>> loader = DictLoader({'index.html': 'source here'})
+
+    Because auto reloading is rarely useful this is disabled per default.
+    """
+
+    def __init__(self, mapping: t.Mapping[str, str]) -> None:
+        self.mapping = mapping
+
+    def get_source(
+        self, environment: "Environment", template: str
+    ) -> t.Tuple[str, None, t.Callable[[], bool]]:
+        if template in self.mapping:
+            source = self.mapping[template]
+            return source, None, lambda: source == self.mapping.get(template)
+        raise TemplateNotFound(template)
+
+    def list_templates(self) -> t.List[str]:
+        return sorted(self.mapping)
+
+
+class FunctionLoader(BaseLoader):
+    """A loader that is passed a function which does the loading.  The
+    function receives the name of the template and has to return either
+    a string with the template source, a tuple in the form ``(source,
+    filename, uptodatefunc)`` or `None` if the template does not exist.
+
+    >>> def load_template(name):
+    ...     if name == 'index.html':
+    ...         return '...'
+    ...
+    >>> loader = FunctionLoader(load_template)
+
+    The `uptodatefunc` is a function that is called if autoreload is enabled
+    and has to return `True` if the template is still up to date.  For more
+    details have a look at :meth:`BaseLoader.get_source` which has the same
+    return value.
+    """
+
+    def __init__(
+        self,
+        load_func: t.Callable[
+            [str],
+            t.Optional[
+                t.Union[
+                    str, t.Tuple[str, t.Optional[str], t.Optional[t.Callable[[], bool]]]
+                ]
+            ],
+        ],
+    ) -> None:
+        self.load_func = load_func
+
+    def get_source(
+        self, environment: "Environment", template: str
+    ) -> t.Tuple[str, t.Optional[str], t.Optional[t.Callable[[], bool]]]:
+        rv = self.load_func(template)
+
+        if rv is None:
+            raise TemplateNotFound(template)
+
+        if isinstance(rv, str):
+            return rv, None, None
+
+        return rv
+
+
+class PrefixLoader(BaseLoader):
+    """A loader that is passed a dict of loaders where each loader is bound
+    to a prefix.  The prefix is delimited from the template by a slash per
+    default, which can be changed by setting the `delimiter` argument to
+    something else::
+
+        loader = PrefixLoader({
+            'app1':     PackageLoader('mypackage.app1'),
+            'app2':     PackageLoader('mypackage.app2')
+        })
+
+    By loading ``'app1/index.html'`` the file from the app1 package is loaded,
+    by loading ``'app2/index.html'`` the file from the second.
+    """
+
+    def __init__(
+        self, mapping: t.Mapping[str, BaseLoader], delimiter: str = "/"
+    ) -> None:
+        self.mapping = mapping
+        self.delimiter = delimiter
+
+    def get_loader(self, template: str) -> t.Tuple[BaseLoader, str]:
+        try:
+            prefix, name = template.split(self.delimiter, 1)
+            loader = self.mapping[prefix]
+        except (ValueError, KeyError) as e:
+            raise TemplateNotFound(template) from e
+        return loader, name
+
+    def get_source(
+        self, environment: "Environment", template: str
+    ) -> t.Tuple[str, t.Optional[str], t.Optional[t.Callable[[], bool]]]:
+        loader, name = self.get_loader(template)
+        try:
+            return loader.get_source(environment, name)
+        except TemplateNotFound as e:
+            # re-raise the exception with the correct filename here.
+            # (the one that includes the prefix)
+            raise TemplateNotFound(template) from e
+
+    @internalcode
+    def load(
+        self,
+        environment: "Environment",
+        name: str,
+        globals: t.Optional[t.MutableMapping[str, t.Any]] = None,
+    ) -> "Template":
+        loader, local_name = self.get_loader(name)
+        try:
+            return loader.load(environment, local_name, globals)
+        except TemplateNotFound as e:
+            # re-raise the exception with the correct filename here.
+            # (the one that includes the prefix)
+            raise TemplateNotFound(name) from e
+
+    def list_templates(self) -> t.List[str]:
+        result = []
+        for prefix, loader in self.mapping.items():
+            for template in loader.list_templates():
+                result.append(prefix + self.delimiter + template)
+        return result
+
+
+class ChoiceLoader(BaseLoader):
+    """This loader works like the `PrefixLoader` just that no prefix is
+    specified.  If a template could not be found by one loader the next one
+    is tried.
+
+    >>> loader = ChoiceLoader([
+    ...     FileSystemLoader('/path/to/user/templates'),
+    ...     FileSystemLoader('/path/to/system/templates')
+    ... ])
+
+    This is useful if you want to allow users to override builtin templates
+    from a different location.
+    """
+
+    def __init__(self, loaders: t.Sequence[BaseLoader]) -> None:
+        self.loaders = loaders
+
+    def get_source(
+        self, environment: "Environment", template: str
+    ) -> t.Tuple[str, t.Optional[str], t.Optional[t.Callable[[], bool]]]:
+        for loader in self.loaders:
+            try:
+                return loader.get_source(environment, template)
+            except TemplateNotFound:
+                pass
+        raise TemplateNotFound(template)
+
+    @internalcode
+    def load(
+        self,
+        environment: "Environment",
+        name: str,
+        globals: t.Optional[t.MutableMapping[str, t.Any]] = None,
+    ) -> "Template":
+        for loader in self.loaders:
+            try:
+                return loader.load(environment, name, globals)
+            except TemplateNotFound:
+                pass
+        raise TemplateNotFound(name)
+
+    def list_templates(self) -> t.List[str]:
+        found = set()
+        for loader in self.loaders:
+            found.update(loader.list_templates())
+        return sorted(found)
+
+
+class _TemplateModule(ModuleType):
+    """Like a normal module but with support for weak references"""
+
+
+class ModuleLoader(BaseLoader):
+    """This loader loads templates from precompiled templates.
+
+    Example usage:
+
+    >>> loader = ChoiceLoader([
+    ...     ModuleLoader('/path/to/compiled/templates'),
+    ...     FileSystemLoader('/path/to/templates')
+    ... ])
+
+    Templates can be precompiled with :meth:`Environment.compile_templates`.
+    """
+
+    has_source_access = False
+
+    def __init__(
+        self, path: t.Union[str, os.PathLike, t.Sequence[t.Union[str, os.PathLike]]]
+    ) -> None:
+        package_name = f"_jinja2_module_templates_{id(self):x}"
+
+        # create a fake module that looks for the templates in the
+        # path given.
+        mod = _TemplateModule(package_name)
+
+        if not isinstance(path, abc.Iterable) or isinstance(path, str):
+            path = [path]
+
+        mod.__path__ = [os.fspath(p) for p in path]
+
+        sys.modules[package_name] = weakref.proxy(
+            mod, lambda x: sys.modules.pop(package_name, None)
+        )
+
+        # the only strong reference, the sys.modules entry is weak
+        # so that the garbage collector can remove it once the
+        # loader that created it goes out of business.
+        self.module = mod
+        self.package_name = package_name
+
+    @staticmethod
+    def get_template_key(name: str) -> str:
+        return "tmpl_" + sha1(name.encode("utf-8")).hexdigest()
+
+    @staticmethod
+    def get_module_filename(name: str) -> str:
+        return ModuleLoader.get_template_key(name) + ".py"
+
+    @internalcode
+    def load(
+        self,
+        environment: "Environment",
+        name: str,
+        globals: t.Optional[t.MutableMapping[str, t.Any]] = None,
+    ) -> "Template":
+        key = self.get_template_key(name)
+        module = f"{self.package_name}.{key}"
+        mod = getattr(self.module, module, None)
+
+        if mod is None:
+            try:
+                mod = __import__(module, None, None, ["root"])
+            except ImportError as e:
+                raise TemplateNotFound(name) from e
+
+            # remove the entry from sys.modules, we only want the attribute
+            # on the module object we have stored on the loader.
+            sys.modules.pop(module, None)
+
+        if globals is None:
+            globals = {}
+
+        return environment.template_class.from_module_dict(
+            environment, mod.__dict__, globals
+        )
diff --git a/src/jinja2/meta.py b/src/jinja2/meta.py
new file mode 100644
index 0000000..0057d6e
--- /dev/null
+++ b/src/jinja2/meta.py
@@ -0,0 +1,111 @@
+"""Functions that expose information about templates that might be
+interesting for introspection.
+"""
+import typing as t
+
+from . import nodes
+from .compiler import CodeGenerator
+from .compiler import Frame
+
+if t.TYPE_CHECKING:
+    from .environment import Environment
+
+
+class TrackingCodeGenerator(CodeGenerator):
+    """We abuse the code generator for introspection."""
+
+    def __init__(self, environment: "Environment") -> None:
+        super().__init__(environment, "<introspection>", "<introspection>")
+        self.undeclared_identifiers: t.Set[str] = set()
+
+    def write(self, x: str) -> None:
+        """Don't write."""
+
+    def enter_frame(self, frame: Frame) -> None:
+        """Remember all undeclared identifiers."""
+        super().enter_frame(frame)
+
+        for _, (action, param) in frame.symbols.loads.items():
+            if action == "resolve" and param not in self.environment.globals:
+                self.undeclared_identifiers.add(param)
+
+
+def find_undeclared_variables(ast: nodes.Template) -> t.Set[str]:
+    """Returns a set of all variables in the AST that will be looked up from
+    the context at runtime.  Because at compile time it's not known which
+    variables will be used depending on the path the execution takes at
+    runtime, all variables are returned.
+
+    >>> from jinja2 import Environment, meta
+    >>> env = Environment()
+    >>> ast = env.parse('{% set foo = 42 %}{{ bar + foo }}')
+    >>> meta.find_undeclared_variables(ast) == {'bar'}
+    True
+
+    .. admonition:: Implementation
+
+       Internally the code generator is used for finding undeclared variables.
+       This is good to know because the code generator might raise a
+       :exc:`TemplateAssertionError` during compilation and as a matter of
+       fact this function can currently raise that exception as well.
+    """
+    codegen = TrackingCodeGenerator(ast.environment)  # type: ignore
+    codegen.visit(ast)
+    return codegen.undeclared_identifiers
+
+
+_ref_types = (nodes.Extends, nodes.FromImport, nodes.Import, nodes.Include)
+_RefType = t.Union[nodes.Extends, nodes.FromImport, nodes.Import, nodes.Include]
+
+
+def find_referenced_templates(ast: nodes.Template) -> t.Iterator[t.Optional[str]]:
+    """Finds all the referenced templates from the AST.  This will return an
+    iterator over all the hardcoded template extensions, inclusions and
+    imports.  If dynamic inheritance or inclusion is used, `None` will be
+    yielded.
+
+    >>> from jinja2 import Environment, meta
+    >>> env = Environment()
+    >>> ast = env.parse('{% extends "layout.html" %}{% include helper %}')
+    >>> list(meta.find_referenced_templates(ast))
+    ['layout.html', None]
+
+    This function is useful for dependency tracking.  For example if you want
+    to rebuild parts of the website after a layout template has changed.
+    """
+    template_name: t.Any
+
+    for node in ast.find_all(_ref_types):
+        template: nodes.Expr = node.template  # type: ignore
+
+        if not isinstance(template, nodes.Const):
+            # a tuple with some non consts in there
+            if isinstance(template, (nodes.Tuple, nodes.List)):
+                for template_name in template.items:
+                    # something const, only yield the strings and ignore
+                    # non-string consts that really just make no sense
+                    if isinstance(template_name, nodes.Const):
+                        if isinstance(template_name.value, str):
+                            yield template_name.value
+                    # something dynamic in there
+                    else:
+                        yield None
+            # something dynamic we don't know about here
+            else:
+                yield None
+            continue
+        # constant is a basestring, direct template name
+        if isinstance(template.value, str):
+            yield template.value
+        # a tuple or list (latter *should* not happen) made of consts,
+        # yield the consts that are strings.  We could warn here for
+        # non string values
+        elif isinstance(node, nodes.Include) and isinstance(
+            template.value, (tuple, list)
+        ):
+            for template_name in template.value:
+                if isinstance(template_name, str):
+                    yield template_name
+        # something else we don't care about, we could warn here
+        else:
+            yield None
diff --git a/src/jinja2/nativetypes.py b/src/jinja2/nativetypes.py
new file mode 100644
index 0000000..ac08610
--- /dev/null
+++ b/src/jinja2/nativetypes.py
@@ -0,0 +1,130 @@
+import typing as t
+from ast import literal_eval
+from ast import parse
+from itertools import chain
+from itertools import islice
+from types import GeneratorType
+
+from . import nodes
+from .compiler import CodeGenerator
+from .compiler import Frame
+from .compiler import has_safe_repr
+from .environment import Environment
+from .environment import Template
+
+
+def native_concat(values: t.Iterable[t.Any]) -> t.Optional[t.Any]:
+    """Return a native Python type from the list of compiled nodes. If
+    the result is a single node, its value is returned. Otherwise, the
+    nodes are concatenated as strings. If the result can be parsed with
+    :func:`ast.literal_eval`, the parsed value is returned. Otherwise,
+    the string is returned.
+
+    :param values: Iterable of outputs to concatenate.
+    """
+    head = list(islice(values, 2))
+
+    if not head:
+        return None
+
+    if len(head) == 1:
+        raw = head[0]
+        if not isinstance(raw, str):
+            return raw
+    else:
+        if isinstance(values, GeneratorType):
+            values = chain(head, values)
+        raw = "".join([str(v) for v in values])
+
+    try:
+        return literal_eval(
+            # In Python 3.10+ ast.literal_eval removes leading spaces/tabs
+            # from the given string. For backwards compatibility we need to
+            # parse the string ourselves without removing leading spaces/tabs.
+            parse(raw, mode="eval")
+        )
+    except (ValueError, SyntaxError, MemoryError):
+        return raw
+
+
+class NativeCodeGenerator(CodeGenerator):
+    """A code generator which renders Python types by not adding
+    ``str()`` around output nodes.
+    """
+
+    @staticmethod
+    def _default_finalize(value: t.Any) -> t.Any:
+        return value
+
+    def _output_const_repr(self, group: t.Iterable[t.Any]) -> str:
+        return repr("".join([str(v) for v in group]))
+
+    def _output_child_to_const(
+        self, node: nodes.Expr, frame: Frame, finalize: CodeGenerator._FinalizeInfo
+    ) -> t.Any:
+        const = node.as_const(frame.eval_ctx)
+
+        if not has_safe_repr(const):
+            raise nodes.Impossible()
+
+        if isinstance(node, nodes.TemplateData):
+            return const
+
+        return finalize.const(const)  # type: ignore
+
+    def _output_child_pre(
+        self, node: nodes.Expr, frame: Frame, finalize: CodeGenerator._FinalizeInfo
+    ) -> None:
+        if finalize.src is not None:
+            self.write(finalize.src)
+
+    def _output_child_post(
+        self, node: nodes.Expr, frame: Frame, finalize: CodeGenerator._FinalizeInfo
+    ) -> None:
+        if finalize.src is not None:
+            self.write(")")
+
+
+class NativeEnvironment(Environment):
+    """An environment that renders templates to native Python types."""
+
+    code_generator_class = NativeCodeGenerator
+    concat = staticmethod(native_concat)  # type: ignore
+
+
+class NativeTemplate(Template):
+    environment_class = NativeEnvironment
+
+    def render(self, *args: t.Any, **kwargs: t.Any) -> t.Any:
+        """Render the template to produce a native Python type. If the
+        result is a single node, its value is returned. Otherwise, the
+        nodes are concatenated as strings. If the result can be parsed
+        with :func:`ast.literal_eval`, the parsed value is returned.
+        Otherwise, the string is returned.
+        """
+        ctx = self.new_context(dict(*args, **kwargs))
+
+        try:
+            return self.environment_class.concat(  # type: ignore
+                self.root_render_func(ctx)  # type: ignore
+            )
+        except Exception:
+            return self.environment.handle_exception()
+
+    async def render_async(self, *args: t.Any, **kwargs: t.Any) -> t.Any:
+        if not self.environment.is_async:
+            raise RuntimeError(
+                "The environment was not created with async mode enabled."
+            )
+
+        ctx = self.new_context(dict(*args, **kwargs))
+
+        try:
+            return self.environment_class.concat(  # type: ignore
+                [n async for n in self.root_render_func(ctx)]  # type: ignore
+            )
+        except Exception:
+            return self.environment.handle_exception()
+
+
+NativeEnvironment.template_class = NativeTemplate
diff --git a/src/jinja2/nodes.py b/src/jinja2/nodes.py
new file mode 100644
index 0000000..b2f88d9
--- /dev/null
+++ b/src/jinja2/nodes.py
@@ -0,0 +1,1204 @@
+"""AST nodes generated by the parser for the compiler. Also provides
+some node tree helper functions used by the parser and compiler in order
+to normalize nodes.
+"""
+import inspect
+import operator
+import typing as t
+from collections import deque
+
+from markupsafe import Markup
+
+from .utils import _PassArg
+
+if t.TYPE_CHECKING:
+    import typing_extensions as te
+    from .environment import Environment
+
+_NodeBound = t.TypeVar("_NodeBound", bound="Node")
+
+_binop_to_func: t.Dict[str, t.Callable[[t.Any, t.Any], t.Any]] = {
+    "*": operator.mul,
+    "/": operator.truediv,
+    "//": operator.floordiv,
+    "**": operator.pow,
+    "%": operator.mod,
+    "+": operator.add,
+    "-": operator.sub,
+}
+
+_uaop_to_func: t.Dict[str, t.Callable[[t.Any], t.Any]] = {
+    "not": operator.not_,
+    "+": operator.pos,
+    "-": operator.neg,
+}
+
+_cmpop_to_func: t.Dict[str, t.Callable[[t.Any, t.Any], t.Any]] = {
+    "eq": operator.eq,
+    "ne": operator.ne,
+    "gt": operator.gt,
+    "gteq": operator.ge,
+    "lt": operator.lt,
+    "lteq": operator.le,
+    "in": lambda a, b: a in b,
+    "notin": lambda a, b: a not in b,
+}
+
+
+class Impossible(Exception):
+    """Raised if the node could not perform a requested action."""
+
+
+class NodeType(type):
+    """A metaclass for nodes that handles the field and attribute
+    inheritance.  fields and attributes from the parent class are
+    automatically forwarded to the child."""
+
+    def __new__(mcs, name, bases, d):  # type: ignore
+        for attr in "fields", "attributes":
+            storage = []
+            storage.extend(getattr(bases[0] if bases else object, attr, ()))
+            storage.extend(d.get(attr, ()))
+            assert len(bases) <= 1, "multiple inheritance not allowed"
+            assert len(storage) == len(set(storage)), "layout conflict"
+            d[attr] = tuple(storage)
+        d.setdefault("abstract", False)
+        return type.__new__(mcs, name, bases, d)
+
+
+class EvalContext:
+    """Holds evaluation time information.  Custom attributes can be attached
+    to it in extensions.
+    """
+
+    def __init__(
+        self, environment: "Environment", template_name: t.Optional[str] = None
+    ) -> None:
+        self.environment = environment
+        if callable(environment.autoescape):
+            self.autoescape = environment.autoescape(template_name)
+        else:
+            self.autoescape = environment.autoescape
+        self.volatile = False
+
+    def save(self) -> t.Mapping[str, t.Any]:
+        return self.__dict__.copy()
+
+    def revert(self, old: t.Mapping[str, t.Any]) -> None:
+        self.__dict__.clear()
+        self.__dict__.update(old)
+
+
+def get_eval_context(node: "Node", ctx: t.Optional[EvalContext]) -> EvalContext:
+    if ctx is None:
+        if node.environment is None:
+            raise RuntimeError(
+                "if no eval context is passed, the node must have an"
+                " attached environment."
+            )
+        return EvalContext(node.environment)
+    return ctx
+
+
+class Node(metaclass=NodeType):
+    """Baseclass for all Jinja nodes.  There are a number of nodes available
+    of different types.  There are four major types:
+
+    -   :class:`Stmt`: statements
+    -   :class:`Expr`: expressions
+    -   :class:`Helper`: helper nodes
+    -   :class:`Template`: the outermost wrapper node
+
+    All nodes have fields and attributes.  Fields may be other nodes, lists,
+    or arbitrary values.  Fields are passed to the constructor as regular
+    positional arguments, attributes as keyword arguments.  Each node has
+    two attributes: `lineno` (the line number of the node) and `environment`.
+    The `environment` attribute is set at the end of the parsing process for
+    all nodes automatically.
+    """
+
+    fields: t.Tuple[str, ...] = ()
+    attributes: t.Tuple[str, ...] = ("lineno", "environment")
+    abstract = True
+
+    lineno: int
+    environment: t.Optional["Environment"]
+
+    def __init__(self, *fields: t.Any, **attributes: t.Any) -> None:
+        if self.abstract:
+            raise TypeError("abstract nodes are not instantiable")
+        if fields:
+            if len(fields) != len(self.fields):
+                if not self.fields:
+                    raise TypeError(f"{type(self).__name__!r} takes 0 arguments")
+                raise TypeError(
+                    f"{type(self).__name__!r} takes 0 or {len(self.fields)}"
+                    f" argument{'s' if len(self.fields) != 1 else ''}"
+                )
+            for name, arg in zip(self.fields, fields):
+                setattr(self, name, arg)
+        for attr in self.attributes:
+            setattr(self, attr, attributes.pop(attr, None))
+        if attributes:
+            raise TypeError(f"unknown attribute {next(iter(attributes))!r}")
+
+    def iter_fields(
+        self,
+        exclude: t.Optional[t.Container[str]] = None,
+        only: t.Optional[t.Container[str]] = None,
+    ) -> t.Iterator[t.Tuple[str, t.Any]]:
+        """This method iterates over all fields that are defined and yields
+        ``(key, value)`` tuples.  Per default all fields are returned, but
+        it's possible to limit that to some fields by providing the `only`
+        parameter or to exclude some using the `exclude` parameter.  Both
+        should be sets or tuples of field names.
