6 files changed, 1508 insertions, 0 deletions
diff --git a/mesonbuild/ast/__init__.py b/mesonbuild/ast/__init__.py
new file mode 100644
index 0000000..d14620f
--- /dev/null
+++ b/mesonbuild/ast/__init__.py
@@ -0,0 +1,34 @@
+# Copyright 2019 The Meson development team
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This class contains the basic functionality needed to run any interpreter
+# or an interpreter-based tool.
+
+__all__ = [
+    'AstConditionLevel',
+    'AstInterpreter',
+    'AstIDGenerator',
+    'AstIndentationGenerator',
+    'AstJSONPrinter',
+    'AstVisitor',
+    'AstPrinter',
+    'IntrospectionInterpreter',
+    'BUILD_TARGET_FUNCTIONS',
+]
+
+from .interpreter import AstInterpreter
+from .introspection import IntrospectionInterpreter, BUILD_TARGET_FUNCTIONS
+from .visitor import AstVisitor
+from .postprocess import AstConditionLevel, AstIDGenerator, AstIndentationGenerator
+from .printer import AstPrinter, AstJSONPrinter
diff --git a/mesonbuild/ast/interpreter.py b/mesonbuild/ast/interpreter.py
new file mode 100644
index 0000000..7484e04
--- /dev/null
+++ b/mesonbuild/ast/interpreter.py
@@ -0,0 +1,447 @@
+# Copyright 2016 The Meson development team
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This class contains the basic functionality needed to run any interpreter
+# or an interpreter-based tool.
+from __future__ import annotations
+
+import os
+import sys
+import typing as T
+
+from .. import mparser, mesonlib
+from .. import environment
+
+from ..interpreterbase import (
+    MesonInterpreterObject,
+    InterpreterBase,
+    InvalidArguments,
+    BreakRequest,
+    ContinueRequest,
+    default_resolve_key,
+)
+
+from ..interpreter import (
+    StringHolder,
+    BooleanHolder,
+    IntegerHolder,
+    ArrayHolder,
+    DictHolder,
+)
+
+from ..mparser import (
+    ArgumentNode,
+    ArithmeticNode,
+    ArrayNode,
+    AssignmentNode,
+    BaseNode,
+    ElementaryNode,
+    EmptyNode,
+    IdNode,
+    MethodNode,
+    NotNode,
+    PlusAssignmentNode,
+    TernaryNode,
+)
+
+if T.TYPE_CHECKING:
+    from .visitor import AstVisitor
+    from ..interpreter import Interpreter
+    from ..interpreterbase import TYPE_nkwargs, TYPE_nvar
+    from ..mparser import (
+        AndNode,
+        ComparisonNode,
+        ForeachClauseNode,
+        IfClauseNode,
+        IndexNode,
+        OrNode,
+        UMinusNode,
+    )
+
+class DontCareObject(MesonInterpreterObject):
+    pass
+
+class MockExecutable(MesonInterpreterObject):
+    pass
+
+class MockStaticLibrary(MesonInterpreterObject):
+    pass
+
+class MockSharedLibrary(MesonInterpreterObject):
+    pass
+
+class MockCustomTarget(MesonInterpreterObject):
+    pass
+
+class MockRunTarget(MesonInterpreterObject):
+    pass
+
+ADD_SOURCE = 0
+REMOVE_SOURCE = 1
+
+_T = T.TypeVar('_T')
+_V = T.TypeVar('_V')
+
+class AstInterpreter(InterpreterBase):
+    def __init__(self, source_root: str, subdir: str, subproject: str, visitors: T.Optional[T.List[AstVisitor]] = None):
+        super().__init__(source_root, subdir, subproject)
+        self.visitors = visitors if visitors is not None else []
+        self.processed_buildfiles = set() # type: T.Set[str]
+        self.assignments = {}             # type: T.Dict[str, BaseNode]
+        self.assign_vals = {}             # type: T.Dict[str, T.Any]
+        self.reverse_assignment = {}      # type: T.Dict[str, BaseNode]
+        self.funcs.update({'project': self.func_do_nothing,
+                           'test': self.func_do_nothing,
+                           'benchmark': self.func_do_nothing,
+                           'install_headers': self.func_do_nothing,
+                           'install_man': self.func_do_nothing,
+                           'install_data': self.func_do_nothing,
+                           'install_subdir': self.func_do_nothing,
+                           'install_symlink': self.func_do_nothing,
+                           'install_emptydir': self.func_do_nothing,
+                           'configuration_data': self.func_do_nothing,
+                           'configure_file': self.func_do_nothing,
+                           'find_program': self.func_do_nothing,
+                           'include_directories': self.func_do_nothing,
+                           'add_global_arguments': self.func_do_nothing,
+                           'add_global_link_arguments': self.func_do_nothing,
+                           'add_project_arguments': self.func_do_nothing,
+                           'add_project_dependencies': self.func_do_nothing,
+                           'add_project_link_arguments': self.func_do_nothing,
+                           'message': self.func_do_nothing,
+                           'generator': self.func_do_nothing,
+                           'error': self.func_do_nothing,
+                           'run_command': self.func_do_nothing,
+                           'assert': self.func_do_nothing,
+                           'subproject': self.func_do_nothing,
+                           'dependency': self.func_do_nothing,
+                           'get_option': self.func_do_nothing,
+                           'join_paths': self.func_do_nothing,
+                           'environment': self.func_do_nothing,
+                           'import': self.func_do_nothing,
+                           'vcs_tag': self.func_do_nothing,
+                           'add_languages': self.func_do_nothing,
+                           'declare_dependency': self.func_do_nothing,
+                           'files': self.func_do_nothing,
+                           'executable': self.func_do_nothing,
+                           'static_library': self.func_do_nothing,
+                           'shared_library': self.func_do_nothing,
+                           'library': self.func_do_nothing,
+                           'build_target': self.func_do_nothing,
+                           'custom_target': self.func_do_nothing,
+                           'run_target': self.func_do_nothing,
+                           'subdir': self.func_subdir,
+                           'set_variable': self.func_do_nothing,
+                           'get_variable': self.func_do_nothing,
+                           'unset_variable': self.func_do_nothing,
+                           'is_disabler': self.func_do_nothing,
+                           'is_variable': self.func_do_nothing,
+                           'disabler': self.func_do_nothing,
+                           'gettext': self.func_do_nothing,
+                           'jar': self.func_do_nothing,
+                           'warning': self.func_do_nothing,
+                           'shared_module': self.func_do_nothing,
+                           'option': self.func_do_nothing,
+                           'both_libraries': self.func_do_nothing,
+                           'add_test_setup': self.func_do_nothing,
+                           'find_library': self.func_do_nothing,
+                           'subdir_done': self.func_do_nothing,
+                           'alias_target': self.func_do_nothing,
+                           'summary': self.func_do_nothing,
+                           'range': self.func_do_nothing,
+                           'structured_sources': self.func_do_nothing,
+                           'debug': self.func_do_nothing,
+                           })
+
+    def _unholder_args(self, args: _T, kwargs: _V) -> T.Tuple[_T, _V]:
+        return args, kwargs
+
+    def _holderify(self, res: _T) -> _T:
+        return res
+
+    def func_do_nothing(self, node: BaseNode, args: T.List[TYPE_nvar], kwargs: T.Dict[str, TYPE_nvar]) -> bool:
+        return True
+
+    def load_root_meson_file(self) -> None:
+        super().load_root_meson_file()
+        for i in self.visitors:
+            self.ast.accept(i)
+
