deps2git: Add support for overriding DEPS vars

deps2git.py

 #!/usr/bin/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.
 
 """Convert SVN based DEPS into .DEPS.git for use with NewGit."""
 
 import collections
 from cStringIO import StringIO
 import json
@@ skipping 262 matching lines @@
   message_th.start()
 
   for th in threads:
     th.join()
   message_q.put(Queue.Empty)
   message_th.join()
 
   return results
 
 
+def convert_json(option, _, value, parser):
+  """Provide an OptionParser callback to unmarshal a JSON string."""
+  setattr(parser.values, option.dest, json.loads(value))
+
+
 def main():
   parser = optparse.OptionParser()
   parser.add_option('-d', '--deps', default='DEPS',
                     help='path to the DEPS file to convert')
   parser.add_option('-o', '--out',
                     help='path to the converted DEPS file (default: stdout)')
   parser.add_option('-j', '--num-threads', type='int', default=4,
                     help='Maximum number of threads')
   parser.add_option('-t', '--type',
                     help='[DEPRECATED] type of DEPS file (public, etc)')
   parser.add_option('-x', '--extra-rules',
                     help='Path to file with additional conversion rules.')
   parser.add_option('-r', '--repos',
                     help='path to the directory holding all the Git repos')
   parser.add_option('-w', '--workspace', metavar='PATH',
                     help='top level of a git-based gclient checkout')
   parser.add_option('-c', '--cache_dir',
                     help='top level of a gclient git cache diretory.')
   parser.add_option('-s', '--shallow', action='store_true',
                     help='Use shallow checkouts when populating cache dirs.')
+  parser.add_option('--var_overrides', action='callback', callback=convert_json,
+                    type='string', default=None,
+                    help='A dict in JSON format containing key-value pairs '
+                         'that will override variables used in the DEPS file.')
   parser.add_option('--no_fail_fast', action='store_true',
                     help='Try to process the whole DEPS, rather than failing '
                     'on the first bad entry.')
   parser.add_option('--verify', action='store_true',
                     help='ping each Git repo to make sure it exists')
   parser.add_option('--json',
                     help='path to a JSON file for machine-readable output')
   options = parser.parse_args()[0]
 
   # Get the content of the DEPS file.
   deps, deps_os, include_rules, skip_child_includes, hooks, deps_vars = (
-      deps_utils.GetDepsContent(options.deps))
+      deps_utils.GetDepsContent(options.deps, options.var_overrides))
 
   if options.extra_rules and options.type:
     parser.error('Can\'t specify type and extra-rules at the same time.')
   elif options.type:
     options.extra_rules = os.path.join(
         os.path.abspath(os.path.dirname(__file__)),
         'svn_to_git_%s.py' % options.type)
   if options.cache_dir and options.repos:
     parser.error('Can\'t specify both cache_dir and repos at the same time.')
   if options.shallow and not options.cache_dir:
@@ skipping 101 matching lines @@
     return 0
 
   # Write the DEPS file to disk.
   deps_utils.WriteDeps(options.out, deps_vars, results.new_deps, deps_os,
                        include_rules, skip_child_includes, hooks)
   return 0
 
 
 if '__main__' == __name__:
   sys.exit(main())