1 files changed, 97 insertions, 0 deletions
diff --git a/third_party/python/pip_tools/piptools/repositories/local.py b/third_party/python/pip_tools/piptools/repositories/local.py
new file mode 100644
index 0000000000..f185f35c3c
--- /dev/null
+++ b/third_party/python/pip_tools/piptools/repositories/local.py
@@ -0,0 +1,97 @@
+# coding: utf-8
+from __future__ import absolute_import, division, print_function, unicode_literals
+
+from contextlib import contextmanager
+
+from pip._internal.utils.hashes import FAVORITE_HASH
+
+from piptools.utils import as_tuple, key_from_ireq, make_install_requirement
+
+from .base import BaseRepository
+
+
+def ireq_satisfied_by_existing_pin(ireq, existing_pin):
+    """
+    Return True if the given InstallationRequirement is satisfied by the
+    previously encountered version pin.
+    """
+    version = next(iter(existing_pin.req.specifier)).version
+    return ireq.req.specifier.contains(
+        version, prereleases=existing_pin.req.specifier.prereleases
+    )
+
+
+class LocalRequirementsRepository(BaseRepository):
+    """
+    The LocalRequirementsRepository proxied the _real_ repository by first
+    checking if a requirement can be satisfied by existing pins (i.e. the
+    result of a previous compile step).
+
+    In effect, if a requirement can be satisfied with a version pinned in the
+    requirements file, we prefer that version over the best match found in
+    PyPI.  This keeps updates to the requirements.txt down to a minimum.
+    """
+
+    def __init__(self, existing_pins, proxied_repository, reuse_hashes=True):
+        self._reuse_hashes = reuse_hashes
+        self.repository = proxied_repository
+        self.existing_pins = existing_pins
+
+    @property
+    def options(self):
+        return self.repository.options
+
+    @property
+    def finder(self):
+        return self.repository.finder
+
+    @property
+    def session(self):
+        return self.repository.session
+
+    @property
+    def DEFAULT_INDEX_URL(self):
+        return self.repository.DEFAULT_INDEX_URL
+
+    def clear_caches(self):
+        self.repository.clear_caches()
+
+    @contextmanager
+    def freshen_build_caches(self):
+        with self.repository.freshen_build_caches():
+            yield
+
+    def find_best_match(self, ireq, prereleases=None):
+        key = key_from_ireq(ireq)
+        existing_pin = self.existing_pins.get(key)
+        if existing_pin and ireq_satisfied_by_existing_pin(ireq, existing_pin):
+            project, version, _ = as_tuple(existing_pin)
+            return make_install_requirement(
+                project, version, ireq.extras, constraint=ireq.constraint
+            )
+        else:
+            return self.repository.find_best_match(ireq, prereleases)
+
+    def get_dependencies(self, ireq):
+        return self.repository.get_dependencies(ireq)
+
+    def get_hashes(self, ireq):
+        existing_pin = self._reuse_hashes and self.existing_pins.get(
+            key_from_ireq(ireq)
+        )
+        if existing_pin and ireq_satisfied_by_existing_pin(ireq, existing_pin):
+            hashes = existing_pin.hash_options
+            hexdigests = hashes.get(FAVORITE_HASH)
+            if hexdigests:
+                return {
+                    ":".join([FAVORITE_HASH, hexdigest]) for hexdigest in hexdigests
+                }
+        return self.repository.get_hashes(ireq)
+
+    @contextmanager
+    def allow_all_wheels(self):
+        with self.repository.allow_all_wheels():
+            yield
+
+    def copy_ireq_dependencies(self, source, dest):
+        self.repository.copy_ireq_dependencies(source, dest)