+    def func_subdir(self, node: BaseNode, args: T.List[TYPE_nvar], kwargs: T.Dict[str, TYPE_nvar]) -> None:
+        args = self.flatten_args(args)
+        if len(args) != 1 or not isinstance(args[0], str):
+            sys.stderr.write(f'Unable to evaluate subdir({args}) in AstInterpreter --> Skipping\n')
+            return
+
+        prev_subdir = self.subdir
+        subdir = os.path.join(prev_subdir, args[0])
+        absdir = os.path.join(self.source_root, subdir)
+        buildfilename = os.path.join(subdir, environment.build_filename)
+        absname = os.path.join(self.source_root, buildfilename)
+        symlinkless_dir = os.path.realpath(absdir)
+        build_file = os.path.join(symlinkless_dir, 'meson.build')
+        if build_file in self.processed_buildfiles:
+            sys.stderr.write('Trying to enter {} which has already been visited --> Skipping\n'.format(args[0]))
+            return
+        self.processed_buildfiles.add(build_file)
+
+        if not os.path.isfile(absname):
+            sys.stderr.write(f'Unable to find build file {buildfilename} --> Skipping\n')
+            return
+        with open(absname, encoding='utf-8') as f:
+            code = f.read()
+        assert isinstance(code, str)
+        try:
+            codeblock = mparser.Parser(code, absname).parse()
+        except mesonlib.MesonException as me:
+            me.file = absname
+            raise me
+
+        self.subdir = subdir
+        for i in self.visitors:
+            codeblock.accept(i)
+        self.evaluate_codeblock(codeblock)
+        self.subdir = prev_subdir
+
+    def method_call(self, node: BaseNode) -> bool:
+        return True
+
+    def evaluate_fstring(self, node: mparser.FormatStringNode) -> str:
+        assert isinstance(node, mparser.FormatStringNode)
+        return node.value
+
+    def evaluate_arraystatement(self, cur: mparser.ArrayNode) -> TYPE_nvar:
+        return self.reduce_arguments(cur.args)[0]
+
+    def evaluate_arithmeticstatement(self, cur: ArithmeticNode) -> int:
+        self.evaluate_statement(cur.left)
+        self.evaluate_statement(cur.right)
+        return 0
+
+    def evaluate_uminusstatement(self, cur: UMinusNode) -> int:
+        self.evaluate_statement(cur.value)
+        return 0
+
+    def evaluate_ternary(self, node: TernaryNode) -> None:
+        assert isinstance(node, TernaryNode)
+        self.evaluate_statement(node.condition)
+        self.evaluate_statement(node.trueblock)
+        self.evaluate_statement(node.falseblock)
+
+    def evaluate_dictstatement(self, node: mparser.DictNode) -> TYPE_nkwargs:
+        def resolve_key(node: mparser.BaseNode) -> str:
+            if isinstance(node, mparser.StringNode):
+                return node.value
+            return '__AST_UNKNOWN__'
+        arguments, kwargs = self.reduce_arguments(node.args, key_resolver=resolve_key)
+        assert not arguments
+        self.argument_depth += 1
+        for key, value in kwargs.items():
+            if isinstance(key, BaseNode):
+                self.evaluate_statement(key)
+        self.argument_depth -= 1
+        return {}
+
+    def evaluate_plusassign(self, node: PlusAssignmentNode) -> None:
+        assert isinstance(node, PlusAssignmentNode)
+        # Cheat by doing a reassignment
+        self.assignments[node.var_name] = node.value  # Save a reference to the value node
+        if node.value.ast_id:
+            self.reverse_assignment[node.value.ast_id] = node
+        self.assign_vals[node.var_name] = self.evaluate_statement(node.value)
+
+    def evaluate_indexing(self, node: IndexNode) -> int:
+        return 0
+
+    def unknown_function_called(self, func_name: str) -> None:
+        pass
+
+    def reduce_arguments(
+                self,
+                args: mparser.ArgumentNode,
+                key_resolver: T.Callable[[mparser.BaseNode], str] = default_resolve_key,
+                duplicate_key_error: T.Optional[str] = None,
+            ) -> T.Tuple[T.List[TYPE_nvar], TYPE_nkwargs]:
+        if isinstance(args, ArgumentNode):
+            kwargs = {}  # type: T.Dict[str, TYPE_nvar]
+            for key, val in args.kwargs.items():
+                kwargs[key_resolver(key)] = val
+            if args.incorrect_order():
+                raise InvalidArguments('All keyword arguments must be after positional arguments.')
+            return self.flatten_args(args.arguments), kwargs
+        else:
+            return self.flatten_args(args), {}
+
+    def evaluate_comparison(self, node: ComparisonNode) -> bool:
+        self.evaluate_statement(node.left)
+        self.evaluate_statement(node.right)
+        return False
+
+    def evaluate_andstatement(self, cur: AndNode) -> bool:
+        self.evaluate_statement(cur.left)
+        self.evaluate_statement(cur.right)
+        return False
+
+    def evaluate_orstatement(self, cur: OrNode) -> bool:
+        self.evaluate_statement(cur.left)
+        self.evaluate_statement(cur.right)
+        return False
+
+    def evaluate_notstatement(self, cur: NotNode) -> bool:
+        self.evaluate_statement(cur.value)
+        return False
+
+    def evaluate_foreach(self, node: ForeachClauseNode) -> None:
+        try:
+            self.evaluate_codeblock(node.block)
+        except ContinueRequest:
+            pass
+        except BreakRequest:
+            pass
+
+    def evaluate_if(self, node: IfClauseNode) -> None:
+        for i in node.ifs:
+            self.evaluate_codeblock(i.block)
+        if not isinstance(node.elseblock, EmptyNode):
+            self.evaluate_codeblock(node.elseblock)
+
+    def get_variable(self, varname: str) -> int:
+        return 0
+
+    def assignment(self, node: AssignmentNode) -> None:
+        assert isinstance(node, AssignmentNode)
+        self.assignments[node.var_name] = node.value # Save a reference to the value node
+        if node.value.ast_id:
+            self.reverse_assignment[node.value.ast_id] = node
+        self.assign_vals[node.var_name] = self.evaluate_statement(node.value) # Evaluate the value just in case
+
+    def resolve_node(self, node: BaseNode, include_unknown_args: bool = False, id_loop_detect: T.Optional[T.List[str]] = None) -> T.Optional[T.Any]:
+        def quick_resolve(n: BaseNode, loop_detect: T.Optional[T.List[str]] = None) -> T.Any:
+            if loop_detect is None:
+                loop_detect = []
+            if isinstance(n, IdNode):
+                assert isinstance(n.value, str)
+                if n.value in loop_detect or n.value not in self.assignments:
+                    return []
+                return quick_resolve(self.assignments[n.value], loop_detect = loop_detect + [n.value])
+            elif isinstance(n, ElementaryNode):
+                return n.value
+            else:
+                return n
+
+        if id_loop_detect is None:
+            id_loop_detect = []
+        result = None
+
+        if not isinstance(node, BaseNode):
+            return None
+
+        assert node.ast_id
+        if node.ast_id in id_loop_detect:
+            return None # Loop detected
+        id_loop_detect += [node.ast_id]
+
+        # Try to evealuate the value of the node
+        if isinstance(node, IdNode):
+            result = quick_resolve(node)
+
+        elif isinstance(node, ElementaryNode):
+            result = node.value
+
+        elif isinstance(node, NotNode):
+            result = self.resolve_node(node.value, include_unknown_args, id_loop_detect)
+            if isinstance(result, bool):
+                result = not result
+
+        elif isinstance(node, ArrayNode):
+            result = node.args.arguments.copy()
+
+        elif isinstance(node, ArgumentNode):
+            result = node.arguments.copy()
+
+        elif isinstance(node, ArithmeticNode):
+            if node.operation != 'add':
+                return None # Only handle string and array concats
