Modify presubmit checks to work on changed lines only.

presubmit_support.py

 #!/usr/bin/python
 # Copyright (c) 2010 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__ = '1.3.5'
 
@@ skipping 68 matching lines @@
 
 def PromptYesNo(input_stream, output_stream, prompt):
   output_stream.write(prompt)
   response = input_stream.readline().strip().lower()
   return response == 'y' or response == 'yes'
 
 
 def _RightHandSideLinesImpl(affected_files):
   """Implements RightHandSideLines for InputApi and GclChange."""
   for af in affected_files:
-    lines = af.NewContents()
-    line_number = 0
+    lines = af.ChangedContents()
     for line in lines:
-      line_number += 1
-      yield (af, line_number, line)
+      yield (af, line[0], line[1])
 
 
 class OutputApi(object):
   """This class (more like a module) gets passed to presubmit scripts so that
   they can specify various types of results.
   """
   # Method could be a function
   # pylint: disable=R0201
   class PresubmitResult(object):
     """Base class for result objects."""
@@ skipping 370 matching lines @@
 
   def OldFileTempPath(self):
     """Returns the path on local disk where the old contents resides.
 
     The old version is the file in depot, i.e. the "left hand side".
     This is a read-only cached copy of the old contents. *DO NOT* try to
     modify this file.
     """
     raise NotImplementedError()  # Implement if/when needed.
 
+  def ChangedContents(self):
+    # Return a list of tuples (line number, line text) of all new lines in the

[M-A Ruel, 2011/02/09 18:30:26]

I think it should be a docstring.

"""Returns a list of ...

[vb, 2011/02/09 18:54:11]

Done.

+    # file. This relies on the scm diff output describing each changed code
+    # section with a line of the form
+    #
+    # ^@@ <old line num>,<old size> <new line num>,<new size> @@$
+    #
+    new_lines = []
+    line_num = 0
+    diff_text = self.GenerateScmDiff()
+    for line in diff_text.splitlines():

[M-A Ruel, 2011/02/09 18:30:26]

You didn't merge lines 491 and 492. You prefer to keep that on two lines? I
don't mind much but I don't think this data needs a named variable.

[vb, 2011/02/09 18:54:11]

good point, it was a leftover of previous code, now refactored. 

+      m = re.match(r'^@@ [0-9\,\+\-]+ \+([0-9]+)\,[0-9]+ @@', line)
+      if m:
+        line_num = int(m.groups(1)[0])
+        continue
+      if re.search(r'^\+[^\+]', line):

[M-A Ruel, 2011/02/09 18:30:26]

Actually, this regexp is wrong:

what if the line was empty, e.g. there's no character on this line, I don't
think this regexp will trigger. Can you confirm?

[vb, 2011/02/09 18:54:11]

Yes, a good catch. Did away with regexp here, I think it is even better readable
this way. And we don't care about the '^---' case , because it would be followed
by a @@ line and reset the line counter anyways.

+        new_lines.append((line_num, line[1:]))
+      if not re.search(r'^\-[^\-]', line):
+        line_num += 1
+    return new_lines
+
   def __str__(self):
     return self.LocalPath()
 
 
 class SvnAffectedFile(AffectedFile):
   """Representation of a file in a change out of a Subversion checkout."""
   # Method 'NNN' is abstract in class 'NNN' but is not overridden
   # pylint: disable=W0223
 
   def __init__(self, *args, **kwargs):
@@ skipping 31 matching lines @@
         # A deleted file is not a text file.
         self._is_text_file = False
       elif self.IsDirectory():
         self._is_text_file = False
       else:
         mime_type = scm.SVN.GetFileProperty(self.AbsoluteLocalPath(),
                                             'svn:mime-type')
         self._is_text_file = (not mime_type or mime_type.startswith('text/'))
     return self._is_text_file
 
+  def GenerateScmDiff(self):
+    return scm.SVN.GenerateDiff(self.AbsoluteLocalPath())
 
 class GitAffectedFile(AffectedFile):
   """Representation of a file in a change out of a git checkout."""
   # Method 'NNN' is abstract in class 'NNN' but is not overridden
   # pylint: disable=W0223
 
   def __init__(self, *args, **kwargs):
     AffectedFile.__init__(self, *args, **kwargs)
     self._server_path = None
     self._is_text_file = None
@@ skipping 25 matching lines @@
       if self.Action() == 'D':
         # A deleted file is not a text file.
         self._is_text_file = False
       elif self.IsDirectory():
         self._is_text_file = False
       else:
         # raise NotImplementedException()  # TODO(maruel) Implement.
         self._is_text_file = os.path.isfile(self.AbsoluteLocalPath())
     return self._is_text_file
 
+  def GenerateScmDiff(self):
+    return scm.GIT.GenerateDiff(
+      os.path.dirname(self.AbsoluteLocalPath()),
+      files=[os.path.basename(self.AbsoluteLocalPath()),])
 
 class Change(object):
   """Describe a change.
 
   Used directly by the presubmit scripts to query the current change being
   tested.
 
   Instance members:
     tags: Dictionnary of KEY=VALUE pairs found in the change description.
     self.KEY: equivalent to tags['KEY']
@@ skipping 538 matching lines @@
                                options.commit,
                                options.verbose,
                                sys.stdout,
                                sys.stdin,
                                options.default_presubmit,
                                options.may_prompt)
 
 
 if __name__ == '__main__':
   sys.exit(Main(sys.argv))