+        """
+        for name in self.fields:
+            if (
+                (exclude is None and only is None)
+                or (exclude is not None and name not in exclude)
+                or (only is not None and name in only)
+            ):
+                try:
+                    yield name, getattr(self, name)
+                except AttributeError:
+                    pass
+
+    def iter_child_nodes(
+        self,
+        exclude: t.Optional[t.Container[str]] = None,
+        only: t.Optional[t.Container[str]] = None,
+    ) -> t.Iterator["Node"]:
+        """Iterates over all direct child nodes of the node.  This iterates
+        over all fields and yields the values of they are nodes.  If the value
+        of a field is a list all the nodes in that list are returned.
+        """
+        for _, item in self.iter_fields(exclude, only):
+            if isinstance(item, list):
+                for n in item:
+                    if isinstance(n, Node):
+                        yield n
+            elif isinstance(item, Node):
+                yield item
+
+    def find(self, node_type: t.Type[_NodeBound]) -> t.Optional[_NodeBound]:
+        """Find the first node of a given type.  If no such node exists the
+        return value is `None`.
+        """
+        for result in self.find_all(node_type):
+            return result
+
+        return None
+
+    def find_all(
+        self, node_type: t.Union[t.Type[_NodeBound], t.Tuple[t.Type[_NodeBound], ...]]
+    ) -> t.Iterator[_NodeBound]:
+        """Find all the nodes of a given type.  If the type is a tuple,
+        the check is performed for any of the tuple items.
+        """
+        for child in self.iter_child_nodes():
+            if isinstance(child, node_type):
+                yield child  # type: ignore
+            yield from child.find_all(node_type)
+
+    def set_ctx(self, ctx: str) -> "Node":
+        """Reset the context of a node and all child nodes.  Per default the
+        parser will all generate nodes that have a 'load' context as it's the
+        most common one.  This method is used in the parser to set assignment
+        targets and other nodes to a store context.
+        """
+        todo = deque([self])
+        while todo:
+            node = todo.popleft()
+            if "ctx" in node.fields:
+                node.ctx = ctx  # type: ignore
+            todo.extend(node.iter_child_nodes())
+        return self
+
+    def set_lineno(self, lineno: int, override: bool = False) -> "Node":
+        """Set the line numbers of the node and children."""
+        todo = deque([self])
+        while todo:
+            node = todo.popleft()
+            if "lineno" in node.attributes:
+                if node.lineno is None or override:
+                    node.lineno = lineno
+            todo.extend(node.iter_child_nodes())
+        return self
+
+    def set_environment(self, environment: "Environment") -> "Node":
+        """Set the environment for all nodes."""
+        todo = deque([self])
+        while todo:
+            node = todo.popleft()
+            node.environment = environment
+            todo.extend(node.iter_child_nodes())
+        return self
+
+    def __eq__(self, other: t.Any) -> bool:
+        if type(self) is not type(other):
+            return NotImplemented
+
+        return tuple(self.iter_fields()) == tuple(other.iter_fields())
+
+    __hash__ = object.__hash__
+
+    def __repr__(self) -> str:
+        args_str = ", ".join(f"{a}={getattr(self, a, None)!r}" for a in self.fields)
+        return f"{type(self).__name__}({args_str})"
+
+    def dump(self) -> str:
+        def _dump(node: t.Union[Node, t.Any]) -> None:
+            if not isinstance(node, Node):
+                buf.append(repr(node))
+                return
+
+            buf.append(f"nodes.{type(node).__name__}(")
+            if not node.fields:
+                buf.append(")")
+                return
+            for idx, field in enumerate(node.fields):
+                if idx:
+                    buf.append(", ")
+                value = getattr(node, field)
+                if isinstance(value, list):
+                    buf.append("[")
+                    for idx, item in enumerate(value):
+                        if idx:
+                            buf.append(", ")
+                        _dump(item)
+                    buf.append("]")
+                else:
+                    _dump(value)
+            buf.append(")")
+
+        buf: t.List[str] = []
+        _dump(self)
+        return "".join(buf)
+
+
+class Stmt(Node):
+    """Base node for all statements."""
+
+    abstract = True
+
+
+class Helper(Node):
+    """Nodes that exist in a specific context only."""
+
+    abstract = True
+
+
+class Template(Node):
+    """Node that represents a template.  This must be the outermost node that
+    is passed to the compiler.
+    """
+
+    fields = ("body",)
+    body: t.List[Node]
+
+
+class Output(Stmt):
+    """A node that holds multiple expressions which are then printed out.
+    This is used both for the `print` statement and the regular template data.
+    """
+
+    fields = ("nodes",)
+    nodes: t.List["Expr"]
+
+
+class Extends(Stmt):
+    """Represents an extends statement."""
+
+    fields = ("template",)
+    template: "Expr"
+
+
+class For(Stmt):
+    """The for loop.  `target` is the target for the iteration (usually a
+    :class:`Name` or :class:`Tuple`), `iter` the iterable.  `body` is a list
+    of nodes that are used as loop-body, and `else_` a list of nodes for the
+    `else` block.  If no else node exists it has to be an empty list.
+
+    For filtered nodes an expression can be stored as `test`, otherwise `None`.
+    """
+
+    fields = ("target", "iter", "body", "else_", "test", "recursive")
+    target: Node
+    iter: Node
+    body: t.List[Node]
+    else_: t.List[Node]
+    test: t.Optional[Node]
+    recursive: bool
+
+
+class If(Stmt):
+    """If `test` is true, `body` is rendered, else `else_`."""
+
+    fields = ("test", "body", "elif_", "else_")
+    test: Node
+    body: t.List[Node]
+    elif_: t.List["If"]
+    else_: t.List[Node]
+
+
+class Macro(Stmt):
+    """A macro definition.  `name` is the name of the macro, `args` a list of
+    arguments and `defaults` a list of defaults if there are any.  `body` is
+    a list of nodes for the macro body.
+    """
+
+    fields = ("name", "args", "defaults", "body")
+    name: str
+    args: t.List["Name"]
+    defaults: t.List["Expr"]
+    body: t.List[Node]
+
+
+class CallBlock(Stmt):
+    """Like a macro without a name but a call instead.  `call` is called with
+    the unnamed macro as `caller` argument this node holds.
+    """
+
+    fields = ("call", "args", "defaults", "body")
+    call: "Call"
+    args: t.List["Name"]
+    defaults: t.List["Expr"]
+    body: t.List[Node]
+
+
+class FilterBlock(Stmt):
+    """Node for filter sections."""
+
+    fields = ("body", "filter")
+    body: t.List[Node]
+    filter: "Filter"
+
+
+class With(Stmt):
+    """Specific node for with statements.  In older versions of Jinja the
+    with statement was implemented on the base of the `Scope` node instead.
+
+    .. versionadded:: 2.9.3
+    """
+
+    fields = ("targets", "values", "body")
+    targets: t.List["Expr"]
+    values: t.List["Expr"]
+    body: t.List[Node]
+
+
+class Block(Stmt):
+    """A node that represents a block.
+
+    .. versionchanged:: 3.0.0
+        the `required` field was added.
+    """
+
+    fields = ("name", "body", "scoped", "required")
+    name: str
+    body: t.List[Node]
+    scoped: bool
+    required: bool
+
+
+class Include(Stmt):
+    """A node that represents the include tag."""
+
+    fields = ("template", "with_context", "ignore_missing")
+    template: "Expr"
+    with_context: bool
+    ignore_missing: bool
+
+
+class Import(Stmt):
+    """A node that represents the import tag."""
+
+    fields = ("template", "target", "with_context")
+    template: "Expr"
+    target: str
+    with_context: bool
+
+
+class FromImport(Stmt):
+    """A node that represents the from import tag.  It's important to not
+    pass unsafe names to the name attribute.  The compiler translates the
+    attribute lookups directly into getattr calls and does *not* use the
+    subscript callback of the interface.  As exported variables may not
+    start with double underscores (which the parser asserts) this is not a
+    problem for regular Jinja code, but if this node is used in an extension
+    extra care must be taken.
+
+    The list of names may contain tuples if aliases are wanted.
+    """
+
+    fields = ("template", "names", "with_context")
+    template: "Expr"
+    names: t.List[t.Union[str, t.Tuple[str, str]]]
+    with_context: bool
+
+
+class ExprStmt(Stmt):
+    """A statement that evaluates an expression and discards the result."""
+
+    fields = ("node",)
+    node: Node
+
+
+class Assign(Stmt):
+    """Assigns an expression to a target."""
+
+    fields = ("target", "node")
+    target: "Expr"
+    node: Node
+
+
+class AssignBlock(Stmt):
+    """Assigns a block to a target."""
+
+    fields = ("target", "filter", "body")
+    target: "Expr"
+    filter: t.Optional["Filter"]
+    body: t.List[Node]
+
+
+class Expr(Node):
+    """Baseclass for all expressions."""
+
+    abstract = True
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.Any:
+        """Return the value of the expression as constant or raise
+        :exc:`Impossible` if this was not possible.
+
+        An :class:`EvalContext` can be provided, if none is given
+        a default context is created which requires the nodes to have
+        an attached environment.
+
+        .. versionchanged:: 2.4
+           the `eval_ctx` parameter was added.
+        """
+        raise Impossible()
+
+    def can_assign(self) -> bool:
+        """Check if it's possible to assign something to this node."""
+        return False
+
+
+class BinExpr(Expr):
+    """Baseclass for all binary expressions."""
+
+    fields = ("left", "right")
+    left: Expr
+    right: Expr
+    operator: str
+    abstract = True
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.Any:
+        eval_ctx = get_eval_context(self, eval_ctx)
+
+        # intercepted operators cannot be folded at compile time
+        if (
+            eval_ctx.environment.sandboxed
+            and self.operator in eval_ctx.environment.intercepted_binops  # type: ignore
+        ):
+            raise Impossible()
+        f = _binop_to_func[self.operator]
+        try:
+            return f(self.left.as_const(eval_ctx), self.right.as_const(eval_ctx))
+        except Exception as e:
+            raise Impossible() from e
+
+
+class UnaryExpr(Expr):
+    """Baseclass for all unary expressions."""
+
+    fields = ("node",)
+    node: Expr
+    operator: str
+    abstract = True
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.Any:
+        eval_ctx = get_eval_context(self, eval_ctx)
+
+        # intercepted operators cannot be folded at compile time
+        if (
+            eval_ctx.environment.sandboxed
+            and self.operator in eval_ctx.environment.intercepted_unops  # type: ignore
+        ):
+            raise Impossible()
+        f = _uaop_to_func[self.operator]
+        try:
+            return f(self.node.as_const(eval_ctx))
+        except Exception as e:
+            raise Impossible() from e
+
+
+class Name(Expr):
+    """Looks up a name or stores a value in a name.
+    The `ctx` of the node can be one of the following values:
+
+    -   `store`: store a value in the name
+    -   `load`: load that name
+    -   `param`: like `store` but if the name was defined as function parameter.
+    """
+
+    fields = ("name", "ctx")
+    name: str
+    ctx: str
+
+    def can_assign(self) -> bool:
+        return self.name not in {"true", "false", "none", "True", "False", "None"}
+
+
+class NSRef(Expr):
+    """Reference to a namespace value assignment"""
+
+    fields = ("name", "attr")
+    name: str
+    attr: str
+
+    def can_assign(self) -> bool:
+        # We don't need any special checks here; NSRef assignments have a
+        # runtime check to ensure the target is a namespace object which will
+        # have been checked already as it is created using a normal assignment
+        # which goes through a `Name` node.
+        return True
+
+
+class Literal(Expr):
+    """Baseclass for literals."""
+
+    abstract = True
+
+
+class Const(Literal):
+    """All constant values.  The parser will return this node for simple
+    constants such as ``42`` or ``"foo"`` but it can be used to store more
+    complex values such as lists too.  Only constants with a safe
+    representation (objects where ``eval(repr(x)) == x`` is true).
+    """
+
+    fields = ("value",)
+    value: t.Any
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.Any:
+        return self.value
+
+    @classmethod
+    def from_untrusted(
+        cls,
+        value: t.Any,
+        lineno: t.Optional[int] = None,
+        environment: "t.Optional[Environment]" = None,
+    ) -> "Const":
+        """Return a const object if the value is representable as
+        constant value in the generated code, otherwise it will raise
+        an `Impossible` exception.
+        """
+        from .compiler import has_safe_repr
+
+        if not has_safe_repr(value):
+            raise Impossible()
+        return cls(value, lineno=lineno, environment=environment)
+
+
+class TemplateData(Literal):
+    """A constant template string."""
+
+    fields = ("data",)
+    data: str
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> str:
+        eval_ctx = get_eval_context(self, eval_ctx)
+        if eval_ctx.volatile:
+            raise Impossible()
+        if eval_ctx.autoescape:
+            return Markup(self.data)
+        return self.data
+
+
+class Tuple(Literal):
+    """For loop unpacking and some other things like multiple arguments
+    for subscripts.  Like for :class:`Name` `ctx` specifies if the tuple
+    is used for loading the names or storing.
+    """
+
+    fields = ("items", "ctx")
+    items: t.List[Expr]
+    ctx: str
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.Tuple[t.Any, ...]:
+        eval_ctx = get_eval_context(self, eval_ctx)
+        return tuple(x.as_const(eval_ctx) for x in self.items)
+
+    def can_assign(self) -> bool:
+        for item in self.items:
+            if not item.can_assign():
+                return False
+        return True
+
+
+class List(Literal):
+    """Any list literal such as ``[1, 2, 3]``"""
+
+    fields = ("items",)
+    items: t.List[Expr]
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.List[t.Any]:
+        eval_ctx = get_eval_context(self, eval_ctx)
+        return [x.as_const(eval_ctx) for x in self.items]
+
+
+class Dict(Literal):
+    """Any dict literal such as ``{1: 2, 3: 4}``.  The items must be a list of
+    :class:`Pair` nodes.
+    """
+
+    fields = ("items",)
+    items: t.List["Pair"]
+
+    def as_const(
+        self, eval_ctx: t.Optional[EvalContext] = None
+    ) -> t.Dict[t.Any, t.Any]:
+        eval_ctx = get_eval_context(self, eval_ctx)
+        return dict(x.as_const(eval_ctx) for x in self.items)
+
+
+class Pair(Helper):
+    """A key, value pair for dicts."""
+
+    fields = ("key", "value")
+    key: Expr
+    value: Expr
+
+    def as_const(
+        self, eval_ctx: t.Optional[EvalContext] = None
+    ) -> t.Tuple[t.Any, t.Any]:
+        eval_ctx = get_eval_context(self, eval_ctx)
+        return self.key.as_const(eval_ctx), self.value.as_const(eval_ctx)
+
+
+class Keyword(Helper):
+    """A key, value pair for keyword arguments where key is a string."""
+
+    fields = ("key", "value")
+    key: str
+    value: Expr
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.Tuple[str, t.Any]:
+        eval_ctx = get_eval_context(self, eval_ctx)
+        return self.key, self.value.as_const(eval_ctx)
+
+
+class CondExpr(Expr):
+    """A conditional expression (inline if expression).  (``{{
+    foo if bar else baz }}``)
+    """
+
+    fields = ("test", "expr1", "expr2")
+    test: Expr
+    expr1: Expr
+    expr2: t.Optional[Expr]
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.Any:
+        eval_ctx = get_eval_context(self, eval_ctx)
+        if self.test.as_const(eval_ctx):
+            return self.expr1.as_const(eval_ctx)
+
+        # if we evaluate to an undefined object, we better do that at runtime
+        if self.expr2 is None:
+            raise Impossible()
+
+        return self.expr2.as_const(eval_ctx)
+
+
+def args_as_const(
+    node: t.Union["_FilterTestCommon", "Call"], eval_ctx: t.Optional[EvalContext]
+) -> t.Tuple[t.List[t.Any], t.Dict[t.Any, t.Any]]:
+    args = [x.as_const(eval_ctx) for x in node.args]
+    kwargs = dict(x.as_const(eval_ctx) for x in node.kwargs)
+
+    if node.dyn_args is not None:
+        try:
+            args.extend(node.dyn_args.as_const(eval_ctx))
+        except Exception as e:
+            raise Impossible() from e
+
+    if node.dyn_kwargs is not None:
+        try:
+            kwargs.update(node.dyn_kwargs.as_const(eval_ctx))
+        except Exception as e:
+            raise Impossible() from e
+
+    return args, kwargs
+
+
+class _FilterTestCommon(Expr):
+    fields = ("node", "name", "args", "kwargs", "dyn_args", "dyn_kwargs")
+    node: Expr
+    name: str
+    args: t.List[Expr]
+    kwargs: t.List[Pair]
+    dyn_args: t.Optional[Expr]
+    dyn_kwargs: t.Optional[Expr]
+    abstract = True
+    _is_filter = True
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.Any:
+        eval_ctx = get_eval_context(self, eval_ctx)
+
+        if eval_ctx.volatile:
+            raise Impossible()
+
+        if self._is_filter:
+            env_map = eval_ctx.environment.filters
+        else:
+            env_map = eval_ctx.environment.tests
+
+        func = env_map.get(self.name)
+        pass_arg = _PassArg.from_obj(func)  # type: ignore
+
+        if func is None or pass_arg is _PassArg.context:
+            raise Impossible()
+
+        if eval_ctx.environment.is_async and (
+            getattr(func, "jinja_async_variant", False) is True
+            or inspect.iscoroutinefunction(func)
+        ):
+            raise Impossible()
+
+        args, kwargs = args_as_const(self, eval_ctx)
+        args.insert(0, self.node.as_const(eval_ctx))
+
+        if pass_arg is _PassArg.eval_context:
+            args.insert(0, eval_ctx)
+        elif pass_arg is _PassArg.environment:
+            args.insert(0, eval_ctx.environment)
+
+        try:
+            return func(*args, **kwargs)
+        except Exception as e:
+            raise Impossible() from e
+
+
+class Filter(_FilterTestCommon):
+    """Apply a filter to an expression. ``name`` is the name of the
+    filter, the other fields are the same as :class:`Call`.
+
+    If ``node`` is ``None``, the filter is being used in a filter block
+    and is applied to the content of the block.
+    """
+
+    node: t.Optional[Expr]  # type: ignore
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.Any:
+        if self.node is None:
+            raise Impossible()
+
+        return super().as_const(eval_ctx=eval_ctx)
+
+
+class Test(_FilterTestCommon):
+    """Apply a test to an expression. ``name`` is the name of the test,
+    the other field are the same as :class:`Call`.
+
+    .. versionchanged:: 3.0
+        ``as_const`` shares the same logic for filters and tests. Tests
+        check for volatile, async, and ``@pass_context`` etc.
+        decorators.
+    """
+
+    _is_filter = False
+
+
+class Call(Expr):
+    """Calls an expression.  `args` is a list of arguments, `kwargs` a list
+    of keyword arguments (list of :class:`Keyword` nodes), and `dyn_args`
+    and `dyn_kwargs` has to be either `None` or a node that is used as
+    node for dynamic positional (``*args``) or keyword (``**kwargs``)
+    arguments.
+    """
+
+    fields = ("node", "args", "kwargs", "dyn_args", "dyn_kwargs")
+    node: Expr
+    args: t.List[Expr]
+    kwargs: t.List[Keyword]
+    dyn_args: t.Optional[Expr]
+    dyn_kwargs: t.Optional[Expr]
+
+
+class Getitem(Expr):
+    """Get an attribute or item from an expression and prefer the item."""
+
+    fields = ("node", "arg", "ctx")
+    node: Expr
+    arg: Expr
+    ctx: str
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.Any:
+        if self.ctx != "load":
+            raise Impossible()
+
+        eval_ctx = get_eval_context(self, eval_ctx)
+
+        try:
+            return eval_ctx.environment.getitem(
+                self.node.as_const(eval_ctx), self.arg.as_const(eval_ctx)
+            )
+        except Exception as e:
+            raise Impossible() from e
+
+
+class Getattr(Expr):
+    """Get an attribute or item from an expression that is a ascii-only
+    bytestring and prefer the attribute.
+    """
+
+    fields = ("node", "attr", "ctx")
+    node: Expr
+    attr: str
+    ctx: str
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.Any:
+        if self.ctx != "load":
+            raise Impossible()
+
+        eval_ctx = get_eval_context(self, eval_ctx)
+
+        try:
+            return eval_ctx.environment.getattr(self.node.as_const(eval_ctx), self.attr)
+        except Exception as e:
+            raise Impossible() from e
+
+
+class Slice(Expr):
+    """Represents a slice object.  This must only be used as argument for
+    :class:`Subscript`.