+            l = quick_resolve(node.left)
+            r = quick_resolve(node.right)
+            if isinstance(l, str) and isinstance(r, str):
+                result = l + r # String concatenation detected
+            else:
+                result = self.flatten_args(l, include_unknown_args, id_loop_detect) + self.flatten_args(r, include_unknown_args, id_loop_detect)
+
+        elif isinstance(node, MethodNode):
+            src = quick_resolve(node.source_object)
+            margs = self.flatten_args(node.args.arguments, include_unknown_args, id_loop_detect)
+            mkwargs = {} # type: T.Dict[str, TYPE_nvar]
+            try:
+                if isinstance(src, str):
+                    result = StringHolder(src, T.cast('Interpreter', self)).method_call(node.name, margs, mkwargs)
+                elif isinstance(src, bool):
+                    result = BooleanHolder(src, T.cast('Interpreter', self)).method_call(node.name, margs, mkwargs)
+                elif isinstance(src, int):
+                    result = IntegerHolder(src, T.cast('Interpreter', self)).method_call(node.name, margs, mkwargs)
+                elif isinstance(src, list):
+                    result = ArrayHolder(src, T.cast('Interpreter', self)).method_call(node.name, margs, mkwargs)
+                elif isinstance(src, dict):
+                    result = DictHolder(src, T.cast('Interpreter', self)).method_call(node.name, margs, mkwargs)
+            except mesonlib.MesonException:
+                return None
+
+        # Ensure that the result is fully resolved (no more nodes)
+        if isinstance(result, BaseNode):
+            result = self.resolve_node(result, include_unknown_args, id_loop_detect)
+        elif isinstance(result, list):
+            new_res = []  # type: T.List[TYPE_nvar]
+            for i in result:
+                if isinstance(i, BaseNode):
+                    resolved = self.resolve_node(i, include_unknown_args, id_loop_detect)
+                    if resolved is not None:
+                        new_res += self.flatten_args(resolved, include_unknown_args, id_loop_detect)
+                else:
+                    new_res += [i]
+            result = new_res
+
+        return result
+
+    def flatten_args(self, args_raw: T.Union[TYPE_nvar, T.Sequence[TYPE_nvar]], include_unknown_args: bool = False, id_loop_detect: T.Optional[T.List[str]] = None) -> T.List[TYPE_nvar]:
+        # Make sure we are always dealing with lists
+        if isinstance(args_raw, list):
+            args = args_raw
+        else:
+            args = [args_raw]
+
+        flattend_args = []  # type: T.List[TYPE_nvar]
+
+        # Resolve the contents of args
+        for i in args:
+            if isinstance(i, BaseNode):
+                resolved = self.resolve_node(i, include_unknown_args, id_loop_detect)
+                if resolved is not None:
+                    if not isinstance(resolved, list):
+                        resolved = [resolved]
+                    flattend_args += resolved
+            elif isinstance(i, (str, bool, int, float)) or include_unknown_args:
+                flattend_args += [i]
+        return flattend_args
+
+    def flatten_kwargs(self, kwargs: T.Dict[str, TYPE_nvar], include_unknown_args: bool = False) -> T.Dict[str, TYPE_nvar]:
+        flattend_kwargs = {}
+        for key, val in kwargs.items():
+            if isinstance(val, BaseNode):
+                resolved = self.resolve_node(val, include_unknown_args)
+                if resolved is not None:
+                    flattend_kwargs[key] = resolved
+            elif isinstance(val, (str, bool, int, float)) or include_unknown_args:
+                flattend_kwargs[key] = val
+        return flattend_kwargs
diff --git a/mesonbuild/ast/introspection.py b/mesonbuild/ast/introspection.py
new file mode 100644
index 0000000..194c15b
--- /dev/null
+++ b/mesonbuild/ast/introspection.py
@@ -0,0 +1,362 @@
+# Copyright 2018 The Meson development team
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This class contains the basic functionality needed to run any interpreter
+# or an interpreter-based tool
+
+from __future__ import annotations
+import argparse
+import copy
+import os
+import typing as T
+
+from .. import compilers, environment, mesonlib, optinterpreter
+from .. import coredata as cdata
+from ..build import Executable, Jar, SharedLibrary, SharedModule, StaticLibrary
+from ..compilers import detect_compiler_for
+from ..interpreterbase import InvalidArguments
+from ..mesonlib import MachineChoice, OptionKey
+from ..mparser import BaseNode, ArithmeticNode, ArrayNode, ElementaryNode, IdNode, FunctionNode, StringNode
+from .interpreter import AstInterpreter
+
+if T.TYPE_CHECKING:
+    from ..build import BuildTarget
+    from ..interpreterbase import TYPE_nvar
+    from .visitor import AstVisitor
+
+
+# TODO: it would be nice to not have to duplicate this
+BUILD_TARGET_FUNCTIONS = [
+    'executable', 'jar', 'library', 'shared_library', 'shared_module',
+    'static_library', 'both_libraries'
+]
+
+class IntrospectionHelper(argparse.Namespace):
+    # mimic an argparse namespace
+    def __init__(self, cross_file: str):
+        super().__init__()
+        self.cross_file = cross_file  # type: str
+        self.native_file = None       # type: str
+        self.cmd_line_options = {}    # type: T.Dict[str, str]
+
+    def __eq__(self, other: object) -> bool:
+        return NotImplemented
+
+class IntrospectionInterpreter(AstInterpreter):
+    # Interpreter to detect the options without a build directory
+    # Most of the code is stolen from interpreter.Interpreter
+    def __init__(self,
+                 source_root: str,
+                 subdir: str,
+                 backend: str,
+                 visitors: T.Optional[T.List[AstVisitor]] = None,
+                 cross_file: T.Optional[str] = None,
+                 subproject: str = '',
+                 subproject_dir: str = 'subprojects',
+                 env: T.Optional[environment.Environment] = None):
+        visitors = visitors if visitors is not None else []
+        super().__init__(source_root, subdir, subproject, visitors=visitors)
+
+        options = IntrospectionHelper(cross_file)
+        self.cross_file = cross_file
+        if env is None:
+            self.environment = environment.Environment(source_root, None, options)
+        else:
+            self.environment = env
+        self.subproject_dir = subproject_dir
+        self.coredata = self.environment.get_coredata()
+        self.option_file = os.path.join(self.source_root, self.subdir, 'meson_options.txt')
+        self.backend = backend
+        self.default_options = {OptionKey('backend'): self.backend}
+        self.project_data = {}    # type: T.Dict[str, T.Any]
+        self.targets = []         # type: T.List[T.Dict[str, T.Any]]
+        self.dependencies = []    # type: T.List[T.Dict[str, T.Any]]
+        self.project_node = None  # type: BaseNode
+
+        self.funcs.update({
+            'add_languages': self.func_add_languages,
+            'dependency': self.func_dependency,
+            'executable': self.func_executable,
+            'jar': self.func_jar,
+            'library': self.func_library,
+            'project': self.func_project,
+            'shared_library': self.func_shared_lib,
+            'shared_module': self.func_shared_module,
+            'static_library': self.func_static_lib,
+            'both_libraries': self.func_both_lib,
+        })
+
+    def func_project(self, node: BaseNode, args: T.List[TYPE_nvar], kwargs: T.Dict[str, TYPE_nvar]) -> None:
+        if self.project_node:
+            raise InvalidArguments('Second call to project()')
+        self.project_node = node
+        if len(args) < 1:
+            raise InvalidArguments('Not enough arguments to project(). Needs at least the project name.')
