Support getting changes of non-HEAD branches

presubmit_support.py

 #!/usr/bin/env python
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Enables directory-specific presubmit checks to run at upload and/or commit.
 """
 
 __version__ = '1.8.0'
 
@@ skipping 490 matching lines @@
     if len(tests) > 1 and parallel:
       # async recipe works around multiprocessing bug handling Ctrl-C
       msgs.extend(self._run_tests_pool.map_async(CallCommand, tests).get(99999))
     else:
       msgs.extend(map(CallCommand, tests))
     return [m for m in msgs if m]
 
 
 class _DiffCache(object):
   """Caches diffs retrieved from a particular SCM."""
-  def __init__(self, upstream=None):
+  def __init__(self, upstream=None, *args, **kwargs):
     """Stores the upstream revision against which all diffs will be computed."""
     self._upstream = upstream
 
   def GetDiff(self, path, local_root):
     """Get the diff for a particular path."""
     raise NotImplementedError()
 
 
 class _SvnDiffCache(_DiffCache):
   """DiffCache implementation for subversion."""
-  def __init__(self, *args, **kwargs):
-    super(_SvnDiffCache, self).__init__(*args, **kwargs)
+  def __init__(self, upstream=None, *args, **kwargs):
+    super(_SvnDiffCache, self).__init__(upstream, *args, **kwargs)
     self._diffs_by_file = {}
 
   def GetDiff(self, path, local_root):
     if path not in self._diffs_by_file:
       self._diffs_by_file[path] = scm.SVN.GenerateDiff([path], local_root,
                                                        False, None)
     return self._diffs_by_file[path]
 
 
 class _GitDiffCache(_DiffCache):
   """DiffCache implementation for git; gets all file diffs at once."""
-  def __init__(self, upstream):
-    super(_GitDiffCache, self).__init__(upstream=upstream)
+  def __init__(self, upstream=None, *args, **kwargs):
+    super(_GitDiffCache, self).__init__(upstream, *args, **kwargs)
     self._diffs_by_file = None
+    self._local_ref = kwargs.get('local_ref', 'HEAD')
 
   def GetDiff(self, path, local_root):
     if not self._diffs_by_file:
-      # Compute a single diff for all files and parse the output; should
-      # with git this is much faster than computing one diff for each file.
+      # Compute a single diff for all files and parse the output; with git
+      # this is much faster than computing one diff for each file.
       diffs = {}
 
       # Don't specify any filenames below, because there are command line length
       # limits on some platforms and GenerateDiff would fail.
       unified_diff = scm.GIT.GenerateDiff(local_root, files=[], full_move=True,
-                                          branch=self._upstream)
+                                          branch=self._upstream,
+                                          branch_head=self._local_ref)
 
       # This regex matches the path twice, separated by a space. Note that
       # filename itself may contain spaces.
       file_marker = re.compile('^diff --git (?P<filename>.*) (?P=filename)$')
       current_diff = []
       keep_line_endings = True
       for x in unified_diff.splitlines(keep_line_endings):
         match = file_marker.match(x)
         if match:
           # Marks the start of a new per-file section.
@@ skipping 236 matching lines @@
 
   _AFFECTED_FILES = AffectedFile
 
   # Matches key/value (or "tag") lines in changelist descriptions.
   TAG_LINE_RE = re.compile(
       '^[ \t]*(?P<key>[A-Z][A-Z_0-9]*)[ \t]*=[ \t]*(?P<value>.*?)[ \t]*$')
   scm = ''
 
   def __init__(
       self, name, description, local_root, files, issue, patchset, author,
-      upstream=None):
+      upstream=None, local_ref='HEAD'):
     if files is None:
       files = []
     self._name = name
     # Convert root into an absolute path.
     self._local_root = os.path.abspath(local_root)
     self._upstream = upstream
+    self._local_ref = local_ref
     self.issue = issue
     self.patchset = patchset
     self.author_email = author
 
     self._full_description = ''
     self.tags = {}
     self._description_without_tags = ''
     self.SetDescriptionText(description)
 
     assert all(
         (isinstance(f, (list, tuple)) and len(f) == 2) for f in files), files
 
-    diff_cache = self._AFFECTED_FILES.DIFF_CACHE(self._upstream)
+    diff_cache = self._AFFECTED_FILES.DIFF_CACHE(self._upstream,
+                                                 local_ref=self._local_ref)
     self._affected_files = [
         self._AFFECTED_FILES(path, action.strip(), self._local_root, diff_cache)
         for action, path in files
     ]
 
   def Name(self):
     """Returns the change name."""
     return self._name
 
   def DescriptionText(self):
@@ skipping 892 matching lines @@
     return 2
 
 
 if __name__ == '__main__':
   fix_encoding.fix_encoding()
   try:
     sys.exit(main())
   except KeyboardInterrupt:
     sys.stderr.write('interrupted\n')
     sys.exit(1)