git map: Add -h, --help option

git_map.py

 #!/usr/bin/env python
 # Copyright 2014 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.
 
 """
-Provides an augmented `git log --graph` view. In particular, it also annotates
-commits with branches + tags that point to them. Items are colorized as follows:
+Enhances `git log --graph` view with information on commit branches + tags that
+point to them. Items are colorized as follows:
+
   * Cyan    - Currently checked out branch
   * Green   - Local branch
   * Red     - Remote branches
   * Magenta - Tags
   * White   - Merge Base Markers
   * Blue background - The currently checked out commit
 """
 
 import sys
 
@@ skipping 11 matching lines @@
 WHITE = colorama.Fore.WHITE
 
 BLUEBAK = colorama.Back.BLUE
 
 BRIGHT = colorama.Style.BRIGHT
 RESET = colorama.Fore.RESET + colorama.Back.RESET + colorama.Style.RESET_ALL
 
 # Git emits combined color
 BRIGHT_RED = '\x1b[1;31m'
 
+
+def print_help():
+  names = {
+    'Cyan': CYAN,
+    'Green': GREEN,
+    'Magenta': MAGENTA,
+    'Red': RED,
+    'White': WHITE,
+    'Blue background': BLUEBAK,
+  }
+  msg = "usage: git map [-h] [<args>]\n"
+
+  for line in __doc__.splitlines():
+    for key in names.keys():
+      if key in line:
+        msg += line.replace('* ', '* ' + names[key])+RESET+'\n'
+        break
+    else:
+      msg += line + '\n'
+  sys.stdout.write(msg)
+
+
 def main(argv):
+  if '-h' in argv:
+    print_help()
+    return 0
+
   map_extra = get_config_list('depot_tools.map_extra')
   fmt = '%C(red bold)%h%x09%Creset%C(green)%d%Creset %C(yellow)%ad%Creset ~ %s'
   log_proc = subprocess2.Popen(
     [GIT_EXE, 'log', '--graph', '--branches', '--tags', root(),
      '--color=always', '--date=short', ('--pretty=format:' + fmt)
     ] + map_extra + argv,
     stdout=subprocess2.PIPE,
     shell=False)
 
   current = current_branch()
@@ skipping 57 matching lines @@
     sys.stdout.close()
   return 0
 
 
 if __name__ == '__main__':
   try:
     sys.exit(main(sys.argv[1:]))
   except KeyboardInterrupt:
     sys.stderr.write('interrupted\n')
     sys.exit(1)