+
+        proj_name = args[0]
+        proj_vers = kwargs.get('version', 'undefined')
+        proj_langs = self.flatten_args(args[1:])
+        if isinstance(proj_vers, ElementaryNode):
+            proj_vers = proj_vers.value
+        if not isinstance(proj_vers, str):
+            proj_vers = 'undefined'
+        self.project_data = {'descriptive_name': proj_name, 'version': proj_vers}
+
+        if os.path.exists(self.option_file):
+            oi = optinterpreter.OptionInterpreter(self.subproject)
+            oi.process(self.option_file)
+            self.coredata.update_project_options(oi.options)
+
+        def_opts = self.flatten_args(kwargs.get('default_options', []))
+        _project_default_options = mesonlib.stringlistify(def_opts)
+        self.project_default_options = cdata.create_options_dict(_project_default_options, self.subproject)
+        self.default_options.update(self.project_default_options)
+        self.coredata.set_default_options(self.default_options, self.subproject, self.environment)
+
+        if not self.is_subproject() and 'subproject_dir' in kwargs:
+            spdirname = kwargs['subproject_dir']
+            if isinstance(spdirname, StringNode):
+                assert isinstance(spdirname.value, str)
+                self.subproject_dir = spdirname.value
+        if not self.is_subproject():
+            self.project_data['subprojects'] = []
+            subprojects_dir = os.path.join(self.source_root, self.subproject_dir)
+            if os.path.isdir(subprojects_dir):
+                for i in os.listdir(subprojects_dir):
+                    if os.path.isdir(os.path.join(subprojects_dir, i)):
+                        self.do_subproject(i)
+
+        self.coredata.init_backend_options(self.backend)
+        options = {k: v for k, v in self.environment.options.items() if k.is_backend()}
+
+        self.coredata.set_options(options)
+        self._add_languages(proj_langs, True, MachineChoice.HOST)
+        self._add_languages(proj_langs, True, MachineChoice.BUILD)
+
+    def do_subproject(self, dirname: str) -> None:
+        subproject_dir_abs = os.path.join(self.environment.get_source_dir(), self.subproject_dir)
+        subpr = os.path.join(subproject_dir_abs, dirname)
+        try:
+            subi = IntrospectionInterpreter(subpr, '', self.backend, cross_file=self.cross_file, subproject=dirname, subproject_dir=self.subproject_dir, env=self.environment, visitors=self.visitors)
+            subi.analyze()
+            subi.project_data['name'] = dirname
+            self.project_data['subprojects'] += [subi.project_data]
+        except (mesonlib.MesonException, RuntimeError):
+            return
+
+    def func_add_languages(self, node: BaseNode, args: T.List[TYPE_nvar], kwargs: T.Dict[str, TYPE_nvar]) -> None:
+        kwargs = self.flatten_kwargs(kwargs)
+        required = kwargs.get('required', True)
+        if isinstance(required, cdata.UserFeatureOption):
+            required = required.is_enabled()
+        if 'native' in kwargs:
+            native = kwargs.get('native', False)
+            self._add_languages(args, required, MachineChoice.BUILD if native else MachineChoice.HOST)
+        else:
+            for for_machine in [MachineChoice.BUILD, MachineChoice.HOST]:
+                self._add_languages(args, required, for_machine)
+
+    def _add_languages(self, raw_langs: T.List[TYPE_nvar], required: bool, for_machine: MachineChoice) -> None:
+        langs = []  # type: T.List[str]
+        for l in self.flatten_args(raw_langs):
+            if isinstance(l, str):
+                langs.append(l)
+            elif isinstance(l, StringNode):
+                langs.append(l.value)
+
+        for lang in sorted(langs, key=compilers.sort_clink):
+            lang = lang.lower()
+            if lang not in self.coredata.compilers[for_machine]:
+                try:
+                    comp = detect_compiler_for(self.environment, lang, for_machine)
+                except mesonlib.MesonException:
+                    # do we even care about introspecting this language?
+                    if required:
+                        raise
+                    else:
+                        continue
+                if self.subproject:
+                    options = {}
+                    for k in comp.get_options():
+                        v = copy.copy(self.coredata.options[k])
+                        k = k.evolve(subproject=self.subproject)
+                        options[k] = v
+                    self.coredata.add_compiler_options(options, lang, for_machine, self.environment)
+
+    def func_dependency(self, node: BaseNode, args: T.List[TYPE_nvar], kwargs: T.Dict[str, TYPE_nvar]) -> None:
+        args = self.flatten_args(args)
+        kwargs = self.flatten_kwargs(kwargs)
+        if not args:
+            return
+        name = args[0]
+        has_fallback = 'fallback' in kwargs
+        required = kwargs.get('required', True)
+        version = kwargs.get('version', [])
+        if not isinstance(version, list):
+            version = [version]
+        if isinstance(required, ElementaryNode):
+            required = required.value
+        if not isinstance(required, bool):
+            required = False
+        self.dependencies += [{
+            'name': name,
+            'required': required,
+            'version': version,
+            'has_fallback': has_fallback,
+            'conditional': node.condition_level > 0,
+            'node': node
+        }]
+
+    def build_target(self, node: BaseNode, args: T.List[TYPE_nvar], kwargs_raw: T.Dict[str, TYPE_nvar], targetclass: T.Type[BuildTarget]) -> T.Optional[T.Dict[str, T.Any]]:
+        args = self.flatten_args(args)
+        if not args or not isinstance(args[0], str):
+            return None
+        name = args[0]
+        srcqueue = [node]
+        extra_queue = []
+
+        # Process the sources BEFORE flattening the kwargs, to preserve the original nodes
+        if 'sources' in kwargs_raw:
+            srcqueue += mesonlib.listify(kwargs_raw['sources'])
+
+        if 'extra_files' in kwargs_raw:
+            extra_queue += mesonlib.listify(kwargs_raw['extra_files'])
+
+        kwargs = self.flatten_kwargs(kwargs_raw, True)
+
+        def traverse_nodes(inqueue: T.List[BaseNode]) -> T.List[BaseNode]:
+            res = []  # type: T.List[BaseNode]
+            while inqueue:
+                curr = inqueue.pop(0)
+                arg_node = None
+                assert isinstance(curr, BaseNode)
+                if isinstance(curr, FunctionNode):
+                    arg_node = curr.args
+                elif isinstance(curr, ArrayNode):
+                    arg_node = curr.args
+                elif isinstance(curr, IdNode):
+                    # Try to resolve the ID and append the node to the queue
+                    assert isinstance(curr.value, str)
+                    var_name = curr.value
+                    if var_name in self.assignments:
+                        tmp_node = self.assignments[var_name]
+                        if isinstance(tmp_node, (ArrayNode, IdNode, FunctionNode)):
+                            inqueue += [tmp_node]
+                elif isinstance(curr, ArithmeticNode):