+    """
+
+    fields = ("start", "stop", "step")
+    start: t.Optional[Expr]
+    stop: t.Optional[Expr]
+    step: t.Optional[Expr]
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> slice:
+        eval_ctx = get_eval_context(self, eval_ctx)
+
+        def const(obj: t.Optional[Expr]) -> t.Optional[t.Any]:
+            if obj is None:
+                return None
+            return obj.as_const(eval_ctx)
+
+        return slice(const(self.start), const(self.stop), const(self.step))
+
+
+class Concat(Expr):
+    """Concatenates the list of expressions provided after converting
+    them to strings.
+    """
+
+    fields = ("nodes",)
+    nodes: t.List[Expr]
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> str:
+        eval_ctx = get_eval_context(self, eval_ctx)
+        return "".join(str(x.as_const(eval_ctx)) for x in self.nodes)
+
+
+class Compare(Expr):
+    """Compares an expression with some other expressions.  `ops` must be a
+    list of :class:`Operand`\\s.
+    """
+
+    fields = ("expr", "ops")
+    expr: Expr
+    ops: t.List["Operand"]
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.Any:
+        eval_ctx = get_eval_context(self, eval_ctx)
+        result = value = self.expr.as_const(eval_ctx)
+
+        try:
+            for op in self.ops:
+                new_value = op.expr.as_const(eval_ctx)
+                result = _cmpop_to_func[op.op](value, new_value)
+
+                if not result:
+                    return False
+
+                value = new_value
+        except Exception as e:
+            raise Impossible() from e
+
+        return result
+
+
+class Operand(Helper):
+    """Holds an operator and an expression."""
+
+    fields = ("op", "expr")
+    op: str
+    expr: Expr
+
+
+class Mul(BinExpr):
+    """Multiplies the left with the right node."""
+
+    operator = "*"
+
+
+class Div(BinExpr):
+    """Divides the left by the right node."""
+
+    operator = "/"
+
+
+class FloorDiv(BinExpr):
+    """Divides the left by the right node and converts the
+    result into an integer by truncating.
+    """
+
+    operator = "//"
+
+
+class Add(BinExpr):
+    """Add the left to the right node."""
+
+    operator = "+"
+
+
+class Sub(BinExpr):
+    """Subtract the right from the left node."""
+
+    operator = "-"
+
+
+class Mod(BinExpr):
+    """Left modulo right."""
+
+    operator = "%"
+
+
+class Pow(BinExpr):
+    """Left to the power of right."""
+
+    operator = "**"
+
+
+class And(BinExpr):
+    """Short circuited AND."""
+
+    operator = "and"
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.Any:
+        eval_ctx = get_eval_context(self, eval_ctx)
+        return self.left.as_const(eval_ctx) and self.right.as_const(eval_ctx)
+
+
+class Or(BinExpr):
+    """Short circuited OR."""
+
+    operator = "or"
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> t.Any:
+        eval_ctx = get_eval_context(self, eval_ctx)
+        return self.left.as_const(eval_ctx) or self.right.as_const(eval_ctx)
+
+
+class Not(UnaryExpr):
+    """Negate the expression."""
+
+    operator = "not"
+
+
+class Neg(UnaryExpr):
+    """Make the expression negative."""
+
+    operator = "-"
+
+
+class Pos(UnaryExpr):
+    """Make the expression positive (noop for most expressions)"""
+
+    operator = "+"
+
+
+# Helpers for extensions
+
+
+class EnvironmentAttribute(Expr):
+    """Loads an attribute from the environment object.  This is useful for
+    extensions that want to call a callback stored on the environment.
+    """
+
+    fields = ("name",)
+    name: str
+
+
+class ExtensionAttribute(Expr):
+    """Returns the attribute of an extension bound to the environment.
+    The identifier is the identifier of the :class:`Extension`.
+
+    This node is usually constructed by calling the
+    :meth:`~jinja2.ext.Extension.attr` method on an extension.
+    """
+
+    fields = ("identifier", "name")
+    identifier: str
+    name: str
+
+
+class ImportedName(Expr):
+    """If created with an import name the import name is returned on node
+    access.  For example ``ImportedName('cgi.escape')`` returns the `escape`
+    function from the cgi module on evaluation.  Imports are optimized by the
+    compiler so there is no need to assign them to local variables.
+    """
+
+    fields = ("importname",)
+    importname: str
+
+
+class InternalName(Expr):
+    """An internal name in the compiler.  You cannot create these nodes
+    yourself but the parser provides a
+    :meth:`~jinja2.parser.Parser.free_identifier` method that creates
+    a new identifier for you.  This identifier is not available from the
+    template and is not treated specially by the compiler.
+    """
+
+    fields = ("name",)
+    name: str
+
+    def __init__(self) -> None:
+        raise TypeError(
+            "Can't create internal names.  Use the "
+            "`free_identifier` method on a parser."
+        )
+
+
+class MarkSafe(Expr):
+    """Mark the wrapped expression as safe (wrap it as `Markup`)."""
+
+    fields = ("expr",)
+    expr: Expr
+
+    def as_const(self, eval_ctx: t.Optional[EvalContext] = None) -> Markup:
+        eval_ctx = get_eval_context(self, eval_ctx)
+        return Markup(self.expr.as_const(eval_ctx))
+
+
+class MarkSafeIfAutoescape(Expr):
+    """Mark the wrapped expression as safe (wrap it as `Markup`) but
+    only if autoescaping is active.
+
+    .. versionadded:: 2.5
+    """
+
+    fields = ("expr",)
+    expr: Expr
+
+    def as_const(
+        self, eval_ctx: t.Optional[EvalContext] = None
+    ) -> t.Union[Markup, t.Any]:
+        eval_ctx = get_eval_context(self, eval_ctx)
+        if eval_ctx.volatile:
+            raise Impossible()
+        expr = self.expr.as_const(eval_ctx)
+        if eval_ctx.autoescape:
+            return Markup(expr)
+        return expr
+
+
+class ContextReference(Expr):
+    """Returns the current template context.  It can be used like a
+    :class:`Name` node, with a ``'load'`` ctx and will return the
+    current :class:`~jinja2.runtime.Context` object.
+
+    Here an example that assigns the current template name to a
+    variable named `foo`::
+
+        Assign(Name('foo', ctx='store'),
+               Getattr(ContextReference(), 'name'))
+
+    This is basically equivalent to using the
+    :func:`~jinja2.pass_context` decorator when using the high-level
+    API, which causes a reference to the context to be passed as the
+    first argument to a function.
+    """
+
+
+class DerivedContextReference(Expr):
+    """Return the current template context including locals. Behaves
+    exactly like :class:`ContextReference`, but includes local
+    variables, such as from a ``for`` loop.
+
+    .. versionadded:: 2.11
+    """
+
+
+class Continue(Stmt):
+    """Continue a loop."""
+
+
+class Break(Stmt):
+    """Break a loop."""
+
+
+class Scope(Stmt):
+    """An artificial scope."""
+
+    fields = ("body",)
+    body: t.List[Node]
+
+
+class OverlayScope(Stmt):
+    """An overlay scope for extensions.  This is a largely unoptimized scope
+    that however can be used to introduce completely arbitrary variables into
+    a sub scope from a dictionary or dictionary like object.  The `context`
+    field has to evaluate to a dictionary object.
+
+    Example usage::
+
+        OverlayScope(context=self.call_method('get_context'),
+                     body=[...])
+
+    .. versionadded:: 2.10
+    """
+
+    fields = ("context", "body")
+    context: Expr
+    body: t.List[Node]
+
+
+class EvalContextModifier(Stmt):
+    """Modifies the eval context.  For each option that should be modified,
+    a :class:`Keyword` has to be added to the :attr:`options` list.
+
+    Example to change the `autoescape` setting::
+
+        EvalContextModifier(options=[Keyword('autoescape', Const(True))])
+    """
+
+    fields = ("options",)
+    options: t.List[Keyword]
+
+
+class ScopedEvalContextModifier(EvalContextModifier):
+    """Modifies the eval context and reverts it later.  Works exactly like
+    :class:`EvalContextModifier` but will only modify the
+    :class:`~jinja2.nodes.EvalContext` for nodes in the :attr:`body`.
+    """
+
+    fields = ("body",)
+    body: t.List[Node]
+
+
+# make sure nobody creates custom nodes
+def _failing_new(*args: t.Any, **kwargs: t.Any) -> "te.NoReturn":
+    raise TypeError("can't create custom node types")
+
+
+NodeType.__new__ = staticmethod(_failing_new)  # type: ignore
+del _failing_new
diff --git a/src/jinja2/optimizer.py b/src/jinja2/optimizer.py
new file mode 100644
index 0000000..fe10107
--- /dev/null
+++ b/src/jinja2/optimizer.py
@@ -0,0 +1,47 @@
+"""The optimizer tries to constant fold expressions and modify the AST
+in place so that it should be faster to evaluate.
+
+Because the AST does not contain all the scoping information and the
+compiler has to find that out, we cannot do all the optimizations we
+want. For example, loop unrolling doesn't work because unrolled loops
+would have a different scope. The solution would be a second syntax tree
+that stored the scoping rules.
+"""
+import typing as t
+
+from . import nodes
+from .visitor import NodeTransformer
+
+if t.TYPE_CHECKING:
+    from .environment import Environment
+
+
+def optimize(node: nodes.Node, environment: "Environment") -> nodes.Node:
+    """The context hint can be used to perform an static optimization
+    based on the context given."""
+    optimizer = Optimizer(environment)
+    return t.cast(nodes.Node, optimizer.visit(node))
+
+
+class Optimizer(NodeTransformer):
+    def __init__(self, environment: "t.Optional[Environment]") -> None:
+        self.environment = environment
+
+    def generic_visit(
+        self, node: nodes.Node, *args: t.Any, **kwargs: t.Any
+    ) -> nodes.Node:
+        node = super().generic_visit(node, *args, **kwargs)
+
+        # Do constant folding. Some other nodes besides Expr have
+        # as_const, but folding them causes errors later on.
+        if isinstance(node, nodes.Expr):
+            try:
+                return nodes.Const.from_untrusted(
+                    node.as_const(args[0] if args else None),
+                    lineno=node.lineno,
+                    environment=self.environment,
+                )
+            except nodes.Impossible:
+                pass
+
+        return node
diff --git a/src/jinja2/parser.py b/src/jinja2/parser.py
new file mode 100644
index 0000000..cefce2d
--- /dev/null
+++ b/src/jinja2/parser.py
@@ -0,0 +1,1032 @@
+"""Parse tokens from the lexer into nodes for the compiler."""
+import typing
+import typing as t
+
+from . import nodes
+from .exceptions import TemplateAssertionError
+from .exceptions import TemplateSyntaxError
+from .lexer import describe_token
+from .lexer import describe_token_expr
+
+if t.TYPE_CHECKING:
+    import typing_extensions as te
+    from .environment import Environment
+
+_ImportInclude = t.TypeVar("_ImportInclude", nodes.Import, nodes.Include)
+_MacroCall = t.TypeVar("_MacroCall", nodes.Macro, nodes.CallBlock)
+
+_statement_keywords = frozenset(
+    [
+        "for",
+        "if",
+        "block",
+        "extends",
+        "print",
+        "macro",
+        "include",
+        "from",
+        "import",
+        "set",
+        "with",
+        "autoescape",
+    ]
+)
+_compare_operators = frozenset(["eq", "ne", "lt", "lteq", "gt", "gteq"])
+
+_math_nodes: t.Dict[str, t.Type[nodes.Expr]] = {
+    "add": nodes.Add,
+    "sub": nodes.Sub,
+    "mul": nodes.Mul,
+    "div": nodes.Div,
+    "floordiv": nodes.FloorDiv,
+    "mod": nodes.Mod,
+}
+
+
+class Parser:
+    """This is the central parsing class Jinja uses.  It's passed to
+    extensions and can be used to parse expressions or statements.
+    """
+
+    def __init__(
+        self,
+        environment: "Environment",
+        source: str,
+        name: t.Optional[str] = None,
+        filename: t.Optional[str] = None,
+        state: t.Optional[str] = None,
+    ) -> None:
+        self.environment = environment
+        self.stream = environment._tokenize(source, name, filename, state)
+        self.name = name
+        self.filename = filename
+        self.closed = False
+        self.extensions: t.Dict[
+            str, t.Callable[["Parser"], t.Union[nodes.Node, t.List[nodes.Node]]]
+        ] = {}
+        for extension in environment.iter_extensions():
+            for tag in extension.tags:
+                self.extensions[tag] = extension.parse
+        self._last_identifier = 0
+        self._tag_stack: t.List[str] = []
+        self._end_token_stack: t.List[t.Tuple[str, ...]] = []
+
+    def fail(
+        self,
+        msg: str,
+        lineno: t.Optional[int] = None,
+        exc: t.Type[TemplateSyntaxError] = TemplateSyntaxError,
+    ) -> "te.NoReturn":
+        """Convenience method that raises `exc` with the message, passed
+        line number or last line number as well as the current name and
+        filename.
+        """
+        if lineno is None:
+            lineno = self.stream.current.lineno
+        raise exc(msg, lineno, self.name, self.filename)
+
+    def _fail_ut_eof(
+        self,
+        name: t.Optional[str],
+        end_token_stack: t.List[t.Tuple[str, ...]],
+        lineno: t.Optional[int],
+    ) -> "te.NoReturn":
+        expected: t.Set[str] = set()
+        for exprs in end_token_stack:
+            expected.update(map(describe_token_expr, exprs))
+        if end_token_stack:
+            currently_looking: t.Optional[str] = " or ".join(
+                map(repr, map(describe_token_expr, end_token_stack[-1]))
+            )
+        else:
+            currently_looking = None
+
+        if name is None:
+            message = ["Unexpected end of template."]
+        else:
+            message = [f"Encountered unknown tag {name!r}."]
+
+        if currently_looking:
+            if name is not None and name in expected:
+                message.append(
+                    "You probably made a nesting mistake. Jinja is expecting this tag,"
+                    f" but currently looking for {currently_looking}."
+                )
+            else:
+                message.append(
+                    f"Jinja was looking for the following tags: {currently_looking}."
+                )
+
+        if self._tag_stack:
+            message.append(
+                "The innermost block that needs to be closed is"
+                f" {self._tag_stack[-1]!r}."
+            )
+
+        self.fail(" ".join(message), lineno)
+
+    def fail_unknown_tag(
+        self, name: str, lineno: t.Optional[int] = None
+    ) -> "te.NoReturn":
+        """Called if the parser encounters an unknown tag.  Tries to fail
+        with a human readable error message that could help to identify
+        the problem.
+        """
+        self._fail_ut_eof(name, self._end_token_stack, lineno)
+
+    def fail_eof(
+        self,
+        end_tokens: t.Optional[t.Tuple[str, ...]] = None,
+        lineno: t.Optional[int] = None,
+    ) -> "te.NoReturn":
+        """Like fail_unknown_tag but for end of template situations."""
+        stack = list(self._end_token_stack)
+        if end_tokens is not None:
+            stack.append(end_tokens)
+        self._fail_ut_eof(None, stack, lineno)
+
+    def is_tuple_end(
+        self, extra_end_rules: t.Optional[t.Tuple[str, ...]] = None
+    ) -> bool:
+        """Are we at the end of a tuple?"""
+        if self.stream.current.type in ("variable_end", "block_end", "rparen"):
+            return True
+        elif extra_end_rules is not None:
+            return self.stream.current.test_any(extra_end_rules)  # type: ignore
+        return False
+
+    def free_identifier(self, lineno: t.Optional[int] = None) -> nodes.InternalName:
+        """Return a new free identifier as :class:`~jinja2.nodes.InternalName`."""
+        self._last_identifier += 1
+        rv = object.__new__(nodes.InternalName)
+        nodes.Node.__init__(rv, f"fi{self._last_identifier}", lineno=lineno)
+        return rv
+
+    def parse_statement(self) -> t.Union[nodes.Node, t.List[nodes.Node]]:
+        """Parse a single statement."""
+        token = self.stream.current
+        if token.type != "name":
+            self.fail("tag name expected", token.lineno)
+        self._tag_stack.append(token.value)
+        pop_tag = True
+        try:
+            if token.value in _statement_keywords:
+                f = getattr(self, f"parse_{self.stream.current.value}")
+                return f()  # type: ignore
+            if token.value == "call":
+                return self.parse_call_block()
+            if token.value == "filter":
+                return self.parse_filter_block()
+            ext = self.extensions.get(token.value)
+            if ext is not None:
+                return ext(self)
+
+            # did not work out, remove the token we pushed by accident
+            # from the stack so that the unknown tag fail function can
+            # produce a proper error message.
+            self._tag_stack.pop()
+            pop_tag = False
+            self.fail_unknown_tag(token.value, token.lineno)
+        finally:
+            if pop_tag:
+                self._tag_stack.pop()
+
+    def parse_statements(
+        self, end_tokens: t.Tuple[str, ...], drop_needle: bool = False
+    ) -> t.List[nodes.Node]:
+        """Parse multiple statements into a list until one of the end tokens
+        is reached.  This is used to parse the body of statements as it also
+        parses template data if appropriate.  The parser checks first if the
+        current token is a colon and skips it if there is one.  Then it checks
+        for the block end and parses until if one of the `end_tokens` is
+        reached.  Per default the active token in the stream at the end of
+        the call is the matched end token.  If this is not wanted `drop_needle`
+        can be set to `True` and the end token is removed.
+        """
+        # the first token may be a colon for python compatibility
+        self.stream.skip_if("colon")
+
+        # in the future it would be possible to add whole code sections
+        # by adding some sort of end of statement token and parsing those here.
+        self.stream.expect("block_end")
+        result = self.subparse(end_tokens)
+
+        # we reached the end of the template too early, the subparser
+        # does not check for this, so we do that now
+        if self.stream.current.type == "eof":
+            self.fail_eof(end_tokens)
+
+        if drop_needle:
+            next(self.stream)
+        return result
+
+    def parse_set(self) -> t.Union[nodes.Assign, nodes.AssignBlock]:
+        """Parse an assign statement."""
+        lineno = next(self.stream).lineno
+        target = self.parse_assign_target(with_namespace=True)
+        if self.stream.skip_if("assign"):
+            expr = self.parse_tuple()
+            return nodes.Assign(target, expr, lineno=lineno)
+        filter_node = self.parse_filter(None)
+        body = self.parse_statements(("name:endset",), drop_needle=True)
+        return nodes.AssignBlock(target, filter_node, body, lineno=lineno)
+
+    def parse_for(self) -> nodes.For:
+        """Parse a for loop."""
+        lineno = self.stream.expect("name:for").lineno
+        target = self.parse_assign_target(extra_end_rules=("name:in",))
+        self.stream.expect("name:in")
+        iter = self.parse_tuple(
+            with_condexpr=False, extra_end_rules=("name:recursive",)
+        )
+        test = None
+        if self.stream.skip_if("name:if"):
+            test = self.parse_expression()
+        recursive = self.stream.skip_if("name:recursive")
+        body = self.parse_statements(("name:endfor", "name:else"))
+        if next(self.stream).value == "endfor":
+            else_ = []
+        else:
+            else_ = self.parse_statements(("name:endfor",), drop_needle=True)
+        return nodes.For(target, iter, body, else_, test, recursive, lineno=lineno)
+
+    def parse_if(self) -> nodes.If:
+        """Parse an if construct."""
+        node = result = nodes.If(lineno=self.stream.expect("name:if").lineno)
+        while True:
+            node.test = self.parse_tuple(with_condexpr=False)
+            node.body = self.parse_statements(("name:elif", "name:else", "name:endif"))
+            node.elif_ = []
+            node.else_ = []
+            token = next(self.stream)
+            if token.test("name:elif"):
+                node = nodes.If(lineno=self.stream.current.lineno)
+                result.elif_.append(node)
+                continue
+            elif token.test("name:else"):
+                result.else_ = self.parse_statements(("name:endif",), drop_needle=True)
+            break
+        return result
+
+    def parse_with(self) -> nodes.With:
+        node = nodes.With(lineno=next(self.stream).lineno)
+        targets: t.List[nodes.Expr] = []
+        values: t.List[nodes.Expr] = []
+        while self.stream.current.type != "block_end":
+            if targets:
+                self.stream.expect("comma")
+            target = self.parse_assign_target()
+            target.set_ctx("param")
+            targets.append(target)
+            self.stream.expect("assign")
+            values.append(self.parse_expression())
+        node.targets = targets
+        node.values = values
+        node.body = self.parse_statements(("name:endwith",), drop_needle=True)
+        return node
+
+    def parse_autoescape(self) -> nodes.Scope:
+        node = nodes.ScopedEvalContextModifier(lineno=next(self.stream).lineno)
+        node.options = [nodes.Keyword("autoescape", self.parse_expression())]
+        node.body = self.parse_statements(("name:endautoescape",), drop_needle=True)
+        return nodes.Scope([node])
+
+    def parse_block(self) -> nodes.Block:
+        node = nodes.Block(lineno=next(self.stream).lineno)
+        node.name = self.stream.expect("name").value
+        node.scoped = self.stream.skip_if("name:scoped")
+        node.required = self.stream.skip_if("name:required")
+
+        # common problem people encounter when switching from django
+        # to jinja.  we do not support hyphens in block names, so let's
+        # raise a nicer error message in that case.
