initial import of the packaging package in the standard library
diff --git a/Lib/packaging/pypi/base.py b/Lib/packaging/pypi/base.py
new file mode 100644
index 0000000..305fca9
--- /dev/null
+++ b/Lib/packaging/pypi/base.py
@@ -0,0 +1,48 @@
+"""Base class for index crawlers."""
+
+from packaging.pypi.dist import ReleasesList
+
+
+class BaseClient:
+ """Base class containing common methods for the index crawlers/clients"""
+
+ def __init__(self, prefer_final, prefer_source):
+ self._prefer_final = prefer_final
+ self._prefer_source = prefer_source
+ self._index = self
+
+ def _get_prefer_final(self, prefer_final=None):
+ """Return the prefer_final internal parameter or the specified one if
+ provided"""
+ if prefer_final:
+ return prefer_final
+ else:
+ return self._prefer_final
+
+ def _get_prefer_source(self, prefer_source=None):
+ """Return the prefer_source internal parameter or the specified one if
+ provided"""
+ if prefer_source:
+ return prefer_source
+ else:
+ return self._prefer_source
+
+ def _get_project(self, project_name):
+ """Return an project instance, create it if necessary"""
+ return self._projects.setdefault(project_name.lower(),
+ ReleasesList(project_name, index=self._index))
+
+ def download_distribution(self, requirements, temp_path=None,
+ prefer_source=None, prefer_final=None):
+ """Download a distribution from the last release according to the
+ requirements.
+
+ If temp_path is provided, download to this path, otherwise, create a
+ temporary location for the download and return it.
+ """
+ prefer_final = self._get_prefer_final(prefer_final)
+ prefer_source = self._get_prefer_source(prefer_source)
+ release = self.get_release(requirements, prefer_final)
+ if release:
+ dist = release.get_distribution(prefer_source=prefer_source)
+ return dist.download(temp_path)