+                    inqueue += [curr.left, curr.right]
+                if arg_node is None:
+                    continue
+                arg_nodes = arg_node.arguments.copy()
+                # Pop the first element if the function is a build target function
+                if isinstance(curr, FunctionNode) and curr.func_name in BUILD_TARGET_FUNCTIONS:
+                    arg_nodes.pop(0)
+                elemetary_nodes = [x for x in arg_nodes if isinstance(x, (str, StringNode))]
+                inqueue += [x for x in arg_nodes if isinstance(x, (FunctionNode, ArrayNode, IdNode, ArithmeticNode))]
+                if elemetary_nodes:
+                    res += [curr]
+            return res
+
+        source_nodes = traverse_nodes(srcqueue)
+        extraf_nodes = traverse_nodes(extra_queue)
+
+        # Make sure nothing can crash when creating the build class
+        kwargs_reduced = {k: v for k, v in kwargs.items() if k in targetclass.known_kwargs and k in {'install', 'build_by_default', 'build_always'}}
+        kwargs_reduced = {k: v.value if isinstance(v, ElementaryNode) else v for k, v in kwargs_reduced.items()}
+        kwargs_reduced = {k: v for k, v in kwargs_reduced.items() if not isinstance(v, BaseNode)}
+        for_machine = MachineChoice.HOST
+        objects = []        # type: T.List[T.Any]
+        empty_sources = []  # type: T.List[T.Any]
+        # Passing the unresolved sources list causes errors
+        target = targetclass(name, self.subdir, self.subproject, for_machine, empty_sources, [], objects,
+                             self.environment, self.coredata.compilers[for_machine], kwargs_reduced)
+        target.process_compilers()
+        target.process_compilers_late([])
+
+        new_target = {
+            'name': target.get_basename(),
+            'id': target.get_id(),
+            'type': target.get_typename(),
+            'defined_in': os.path.normpath(os.path.join(self.source_root, self.subdir, environment.build_filename)),
+            'subdir': self.subdir,
+            'build_by_default': target.build_by_default,
+            'installed': target.should_install(),
+            'outputs': target.get_outputs(),
+            'sources': source_nodes,
+            'extra_files': extraf_nodes,
+            'kwargs': kwargs,
+            'node': node,
+        }
+
+        self.targets += [new_target]
+        return new_target
+
+    def build_library(self, node: BaseNode, args: T.List[TYPE_nvar], kwargs: T.Dict[str, TYPE_nvar]) -> T.Optional[T.Dict[str, T.Any]]:
+        default_library = self.coredata.get_option(OptionKey('default_library'))
+        if default_library == 'shared':
+            return self.build_target(node, args, kwargs, SharedLibrary)
+        elif default_library == 'static':
+            return self.build_target(node, args, kwargs, StaticLibrary)
+        elif default_library == 'both':
+            return self.build_target(node, args, kwargs, SharedLibrary)
+        return None
+
+    def func_executable(self, node: BaseNode, args: T.List[TYPE_nvar], kwargs: T.Dict[str, TYPE_nvar]) -> T.Optional[T.Dict[str, T.Any]]:
+        return self.build_target(node, args, kwargs, Executable)
+
+    def func_static_lib(self, node: BaseNode, args: T.List[TYPE_nvar], kwargs: T.Dict[str, TYPE_nvar]) -> T.Optional[T.Dict[str, T.Any]]:
+        return self.build_target(node, args, kwargs, StaticLibrary)
+
+    def func_shared_lib(self, node: BaseNode, args: T.List[TYPE_nvar], kwargs: T.Dict[str, TYPE_nvar]) -> T.Optional[T.Dict[str, T.Any]]:
+        return self.build_target(node, args, kwargs, SharedLibrary)
+
+    def func_both_lib(self, node: BaseNode, args: T.List[TYPE_nvar], kwargs: T.Dict[str, TYPE_nvar]) -> T.Optional[T.Dict[str, T.Any]]:
+        return self.build_target(node, args, kwargs, SharedLibrary)
+
+    def func_shared_module(self, node: BaseNode, args: T.List[TYPE_nvar], kwargs: T.Dict[str, TYPE_nvar]) -> T.Optional[T.Dict[str, T.Any]]:
+        return self.build_target(node, args, kwargs, SharedModule)
+
+    def func_library(self, node: BaseNode, args: T.List[TYPE_nvar], kwargs: T.Dict[str, TYPE_nvar]) -> T.Optional[T.Dict[str, T.Any]]:
+        return self.build_library(node, args, kwargs)
+
+    def func_jar(self, node: BaseNode, args: T.List[TYPE_nvar], kwargs: T.Dict[str, TYPE_nvar]) -> T.Optional[T.Dict[str, T.Any]]:
+        return self.build_target(node, args, kwargs, Jar)
+
+    def func_build_target(self, node: BaseNode, args: T.List[TYPE_nvar], kwargs: T.Dict[str, TYPE_nvar]) -> T.Optional[T.Dict[str, T.Any]]:
+        if 'target_type' not in kwargs:
+            return None
+        target_type = kwargs.pop('target_type')
+        if isinstance(target_type, ElementaryNode):
+            target_type = target_type.value
+        if target_type == 'executable':
+            return self.build_target(node, args, kwargs, Executable)
+        elif target_type == 'shared_library':
+            return self.build_target(node, args, kwargs, SharedLibrary)
+        elif target_type == 'static_library':
+            return self.build_target(node, args, kwargs, StaticLibrary)
+        elif target_type == 'both_libraries':
+            return self.build_target(node, args, kwargs, SharedLibrary)
+        elif target_type == 'library':
+            return self.build_library(node, args, kwargs)
+        elif target_type == 'jar':
+            return self.build_target(node, args, kwargs, Jar)
+        return None
+
+    def is_subproject(self) -> bool:
+        return self.subproject != ''
+
+    def analyze(self) -> None:
+        self.load_root_meson_file()
+        self.sanity_check_ast()
+        self.parse_project()
+        self.run()
diff --git a/mesonbuild/ast/postprocess.py b/mesonbuild/ast/postprocess.py
new file mode 100644
index 0000000..0c28af0
--- /dev/null
+++ b/mesonbuild/ast/postprocess.py
@@ -0,0 +1,120 @@
+# Copyright 2019 The Meson development team
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This class contains the basic functionality needed to run any interpreter
+# or an interpreter-based tool
+from __future__ import annotations
+
+from . import AstVisitor
+import typing as T
+
+if T.TYPE_CHECKING:
+    from .. import mparser
+
+class AstIndentationGenerator(AstVisitor):
+    def __init__(self) -> None:
+        self.level = 0
+
+    def visit_default_func(self, node: mparser.BaseNode) -> None:
+        # Store the current level in the node
+        node.level = self.level
+
+    def visit_ArrayNode(self, node: mparser.ArrayNode) -> None:
+        self.visit_default_func(node)
+        self.level += 1
+        node.args.accept(self)
+        self.level -= 1
+
+    def visit_DictNode(self, node: mparser.DictNode) -> None:
+        self.visit_default_func(node)
+        self.level += 1
+        node.args.accept(self)
+        self.level -= 1
+
+    def visit_MethodNode(self, node: mparser.MethodNode) -> None:
+        self.visit_default_func(node)
+        node.source_object.accept(self)
+        self.level += 1
+        node.args.accept(self)
+        self.level -= 1
+
+    def visit_FunctionNode(self, node: mparser.FunctionNode) -> None:
+        self.visit_default_func(node)
+        self.level += 1
+        node.args.accept(self)
+        self.level -= 1
+