+        if self.stream.current.type == "sub":
+            self.fail(
+                "Block names in Jinja have to be valid Python identifiers and may not"
+                " contain hyphens, use an underscore instead."
+            )
+
+        node.body = self.parse_statements(("name:endblock",), drop_needle=True)
+
+        # enforce that required blocks only contain whitespace or comments
+        # by asserting that the body, if not empty, is just TemplateData nodes
+        # with whitespace data
+        if node.required and not all(
+            isinstance(child, nodes.TemplateData) and child.data.isspace()
+            for body in node.body
+            for child in body.nodes  # type: ignore
+        ):
+            self.fail("Required blocks can only contain comments or whitespace")
+
+        self.stream.skip_if("name:" + node.name)
+        return node
+
+    def parse_extends(self) -> nodes.Extends:
+        node = nodes.Extends(lineno=next(self.stream).lineno)
+        node.template = self.parse_expression()
+        return node
+
+    def parse_import_context(
+        self, node: _ImportInclude, default: bool
+    ) -> _ImportInclude:
+        if self.stream.current.test_any(
+            "name:with", "name:without"
+        ) and self.stream.look().test("name:context"):
+            node.with_context = next(self.stream).value == "with"
+            self.stream.skip()
+        else:
+            node.with_context = default
+        return node
+
+    def parse_include(self) -> nodes.Include:
+        node = nodes.Include(lineno=next(self.stream).lineno)
+        node.template = self.parse_expression()
+        if self.stream.current.test("name:ignore") and self.stream.look().test(
+            "name:missing"
+        ):
+            node.ignore_missing = True
+            self.stream.skip(2)
+        else:
+            node.ignore_missing = False
+        return self.parse_import_context(node, True)
+
+    def parse_import(self) -> nodes.Import:
+        node = nodes.Import(lineno=next(self.stream).lineno)
+        node.template = self.parse_expression()
+        self.stream.expect("name:as")
+        node.target = self.parse_assign_target(name_only=True).name
+        return self.parse_import_context(node, False)
+
+    def parse_from(self) -> nodes.FromImport:
+        node = nodes.FromImport(lineno=next(self.stream).lineno)
+        node.template = self.parse_expression()
+        self.stream.expect("name:import")
+        node.names = []
+
+        def parse_context() -> bool:
+            if self.stream.current.value in {
+                "with",
+                "without",
+            } and self.stream.look().test("name:context"):
+                node.with_context = next(self.stream).value == "with"
+                self.stream.skip()
+                return True
+            return False
+
+        while True:
+            if node.names:
+                self.stream.expect("comma")
+            if self.stream.current.type == "name":
+                if parse_context():
+                    break
+                target = self.parse_assign_target(name_only=True)
+                if target.name.startswith("_"):
+                    self.fail(
+                        "names starting with an underline can not be imported",
+                        target.lineno,
+                        exc=TemplateAssertionError,
+                    )
+                if self.stream.skip_if("name:as"):
+                    alias = self.parse_assign_target(name_only=True)
+                    node.names.append((target.name, alias.name))
+                else:
+                    node.names.append(target.name)
+                if parse_context() or self.stream.current.type != "comma":
+                    break
+            else:
+                self.stream.expect("name")
+        if not hasattr(node, "with_context"):
+            node.with_context = False
+        return node
+
+    def parse_signature(self, node: _MacroCall) -> None:
+        args = node.args = []
+        defaults = node.defaults = []
+        self.stream.expect("lparen")
+        while self.stream.current.type != "rparen":
+            if args:
+                self.stream.expect("comma")
+            arg = self.parse_assign_target(name_only=True)
+            arg.set_ctx("param")
+            if self.stream.skip_if("assign"):
+                defaults.append(self.parse_expression())
+            elif defaults:
+                self.fail("non-default argument follows default argument")
+            args.append(arg)
+        self.stream.expect("rparen")
+
+    def parse_call_block(self) -> nodes.CallBlock:
+        node = nodes.CallBlock(lineno=next(self.stream).lineno)
+        if self.stream.current.type == "lparen":
+            self.parse_signature(node)
+        else:
+            node.args = []
+            node.defaults = []
+
+        call_node = self.parse_expression()
+        if not isinstance(call_node, nodes.Call):
+            self.fail("expected call", node.lineno)
+        node.call = call_node
+        node.body = self.parse_statements(("name:endcall",), drop_needle=True)
+        return node
+
+    def parse_filter_block(self) -> nodes.FilterBlock:
+        node = nodes.FilterBlock(lineno=next(self.stream).lineno)
+        node.filter = self.parse_filter(None, start_inline=True)  # type: ignore
+        node.body = self.parse_statements(("name:endfilter",), drop_needle=True)
+        return node
+
+    def parse_macro(self) -> nodes.Macro:
+        node = nodes.Macro(lineno=next(self.stream).lineno)
+        node.name = self.parse_assign_target(name_only=True).name
+        self.parse_signature(node)
+        node.body = self.parse_statements(("name:endmacro",), drop_needle=True)
+        return node
+
+    def parse_print(self) -> nodes.Output:
+        node = nodes.Output(lineno=next(self.stream).lineno)
+        node.nodes = []
+        while self.stream.current.type != "block_end":
+            if node.nodes:
+                self.stream.expect("comma")
+            node.nodes.append(self.parse_expression())
+        return node
+
+    @typing.overload
+    def parse_assign_target(
+        self, with_tuple: bool = ..., name_only: "te.Literal[True]" = ...
+    ) -> nodes.Name:
+        ...
+
+    @typing.overload
+    def parse_assign_target(
+        self,
+        with_tuple: bool = True,
+        name_only: bool = False,
+        extra_end_rules: t.Optional[t.Tuple[str, ...]] = None,
+        with_namespace: bool = False,
+    ) -> t.Union[nodes.NSRef, nodes.Name, nodes.Tuple]:
+        ...
+
+    def parse_assign_target(
+        self,
+        with_tuple: bool = True,
+        name_only: bool = False,
+        extra_end_rules: t.Optional[t.Tuple[str, ...]] = None,
+        with_namespace: bool = False,
+    ) -> t.Union[nodes.NSRef, nodes.Name, nodes.Tuple]:
+        """Parse an assignment target.  As Jinja allows assignments to
+        tuples, this function can parse all allowed assignment targets.  Per
+        default assignments to tuples are parsed, that can be disable however
+        by setting `with_tuple` to `False`.  If only assignments to names are
+        wanted `name_only` can be set to `True`.  The `extra_end_rules`
+        parameter is forwarded to the tuple parsing function.  If
+        `with_namespace` is enabled, a namespace assignment may be parsed.
+        """
+        target: nodes.Expr
+
+        if with_namespace and self.stream.look().type == "dot":
+            token = self.stream.expect("name")
+            next(self.stream)  # dot
+            attr = self.stream.expect("name")
+            target = nodes.NSRef(token.value, attr.value, lineno=token.lineno)
+        elif name_only:
+            token = self.stream.expect("name")
+            target = nodes.Name(token.value, "store", lineno=token.lineno)
+        else:
+            if with_tuple:
+                target = self.parse_tuple(
+                    simplified=True, extra_end_rules=extra_end_rules
+                )
+            else:
+                target = self.parse_primary()
+
+            target.set_ctx("store")
+
+        if not target.can_assign():
+            self.fail(
+                f"can't assign to {type(target).__name__.lower()!r}", target.lineno
+            )
+
+        return target  # type: ignore
+
+    def parse_expression(self, with_condexpr: bool = True) -> nodes.Expr:
+        """Parse an expression.  Per default all expressions are parsed, if
+        the optional `with_condexpr` parameter is set to `False` conditional
+        expressions are not parsed.
+        """
+        if with_condexpr:
+            return self.parse_condexpr()
+        return self.parse_or()
+
+    def parse_condexpr(self) -> nodes.Expr:
+        lineno = self.stream.current.lineno
+        expr1 = self.parse_or()
+        expr3: t.Optional[nodes.Expr]
+
+        while self.stream.skip_if("name:if"):
+            expr2 = self.parse_or()
+            if self.stream.skip_if("name:else"):
+                expr3 = self.parse_condexpr()
+            else:
+                expr3 = None
+            expr1 = nodes.CondExpr(expr2, expr1, expr3, lineno=lineno)
+            lineno = self.stream.current.lineno
+        return expr1
+
+    def parse_or(self) -> nodes.Expr:
+        lineno = self.stream.current.lineno
+        left = self.parse_and()
+        while self.stream.skip_if("name:or"):
+            right = self.parse_and()
+            left = nodes.Or(left, right, lineno=lineno)
+            lineno = self.stream.current.lineno
+        return left
+
+    def parse_and(self) -> nodes.Expr:
+        lineno = self.stream.current.lineno
+        left = self.parse_not()
+        while self.stream.skip_if("name:and"):
+            right = self.parse_not()
+            left = nodes.And(left, right, lineno=lineno)
+            lineno = self.stream.current.lineno
+        return left
+
+    def parse_not(self) -> nodes.Expr:
+        if self.stream.current.test("name:not"):
+            lineno = next(self.stream).lineno
+            return nodes.Not(self.parse_not(), lineno=lineno)
+        return self.parse_compare()
+
+    def parse_compare(self) -> nodes.Expr:
+        lineno = self.stream.current.lineno
+        expr = self.parse_math1()
+        ops = []
+        while True:
+            token_type = self.stream.current.type
+            if token_type in _compare_operators:
+                next(self.stream)
+                ops.append(nodes.Operand(token_type, self.parse_math1()))
+            elif self.stream.skip_if("name:in"):
+                ops.append(nodes.Operand("in", self.parse_math1()))
+            elif self.stream.current.test("name:not") and self.stream.look().test(
+                "name:in"
+            ):
+                self.stream.skip(2)
+                ops.append(nodes.Operand("notin", self.parse_math1()))
+            else:
+                break
+            lineno = self.stream.current.lineno
+        if not ops:
+            return expr
+        return nodes.Compare(expr, ops, lineno=lineno)
+
+    def parse_math1(self) -> nodes.Expr:
+        lineno = self.stream.current.lineno
+        left = self.parse_concat()
+        while self.stream.current.type in ("add", "sub"):
+            cls = _math_nodes[self.stream.current.type]
+            next(self.stream)
+            right = self.parse_concat()
+            left = cls(left, right, lineno=lineno)
+            lineno = self.stream.current.lineno
+        return left
+
+    def parse_concat(self) -> nodes.Expr:
+        lineno = self.stream.current.lineno
+        args = [self.parse_math2()]
+        while self.stream.current.type == "tilde":
+            next(self.stream)
+            args.append(self.parse_math2())
+        if len(args) == 1:
+            return args[0]
+        return nodes.Concat(args, lineno=lineno)
+
+    def parse_math2(self) -> nodes.Expr:
+        lineno = self.stream.current.lineno
+        left = self.parse_pow()
+        while self.stream.current.type in ("mul", "div", "floordiv", "mod"):
+            cls = _math_nodes[self.stream.current.type]
+            next(self.stream)
+            right = self.parse_pow()
+            left = cls(left, right, lineno=lineno)
+            lineno = self.stream.current.lineno
+        return left
+
+    def parse_pow(self) -> nodes.Expr:
+        lineno = self.stream.current.lineno
+        left = self.parse_unary()
+        while self.stream.current.type == "pow":
+            next(self.stream)
+            right = self.parse_unary()
+            left = nodes.Pow(left, right, lineno=lineno)
+            lineno = self.stream.current.lineno
+        return left
+
+    def parse_unary(self, with_filter: bool = True) -> nodes.Expr:
+        token_type = self.stream.current.type
+        lineno = self.stream.current.lineno
+        node: nodes.Expr
+
+        if token_type == "sub":
+            next(self.stream)
+            node = nodes.Neg(self.parse_unary(False), lineno=lineno)
+        elif token_type == "add":
+            next(self.stream)
+            node = nodes.Pos(self.parse_unary(False), lineno=lineno)
+        else:
+            node = self.parse_primary()
+        node = self.parse_postfix(node)
+        if with_filter:
+            node = self.parse_filter_expr(node)
+        return node
+
+    def parse_primary(self) -> nodes.Expr:
+        token = self.stream.current
+        node: nodes.Expr
+        if token.type == "name":
+            if token.value in ("true", "false", "True", "False"):
+                node = nodes.Const(token.value in ("true", "True"), lineno=token.lineno)
+            elif token.value in ("none", "None"):
+                node = nodes.Const(None, lineno=token.lineno)
+            else:
+                node = nodes.Name(token.value, "load", lineno=token.lineno)
+            next(self.stream)
+        elif token.type == "string":
+            next(self.stream)
+            buf = [token.value]
+            lineno = token.lineno
+            while self.stream.current.type == "string":
+                buf.append(self.stream.current.value)
+                next(self.stream)
+            node = nodes.Const("".join(buf), lineno=lineno)
+        elif token.type in ("integer", "float"):
+            next(self.stream)
+            node = nodes.Const(token.value, lineno=token.lineno)
+        elif token.type == "lparen":
+            next(self.stream)
+            node = self.parse_tuple(explicit_parentheses=True)
+            self.stream.expect("rparen")
+        elif token.type == "lbracket":
+            node = self.parse_list()
+        elif token.type == "lbrace":
+            node = self.parse_dict()
+        else:
+            self.fail(f"unexpected {describe_token(token)!r}", token.lineno)
+        return node
+
+    def parse_tuple(
+        self,
+        simplified: bool = False,
+        with_condexpr: bool = True,
+        extra_end_rules: t.Optional[t.Tuple[str, ...]] = None,
+        explicit_parentheses: bool = False,
+    ) -> t.Union[nodes.Tuple, nodes.Expr]:
+        """Works like `parse_expression` but if multiple expressions are
+        delimited by a comma a :class:`~jinja2.nodes.Tuple` node is created.
+        This method could also return a regular expression instead of a tuple
+        if no commas where found.
+
+        The default parsing mode is a full tuple.  If `simplified` is `True`
+        only names and literals are parsed.  The `no_condexpr` parameter is
+        forwarded to :meth:`parse_expression`.
+
+        Because tuples do not require delimiters and may end in a bogus comma
+        an extra hint is needed that marks the end of a tuple.  For example
+        for loops support tuples between `for` and `in`.  In that case the
+        `extra_end_rules` is set to ``['name:in']``.
+
+        `explicit_parentheses` is true if the parsing was triggered by an
+        expression in parentheses.  This is used to figure out if an empty
+        tuple is a valid expression or not.
+        """
+        lineno = self.stream.current.lineno
+        if simplified:
+            parse = self.parse_primary
+        elif with_condexpr:
+            parse = self.parse_expression
+        else:
+
+            def parse() -> nodes.Expr:
+                return self.parse_expression(with_condexpr=False)
+
+        args: t.List[nodes.Expr] = []
+        is_tuple = False
+
+        while True:
+            if args:
+                self.stream.expect("comma")
+            if self.is_tuple_end(extra_end_rules):
+                break
+            args.append(parse())
+            if self.stream.current.type == "comma":
+                is_tuple = True
+            else:
+                break
+            lineno = self.stream.current.lineno
+
+        if not is_tuple:
+            if args:
+                return args[0]
+
+            # if we don't have explicit parentheses, an empty tuple is
+            # not a valid expression.  This would mean nothing (literally
+            # nothing) in the spot of an expression would be an empty
+            # tuple.
+            if not explicit_parentheses:
+                self.fail(
+                    "Expected an expression,"
+                    f" got {describe_token(self.stream.current)!r}"
+                )
+
+        return nodes.Tuple(args, "load", lineno=lineno)
+
+    def parse_list(self) -> nodes.List:
+        token = self.stream.expect("lbracket")
+        items: t.List[nodes.Expr] = []
+        while self.stream.current.type != "rbracket":
+            if items:
+                self.stream.expect("comma")
+            if self.stream.current.type == "rbracket":
+                break
+            items.append(self.parse_expression())
+        self.stream.expect("rbracket")
+        return nodes.List(items, lineno=token.lineno)
+
+    def parse_dict(self) -> nodes.Dict:
+        token = self.stream.expect("lbrace")
+        items: t.List[nodes.Pair] = []
+        while self.stream.current.type != "rbrace":
+            if items:
+                self.stream.expect("comma")
+            if self.stream.current.type == "rbrace":
+                break
+            key = self.parse_expression()
+            self.stream.expect("colon")
+            value = self.parse_expression()
+            items.append(nodes.Pair(key, value, lineno=key.lineno))
+        self.stream.expect("rbrace")
+        return nodes.Dict(items, lineno=token.lineno)
+
+    def parse_postfix(self, node: nodes.Expr) -> nodes.Expr:
+        while True:
+            token_type = self.stream.current.type
+            if token_type == "dot" or token_type == "lbracket":
+                node = self.parse_subscript(node)
+            # calls are valid both after postfix expressions (getattr
+            # and getitem) as well as filters and tests
+            elif token_type == "lparen":
+                node = self.parse_call(node)
+            else:
+                break
+        return node
+
+    def parse_filter_expr(self, node: nodes.Expr) -> nodes.Expr:
+        while True:
+            token_type = self.stream.current.type
+            if token_type == "pipe":
+                node = self.parse_filter(node)  # type: ignore
+            elif token_type == "name" and self.stream.current.value == "is":
+                node = self.parse_test(node)
+            # calls are valid both after postfix expressions (getattr
+            # and getitem) as well as filters and tests
+            elif token_type == "lparen":
+                node = self.parse_call(node)
+            else:
+                break
+        return node
+
+    def parse_subscript(
+        self, node: nodes.Expr
+    ) -> t.Union[nodes.Getattr, nodes.Getitem]:
+        token = next(self.stream)
+        arg: nodes.Expr
+
+        if token.type == "dot":
+            attr_token = self.stream.current
+            next(self.stream)
+            if attr_token.type == "name":
+                return nodes.Getattr(
+                    node, attr_token.value, "load", lineno=token.lineno
+                )
+            elif attr_token.type != "integer":
+                self.fail("expected name or number", attr_token.lineno)
+            arg = nodes.Const(attr_token.value, lineno=attr_token.lineno)
+            return nodes.Getitem(node, arg, "load", lineno=token.lineno)
+        if token.type == "lbracket":
+            args: t.List[nodes.Expr] = []
+            while self.stream.current.type != "rbracket":
+                if args:
+                    self.stream.expect("comma")
+                args.append(self.parse_subscribed())
+            self.stream.expect("rbracket")
+            if len(args) == 1:
+                arg = args[0]
+            else:
+                arg = nodes.Tuple(args, "load", lineno=token.lineno)
+            return nodes.Getitem(node, arg, "load", lineno=token.lineno)
+        self.fail("expected subscript expression", token.lineno)
+
+    def parse_subscribed(self) -> nodes.Expr:
+        lineno = self.stream.current.lineno
+        args: t.List[t.Optional[nodes.Expr]]
+
+        if self.stream.current.type == "colon":
+            next(self.stream)
+            args = [None]
+        else:
+            node = self.parse_expression()
+            if self.stream.current.type != "colon":
+                return node
+            next(self.stream)
+            args = [node]
+
+        if self.stream.current.type == "colon":
+            args.append(None)
+        elif self.stream.current.type not in ("rbracket", "comma"):
+            args.append(self.parse_expression())
+        else:
+            args.append(None)
+
+        if self.stream.current.type == "colon":
+            next(self.stream)
+            if self.stream.current.type not in ("rbracket", "comma"):
+                args.append(self.parse_expression())
+            else:
+                args.append(None)
+        else:
+            args.append(None)
+
+        return nodes.Slice(lineno=lineno, *args)
+
+    def parse_call_args(self) -> t.Tuple:
+        token = self.stream.expect("lparen")
+        args = []
+        kwargs = []
+        dyn_args = None
+        dyn_kwargs = None
+        require_comma = False
+
+        def ensure(expr: bool) -> None:
+            if not expr:
+                self.fail("invalid syntax for function call expression", token.lineno)
+
+        while self.stream.current.type != "rparen":
+            if require_comma:
+                self.stream.expect("comma")
+
+                # support for trailing comma
+                if self.stream.current.type == "rparen":
+                    break
+
+            if self.stream.current.type == "mul":
+                ensure(dyn_args is None and dyn_kwargs is None)
+                next(self.stream)
+                dyn_args = self.parse_expression()
+            elif self.stream.current.type == "pow":
+                ensure(dyn_kwargs is None)
+                next(self.stream)
+                dyn_kwargs = self.parse_expression()
+            else:
+                if (
+                    self.stream.current.type == "name"
+                    and self.stream.look().type == "assign"
+                ):
+                    # Parsing a kwarg
+                    ensure(dyn_kwargs is None)
+                    key = self.stream.current.value
+                    self.stream.skip(2)
+                    value = self.parse_expression()
+                    kwargs.append(nodes.Keyword(key, value, lineno=value.lineno))
+                else:
+                    # Parsing an arg
+                    ensure(dyn_args is None and dyn_kwargs is None and not kwargs)
+                    args.append(self.parse_expression())
+
+            require_comma = True
+
+        self.stream.expect("rparen")
+        return args, kwargs, dyn_args, dyn_kwargs
+
+    def parse_call(self, node: nodes.Expr) -> nodes.Call:
+        # The lparen will be expected in parse_call_args, but the lineno
+        # needs to be recorded before the stream is advanced.
