Add experimental support for python in 'git cl format'

git_cl.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.
 
 # Copyright (C) 2008 Evan Martin <martine@danga.com>
 
 """A git-command for integrating reviews on Rietveld."""
 
 from distutils.version import LooseVersion
@@ skipping 3165 matching lines @@
       else:
         DieWithError('Argument "%s" is not a file or a directory' % arg)
   else:
     diff_cmd.extend('*' + ext for ext in extensions)
 
   return diff_cmd
 
 
 @subcommand.usage('[files or directories to diff]')
 def CMDformat(parser, args):
-  """Runs clang-format on the diff."""
+  """Runs auto-formatting tools (clang-format etc.) on the diff."""
   CLANG_EXTS = ['.cc', '.cpp', '.h', '.mm', '.proto', '.java']
   parser.add_option('--full', action='store_true',
                     help='Reformat the full content of all touched files')
   parser.add_option('--dry-run', action='store_true',
                     help='Don\'t modify any file on disk.')
+  parser.add_option('--python', action='store_true',
+                    help='Format python code with yapf (experimental).')
   parser.add_option('--diff', action='store_true',
                     help='Print diff to stdout rather than modifying files.')
   opts, args = parser.parse_args(args)
 
   # git diff generates paths against the root of the repository.  Change
   # to that directory so clang-format can find files even within subdirs.
   rel_base_path = settings.GetRelativeRoot()
   if rel_base_path:
     os.chdir(rel_base_path)
 
   # Grab the merge-base commit, i.e. the upstream commit of the current
   # branch when it was created or the last time it was rebased. This is
   # to cover the case where the user may have called "git fetch origin",
   # moving the origin branch to a newer commit, but hasn't rebased yet.
   upstream_commit = None
   cl = Changelist()
   upstream_branch = cl.GetUpstreamBranch()
   if upstream_branch:
     upstream_commit = RunGit(['merge-base', 'HEAD', upstream_branch])
     upstream_commit = upstream_commit.strip()
 
   if not upstream_commit:
     DieWithError('Could not find base commit for this branch. '
                  'Are you in detached state?')
 
   if opts.full:
     # Only list the names of modified files.
-    clang_diff_type = '--name-only'
+    diff_type = '--name-only'
   else:
     # Only generate context-less patches.
-    clang_diff_type = '-U0'
+    diff_type = '-U0'
 
-  diff_cmd = BuildGitDiffCmd(clang_diff_type, upstream_commit, args, CLANG_EXTS)
+  diff_cmd = BuildGitDiffCmd(diff_type, upstream_commit, args, CLANG_EXTS)
   diff_output = RunGit(diff_cmd)
 
   top_dir = os.path.normpath(
       RunGit(["rev-parse", "--show-toplevel"]).rstrip('\n'))
 
   # Locate the clang-format binary in the checkout
   try:
     clang_format_tool = clang_format.FindClangFormatToolInChromiumTree()
   except clang_format.NotFoundError, e:
     DieWithError(e)
@@ skipping 25 matching lines @@
     cmd = [sys.executable, script, '-p0']
     if not opts.dry_run and not opts.diff:
       cmd.append('-i')
 
     stdout = RunCommand(cmd, stdin=diff_output, cwd=top_dir, env=env)
     if opts.diff:
       sys.stdout.write(stdout)
     if opts.dry_run and len(stdout) > 0:
       return_value = 2
 
+  # Similar code to above, but using yapf on .py files rather than clang-format
+  # on C/C++ files
+  if opts.python:
+    diff_cmd = BuildGitDiffCmd(diff_type, upstream_commit, args, ['.py'])
+    diff_output = RunGit(diff_cmd)
+    yapf_tool = gclient_utils.FindExecutable('yapf')
+    if yapf_tool is None:
+      DieWithError('yapf not found in PATH')
+
+    if opts.full:
+      files = diff_output.splitlines()
+      if files:
+        cmd = [yapf_tool]
+        if not opts.dry_run and not opts.diff:
+          cmd.append('-i')
+        stdout = RunCommand(cmd + files, cwd=top_dir)
+        if opts.diff:
+          sys.stdout.write(stdout)
+    else:
+      # TODO(sbc): yapf --lines mode still has some issues.
+      # https://github.com/google/yapf/issues/154
+      DieWithError('--python currently only works with --full')
+
   # Build a diff command that only operates on dart files. dart's formatter
   # does not have the nice property of only operating on modified chunks, so
   # hard code full.
   dart_diff_cmd = BuildGitDiffCmd('--name-only', upstream_commit,
                                   args, ['.dart'])
   dart_diff_output = RunGit(dart_diff_cmd)
   if dart_diff_output:
     try:
       command = [dart_format.FindDartFmtToolInChromiumTree()]
       if not opts.dry_run and not opts.diff:
@@ skipping 65 matching lines @@
 if __name__ == '__main__':
   # These affect sys.stdout so do it outside of main() to simplify mocks in
   # unit testing.
   fix_encoding.fix_encoding()
   colorama.init()
   try:
     sys.exit(main(sys.argv[1:]))
   except KeyboardInterrupt:
     sys.stderr.write('interrupted\n')
     sys.exit(1)