+    def visit_ForeachClauseNode(self, node: mparser.ForeachClauseNode) -> None:
+        self.visit_default_func(node)
+        self.level += 1
+        node.items.accept(self)
+        node.block.accept(self)
+        self.level -= 1
+
+    def visit_IfClauseNode(self, node: mparser.IfClauseNode) -> None:
+        self.visit_default_func(node)
+        for i in node.ifs:
+            i.accept(self)
+        if node.elseblock:
+            self.level += 1
+            node.elseblock.accept(self)
+            self.level -= 1
+
+    def visit_IfNode(self, node: mparser.IfNode) -> None:
+        self.visit_default_func(node)
+        self.level += 1
+        node.condition.accept(self)
+        node.block.accept(self)
+        self.level -= 1
+
+class AstIDGenerator(AstVisitor):
+    def __init__(self) -> None:
+        self.counter = {}  # type: T.Dict[str, int]
+
+    def visit_default_func(self, node: mparser.BaseNode) -> None:
+        name = type(node).__name__
+        if name not in self.counter:
+            self.counter[name] = 0
+        node.ast_id = name + '#' + str(self.counter[name])
+        self.counter[name] += 1
+
+class AstConditionLevel(AstVisitor):
+    def __init__(self) -> None:
+        self.condition_level = 0
+
+    def visit_default_func(self, node: mparser.BaseNode) -> None:
+        node.condition_level = self.condition_level
+
+    def visit_ForeachClauseNode(self, node: mparser.ForeachClauseNode) -> None:
+        self.visit_default_func(node)
+        self.condition_level += 1
+        node.items.accept(self)
+        node.block.accept(self)
+        self.condition_level -= 1
+
+    def visit_IfClauseNode(self, node: mparser.IfClauseNode) -> None:
+        self.visit_default_func(node)
+        for i in node.ifs:
+            i.accept(self)
+        if node.elseblock:
+            self.condition_level += 1
+            node.elseblock.accept(self)
+            self.condition_level -= 1
+
+    def visit_IfNode(self, node: mparser.IfNode) -> None:
+        self.visit_default_func(node)
+        self.condition_level += 1
+        node.condition.accept(self)
+        node.block.accept(self)
+        self.condition_level -= 1
diff --git a/mesonbuild/ast/printer.py b/mesonbuild/ast/printer.py
new file mode 100644
index 0000000..3c53910
--- /dev/null
+++ b/mesonbuild/ast/printer.py
@@ -0,0 +1,399 @@
+# Copyright 2019 The Meson development team
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This class contains the basic functionality needed to run any interpreter
+# or an interpreter-based tool
+from __future__ import annotations
+
+from .. import mparser
+from . import AstVisitor
+import re
+import typing as T
+
+arithmic_map = {
+    'add': '+',
+    'sub': '-',
+    'mod': '%',
+    'mul': '*',
+    'div': '/'
+}
+
+class AstPrinter(AstVisitor):
+    def __init__(self, indent: int = 2, arg_newline_cutoff: int = 5, update_ast_line_nos: bool = False):
+        self.result = ''
+        self.indent = indent
+        self.arg_newline_cutoff = arg_newline_cutoff
+        self.ci = ''
+        self.is_newline = True
+        self.last_level = 0
+        self.curr_line = 1 if update_ast_line_nos else None
+
+    def post_process(self) -> None:
+        self.result = re.sub(r'\s+\n', '\n', self.result)
+
+    def append(self, data: str, node: mparser.BaseNode) -> None:
+        self.last_level = node.level
+        if self.is_newline:
+            self.result += ' ' * (node.level * self.indent)
+        self.result += data
+        self.is_newline = False
+
+    def append_padded(self, data: str, node: mparser.BaseNode) -> None:
+        if self.result and self.result[-1] not in [' ', '\n']:
+            data = ' ' + data
+        self.append(data + ' ', node)
+
+    def newline(self) -> None:
+        self.result += '\n'
+        self.is_newline = True
+        if self.curr_line is not None:
+            self.curr_line += 1
+
+    def visit_BooleanNode(self, node: mparser.BooleanNode) -> None:
+        self.append('true' if node.value else 'false', node)
+        node.lineno = self.curr_line or node.lineno
+
+    def visit_IdNode(self, node: mparser.IdNode) -> None:
+        assert isinstance(node.value, str)
+        self.append(node.value, node)
+        node.lineno = self.curr_line or node.lineno
+
+    def visit_NumberNode(self, node: mparser.NumberNode) -> None:
+        self.append(str(node.value), node)
+        node.lineno = self.curr_line or node.lineno
+
+    def escape(self, val: str) -> str:
+        return val.translate(str.maketrans({'\'': '\\\'',
+                                            '\\': '\\\\'}))
+
+    def visit_StringNode(self, node: mparser.StringNode) -> None:
+        assert isinstance(node.value, str)
+        self.append("'" + self.escape(node.value) + "'", node)
+        node.lineno = self.curr_line or node.lineno
+
+    def visit_FormatStringNode(self, node: mparser.FormatStringNode) -> None:
+        assert isinstance(node.value, str)
+        self.append("f'" + node.value + "'", node)
+        node.lineno = self.curr_line or node.lineno
+
+    def visit_ContinueNode(self, node: mparser.ContinueNode) -> None:
+        self.append('continue', node)
+        node.lineno = self.curr_line or node.lineno
+
+    def visit_BreakNode(self, node: mparser.BreakNode) -> None:
+        self.append('break', node)
+        node.lineno = self.curr_line or node.lineno
+
+    def visit_ArrayNode(self, node: mparser.ArrayNode) -> None:
+        node.lineno = self.curr_line or node.lineno
+        self.append('[', node)
+        node.args.accept(self)
+        self.append(']', node)
+
+    def visit_DictNode(self, node: mparser.DictNode) -> None:
+        node.lineno = self.curr_line or node.lineno
+        self.append('{', node)
+        node.args.accept(self)
+        self.append('}', node)
+
+    def visit_OrNode(self, node: mparser.OrNode) -> None:
+        node.left.accept(self)
+        self.append_padded('or', node)
+        node.lineno = self.curr_line or node.lineno
+        node.right.accept(self)
+
+    def visit_AndNode(self, node: mparser.AndNode) -> None:
+        node.left.accept(self)
+        self.append_padded('and', node)
+        node.lineno = self.curr_line or node.lineno
+        node.right.accept(self)
+
+    def visit_ComparisonNode(self, node: mparser.ComparisonNode) -> None:
+        node.left.accept(self)
+        self.append_padded(node.ctype, node)
+        node.lineno = self.curr_line or node.lineno
+        node.right.accept(self)
+
+    def visit_ArithmeticNode(self, node: mparser.ArithmeticNode) -> None:
+        node.left.accept(self)
+        self.append_padded(arithmic_map[node.operation], node)
+        node.lineno = self.curr_line or node.lineno
+        node.right.accept(self)
+
+    def visit_NotNode(self, node: mparser.NotNode) -> None:
+        node.lineno = self.curr_line or node.lineno
+        self.append_padded('not', node)
+        node.value.accept(self)
+
+    def visit_CodeBlockNode(self, node: mparser.CodeBlockNode) -> None:
+        node.lineno = self.curr_line or node.lineno
+        for i in node.lines:
+            i.accept(self)
+            self.newline()
+
+    def visit_IndexNode(self, node: mparser.IndexNode) -> None:
+        node.iobject.accept(self)