+        token = self.stream.current
+        args, kwargs, dyn_args, dyn_kwargs = self.parse_call_args()
+        return nodes.Call(node, args, kwargs, dyn_args, dyn_kwargs, lineno=token.lineno)
+
+    def parse_filter(
+        self, node: t.Optional[nodes.Expr], start_inline: bool = False
+    ) -> t.Optional[nodes.Expr]:
+        while self.stream.current.type == "pipe" or start_inline:
+            if not start_inline:
+                next(self.stream)
+            token = self.stream.expect("name")
+            name = token.value
+            while self.stream.current.type == "dot":
+                next(self.stream)
+                name += "." + self.stream.expect("name").value
+            if self.stream.current.type == "lparen":
+                args, kwargs, dyn_args, dyn_kwargs = self.parse_call_args()
+            else:
+                args = []
+                kwargs = []
+                dyn_args = dyn_kwargs = None
+            node = nodes.Filter(
+                node, name, args, kwargs, dyn_args, dyn_kwargs, lineno=token.lineno
+            )
+            start_inline = False
+        return node
+
+    def parse_test(self, node: nodes.Expr) -> nodes.Expr:
+        token = next(self.stream)
+        if self.stream.current.test("name:not"):
+            next(self.stream)
+            negated = True
+        else:
+            negated = False
+        name = self.stream.expect("name").value
+        while self.stream.current.type == "dot":
+            next(self.stream)
+            name += "." + self.stream.expect("name").value
+        dyn_args = dyn_kwargs = None
+        kwargs = []
+        if self.stream.current.type == "lparen":
+            args, kwargs, dyn_args, dyn_kwargs = self.parse_call_args()
+        elif self.stream.current.type in {
+            "name",
+            "string",
+            "integer",
+            "float",
+            "lparen",
+            "lbracket",
+            "lbrace",
+        } and not self.stream.current.test_any("name:else", "name:or", "name:and"):
+            if self.stream.current.test("name:is"):
+                self.fail("You cannot chain multiple tests with is")
+            arg_node = self.parse_primary()
+            arg_node = self.parse_postfix(arg_node)
+            args = [arg_node]
+        else:
+            args = []
+        node = nodes.Test(
+            node, name, args, kwargs, dyn_args, dyn_kwargs, lineno=token.lineno
+        )
+        if negated:
+            node = nodes.Not(node, lineno=token.lineno)
+        return node
+
+    def subparse(
+        self, end_tokens: t.Optional[t.Tuple[str, ...]] = None
+    ) -> t.List[nodes.Node]:
+        body: t.List[nodes.Node] = []
+        data_buffer: t.List[nodes.Node] = []
+        add_data = data_buffer.append
+
+        if end_tokens is not None:
+            self._end_token_stack.append(end_tokens)
+
+        def flush_data() -> None:
+            if data_buffer:
+                lineno = data_buffer[0].lineno
+                body.append(nodes.Output(data_buffer[:], lineno=lineno))
+                del data_buffer[:]
+
+        try:
+            while self.stream:
+                token = self.stream.current
+                if token.type == "data":
+                    if token.value:
+                        add_data(nodes.TemplateData(token.value, lineno=token.lineno))
+                    next(self.stream)
+                elif token.type == "variable_begin":
+                    next(self.stream)
+                    add_data(self.parse_tuple(with_condexpr=True))
+                    self.stream.expect("variable_end")
+                elif token.type == "block_begin":
+                    flush_data()
+                    next(self.stream)
+                    if end_tokens is not None and self.stream.current.test_any(
+                        *end_tokens
+                    ):
+                        return body
+                    rv = self.parse_statement()
+                    if isinstance(rv, list):
+                        body.extend(rv)
+                    else:
+                        body.append(rv)
+                    self.stream.expect("block_end")
+                else:
+                    raise AssertionError("internal parsing error")
+
+            flush_data()
+        finally:
+            if end_tokens is not None:
+                self._end_token_stack.pop()
+        return body
+
+    def parse(self) -> nodes.Template:
+        """Parse the whole template into a `Template` node."""
+        result = nodes.Template(self.subparse(), lineno=1)
+        result.set_environment(self.environment)
+        return result
diff --git a/src/jinja2/py.typed b/src/jinja2/py.typed
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/src/jinja2/py.typed
diff --git a/src/jinja2/runtime.py b/src/jinja2/runtime.py
new file mode 100644
index 0000000..985842b
--- /dev/null
+++ b/src/jinja2/runtime.py
@@ -0,0 +1,1053 @@
+"""The runtime functions and state used by compiled templates."""
+import functools
+import sys
+import typing as t
+from collections import abc
+from itertools import chain
+
+from markupsafe import escape  # noqa: F401
+from markupsafe import Markup
+from markupsafe import soft_str
+
+from .async_utils import auto_aiter
+from .async_utils import auto_await  # noqa: F401
+from .exceptions import TemplateNotFound  # noqa: F401
+from .exceptions import TemplateRuntimeError  # noqa: F401
+from .exceptions import UndefinedError
+from .nodes import EvalContext
+from .utils import _PassArg
+from .utils import concat
+from .utils import internalcode
+from .utils import missing
+from .utils import Namespace  # noqa: F401
+from .utils import object_type_repr
+from .utils import pass_eval_context
+
+V = t.TypeVar("V")
+F = t.TypeVar("F", bound=t.Callable[..., t.Any])
+
+if t.TYPE_CHECKING:
+    import logging
+    import typing_extensions as te
+    from .environment import Environment
+
+    class LoopRenderFunc(te.Protocol):
+        def __call__(
+            self,
+            reciter: t.Iterable[V],
+            loop_render_func: "LoopRenderFunc",
+            depth: int = 0,
+        ) -> str:
+            ...
+
+
+# these variables are exported to the template runtime
+exported = [
+    "LoopContext",
+    "TemplateReference",
+    "Macro",
+    "Markup",
+    "TemplateRuntimeError",
+    "missing",
+    "escape",
+    "markup_join",
+    "str_join",
+    "identity",
+    "TemplateNotFound",
+    "Namespace",
+    "Undefined",
+    "internalcode",
+]
+async_exported = [
+    "AsyncLoopContext",
+    "auto_aiter",
+    "auto_await",
+]
+
+
+def identity(x: V) -> V:
+    """Returns its argument. Useful for certain things in the
+    environment.
+    """
+    return x
+
+
+def markup_join(seq: t.Iterable[t.Any]) -> str:
+    """Concatenation that escapes if necessary and converts to string."""
+    buf = []
+    iterator = map(soft_str, seq)
+    for arg in iterator:
+        buf.append(arg)
+        if hasattr(arg, "__html__"):
+            return Markup("").join(chain(buf, iterator))
+    return concat(buf)
+
+
+def str_join(seq: t.Iterable[t.Any]) -> str:
+    """Simple args to string conversion and concatenation."""
+    return concat(map(str, seq))
+
+
+def new_context(
+    environment: "Environment",
+    template_name: t.Optional[str],
+    blocks: t.Dict[str, t.Callable[["Context"], t.Iterator[str]]],
+    vars: t.Optional[t.Dict[str, t.Any]] = None,
+    shared: bool = False,
+    globals: t.Optional[t.MutableMapping[str, t.Any]] = None,
+    locals: t.Optional[t.Mapping[str, t.Any]] = None,
+) -> "Context":
+    """Internal helper for context creation."""
+    if vars is None:
+        vars = {}
+    if shared:
+        parent = vars
+    else:
+        parent = dict(globals or (), **vars)
+    if locals:
+        # if the parent is shared a copy should be created because
+        # we don't want to modify the dict passed
+        if shared:
+            parent = dict(parent)
+        for key, value in locals.items():
+            if value is not missing:
+                parent[key] = value
+    return environment.context_class(
+        environment, parent, template_name, blocks, globals=globals
+    )
+
+
+class TemplateReference:
+    """The `self` in templates."""
+
+    def __init__(self, context: "Context") -> None:
+        self.__context = context
+
+    def __getitem__(self, name: str) -> t.Any:
+        blocks = self.__context.blocks[name]
+        return BlockReference(name, self.__context, blocks, 0)
+
+    def __repr__(self) -> str:
+        return f"<{type(self).__name__} {self.__context.name!r}>"
+
+
+def _dict_method_all(dict_method: F) -> F:
+    @functools.wraps(dict_method)
+    def f_all(self: "Context") -> t.Any:
+        return dict_method(self.get_all())
+
+    return t.cast(F, f_all)
+
+
+@abc.Mapping.register
+class Context:
+    """The template context holds the variables of a template.  It stores the
+    values passed to the template and also the names the template exports.
+    Creating instances is neither supported nor useful as it's created
+    automatically at various stages of the template evaluation and should not
+    be created by hand.
+
+    The context is immutable.  Modifications on :attr:`parent` **must not**
+    happen and modifications on :attr:`vars` are allowed from generated
+    template code only.  Template filters and global functions marked as
+    :func:`pass_context` get the active context passed as first argument
+    and are allowed to access the context read-only.
+
+    The template context supports read only dict operations (`get`,
+    `keys`, `values`, `items`, `iterkeys`, `itervalues`, `iteritems`,
+    `__getitem__`, `__contains__`).  Additionally there is a :meth:`resolve`
+    method that doesn't fail with a `KeyError` but returns an
+    :class:`Undefined` object for missing variables.
+    """
+
+    def __init__(
+        self,
+        environment: "Environment",
+        parent: t.Dict[str, t.Any],
+        name: t.Optional[str],
+        blocks: t.Dict[str, t.Callable[["Context"], t.Iterator[str]]],
+        globals: t.Optional[t.MutableMapping[str, t.Any]] = None,
+    ):
+        self.parent = parent
+        self.vars: t.Dict[str, t.Any] = {}
+        self.environment: "Environment" = environment
+        self.eval_ctx = EvalContext(self.environment, name)
+        self.exported_vars: t.Set[str] = set()
+        self.name = name
+        self.globals_keys = set() if globals is None else set(globals)
+
+        # create the initial mapping of blocks.  Whenever template inheritance
+        # takes place the runtime will update this mapping with the new blocks
+        # from the template.
+        self.blocks = {k: [v] for k, v in blocks.items()}
+
+    def super(
+        self, name: str, current: t.Callable[["Context"], t.Iterator[str]]
+    ) -> t.Union["BlockReference", "Undefined"]:
+        """Render a parent block."""
+        try:
+            blocks = self.blocks[name]
+            index = blocks.index(current) + 1
+            blocks[index]
+        except LookupError:
+            return self.environment.undefined(
+                f"there is no parent block called {name!r}.", name="super"
+            )
+        return BlockReference(name, self, blocks, index)
+
+    def get(self, key: str, default: t.Any = None) -> t.Any:
+        """Look up a variable by name, or return a default if the key is
+        not found.
+
+        :param key: The variable name to look up.
+        :param default: The value to return if the key is not found.
+        """
+        try:
+            return self[key]
+        except KeyError:
+            return default
+
+    def resolve(self, key: str) -> t.Union[t.Any, "Undefined"]:
+        """Look up a variable by name, or return an :class:`Undefined`
+        object if the key is not found.
+
+        If you need to add custom behavior, override
+        :meth:`resolve_or_missing`, not this method. The various lookup
+        functions use that method, not this one.
+
+        :param key: The variable name to look up.
+        """
+        rv = self.resolve_or_missing(key)
+
+        if rv is missing:
+            return self.environment.undefined(name=key)
+
+        return rv
+
+    def resolve_or_missing(self, key: str) -> t.Any:
+        """Look up a variable by name, or return a ``missing`` sentinel
+        if the key is not found.
+
+        Override this method to add custom lookup behavior.
+        :meth:`resolve`, :meth:`get`, and :meth:`__getitem__` use this
+        method. Don't call this method directly.
+
+        :param key: The variable name to look up.
+        """
+        if key in self.vars:
+            return self.vars[key]
+
+        if key in self.parent:
+            return self.parent[key]
+
+        return missing
+
+    def get_exported(self) -> t.Dict[str, t.Any]:
+        """Get a new dict with the exported variables."""
+        return {k: self.vars[k] for k in self.exported_vars}
+
+    def get_all(self) -> t.Dict[str, t.Any]:
+        """Return the complete context as dict including the exported
+        variables.  For optimizations reasons this might not return an
+        actual copy so be careful with using it.
+        """
+        if not self.vars:
+            return self.parent
+        if not self.parent:
+            return self.vars
+        return dict(self.parent, **self.vars)
+
+    @internalcode
+    def call(
+        __self, __obj: t.Callable, *args: t.Any, **kwargs: t.Any  # noqa: B902
+    ) -> t.Union[t.Any, "Undefined"]:
+        """Call the callable with the arguments and keyword arguments
+        provided but inject the active context or environment as first
+        argument if the callable has :func:`pass_context` or
+        :func:`pass_environment`.
+        """
+        if __debug__:
+            __traceback_hide__ = True  # noqa
+
+        # Allow callable classes to take a context
+        if (
+            hasattr(__obj, "__call__")  # noqa: B004
+            and _PassArg.from_obj(__obj.__call__) is not None  # type: ignore
+        ):
+            __obj = __obj.__call__  # type: ignore
+
+        pass_arg = _PassArg.from_obj(__obj)
+
+        if pass_arg is _PassArg.context:
+            # the active context should have access to variables set in
+            # loops and blocks without mutating the context itself
+            if kwargs.get("_loop_vars"):
+                __self = __self.derived(kwargs["_loop_vars"])
+            if kwargs.get("_block_vars"):
+                __self = __self.derived(kwargs["_block_vars"])
+            args = (__self,) + args
+        elif pass_arg is _PassArg.eval_context:
+            args = (__self.eval_ctx,) + args
+        elif pass_arg is _PassArg.environment:
+            args = (__self.environment,) + args
+
+        kwargs.pop("_block_vars", None)
+        kwargs.pop("_loop_vars", None)
+
+        try:
+            return __obj(*args, **kwargs)
+        except StopIteration:
+            return __self.environment.undefined(
+                "value was undefined because a callable raised a"
+                " StopIteration exception"
+            )
+
+    def derived(self, locals: t.Optional[t.Dict[str, t.Any]] = None) -> "Context":
+        """Internal helper function to create a derived context.  This is
+        used in situations where the system needs a new context in the same
+        template that is independent.
+        """
+        context = new_context(
+            self.environment, self.name, {}, self.get_all(), True, None, locals
+        )
+        context.eval_ctx = self.eval_ctx
+        context.blocks.update((k, list(v)) for k, v in self.blocks.items())
+        return context
+
+    keys = _dict_method_all(dict.keys)
+    values = _dict_method_all(dict.values)
+    items = _dict_method_all(dict.items)
+
+    def __contains__(self, name: str) -> bool:
+        return name in self.vars or name in self.parent
+
+    def __getitem__(self, key: str) -> t.Any:
+        """Look up a variable by name with ``[]`` syntax, or raise a
+        ``KeyError`` if the key is not found.
+        """
+        item = self.resolve_or_missing(key)
+
+        if item is missing:
+            raise KeyError(key)
+
+        return item
+
+    def __repr__(self) -> str:
+        return f"<{type(self).__name__} {self.get_all()!r} of {self.name!r}>"
+
+
+class BlockReference:
+    """One block on a template reference."""
+
+    def __init__(
+        self,
+        name: str,
+        context: "Context",
+        stack: t.List[t.Callable[["Context"], t.Iterator[str]]],
+        depth: int,
+    ) -> None:
+        self.name = name
+        self._context = context
+        self._stack = stack
+        self._depth = depth
+
+    @property
+    def super(self) -> t.Union["BlockReference", "Undefined"]:
+        """Super the block."""
+        if self._depth + 1 >= len(self._stack):
+            return self._context.environment.undefined(
+                f"there is no parent block called {self.name!r}.", name="super"
+            )
+        return BlockReference(self.name, self._context, self._stack, self._depth + 1)
+
+    @internalcode
+    async def _async_call(self) -> str:
+        rv = concat(
+            [x async for x in self._stack[self._depth](self._context)]  # type: ignore
+        )
+
+        if self._context.eval_ctx.autoescape:
+            return Markup(rv)
+
+        return rv
+
+    @internalcode
+    def __call__(self) -> str:
+        if self._context.environment.is_async:
+            return self._async_call()  # type: ignore
+
+        rv = concat(self._stack[self._depth](self._context))
+
+        if self._context.eval_ctx.autoescape:
+            return Markup(rv)
+
+        return rv
+
+
+class LoopContext:
+    """A wrapper iterable for dynamic ``for`` loops, with information
+    about the loop and iteration.
+    """
+
+    #: Current iteration of the loop, starting at 0.
+    index0 = -1
+
+    _length: t.Optional[int] = None
+    _after: t.Any = missing
+    _current: t.Any = missing
+    _before: t.Any = missing
+    _last_changed_value: t.Any = missing
+
+    def __init__(
+        self,
+        iterable: t.Iterable[V],
+        undefined: t.Type["Undefined"],
+        recurse: t.Optional["LoopRenderFunc"] = None,
+        depth0: int = 0,
+    ) -> None:
+        """
+        :param iterable: Iterable to wrap.
+        :param undefined: :class:`Undefined` class to use for next and
+            previous items.
+        :param recurse: The function to render the loop body when the
+            loop is marked recursive.
+        :param depth0: Incremented when looping recursively.
+        """
+        self._iterable = iterable
+        self._iterator = self._to_iterator(iterable)
+        self._undefined = undefined
+        self._recurse = recurse
+        #: How many levels deep a recursive loop currently is, starting at 0.
+        self.depth0 = depth0
+
+    @staticmethod
+    def _to_iterator(iterable: t.Iterable[V]) -> t.Iterator[V]:
+        return iter(iterable)
+
+    @property
+    def length(self) -> int:
+        """Length of the iterable.
+
+        If the iterable is a generator or otherwise does not have a
+        size, it is eagerly evaluated to get a size.
+        """
+        if self._length is not None:
+            return self._length
+
+        try:
+            self._length = len(self._iterable)  # type: ignore
+        except TypeError:
+            iterable = list(self._iterator)
+            self._iterator = self._to_iterator(iterable)
+            self._length = len(iterable) + self.index + (self._after is not missing)
+
+        return self._length
+
+    def __len__(self) -> int:
+        return self.length
+
+    @property
+    def depth(self) -> int:
+        """How many levels deep a recursive loop currently is, starting at 1."""
+        return self.depth0 + 1
+
+    @property
+    def index(self) -> int:
+        """Current iteration of the loop, starting at 1."""
+        return self.index0 + 1
+
+    @property
+    def revindex0(self) -> int:
+        """Number of iterations from the end of the loop, ending at 0.
+
+        Requires calculating :attr:`length`.
+        """
+        return self.length - self.index
+
+    @property
+    def revindex(self) -> int:
+        """Number of iterations from the end of the loop, ending at 1.
+
+        Requires calculating :attr:`length`.
+        """
+        return self.length - self.index0
+
+    @property
+    def first(self) -> bool:
+        """Whether this is the first iteration of the loop."""
+        return self.index0 == 0
+
+    def _peek_next(self) -> t.Any:
+        """Return the next element in the iterable, or :data:`missing`
+        if the iterable is exhausted. Only peeks one item ahead, caching
+        the result in :attr:`_last` for use in subsequent checks. The
+        cache is reset when :meth:`__next__` is called.
+        """
+        if self._after is not missing:
+            return self._after
+
+        self._after = next(self._iterator, missing)
+        return self._after
+
+    @property
+    def last(self) -> bool:
+        """Whether this is the last iteration of the loop.
+
+        Causes the iterable to advance early. See
+        :func:`itertools.groupby` for issues this can cause.
+        The :func:`groupby` filter avoids that issue.
+        """
+        return self._peek_next() is missing
+
+    @property
+    def previtem(self) -> t.Union[t.Any, "Undefined"]:
+        """The item in the previous iteration. Undefined during the
+        first iteration.
+        """
+        if self.first:
+            return self._undefined("there is no previous item")
+
+        return self._before
+
+    @property
+    def nextitem(self) -> t.Union[t.Any, "Undefined"]:
+        """The item in the next iteration. Undefined during the last
+        iteration.
+
+        Causes the iterable to advance early. See
+        :func:`itertools.groupby` for issues this can cause.
+        The :func:`jinja-filters.groupby` filter avoids that issue.
+        """
+        rv = self._peek_next()
+
+        if rv is missing:
+            return self._undefined("there is no next item")
+
+        return rv
+
+    def cycle(self, *args: V) -> V:
+        """Return a value from the given args, cycling through based on
+        the current :attr:`index0`.
+
+        :param args: One or more values to cycle through.
+        """
+        if not args:
+            raise TypeError("no items for cycling given")
+
+        return args[self.index0 % len(args)]
+
+    def changed(self, *value: t.Any) -> bool:
+        """Return ``True`` if previously called with a different value
+        (including when called for the first time).
+
+        :param value: One or more values to compare to the last call.
+        """
+        if self._last_changed_value != value:
+            self._last_changed_value = value
+            return True
+
+        return False
+
+    def __iter__(self) -> "LoopContext":
+        return self
+
+    def __next__(self) -> t.Tuple[t.Any, "LoopContext"]:
+        if self._after is not missing:
+            rv = self._after
+            self._after = missing
+        else:
+            rv = next(self._iterator)
+
+        self.index0 += 1
+        self._before = self._current
+        self._current = rv
+        return rv, self
+
+    @internalcode
+    def __call__(self, iterable: t.Iterable[V]) -> str:
+        """When iterating over nested data, render the body of the loop
+        recursively with the given inner iterable data.