+        node.lineno = self.curr_line or node.lineno
+        self.append('[', node)
+        node.index.accept(self)
+        self.append(']', node)
+
+    def visit_MethodNode(self, node: mparser.MethodNode) -> None:
+        node.lineno = self.curr_line or node.lineno
+        node.source_object.accept(self)
+        self.append('.' + node.name + '(', node)
+        node.args.accept(self)
+        self.append(')', node)
+
+    def visit_FunctionNode(self, node: mparser.FunctionNode) -> None:
+        node.lineno = self.curr_line or node.lineno
+        self.append(node.func_name + '(', node)
+        node.args.accept(self)
+        self.append(')', node)
+
+    def visit_AssignmentNode(self, node: mparser.AssignmentNode) -> None:
+        node.lineno = self.curr_line or node.lineno
+        self.append(node.var_name + ' = ', node)
+        node.value.accept(self)
+
+    def visit_PlusAssignmentNode(self, node: mparser.PlusAssignmentNode) -> None:
+        node.lineno = self.curr_line or node.lineno
+        self.append(node.var_name + ' += ', node)
+        node.value.accept(self)
+
+    def visit_ForeachClauseNode(self, node: mparser.ForeachClauseNode) -> None:
+        node.lineno = self.curr_line or node.lineno
+        self.append_padded('foreach', node)
+        self.append_padded(', '.join(node.varnames), node)
+        self.append_padded(':', node)
+        node.items.accept(self)
+        self.newline()
+        node.block.accept(self)
+        self.append('endforeach', node)
+
+    def visit_IfClauseNode(self, node: mparser.IfClauseNode) -> None:
+        node.lineno = self.curr_line or node.lineno
+        prefix = ''
+        for i in node.ifs:
+            self.append_padded(prefix + 'if', node)
+            prefix = 'el'
+            i.accept(self)
+        if not isinstance(node.elseblock, mparser.EmptyNode):
+            self.append('else', node)
+            node.elseblock.accept(self)
+        self.append('endif', node)
+
+    def visit_UMinusNode(self, node: mparser.UMinusNode) -> None:
+        node.lineno = self.curr_line or node.lineno
+        self.append_padded('-', node)
+        node.value.accept(self)
+
+    def visit_IfNode(self, node: mparser.IfNode) -> None:
+        node.lineno = self.curr_line or node.lineno
+        node.condition.accept(self)
+        self.newline()
+        node.block.accept(self)
+
+    def visit_TernaryNode(self, node: mparser.TernaryNode) -> None:
+        node.lineno = self.curr_line or node.lineno
+        node.condition.accept(self)
+        self.append_padded('?', node)
+        node.trueblock.accept(self)
+        self.append_padded(':', node)
+        node.falseblock.accept(self)
+
+    def visit_ArgumentNode(self, node: mparser.ArgumentNode) -> None:
+        node.lineno = self.curr_line or node.lineno
+        break_args = (len(node.arguments) + len(node.kwargs)) > self.arg_newline_cutoff
+        for i in node.arguments + list(node.kwargs.values()):
+            if not isinstance(i, (mparser.ElementaryNode, mparser.IndexNode)):
+                break_args = True
+        if break_args:
+            self.newline()
+        for i in node.arguments:
+            i.accept(self)
+            self.append(', ', node)
+            if break_args:
+                self.newline()
+        for key, val in node.kwargs.items():
+            key.accept(self)
+            self.append_padded(':', node)
+            val.accept(self)
+            self.append(', ', node)
+            if break_args:
+                self.newline()
+        if break_args:
+            self.result = re.sub(r', \n$', '\n', self.result)
+        else:
+            self.result = re.sub(r', $', '', self.result)
+
+class AstJSONPrinter(AstVisitor):
+    def __init__(self) -> None:
+        self.result = {}  # type: T.Dict[str, T.Any]
+        self.current = self.result
+
+    def _accept(self, key: str, node: mparser.BaseNode) -> None:
+        old = self.current
+        data = {}  # type: T.Dict[str, T.Any]
+        self.current = data
+        node.accept(self)
+        self.current = old
+        self.current[key] = data
+
+    def _accept_list(self, key: str, nodes: T.Sequence[mparser.BaseNode]) -> None:
+        old = self.current
+        datalist = []  # type: T.List[T.Dict[str, T.Any]]
+        for i in nodes:
+            self.current = {}
+            i.accept(self)
+            datalist += [self.current]
+        self.current = old
+        self.current[key] = datalist
+
+    def _raw_accept(self, node: mparser.BaseNode, data: T.Dict[str, T.Any]) -> None:
+        old = self.current
+        self.current = data
+        node.accept(self)
+        self.current = old
+
+    def setbase(self, node: mparser.BaseNode) -> None:
+        self.current['node'] = type(node).__name__
+        self.current['lineno'] = node.lineno
+        self.current['colno'] = node.colno
+        self.current['end_lineno'] = node.end_lineno
+        self.current['end_colno'] = node.end_colno
+
+    def visit_default_func(self, node: mparser.BaseNode) -> None:
+        self.setbase(node)
+
+    def gen_ElementaryNode(self, node: mparser.ElementaryNode) -> None:
+        self.current['value'] = node.value
+        self.setbase(node)
+
+    def visit_BooleanNode(self, node: mparser.BooleanNode) -> None:
+        self.gen_ElementaryNode(node)
+
+    def visit_IdNode(self, node: mparser.IdNode) -> None:
+        self.gen_ElementaryNode(node)
+
+    def visit_NumberNode(self, node: mparser.NumberNode) -> None:
+        self.gen_ElementaryNode(node)
+
+    def visit_StringNode(self, node: mparser.StringNode) -> None:
+        self.gen_ElementaryNode(node)
+
+    def visit_FormatStringNode(self, node: mparser.FormatStringNode) -> None:
+        self.gen_ElementaryNode(node)
+
+    def visit_ArrayNode(self, node: mparser.ArrayNode) -> None:
+        self._accept('args', node.args)
+        self.setbase(node)
+
+    def visit_DictNode(self, node: mparser.DictNode) -> None:
+        self._accept('args', node.args)
+        self.setbase(node)
+
+    def visit_OrNode(self, node: mparser.OrNode) -> None:
+        self._accept('left', node.left)
+        self._accept('right', node.right)
+        self.setbase(node)
+
+    def visit_AndNode(self, node: mparser.AndNode) -> None:
+        self._accept('left', node.left)
+        self._accept('right', node.right)
+        self.setbase(node)
+
+    def visit_ComparisonNode(self, node: mparser.ComparisonNode) -> None:
+        self._accept('left', node.left)
+        self._accept('right', node.right)
+        self.current['ctype'] = node.ctype
+        self.setbase(node)
+
+    def visit_ArithmeticNode(self, node: mparser.ArithmeticNode) -> None:
+        self._accept('left', node.left)
+        self._accept('right', node.right)
+        self.current['op'] = arithmic_map[node.operation]
+        self.setbase(node)
+
+    def visit_NotNode(self, node: mparser.NotNode) -> None:
+        self._accept('right', node.value)
+        self.setbase(node)
+
+    def visit_CodeBlockNode(self, node: mparser.CodeBlockNode) -> None:
+        self._accept_list('lines', node.lines)
+        self.setbase(node)
+
+    def visit_IndexNode(self, node: mparser.IndexNode) -> None:
+        self._accept('object', node.iobject)
+        self._accept('index', node.index)
+        self.setbase(node)
+
+    def visit_MethodNode(self, node: mparser.MethodNode) -> None:
+        self._accept('object', node.source_object)
+        self._accept('args', node.args)
+        self.current['name'] = node.name
+        self.setbase(node)
+
+    def visit_FunctionNode(self, node: mparser.FunctionNode) -> None:
+        self._accept('args', node.args)
+        self.current['name'] = node.func_name
+        self.setbase(node)
+
+    def visit_AssignmentNode(self, node: mparser.AssignmentNode) -> None:
+        self._accept('value', node.value)
+        self.current['var_name'] = node.var_name
+        self.setbase(node)
+
+    def visit_PlusAssignmentNode(self, node: mparser.PlusAssignmentNode) -> None:
+        self._accept('value', node.value)
+        self.current['var_name'] = node.var_name
+        self.setbase(node)
+
+    def visit_ForeachClauseNode(self, node: mparser.ForeachClauseNode) -> None:
+        self._accept('items', node.items)
+        self._accept('block', node.block)
+        self.current['varnames'] = node.varnames
+        self.setbase(node)
+
+    def visit_IfClauseNode(self, node: mparser.IfClauseNode) -> None:
+        self._accept_list('ifs', node.ifs)
+        self._accept('else', node.elseblock)
+        self.setbase(node)
+
+    def visit_UMinusNode(self, node: mparser.UMinusNode) -> None:
+        self._accept('right', node.value)
+        self.setbase(node)
+
+    def visit_IfNode(self, node: mparser.IfNode) -> None:
+        self._accept('condition', node.condition)
+        self._accept('block', node.block)
+        self.setbase(node)
+
+    def visit_TernaryNode(self, node: mparser.TernaryNode) -> None:
+        self._accept('condition', node.condition)
+        self._accept('true', node.trueblock)
+        self._accept('false', node.falseblock)
+        self.setbase(node)
+
+    def visit_ArgumentNode(self, node: mparser.ArgumentNode) -> None:
+        self._accept_list('positional', node.arguments)
+        kwargs_list = []  # type: T.List[T.Dict[str, T.Dict[str, T.Any]]]
+        for key, val in node.kwargs.items():
+            key_res = {}  # type: T.Dict[str, T.Any]
+            val_res = {}  # type: T.Dict[str, T.Any]
+            self._raw_accept(key, key_res)
+            self._raw_accept(val, val_res)
+            kwargs_list += [{'key': key_res, 'val': val_res}]
+        self.current['kwargs'] = kwargs_list
+        self.setbase(node)
diff --git a/mesonbuild/ast/visitor.py b/mesonbuild/ast/visitor.py
new file mode 100644
index 0000000..8a0e77b
--- /dev/null
+++ b/mesonbuild/ast/visitor.py
@@ -0,0 +1,146 @@
+# Copyright 2019 The Meson development team
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This class contains the basic functionality needed to run any interpreter
+# or an interpreter-based tool
+from __future__ import annotations
+
+import typing as T
+
+if T.TYPE_CHECKING:
+    from .. import mparser
+
+class AstVisitor:
+    def __init__(self) -> None:
+        pass
+
+    def visit_default_func(self, node: mparser.BaseNode) -> None:
+        pass
+
+    def visit_BooleanNode(self, node: mparser.BooleanNode) -> None:
+        self.visit_default_func(node)
+
+    def visit_IdNode(self, node: mparser.IdNode) -> None:
+        self.visit_default_func(node)
+
+    def visit_NumberNode(self, node: mparser.NumberNode) -> None:
+        self.visit_default_func(node)
+
+    def visit_StringNode(self, node: mparser.StringNode) -> None:
+        self.visit_default_func(node)
+
+    def visit_FormatStringNode(self, node: mparser.FormatStringNode) -> None:
+        self.visit_default_func(node)
+
+    def visit_ContinueNode(self, node: mparser.ContinueNode) -> None:
+        self.visit_default_func(node)
+
+    def visit_BreakNode(self, node: mparser.BreakNode) -> None:
+        self.visit_default_func(node)
+
+    def visit_ArrayNode(self, node: mparser.ArrayNode) -> None:
+        self.visit_default_func(node)
+        node.args.accept(self)
+
+    def visit_DictNode(self, node: mparser.DictNode) -> None:
+        self.visit_default_func(node)
+        node.args.accept(self)
+
+    def visit_EmptyNode(self, node: mparser.EmptyNode) -> None:
+        self.visit_default_func(node)
+
+    def visit_OrNode(self, node: mparser.OrNode) -> None:
+        self.visit_default_func(node)
+        node.left.accept(self)
+        node.right.accept(self)
+
+    def visit_AndNode(self, node: mparser.AndNode) -> None:
+        self.visit_default_func(node)
+        node.left.accept(self)
+        node.right.accept(self)
+
+    def visit_ComparisonNode(self, node: mparser.ComparisonNode) -> None:
+        self.visit_default_func(node)
+        node.left.accept(self)
+        node.right.accept(self)
+
+    def visit_ArithmeticNode(self, node: mparser.ArithmeticNode) -> None:
+        self.visit_default_func(node)
+        node.left.accept(self)
+        node.right.accept(self)
+
+    def visit_NotNode(self, node: mparser.NotNode) -> None:
+        self.visit_default_func(node)
+        node.value.accept(self)
+
+    def visit_CodeBlockNode(self, node: mparser.CodeBlockNode) -> None:
+        self.visit_default_func(node)
+        for i in node.lines:
+            i.accept(self)
+
+    def visit_IndexNode(self, node: mparser.IndexNode) -> None:
+        self.visit_default_func(node)
+        node.iobject.accept(self)
+        node.index.accept(self)
+
+    def visit_MethodNode(self, node: mparser.MethodNode) -> None:
+        self.visit_default_func(node)
+        node.source_object.accept(self)
+        node.args.accept(self)
+
+    def visit_FunctionNode(self, node: mparser.FunctionNode) -> None:
+        self.visit_default_func(node)
+        node.args.accept(self)
+
+    def visit_AssignmentNode(self, node: mparser.AssignmentNode) -> None:
+        self.visit_default_func(node)
+        node.value.accept(self)
+
+    def visit_PlusAssignmentNode(self, node: mparser.PlusAssignmentNode) -> None:
+        self.visit_default_func(node)
+        node.value.accept(self)
+
+    def visit_ForeachClauseNode(self, node: mparser.ForeachClauseNode) -> None:
+        self.visit_default_func(node)
+        node.items.accept(self)
+        node.block.accept(self)
+
+    def visit_IfClauseNode(self, node: mparser.IfClauseNode) -> None:
+        self.visit_default_func(node)
+        for i in node.ifs:
+            i.accept(self)
+        node.elseblock.accept(self)
+
+    def visit_UMinusNode(self, node: mparser.UMinusNode) -> None:
+        self.visit_default_func(node)
+        node.value.accept(self)
+
+    def visit_IfNode(self, node: mparser.IfNode) -> None:
+        self.visit_default_func(node)
+        node.condition.accept(self)
+        node.block.accept(self)
+
+    def visit_TernaryNode(self, node: mparser.TernaryNode) -> None:
+        self.visit_default_func(node)
+        node.condition.accept(self)
+        node.trueblock.accept(self)
+        node.falseblock.accept(self)
+
+    def visit_ArgumentNode(self, node: mparser.ArgumentNode) -> None:
+        self.visit_default_func(node)
+        for i in node.arguments:
+            i.accept(self)
+        for key, val in node.kwargs.items():
+            key.accept(self)
+            val.accept(self)