+
+        The loop must have the ``recursive`` marker for this to work.
+        """
+        if self._recurse is None:
+            raise TypeError(
+                "The loop must have the 'recursive' marker to be called recursively."
+            )
+
+        return self._recurse(iterable, self._recurse, depth=self.depth)
+
+    def __repr__(self) -> str:
+        return f"<{type(self).__name__} {self.index}/{self.length}>"
+
+
+class AsyncLoopContext(LoopContext):
+    _iterator: t.AsyncIterator[t.Any]  # type: ignore
+
+    @staticmethod
+    def _to_iterator(  # type: ignore
+        iterable: t.Union[t.Iterable[V], t.AsyncIterable[V]]
+    ) -> t.AsyncIterator[V]:
+        return auto_aiter(iterable)
+
+    @property
+    async def length(self) -> int:  # type: ignore
+        if self._length is not None:
+            return self._length
+
+        try:
+            self._length = len(self._iterable)  # type: ignore
+        except TypeError:
+            iterable = [x async for x in self._iterator]
+            self._iterator = self._to_iterator(iterable)
+            self._length = len(iterable) + self.index + (self._after is not missing)
+
+        return self._length
+
+    @property
+    async def revindex0(self) -> int:  # type: ignore
+        return await self.length - self.index
+
+    @property
+    async def revindex(self) -> int:  # type: ignore
+        return await self.length - self.index0
+
+    async def _peek_next(self) -> t.Any:
+        if self._after is not missing:
+            return self._after
+
+        try:
+            self._after = await self._iterator.__anext__()
+        except StopAsyncIteration:
+            self._after = missing
+
+        return self._after
+
+    @property
+    async def last(self) -> bool:  # type: ignore
+        return await self._peek_next() is missing
+
+    @property
+    async def nextitem(self) -> t.Union[t.Any, "Undefined"]:
+        rv = await self._peek_next()
+
+        if rv is missing:
+            return self._undefined("there is no next item")
+
+        return rv
+
+    def __aiter__(self) -> "AsyncLoopContext":
+        return self
+
+    async def __anext__(self) -> t.Tuple[t.Any, "AsyncLoopContext"]:
+        if self._after is not missing:
+            rv = self._after
+            self._after = missing
+        else:
+            rv = await self._iterator.__anext__()
+
+        self.index0 += 1
+        self._before = self._current
+        self._current = rv
+        return rv, self
+
+
+class Macro:
+    """Wraps a macro function."""
+
+    def __init__(
+        self,
+        environment: "Environment",
+        func: t.Callable[..., str],
+        name: str,
+        arguments: t.List[str],
+        catch_kwargs: bool,
+        catch_varargs: bool,
+        caller: bool,
+        default_autoescape: t.Optional[bool] = None,
+    ):
+        self._environment = environment
+        self._func = func
+        self._argument_count = len(arguments)
+        self.name = name
+        self.arguments = arguments
+        self.catch_kwargs = catch_kwargs
+        self.catch_varargs = catch_varargs
+        self.caller = caller
+        self.explicit_caller = "caller" in arguments
+
+        if default_autoescape is None:
+            if callable(environment.autoescape):
+                default_autoescape = environment.autoescape(None)
+            else:
+                default_autoescape = environment.autoescape
+
+        self._default_autoescape = default_autoescape
+
+    @internalcode
+    @pass_eval_context
+    def __call__(self, *args: t.Any, **kwargs: t.Any) -> str:
+        # This requires a bit of explanation,  In the past we used to
+        # decide largely based on compile-time information if a macro is
+        # safe or unsafe.  While there was a volatile mode it was largely
+        # unused for deciding on escaping.  This turns out to be
+        # problematic for macros because whether a macro is safe depends not
+        # on the escape mode when it was defined, but rather when it was used.
+        #
+        # Because however we export macros from the module system and
+        # there are historic callers that do not pass an eval context (and
+        # will continue to not pass one), we need to perform an instance
+        # check here.
+        #
+        # This is considered safe because an eval context is not a valid
+        # argument to callables otherwise anyway.  Worst case here is
+        # that if no eval context is passed we fall back to the compile
+        # time autoescape flag.
+        if args and isinstance(args[0], EvalContext):
+            autoescape = args[0].autoescape
+            args = args[1:]
+        else:
+            autoescape = self._default_autoescape
+
+        # try to consume the positional arguments
+        arguments = list(args[: self._argument_count])
+        off = len(arguments)
+
+        # For information why this is necessary refer to the handling
+        # of caller in the `macro_body` handler in the compiler.
+        found_caller = False
+
+        # if the number of arguments consumed is not the number of
+        # arguments expected we start filling in keyword arguments
+        # and defaults.
+        if off != self._argument_count:
+            for name in self.arguments[len(arguments) :]:
+                try:
+                    value = kwargs.pop(name)
+                except KeyError:
+                    value = missing
+                if name == "caller":
+                    found_caller = True
+                arguments.append(value)
+        else:
+            found_caller = self.explicit_caller
+
+        # it's important that the order of these arguments does not change
+        # if not also changed in the compiler's `function_scoping` method.
+        # the order is caller, keyword arguments, positional arguments!
+        if self.caller and not found_caller:
+            caller = kwargs.pop("caller", None)
+            if caller is None:
+                caller = self._environment.undefined("No caller defined", name="caller")
+            arguments.append(caller)
+
+        if self.catch_kwargs:
+            arguments.append(kwargs)
+        elif kwargs:
+            if "caller" in kwargs:
+                raise TypeError(
+                    f"macro {self.name!r} was invoked with two values for the special"
+                    " caller argument. This is most likely a bug."
+                )
+            raise TypeError(
+                f"macro {self.name!r} takes no keyword argument {next(iter(kwargs))!r}"
+            )
+        if self.catch_varargs:
+            arguments.append(args[self._argument_count :])
+        elif len(args) > self._argument_count:
+            raise TypeError(
+                f"macro {self.name!r} takes not more than"
+                f" {len(self.arguments)} argument(s)"
+            )
+
+        return self._invoke(arguments, autoescape)
+
+    async def _async_invoke(self, arguments: t.List[t.Any], autoescape: bool) -> str:
+        rv = await self._func(*arguments)  # type: ignore
+
+        if autoescape:
+            return Markup(rv)
+
+        return rv  # type: ignore
+
+    def _invoke(self, arguments: t.List[t.Any], autoescape: bool) -> str:
+        if self._environment.is_async:
+            return self._async_invoke(arguments, autoescape)  # type: ignore
+
+        rv = self._func(*arguments)
+
+        if autoescape:
+            rv = Markup(rv)
+
+        return rv
+
+    def __repr__(self) -> str:
+        name = "anonymous" if self.name is None else repr(self.name)
+        return f"<{type(self).__name__} {name}>"
+
+
+class Undefined:
+    """The default undefined type.  This undefined type can be printed and
+    iterated over, but every other access will raise an :exc:`UndefinedError`:
+
+    >>> foo = Undefined(name='foo')
+    >>> str(foo)
+    ''
+    >>> not foo
+    True
+    >>> foo + 42
+    Traceback (most recent call last):
+      ...
+    jinja2.exceptions.UndefinedError: 'foo' is undefined
+    """
+
+    __slots__ = (
+        "_undefined_hint",
+        "_undefined_obj",
+        "_undefined_name",
+        "_undefined_exception",
+    )
+
+    def __init__(
+        self,
+        hint: t.Optional[str] = None,
+        obj: t.Any = missing,
+        name: t.Optional[str] = None,
+        exc: t.Type[TemplateRuntimeError] = UndefinedError,
+    ) -> None:
+        self._undefined_hint = hint
+        self._undefined_obj = obj
+        self._undefined_name = name
+        self._undefined_exception = exc
+
+    @property
+    def _undefined_message(self) -> str:
+        """Build a message about the undefined value based on how it was
+        accessed.
+        """
+        if self._undefined_hint:
+            return self._undefined_hint
+
+        if self._undefined_obj is missing:
+            return f"{self._undefined_name!r} is undefined"
+
+        if not isinstance(self._undefined_name, str):
+            return (
+                f"{object_type_repr(self._undefined_obj)} has no"
+                f" element {self._undefined_name!r}"
+            )
+
+        return (
+            f"{object_type_repr(self._undefined_obj)!r} has no"
+            f" attribute {self._undefined_name!r}"
+        )
+
+    @internalcode
+    def _fail_with_undefined_error(
+        self, *args: t.Any, **kwargs: t.Any
+    ) -> "te.NoReturn":
+        """Raise an :exc:`UndefinedError` when operations are performed
+        on the undefined value.
+        """
+        raise self._undefined_exception(self._undefined_message)
+
+    @internalcode
+    def __getattr__(self, name: str) -> t.Any:
+        if name[:2] == "__":
+            raise AttributeError(name)
+
+        return self._fail_with_undefined_error()
+
+    __add__ = __radd__ = __sub__ = __rsub__ = _fail_with_undefined_error
+    __mul__ = __rmul__ = __div__ = __rdiv__ = _fail_with_undefined_error
+    __truediv__ = __rtruediv__ = _fail_with_undefined_error
+    __floordiv__ = __rfloordiv__ = _fail_with_undefined_error
+    __mod__ = __rmod__ = _fail_with_undefined_error
+    __pos__ = __neg__ = _fail_with_undefined_error
+    __call__ = __getitem__ = _fail_with_undefined_error
+    __lt__ = __le__ = __gt__ = __ge__ = _fail_with_undefined_error
+    __int__ = __float__ = __complex__ = _fail_with_undefined_error
+    __pow__ = __rpow__ = _fail_with_undefined_error
+
+    def __eq__(self, other: t.Any) -> bool:
+        return type(self) is type(other)
+
+    def __ne__(self, other: t.Any) -> bool:
+        return not self.__eq__(other)
+
+    def __hash__(self) -> int:
+        return id(type(self))
+
+    def __str__(self) -> str:
+        return ""
+
+    def __len__(self) -> int:
+        return 0
+
+    def __iter__(self) -> t.Iterator[t.Any]:
+        yield from ()
+
+    async def __aiter__(self) -> t.AsyncIterator[t.Any]:
+        for _ in ():
+            yield
+
+    def __bool__(self) -> bool:
+        return False
+
+    def __repr__(self) -> str:
+        return "Undefined"
+
+
+def make_logging_undefined(
+    logger: t.Optional["logging.Logger"] = None, base: t.Type[Undefined] = Undefined
+) -> t.Type[Undefined]:
+    """Given a logger object this returns a new undefined class that will
+    log certain failures.  It will log iterations and printing.  If no
+    logger is given a default logger is created.
+
+    Example::
+
+        logger = logging.getLogger(__name__)
+        LoggingUndefined = make_logging_undefined(
+            logger=logger,
+            base=Undefined
+        )
+
+    .. versionadded:: 2.8
+
+    :param logger: the logger to use.  If not provided, a default logger
+                   is created.
+    :param base: the base class to add logging functionality to.  This
+                 defaults to :class:`Undefined`.
+    """
+    if logger is None:
+        import logging
+
+        logger = logging.getLogger(__name__)
+        logger.addHandler(logging.StreamHandler(sys.stderr))
+
+    def _log_message(undef: Undefined) -> None:
+        logger.warning(  # type: ignore
+            "Template variable warning: %s", undef._undefined_message
+        )
+
+    class LoggingUndefined(base):  # type: ignore
+        __slots__ = ()
+
+        def _fail_with_undefined_error(  # type: ignore
+            self, *args: t.Any, **kwargs: t.Any
+        ) -> "te.NoReturn":
+            try:
+                super()._fail_with_undefined_error(*args, **kwargs)
+            except self._undefined_exception as e:
+                logger.error("Template variable error: %s", e)  # type: ignore
+                raise e
+
+        def __str__(self) -> str:
+            _log_message(self)
+            return super().__str__()  # type: ignore
+
+        def __iter__(self) -> t.Iterator[t.Any]:
+            _log_message(self)
+            return super().__iter__()  # type: ignore
+
+        def __bool__(self) -> bool:
+            _log_message(self)
+            return super().__bool__()  # type: ignore
+
+    return LoggingUndefined
+
+
+class ChainableUndefined(Undefined):
+    """An undefined that is chainable, where both ``__getattr__`` and
+    ``__getitem__`` return itself rather than raising an
+    :exc:`UndefinedError`.
+
+    >>> foo = ChainableUndefined(name='foo')
+    >>> str(foo.bar['baz'])
+    ''
+    >>> foo.bar['baz'] + 42
+    Traceback (most recent call last):
+      ...
+    jinja2.exceptions.UndefinedError: 'foo' is undefined
+
+    .. versionadded:: 2.11.0
+    """
+
+    __slots__ = ()
+
+    def __html__(self) -> str:
+        return str(self)
+
+    def __getattr__(self, _: str) -> "ChainableUndefined":
+        return self
+
+    __getitem__ = __getattr__  # type: ignore
+
+
+class DebugUndefined(Undefined):
+    """An undefined that returns the debug info when printed.
+
+    >>> foo = DebugUndefined(name='foo')
+    >>> str(foo)
+    '{{ foo }}'
+    >>> not foo
+    True
+    >>> foo + 42
+    Traceback (most recent call last):
+      ...
+    jinja2.exceptions.UndefinedError: 'foo' is undefined
+    """
+
+    __slots__ = ()
+
+    def __str__(self) -> str:
+        if self._undefined_hint:
+            message = f"undefined value printed: {self._undefined_hint}"
+
+        elif self._undefined_obj is missing:
+            message = self._undefined_name  # type: ignore
+
+        else:
+            message = (
+                f"no such element: {object_type_repr(self._undefined_obj)}"
+                f"[{self._undefined_name!r}]"
+            )
+
+        return f"{{{{ {message} }}}}"
+
+
+class StrictUndefined(Undefined):
+    """An undefined that barks on print and iteration as well as boolean
+    tests and all kinds of comparisons.  In other words: you can do nothing
+    with it except checking if it's defined using the `defined` test.
+
+    >>> foo = StrictUndefined(name='foo')
+    >>> str(foo)
+    Traceback (most recent call last):
+      ...
+    jinja2.exceptions.UndefinedError: 'foo' is undefined
+    >>> not foo
+    Traceback (most recent call last):
+      ...
+    jinja2.exceptions.UndefinedError: 'foo' is undefined
+    >>> foo + 42
+    Traceback (most recent call last):
+      ...
+    jinja2.exceptions.UndefinedError: 'foo' is undefined
+    """
+
+    __slots__ = ()
+    __iter__ = __str__ = __len__ = Undefined._fail_with_undefined_error
+    __eq__ = __ne__ = __bool__ = __hash__ = Undefined._fail_with_undefined_error
+    __contains__ = Undefined._fail_with_undefined_error
+
+
+# Remove slots attributes, after the metaclass is applied they are
+# unneeded and contain wrong data for subclasses.
+del (
+    Undefined.__slots__,
+    ChainableUndefined.__slots__,
+    DebugUndefined.__slots__,
+    StrictUndefined.__slots__,
+)
diff --git a/src/jinja2/sandbox.py b/src/jinja2/sandbox.py
new file mode 100644
index 0000000..06d7414
--- /dev/null
+++ b/src/jinja2/sandbox.py
@@ -0,0 +1,428 @@
+"""A sandbox layer that ensures unsafe operations cannot be performed.
+Useful when the template itself comes from an untrusted source.
+"""
+import operator
+import types
+import typing as t
+from _string import formatter_field_name_split  # type: ignore
+from collections import abc
+from collections import deque
+from string import Formatter
+
+from markupsafe import EscapeFormatter
+from markupsafe import Markup
+
+from .environment import Environment
+from .exceptions import SecurityError
+from .runtime import Context
+from .runtime import Undefined
+
+F = t.TypeVar("F", bound=t.Callable[..., t.Any])
+
+#: maximum number of items a range may produce
+MAX_RANGE = 100000
+
+#: Unsafe function attributes.
+UNSAFE_FUNCTION_ATTRIBUTES: t.Set[str] = set()
+
+#: Unsafe method attributes. Function attributes are unsafe for methods too.
+UNSAFE_METHOD_ATTRIBUTES: t.Set[str] = set()
+
+#: unsafe generator attributes.
+UNSAFE_GENERATOR_ATTRIBUTES = {"gi_frame", "gi_code"}
+
+#: unsafe attributes on coroutines
+UNSAFE_COROUTINE_ATTRIBUTES = {"cr_frame", "cr_code"}
+
+#: unsafe attributes on async generators
+UNSAFE_ASYNC_GENERATOR_ATTRIBUTES = {"ag_code", "ag_frame"}
+
+_mutable_spec: t.Tuple[t.Tuple[t.Type, t.FrozenSet[str]], ...] = (
+    (
+        abc.MutableSet,
+        frozenset(
+            [
+                "add",
+                "clear",
+                "difference_update",
+                "discard",
+                "pop",
+                "remove",
+                "symmetric_difference_update",
+                "update",
+            ]
+        ),
+    ),
+    (
+        abc.MutableMapping,
+        frozenset(["clear", "pop", "popitem", "setdefault", "update"]),
+    ),
+    (
+        abc.MutableSequence,
+        frozenset(["append", "reverse", "insert", "sort", "extend", "remove"]),
+    ),
+    (
+        deque,
+        frozenset(
+            [
+                "append",
+                "appendleft",
+                "clear",
+                "extend",
+                "extendleft",
+                "pop",
+                "popleft",
+                "remove",
+                "rotate",
+            ]
+        ),
+    ),
+)
+
+
+def inspect_format_method(callable: t.Callable) -> t.Optional[str]:
+    if not isinstance(
+        callable, (types.MethodType, types.BuiltinMethodType)
+    ) or callable.__name__ not in ("format", "format_map"):
+        return None
+
+    obj = callable.__self__
+
+    if isinstance(obj, str):
+        return obj
+
+    return None
+
+
+def safe_range(*args: int) -> range:
+    """A range that can't generate ranges with a length of more than
+    MAX_RANGE items.
+    """
+    rng = range(*args)
+
+    if len(rng) > MAX_RANGE:
+        raise OverflowError(
+            "Range too big. The sandbox blocks ranges larger than"
+            f" MAX_RANGE ({MAX_RANGE})."
+        )
+
+    return rng
+
+
+def unsafe(f: F) -> F:
+    """Marks a function or method as unsafe.
+
+    .. code-block: python
+
+        @unsafe
+        def delete(self):
+            pass
+    """
+    f.unsafe_callable = True  # type: ignore
+    return f
+
+
+def is_internal_attribute(obj: t.Any, attr: str) -> bool:
+    """Test if the attribute given is an internal python attribute.  For
+    example this function returns `True` for the `func_code` attribute of
+    python objects.  This is useful if the environment method
+    :meth:`~SandboxedEnvironment.is_safe_attribute` is overridden.
+
+    >>> from jinja2.sandbox import is_internal_attribute
+    >>> is_internal_attribute(str, "mro")
+    True
+    >>> is_internal_attribute(str, "upper")
+    False
+    """
+    if isinstance(obj, types.FunctionType):
+        if attr in UNSAFE_FUNCTION_ATTRIBUTES:
+            return True
+    elif isinstance(obj, types.MethodType):
+        if attr in UNSAFE_FUNCTION_ATTRIBUTES or attr in UNSAFE_METHOD_ATTRIBUTES:
+            return True
+    elif isinstance(obj, type):
+        if attr == "mro":
+            return True
+    elif isinstance(obj, (types.CodeType, types.TracebackType, types.FrameType)):
+        return True
+    elif isinstance(obj, types.GeneratorType):
+        if attr in UNSAFE_GENERATOR_ATTRIBUTES:
+            return True
+    elif hasattr(types, "CoroutineType") and isinstance(obj, types.CoroutineType):
+        if attr in UNSAFE_COROUTINE_ATTRIBUTES:
+            return True
+    elif hasattr(types, "AsyncGeneratorType") and isinstance(
+        obj, types.AsyncGeneratorType
+    ):
+        if attr in UNSAFE_ASYNC_GENERATOR_ATTRIBUTES:
+            return True
+    return attr.startswith("__")
+
+
+def modifies_known_mutable(obj: t.Any, attr: str) -> bool:
+    """This function checks if an attribute on a builtin mutable object
+    (list, dict, set or deque) or the corresponding ABCs would modify it
+    if called.
+
+    >>> modifies_known_mutable({}, "clear")
+    True
+    >>> modifies_known_mutable({}, "keys")
+    False
+    >>> modifies_known_mutable([], "append")
+    True
+    >>> modifies_known_mutable([], "index")
+    False
+
+    If called with an unsupported object, ``False`` is returned.
+
+    >>> modifies_known_mutable("foo", "upper")
+    False
+    """
+    for typespec, unsafe in _mutable_spec:
+        if isinstance(obj, typespec):
+            return attr in unsafe
+    return False
+
+
+class SandboxedEnvironment(Environment):
+    """The sandboxed environment.  It works like the regular environment but
+    tells the compiler to generate sandboxed code.  Additionally subclasses of
+    this environment may override the methods that tell the runtime what
+    attributes or functions are safe to access.
+
+    If the template tries to access insecure code a :exc:`SecurityError` is
+    raised.  However also other exceptions may occur during the rendering so
+    the caller has to ensure that all exceptions are caught.
+    """
+
+    sandboxed = True
+
+    #: default callback table for the binary operators.  A copy of this is
+    #: available on each instance of a sandboxed environment as
+    #: :attr:`binop_table`
+    default_binop_table: t.Dict[str, t.Callable[[t.Any, t.Any], t.Any]] = {
+        "+": operator.add,
+        "-": operator.sub,
+        "*": operator.mul,
+        "/": operator.truediv,
+        "//": operator.floordiv,
+        "**": operator.pow,
+        "%": operator.mod,
+    }
+
+    #: default callback table for the unary operators.  A copy of this is
+    #: available on each instance of a sandboxed environment as
+    #: :attr:`unop_table`
+    default_unop_table: t.Dict[str, t.Callable[[t.Any], t.Any]] = {
+        "+": operator.pos,
+        "-": operator.neg,
+    }
+
+    #: a set of binary operators that should be intercepted.  Each operator
+    #: that is added to this set (empty by default) is delegated to the
+    #: :meth:`call_binop` method that will perform the operator.  The default
+    #: operator callback is specified by :attr:`binop_table`.
+    #:
+    #: The following binary operators are interceptable:
+    #: ``//``, ``%``, ``+``, ``*``, ``-``, ``/``, and ``**``
+    #:
+    #: The default operation form the operator table corresponds to the
+    #: builtin function.  Intercepted calls are always slower than the native
+    #: operator call, so make sure only to intercept the ones you are
+    #: interested in.
+    #:
+    #: .. versionadded:: 2.6
+    intercepted_binops: t.FrozenSet[str] = frozenset()
+
+    #: a set of unary operators that should be intercepted.  Each operator
+    #: that is added to this set (empty by default) is delegated to the
+    #: :meth:`call_unop` method that will perform the operator.  The default
+    #: operator callback is specified by :attr:`unop_table`.
+    #:
+    #: The following unary operators are interceptable: ``+``, ``-``
+    #:
+    #: The default operation form the operator table corresponds to the
+    #: builtin function.  Intercepted calls are always slower than the native
+    #: operator call, so make sure only to intercept the ones you are
+    #: interested in.
+    #:
+    #: .. versionadded:: 2.6
+    intercepted_unops: t.FrozenSet[str] = frozenset()
+
+    def __init__(self, *args: t.Any, **kwargs: t.Any) -> None:
+        super().__init__(*args, **kwargs)
+        self.globals["range"] = safe_range
+        self.binop_table = self.default_binop_table.copy()
+        self.unop_table = self.default_unop_table.copy()
+
+    def is_safe_attribute(self, obj: t.Any, attr: str, value: t.Any) -> bool:
+        """The sandboxed environment will call this method to check if the
+        attribute of an object is safe to access.  Per default all attributes
+        starting with an underscore are considered private as well as the
+        special attributes of internal python objects as returned by the
+        :func:`is_internal_attribute` function.
+        """
+        return not (attr.startswith("_") or is_internal_attribute(obj, attr))
+
+    def is_safe_callable(self, obj: t.Any) -> bool:
+        """Check if an object is safely callable. By default callables
+        are considered safe unless decorated with :func:`unsafe`.
+
+        This also recognizes the Django convention of setting
+        ``func.alters_data = True``.
+        """
+        return not (
+            getattr(obj, "unsafe_callable", False) or getattr(obj, "alters_data", False)
+        )
+
+    def call_binop(
+        self, context: Context, operator: str, left: t.Any, right: t.Any
+    ) -> t.Any:
+        """For intercepted binary operator calls (:meth:`intercepted_binops`)
+        this function is executed instead of the builtin operator.  This can
+        be used to fine tune the behavior of certain operators.
+
+        .. versionadded:: 2.6
+        """
+        return self.binop_table[operator](left, right)
+
+    def call_unop(self, context: Context, operator: str, arg: t.Any) -> t.Any:
+        """For intercepted unary operator calls (:meth:`intercepted_unops`)
+        this function is executed instead of the builtin operator.  This can
+        be used to fine tune the behavior of certain operators.
+
+        .. versionadded:: 2.6
+        """
+        return self.unop_table[operator](arg)
+
+    def getitem(
+        self, obj: t.Any, argument: t.Union[str, t.Any]
+    ) -> t.Union[t.Any, Undefined]:
+        """Subscribe an object from sandboxed code."""
+        try:
+            return obj[argument]
+        except (TypeError, LookupError):
+            if isinstance(argument, str):
+                try:
+                    attr = str(argument)
+                except Exception:
+                    pass
+                else:
+                    try:
+                        value = getattr(obj, attr)
+                    except AttributeError:
+                        pass
+                    else:
+                        if self.is_safe_attribute(obj, argument, value):
+                            return value
+                        return self.unsafe_undefined(obj, argument)
+        return self.undefined(obj=obj, name=argument)
+
+    def getattr(self, obj: t.Any, attribute: str) -> t.Union[t.Any, Undefined]:
+        """Subscribe an object from sandboxed code and prefer the
+        attribute.  The attribute passed *must* be a bytestring.
+        """
+        try:
+            value = getattr(obj, attribute)
+        except AttributeError:
+            try:
+                return obj[attribute]
+            except (TypeError, LookupError):
+                pass
+        else:
+            if self.is_safe_attribute(obj, attribute, value):
+                return value
+            return self.unsafe_undefined(obj, attribute)
+        return self.undefined(obj=obj, name=attribute)
+
+    def unsafe_undefined(self, obj: t.Any, attribute: str) -> Undefined:
+        """Return an undefined object for unsafe attributes."""
+        return self.undefined(
+            f"access to attribute {attribute!r} of"
+            f" {type(obj).__name__!r} object is unsafe.",
+            name=attribute,
+            obj=obj,
+            exc=SecurityError,
+        )
+
+    def format_string(
+        self,
+        s: str,
+        args: t.Tuple[t.Any, ...],
+        kwargs: t.Dict[str, t.Any],
+        format_func: t.Optional[t.Callable] = None,
+    ) -> str:
+        """If a format call is detected, then this is routed through this
+        method so that our safety sandbox can be used for it.
+        """
+        formatter: SandboxedFormatter
+        if isinstance(s, Markup):
+            formatter = SandboxedEscapeFormatter(self, escape=s.escape)
+        else:
+            formatter = SandboxedFormatter(self)
+
+        if format_func is not None and format_func.__name__ == "format_map":
+            if len(args) != 1 or kwargs:
+                raise TypeError(
+                    "format_map() takes exactly one argument"
+                    f" {len(args) + (kwargs is not None)} given"
+                )
+
+            kwargs = args[0]
+            args = ()
+
+        rv = formatter.vformat(s, args, kwargs)
+        return type(s)(rv)
+
+    def call(
+        __self,  # noqa: B902
+        __context: Context,
+        __obj: t.Any,
+        *args: t.Any,
+        **kwargs: t.Any,
+    ) -> t.Any:
+        """Call an object from sandboxed code."""
+        fmt = inspect_format_method(__obj)
+        if fmt is not None:
+            return __self.format_string(fmt, args, kwargs, __obj)
+
+        # the double prefixes are to avoid double keyword argument
+        # errors when proxying the call.
+        if not __self.is_safe_callable(__obj):
+            raise SecurityError(f"{__obj!r} is not safely callable")
+        return __context.call(__obj, *args, **kwargs)
+
+
+class ImmutableSandboxedEnvironment(SandboxedEnvironment):
+    """Works exactly like the regular `SandboxedEnvironment` but does not
+    permit modifications on the builtin mutable objects `list`, `set`, and
+    `dict` by using the :func:`modifies_known_mutable` function.
+    """
+
+    def is_safe_attribute(self, obj: t.Any, attr: str, value: t.Any) -> bool:
+        if not super().is_safe_attribute(obj, attr, value):
+            return False
+
+        return not modifies_known_mutable(obj, attr)
+
+
+class SandboxedFormatter(Formatter):
+    def __init__(self, env: Environment, **kwargs: t.Any) -> None:
+        self._env = env
+        super().__init__(**kwargs)
+
+    def get_field(
+        self, field_name: str, args: t.Sequence[t.Any], kwargs: t.Mapping[str, t.Any]
+    ) -> t.Tuple[t.Any, str]:
+        first, rest = formatter_field_name_split(field_name)
+        obj = self.get_value(first, args, kwargs)
+        for is_attr, i in rest:
+            if is_attr:
+                obj = self._env.getattr(obj, i)
+            else:
+                obj = self._env.getitem(obj, i)
+        return obj, first
+
+
+class SandboxedEscapeFormatter(SandboxedFormatter, EscapeFormatter):
+    pass
diff --git a/src/jinja2/tests.py b/src/jinja2/tests.py
new file mode 100644
index 0000000..a467cf0
--- /dev/null
+++ b/src/jinja2/tests.py
@@ -0,0 +1,255 @@
+"""Built-in template tests used with the ``is`` operator."""
+import operator
+import typing as t
+from collections import abc
+from numbers import Number
+
+from .runtime import Undefined
+from .utils import pass_environment
+
+if t.TYPE_CHECKING:
+    from .environment import Environment
+
+
+def test_odd(value: int) -> bool:
+    """Return true if the variable is odd."""
+    return value % 2 == 1
+
+
+def test_even(value: int) -> bool:
+    """Return true if the variable is even."""
+    return value % 2 == 0
+
+
+def test_divisibleby(value: int, num: int) -> bool:
+    """Check if a variable is divisible by a number."""
+    return value % num == 0
+
+
+def test_defined(value: t.Any) -> bool:
+    """Return true if the variable is defined:
+
+    .. sourcecode:: jinja
+
+        {% if variable is defined %}
+            value of variable: {{ variable }}
+        {% else %}
+            variable is not defined
+        {% endif %}
+
+    See the :func:`default` filter for a simple way to set undefined
+    variables.
+    """
+    return not isinstance(value, Undefined)
+
+
+def test_undefined(value: t.Any) -> bool:
+    """Like :func:`defined` but the other way round."""
+    return isinstance(value, Undefined)
+
+
+@pass_environment
+def test_filter(env: "Environment", value: str) -> bool:
+    """Check if a filter exists by name. Useful if a filter may be
+    optionally available.
+
+    .. code-block:: jinja
+
+        {% if 'markdown' is filter %}
+            {{ value | markdown }}
+        {% else %}
+            {{ value }}
+        {% endif %}
+
+    .. versionadded:: 3.0
+    """
+    return value in env.filters
+
+
+@pass_environment
+def test_test(env: "Environment", value: str) -> bool:
+    """Check if a test exists by name. Useful if a test may be
+    optionally available.
+
+    .. code-block:: jinja
+
+        {% if 'loud' is test %}
+            {% if value is loud %}
+                {{ value|upper }}
+            {% else %}
+                {{ value|lower }}
+            {% endif %}
+        {% else %}
+            {{ value }}
+        {% endif %}
+
+    .. versionadded:: 3.0
+    """
+    return value in env.tests
+
+
+def test_none(value: t.Any) -> bool:
+    """Return true if the variable is none."""
+    return value is None
+
+
+def test_boolean(value: t.Any) -> bool:
+    """Return true if the object is a boolean value.
+
+    .. versionadded:: 2.11
+    """
+    return value is True or value is False
+
+
+def test_false(value: t.Any) -> bool:
+    """Return true if the object is False.
+
+    .. versionadded:: 2.11
+    """
+    return value is False
+
+
+def test_true(value: t.Any) -> bool:
+    """Return true if the object is True.
+
+    .. versionadded:: 2.11
+    """
+    return value is True
+
+
+# NOTE: The existing 'number' test matches booleans and floats
+def test_integer(value: t.Any) -> bool:
+    """Return true if the object is an integer.
+
+    .. versionadded:: 2.11
+    """
+    return isinstance(value, int) and value is not True and value is not False
+
+
+# NOTE: The existing 'number' test matches booleans and integers
+def test_float(value: t.Any) -> bool:
+    """Return true if the object is a float.
+
+    .. versionadded:: 2.11
+    """
+    return isinstance(value, float)
+
+
+def test_lower(value: str) -> bool:
+    """Return true if the variable is lowercased."""
+    return str(value).islower()
+
+
+def test_upper(value: str) -> bool:
+    """Return true if the variable is uppercased."""
+    return str(value).isupper()
+
+
+def test_string(value: t.Any) -> bool:
+    """Return true if the object is a string."""
+    return isinstance(value, str)
+
+
+def test_mapping(value: t.Any) -> bool:
+    """Return true if the object is a mapping (dict etc.).
+
+    .. versionadded:: 2.6
+    """
+    return isinstance(value, abc.Mapping)
+
+
+def test_number(value: t.Any) -> bool:
+    """Return true if the variable is a number."""
+    return isinstance(value, Number)
+
+
+def test_sequence(value: t.Any) -> bool:
+    """Return true if the variable is a sequence. Sequences are variables
+    that are iterable.
+    """
+    try:
+        len(value)
+        value.__getitem__
+    except Exception:
+        return False
+
+    return True
+
+
+def test_sameas(value: t.Any, other: t.Any) -> bool:
+    """Check if an object points to the same memory address than another
+    object:
+
+    .. sourcecode:: jinja
+
+        {% if foo.attribute is sameas false %}
+            the foo attribute really is the `False` singleton
+        {% endif %}
+    """
+    return value is other
+
+
+def test_iterable(value: t.Any) -> bool:
+    """Check if it's possible to iterate over an object."""
+    try:
+        iter(value)
+    except TypeError:
+        return False
+
+    return True
+
+
+def test_escaped(value: t.Any) -> bool:
+    """Check if the value is escaped."""
+    return hasattr(value, "__html__")
+
+
+def test_in(value: t.Any, seq: t.Container) -> bool:
+    """Check if value is in seq.
+
+    .. versionadded:: 2.10
+    """
+    return value in seq
+
+
+TESTS = {
+    "odd": test_odd,
+    "even": test_even,
+    "divisibleby": test_divisibleby,
+    "defined": test_defined,
+    "undefined": test_undefined,
+    "filter": test_filter,
+    "test": test_test,
+    "none": test_none,
+    "boolean": test_boolean,
+    "false": test_false,
+    "true": test_true,
+    "integer": test_integer,
+    "float": test_float,
+    "lower": test_lower,
+    "upper": test_upper,
+    "string": test_string,
+    "mapping": test_mapping,
+    "number": test_number,
+    "sequence": test_sequence,
+    "iterable": test_iterable,
+    "callable": callable,
+    "sameas": test_sameas,
+    "escaped": test_escaped,
+    "in": test_in,
+    "==": operator.eq,
+    "eq": operator.eq,
+    "equalto": operator.eq,
+    "!=": operator.ne,
+    "ne": operator.ne,
+    ">": operator.gt,
+    "gt": operator.gt,
+    "greaterthan": operator.gt,
+    "ge": operator.ge,
+    ">=": operator.ge,
+    "<": operator.lt,
+    "lt": operator.lt,
+    "lessthan": operator.lt,
+    "<=": operator.le,
+    "le": operator.le,
+}
diff --git a/src/jinja2/utils.py b/src/jinja2/utils.py
new file mode 100644
index 0000000..9b5f5a5
--- /dev/null
+++ b/src/jinja2/utils.py
@@ -0,0 +1,755 @@
+import enum
+import json
+import os
+import re
+import typing as t
+from collections import abc
+from collections import deque
+from random import choice
+from random import randrange
+from threading import Lock
+from types import CodeType
+from urllib.parse import quote_from_bytes
+
+import markupsafe
+
+if t.TYPE_CHECKING:
+    import typing_extensions as te
+
+F = t.TypeVar("F", bound=t.Callable[..., t.Any])
+
+# special singleton representing missing values for the runtime
+missing: t.Any = type("MissingType", (), {"__repr__": lambda x: "missing"})()
+
+internal_code: t.MutableSet[CodeType] = set()
+
+concat = "".join
+
+
+def pass_context(f: F) -> F:
+    """Pass the :class:`~jinja2.runtime.Context` as the first argument
+    to the decorated function when called while rendering a template.
+
+    Can be used on functions, filters, and tests.
+
+    If only ``Context.eval_context`` is needed, use
+    :func:`pass_eval_context`. If only ``Context.environment`` is
+    needed, use :func:`pass_environment`.
+
+    .. versionadded:: 3.0.0
+        Replaces ``contextfunction`` and ``contextfilter``.
+    """
+    f.jinja_pass_arg = _PassArg.context  # type: ignore
+    return f
+
+
+def pass_eval_context(f: F) -> F:
+    """Pass the :class:`~jinja2.nodes.EvalContext` as the first argument
+    to the decorated function when called while rendering a template.
+    See :ref:`eval-context`.
+
+    Can be used on functions, filters, and tests.
+
+    If only ``EvalContext.environment`` is needed, use
+    :func:`pass_environment`.
+
+    .. versionadded:: 3.0.0
+        Replaces ``evalcontextfunction`` and ``evalcontextfilter``.
+    """
+    f.jinja_pass_arg = _PassArg.eval_context  # type: ignore
+    return f
+
+
+def pass_environment(f: F) -> F:
+    """Pass the :class:`~jinja2.Environment` as the first argument to
+    the decorated function when called while rendering a template.
+
+    Can be used on functions, filters, and tests.
+
+    .. versionadded:: 3.0.0
+        Replaces ``environmentfunction`` and ``environmentfilter``.
+    """
+    f.jinja_pass_arg = _PassArg.environment  # type: ignore
+    return f
+
+
+class _PassArg(enum.Enum):
+    context = enum.auto()
+    eval_context = enum.auto()
+    environment = enum.auto()
+
+    @classmethod
+    def from_obj(cls, obj: F) -> t.Optional["_PassArg"]:
+        if hasattr(obj, "jinja_pass_arg"):
+            return obj.jinja_pass_arg  # type: ignore
+
+        return None
+
+
+def internalcode(f: F) -> F:
+    """Marks the function as internally used"""
+    internal_code.add(f.__code__)
+    return f
+
+
+def is_undefined(obj: t.Any) -> bool:
+    """Check if the object passed is undefined.  This does nothing more than
+    performing an instance check against :class:`Undefined` but looks nicer.
+    This can be used for custom filters or tests that want to react to
+    undefined variables.  For example a custom default filter can look like
+    this::
+
+        def default(var, default=''):
+            if is_undefined(var):
+                return default
+            return var
+    """
+    from .runtime import Undefined
+
+    return isinstance(obj, Undefined)
+
+
+def consume(iterable: t.Iterable[t.Any]) -> None:
+    """Consumes an iterable without doing anything with it."""
+    for _ in iterable:
+        pass
+
+
+def clear_caches() -> None:
+    """Jinja keeps internal caches for environments and lexers.  These are
+    used so that Jinja doesn't have to recreate environments and lexers all
+    the time.  Normally you don't have to care about that but if you are
+    measuring memory consumption you may want to clean the caches.
+    """
+    from .environment import get_spontaneous_environment
+    from .lexer import _lexer_cache
+
+    get_spontaneous_environment.cache_clear()
+    _lexer_cache.clear()
+
+
+def import_string(import_name: str, silent: bool = False) -> t.Any:
+    """Imports an object based on a string.  This is useful if you want to
+    use import paths as endpoints or something similar.  An import path can
+    be specified either in dotted notation (``xml.sax.saxutils.escape``)
+    or with a colon as object delimiter (``xml.sax.saxutils:escape``).
+
+    If the `silent` is True the return value will be `None` if the import
+    fails.
+
+    :return: imported object
+    """
+    try:
+        if ":" in import_name:
+            module, obj = import_name.split(":", 1)
+        elif "." in import_name:
+            module, _, obj = import_name.rpartition(".")
+        else:
+            return __import__(import_name)
+        return getattr(__import__(module, None, None, [obj]), obj)
+    except (ImportError, AttributeError):
+        if not silent:
+            raise
+
+
+def open_if_exists(filename: str, mode: str = "rb") -> t.Optional[t.IO]:
+    """Returns a file descriptor for the filename if that file exists,
+    otherwise ``None``.
+    """
+    if not os.path.isfile(filename):
+        return None
+
+    return open(filename, mode)
+
+
+def object_type_repr(obj: t.Any) -> str:
+    """Returns the name of the object's type.  For some recognized
+    singletons the name of the object is returned instead. (For
+    example for `None` and `Ellipsis`).
+    """
+    if obj is None:
+        return "None"
+    elif obj is Ellipsis:
+        return "Ellipsis"
+
+    cls = type(obj)
+
+    if cls.__module__ == "builtins":
+        return f"{cls.__name__} object"
+
+    return f"{cls.__module__}.{cls.__name__} object"
+
+
+def pformat(obj: t.Any) -> str:
+    """Format an object using :func:`pprint.pformat`."""
+    from pprint import pformat  # type: ignore
+
+    return pformat(obj)
+
+
+_http_re = re.compile(
+    r"""
+    ^
+    (
+        (https?://|www\.)  # scheme or www
+        (([\w%-]+\.)+)?  # subdomain
+        (
+            [a-z]{2,63}  # basic tld
+        |
+            xn--[\w%]{2,59}  # idna tld
+        )
+    |
+        ([\w%-]{2,63}\.)+  # basic domain
+        (com|net|int|edu|gov|org|info|mil)  # basic tld
+    |
+        (https?://)  # scheme
+        (
+            (([\d]{1,3})(\.[\d]{1,3}){3})  # IPv4
+        |
+            (\[([\da-f]{0,4}:){2}([\da-f]{0,4}:?){1,6}])  # IPv6
+        )
+    )
+    (?::[\d]{1,5})?  # port
+    (?:[/?#]\S*)?  # path, query, and fragment
+    $
+    """,
+    re.IGNORECASE | re.VERBOSE,
+)
+_email_re = re.compile(r"^\S+@\w[\w.-]*\.\w+$")
+
+
+def urlize(
+    text: str,
+    trim_url_limit: t.Optional[int] = None,
+    rel: t.Optional[str] = None,
+    target: t.Optional[str] = None,
+    extra_schemes: t.Optional[t.Iterable[str]] = None,
+) -> str:
+    """Convert URLs in text into clickable links.
+
+    This may not recognize links in some situations. Usually, a more
+    comprehensive formatter, such as a Markdown library, is a better
+    choice.
+
+    Works on ``http://``, ``https://``, ``www.``, ``mailto:``, and email
+    addresses. Links with trailing punctuation (periods, commas, closing
+    parentheses) and leading punctuation (opening parentheses) are
+    recognized excluding the punctuation. Email addresses that include
+    header fields are not recognized (for example,
+    ``mailto:address@example.com?cc=copy@example.com``).
+
+    :param text: Original text containing URLs to link.
+    :param trim_url_limit: Shorten displayed URL values to this length.
+    :param target: Add the ``target`` attribute to links.
+    :param rel: Add the ``rel`` attribute to links.
+    :param extra_schemes: Recognize URLs that start with these schemes
+        in addition to the default behavior.
+
+    .. versionchanged:: 3.0
+        The ``extra_schemes`` parameter was added.
+
+    .. versionchanged:: 3.0
+        Generate ``https://`` links for URLs without a scheme.
+
+    .. versionchanged:: 3.0
+        The parsing rules were updated. Recognize email addresses with
+        or without the ``mailto:`` scheme. Validate IP addresses. Ignore
+        parentheses and brackets in more cases.
+    """
+    if trim_url_limit is not None:
+
+        def trim_url(x: str) -> str:
+            if len(x) > trim_url_limit:  # type: ignore
+                return f"{x[:trim_url_limit]}..."
+
+            return x
+
+    else:
+
+        def trim_url(x: str) -> str:
+            return x
+
+    words = re.split(r"(\s+)", str(markupsafe.escape(text)))
+    rel_attr = f' rel="{markupsafe.escape(rel)}"' if rel else ""
+    target_attr = f' target="{markupsafe.escape(target)}"' if target else ""
+
+    for i, word in enumerate(words):
+        head, middle, tail = "", word, ""
+        match = re.match(r"^([(<]|&lt;)+", middle)
+
+        if match:
+            head = match.group()
+            middle = middle[match.end() :]
+
+        # Unlike lead, which is anchored to the start of the string,
+        # need to check that the string ends with any of the characters
+        # before trying to match all of them, to avoid backtracking.
+        if middle.endswith((")", ">", ".", ",", "\n", "&gt;")):
+            match = re.search(r"([)>.,\n]|&gt;)+$", middle)
+
+            if match:
+                tail = match.group()
+                middle = middle[: match.start()]
+
+        # Prefer balancing parentheses in URLs instead of ignoring a
+        # trailing character.
+        for start_char, end_char in ("(", ")"), ("<", ">"), ("&lt;", "&gt;"):
+            start_count = middle.count(start_char)
+
+            if start_count <= middle.count(end_char):
+                # Balanced, or lighter on the left
+                continue
+
+            # Move as many as possible from the tail to balance
+            for _ in range(min(start_count, tail.count(end_char))):
+                end_index = tail.index(end_char) + len(end_char)
+                # Move anything in the tail before the end char too
+                middle += tail[:end_index]
+                tail = tail[end_index:]
+
+        if _http_re.match(middle):
+            if middle.startswith("https://") or middle.startswith("http://"):
+                middle = (
+                    f'<a href="{middle}"{rel_attr}{target_attr}>{trim_url(middle)}</a>'
+                )
+            else:
+                middle = (
+                    f'<a href="https://{middle}"{rel_attr}{target_attr}>'
+                    f"{trim_url(middle)}</a>"
+                )
+
+        elif middle.startswith("mailto:") and _email_re.match(middle[7:]):
+            middle = f'<a href="{middle}">{middle[7:]}</a>'
+
+        elif (
+            "@" in middle
+            and not middle.startswith("www.")
+            and ":" not in middle
+            and _email_re.match(middle)
+        ):
+            middle = f'<a href="mailto:{middle}">{middle}</a>'
+
+        elif extra_schemes is not None:
+            for scheme in extra_schemes:
+                if middle != scheme and middle.startswith(scheme):
+                    middle = f'<a href="{middle}"{rel_attr}{target_attr}>{middle}</a>'
+
+        words[i] = f"{head}{middle}{tail}"
+
+    return "".join(words)
+
+
+def generate_lorem_ipsum(
+    n: int = 5, html: bool = True, min: int = 20, max: int = 100
+) -> str:
+    """Generate some lorem ipsum for the template."""
+    from .constants import LOREM_IPSUM_WORDS
+
+    words = LOREM_IPSUM_WORDS.split()
+    result = []
+
+    for _ in range(n):
+        next_capitalized = True
+        last_comma = last_fullstop = 0
+        word = None
+        last = None
+        p = []
+
+        # each paragraph contains out of 20 to 100 words.
+        for idx, _ in enumerate(range(randrange(min, max))):
+            while True:
+                word = choice(words)
+                if word != last:
+                    last = word
+                    break
+            if next_capitalized:
+                word = word.capitalize()
+                next_capitalized = False
+            # add commas
+            if idx - randrange(3, 8) > last_comma:
+                last_comma = idx
+                last_fullstop += 2
+                word += ","
+            # add end of sentences
+            if idx - randrange(10, 20) > last_fullstop:
+                last_comma = last_fullstop = idx
+                word += "."
+                next_capitalized = True
+            p.append(word)
+
+        # ensure that the paragraph ends with a dot.
+        p_str = " ".join(p)
+
+        if p_str.endswith(","):
+            p_str = p_str[:-1] + "."
+        elif not p_str.endswith("."):
+            p_str += "."
+
+        result.append(p_str)
+
+    if not html:
+        return "\n\n".join(result)
+    return markupsafe.Markup(
+        "\n".join(f"<p>{markupsafe.escape(x)}</p>" for x in result)
+    )
+
+
+def url_quote(obj: t.Any, charset: str = "utf-8", for_qs: bool = False) -> str:
+    """Quote a string for use in a URL using the given charset.
+
+    :param obj: String or bytes to quote. Other types are converted to
+        string then encoded to bytes using the given charset.
+    :param charset: Encode text to bytes using this charset.
+    :param for_qs: Quote "/" and use "+" for spaces.
+    """
+    if not isinstance(obj, bytes):
+        if not isinstance(obj, str):
+            obj = str(obj)
+
+        obj = obj.encode(charset)
+
+    safe = b"" if for_qs else b"/"
+    rv = quote_from_bytes(obj, safe)
+
+    if for_qs:
+        rv = rv.replace("%20", "+")
+
+    return rv
+
+
+@abc.MutableMapping.register
+class LRUCache:
+    """A simple LRU Cache implementation."""
+
+    # this is fast for small capacities (something below 1000) but doesn't
+    # scale.  But as long as it's only used as storage for templates this
+    # won't do any harm.
+
+    def __init__(self, capacity: int) -> None:
+        self.capacity = capacity
+        self._mapping: t.Dict[t.Any, t.Any] = {}
+        self._queue: "te.Deque[t.Any]" = deque()
+        self._postinit()
+
+    def _postinit(self) -> None:
+        # alias all queue methods for faster lookup
+        self._popleft = self._queue.popleft
+        self._pop = self._queue.pop
+        self._remove = self._queue.remove
+        self._wlock = Lock()
+        self._append = self._queue.append
+
+    def __getstate__(self) -> t.Mapping[str, t.Any]:
+        return {
+            "capacity": self.capacity,
+            "_mapping": self._mapping,
+            "_queue": self._queue,
+        }
+
+    def __setstate__(self, d: t.Mapping[str, t.Any]) -> None:
+        self.__dict__.update(d)
+        self._postinit()
+
+    def __getnewargs__(self) -> t.Tuple:
+        return (self.capacity,)
+
+    def copy(self) -> "LRUCache":
+        """Return a shallow copy of the instance."""
+        rv = self.__class__(self.capacity)
+        rv._mapping.update(self._mapping)
+        rv._queue.extend(self._queue)
+        return rv
+
+    def get(self, key: t.Any, default: t.Any = None) -> t.Any:
+        """Return an item from the cache dict or `default`"""
+        try:
+            return self[key]
+        except KeyError:
+            return default
+
+    def setdefault(self, key: t.Any, default: t.Any = None) -> t.Any:
+        """Set `default` if the key is not in the cache otherwise
+        leave unchanged. Return the value of this key.
+        """
+        try:
+            return self[key]
+        except KeyError:
+            self[key] = default
+            return default
+
+    def clear(self) -> None:
+        """Clear the cache."""
+        with self._wlock:
+            self._mapping.clear()
+            self._queue.clear()
+
+    def __contains__(self, key: t.Any) -> bool:
+        """Check if a key exists in this cache."""
+        return key in self._mapping
+
+    def __len__(self) -> int:
+        """Return the current size of the cache."""
+        return len(self._mapping)
+
+    def __repr__(self) -> str:
+        return f"<{type(self).__name__} {self._mapping!r}>"
+
+    def __getitem__(self, key: t.Any) -> t.Any:
+        """Get an item from the cache. Moves the item up so that it has the
+        highest priority then.
+
+        Raise a `KeyError` if it does not exist.
+        """
+        with self._wlock:
+            rv = self._mapping[key]
+
+            if self._queue[-1] != key:
+                try:
+                    self._remove(key)
+                except ValueError:
+                    # if something removed the key from the container
+                    # when we read, ignore the ValueError that we would
+                    # get otherwise.
+                    pass
+
+                self._append(key)
+
+            return rv
+
+    def __setitem__(self, key: t.Any, value: t.Any) -> None:
+        """Sets the value for an item. Moves the item up so that it
+        has the highest priority then.
+        """
+        with self._wlock:
+            if key in self._mapping:
+                self._remove(key)
+            elif len(self._mapping) == self.capacity:
+                del self._mapping[self._popleft()]
+
+            self._append(key)
+            self._mapping[key] = value
+
+    def __delitem__(self, key: t.Any) -> None:
+        """Remove an item from the cache dict.
+        Raise a `KeyError` if it does not exist.
+        """
+        with self._wlock:
+            del self._mapping[key]
+
+            try:
+                self._remove(key)
+            except ValueError:
+                pass
+
+    def items(self) -> t.Iterable[t.Tuple[t.Any, t.Any]]:
+        """Return a list of items."""
+        result = [(key, self._mapping[key]) for key in list(self._queue)]
+        result.reverse()
+        return result
+
+    def values(self) -> t.Iterable[t.Any]:
+        """Return a list of all values."""
+        return [x[1] for x in self.items()]
+
+    def keys(self) -> t.Iterable[t.Any]:
+        """Return a list of all keys ordered by most recent usage."""
+        return list(self)
+
+    def __iter__(self) -> t.Iterator[t.Any]:
+        return reversed(tuple(self._queue))
+
+    def __reversed__(self) -> t.Iterator[t.Any]:
+        """Iterate over the keys in the cache dict, oldest items
+        coming first.
+        """
+        return iter(tuple(self._queue))
+
+    __copy__ = copy
+
+
+def select_autoescape(
+    enabled_extensions: t.Collection[str] = ("html", "htm", "xml"),
+    disabled_extensions: t.Collection[str] = (),
+    default_for_string: bool = True,
+    default: bool = False,
+) -> t.Callable[[t.Optional[str]], bool]:
+    """Intelligently sets the initial value of autoescaping based on the
+    filename of the template.  This is the recommended way to configure
+    autoescaping if you do not want to write a custom function yourself.
+
+    If you want to enable it for all templates created from strings or
+    for all templates with `.html` and `.xml` extensions::
+
+        from jinja2 import Environment, select_autoescape
+        env = Environment(autoescape=select_autoescape(
+            enabled_extensions=('html', 'xml'),
+            default_for_string=True,
+        ))
+
+    Example configuration to turn it on at all times except if the template
+    ends with `.txt`::
+
+        from jinja2 import Environment, select_autoescape
+        env = Environment(autoescape=select_autoescape(
+            disabled_extensions=('txt',),
+            default_for_string=True,
+            default=True,
+        ))
+
+    The `enabled_extensions` is an iterable of all the extensions that
+    autoescaping should be enabled for.  Likewise `disabled_extensions` is
+    a list of all templates it should be disabled for.  If a template is
+    loaded from a string then the default from `default_for_string` is used.
+    If nothing matches then the initial value of autoescaping is set to the
+    value of `default`.
+
+    For security reasons this function operates case insensitive.
+
+    .. versionadded:: 2.9
+    """
+    enabled_patterns = tuple(f".{x.lstrip('.').lower()}" for x in enabled_extensions)
+    disabled_patterns = tuple(f".{x.lstrip('.').lower()}" for x in disabled_extensions)
+
+    def autoescape(template_name: t.Optional[str]) -> bool:
+        if template_name is None:
+            return default_for_string
+        template_name = template_name.lower()
+        if template_name.endswith(enabled_patterns):
+            return True
+        if template_name.endswith(disabled_patterns):
+            return False
+        return default
+
+    return autoescape
+
+
+def htmlsafe_json_dumps(
+    obj: t.Any, dumps: t.Optional[t.Callable[..., str]] = None, **kwargs: t.Any
+) -> markupsafe.Markup:
+    """Serialize an object to a string of JSON with :func:`json.dumps`,
+    then replace HTML-unsafe characters with Unicode escapes and mark
+    the result safe with :class:`~markupsafe.Markup`.
+
+    This is available in templates as the ``|tojson`` filter.
+
+    The following characters are escaped: ``<``, ``>``, ``&``, ``'``.
+
+    The returned string is safe to render in HTML documents and
+    ``<script>`` tags. The exception is in HTML attributes that are
+    double quoted; either use single quotes or the ``|forceescape``
+    filter.
+
+    :param obj: The object to serialize to JSON.
+    :param dumps: The ``dumps`` function to use. Defaults to
+        ``env.policies["json.dumps_function"]``, which defaults to
+        :func:`json.dumps`.
+    :param kwargs: Extra arguments to pass to ``dumps``. Merged onto
+        ``env.policies["json.dumps_kwargs"]``.
+
+    .. versionchanged:: 3.0
+        The ``dumper`` parameter is renamed to ``dumps``.
+
+    .. versionadded:: 2.9
+    """
+    if dumps is None:
+        dumps = json.dumps
+
+    return markupsafe.Markup(
+        dumps(obj, **kwargs)
+        .replace("<", "\\u003c")
+        .replace(">", "\\u003e")
+        .replace("&", "\\u0026")
+        .replace("'", "\\u0027")
+    )
+
+
+class Cycler:
+    """Cycle through values by yield them one at a time, then restarting
+    once the end is reached. Available as ``cycler`` in templates.
+
+    Similar to ``loop.cycle``, but can be used outside loops or across
+    multiple loops. For example, render a list of folders and files in a
+    list, alternating giving them "odd" and "even" classes.
+
+    .. code-block:: html+jinja
+
+        {% set row_class = cycler("odd", "even") %}
+        <ul class="browser">
+        {% for folder in folders %}
+          <li class="folder {{ row_class.next() }}">{{ folder }}
+        {% endfor %}
+        {% for file in files %}
+          <li class="file {{ row_class.next() }}">{{ file }}
+        {% endfor %}
+        </ul>
+
+    :param items: Each positional argument will be yielded in the order
+        given for each cycle.
+
+    .. versionadded:: 2.1
+    """
+
+    def __init__(self, *items: t.Any) -> None:
+        if not items:
+            raise RuntimeError("at least one item has to be provided")
+        self.items = items
+        self.pos = 0
+
+    def reset(self) -> None:
+        """Resets the current item to the first item."""
+        self.pos = 0
+
+    @property
+    def current(self) -> t.Any:
+        """Return the current item. Equivalent to the item that will be
+        returned next time :meth:`next` is called.
+        """
+        return self.items[self.pos]
+
+    def next(self) -> t.Any:
+        """Return the current item, then advance :attr:`current` to the
+        next item.
+        """
+        rv = self.current
+        self.pos = (self.pos + 1) % len(self.items)
+        return rv
+
+    __next__ = next
+
+
+class Joiner:
+    """A joining helper for templates."""
+
+    def __init__(self, sep: str = ", ") -> None:
+        self.sep = sep
+        self.used = False
+
+    def __call__(self) -> str:
+        if not self.used:
+            self.used = True
+            return ""
+        return self.sep
+
+
+class Namespace:
+    """A namespace object that can hold arbitrary attributes.  It may be
+    initialized from a dictionary or with keyword arguments."""
+
+    def __init__(*args: t.Any, **kwargs: t.Any) -> None:  # noqa: B902
+        self, args = args[0], args[1:]
+        self.__attrs = dict(*args, **kwargs)
+
+    def __getattribute__(self, name: str) -> t.Any:
+        # __class__ is needed for the awaitable check in async mode
+        if name in {"_Namespace__attrs", "__class__"}:
+            return object.__getattribute__(self, name)
+        try:
+            return self.__attrs[name]
+        except KeyError:
+            raise AttributeError(name) from None
+
+    def __setitem__(self, name: str, value: t.Any) -> None:
+        self.__attrs[name] = value
+
+    def __repr__(self) -> str:
+        return f"<Namespace {self.__attrs!r}>"
diff --git a/src/jinja2/visitor.py b/src/jinja2/visitor.py
new file mode 100644
index 0000000..17c6aab
--- /dev/null
+++ b/src/jinja2/visitor.py
@@ -0,0 +1,92 @@
+"""API for traversing the AST nodes. Implemented by the compiler and
+meta introspection.
+"""
+import typing as t
+
+from .nodes import Node
+
+if t.TYPE_CHECKING:
+    import typing_extensions as te
+
+    class VisitCallable(te.Protocol):
+        def __call__(self, node: Node, *args: t.Any, **kwargs: t.Any) -> t.Any:
+            ...
+
+
+class NodeVisitor:
+    """Walks the abstract syntax tree and call visitor functions for every
+    node found.  The visitor functions may return values which will be
+    forwarded by the `visit` method.
+
+    Per default the visitor functions for the nodes are ``'visit_'`` +
+    class name of the node.  So a `TryFinally` node visit function would
+    be `visit_TryFinally`.  This behavior can be changed by overriding
+    the `get_visitor` function.  If no visitor function exists for a node
+    (return value `None`) the `generic_visit` visitor is used instead.
+    """
+
+    def get_visitor(self, node: Node) -> "t.Optional[VisitCallable]":
+        """Return the visitor function for this node or `None` if no visitor
+        exists for this node.  In that case the generic visit function is
+        used instead.
+        """
+        return getattr(self, f"visit_{type(node).__name__}", None)
+
+    def visit(self, node: Node, *args: t.Any, **kwargs: t.Any) -> t.Any:
+        """Visit a node."""
+        f = self.get_visitor(node)
+
+        if f is not None:
+            return f(node, *args, **kwargs)
+
+        return self.generic_visit(node, *args, **kwargs)
+
+    def generic_visit(self, node: Node, *args: t.Any, **kwargs: t.Any) -> t.Any:
+        """Called if no explicit visitor function exists for a node."""
+        for child_node in node.iter_child_nodes():
+            self.visit(child_node, *args, **kwargs)
+
+
+class NodeTransformer(NodeVisitor):
+    """Walks the abstract syntax tree and allows modifications of nodes.
+
+    The `NodeTransformer` will walk the AST and use the return value of the
+    visitor functions to replace or remove the old node.  If the return
+    value of the visitor function is `None` the node will be removed
+    from the previous location otherwise it's replaced with the return
+    value.  The return value may be the original node in which case no
+    replacement takes place.
+    """
+
+    def generic_visit(self, node: Node, *args: t.Any, **kwargs: t.Any) -> Node:
+        for field, old_value in node.iter_fields():
+            if isinstance(old_value, list):
+                new_values = []
+                for value in old_value:
+                    if isinstance(value, Node):
+                        value = self.visit(value, *args, **kwargs)
+                        if value is None:
+                            continue
+                        elif not isinstance(value, Node):
+                            new_values.extend(value)
+                            continue
+                    new_values.append(value)
+                old_value[:] = new_values
+            elif isinstance(old_value, Node):
+                new_node = self.visit(old_value, *args, **kwargs)
+                if new_node is None:
+                    delattr(node, field)
+                else:
+                    setattr(node, field, new_node)
+        return node
+
+    def visit_list(self, node: Node, *args: t.Any, **kwargs: t.Any) -> t.List[Node]:
+        """As transformers may return lists in some places this method
+        can be used to enforce a list as return value.
+        """
+        rv = self.visit(node, *args, **kwargs)
+
+        if not isinstance(rv, list):
+            return [rv]
+
+        return rv