Mojo: Mojom: Add flag to force using bundled Python modules.

mojo/public/tools/bindings/mojom_bindings_generator.py

 #!/usr/bin/env python
 # Copyright 2013 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.
 
 """The frontend for the Mojo bindings system."""
 
 
 import argparse
 import imp
 import os
 import pprint
 import sys
 
 # Disable lint check for finding modules:
 # pylint: disable=F0401
 
-script_dir = os.path.dirname(os.path.abspath(__file__))
-sys.path.insert(0, os.path.join(script_dir, "pylib"))
+def _GetDirAbove(dirname):
+  """Returns the directory "above" this file containing |dirname| (which must
+  also be "above" this file)."""
+  path = os.path.abspath(__file__)
+  while True:
+    path, tail = os.path.split(path)
+    assert tail
+    if tail == dirname:
+      return path
+
+# Manually check for the command-line flag. (This isn't quite right, since it
+# ignores, e.g., "--", but it's close enough.)
+if "--use_chromium_bundled_pylibs" in sys.argv[1:]:
+  sys.path.insert(0, os.path.join(_GetDirAbove("mojo"), "third_party"))
+
+sys.path.insert(0, os.path.join(os.path.dirname(os.path.abspath(__file__)),
+                                "pylib"))
 
 from mojom.error import Error
 from mojom.generate.data import OrderedModuleFromData
 from mojom.parse.parser import Parse
 from mojom.parse.translate import Translate
 
 
 def LoadGenerators(generators_string):
   if not generators_string:
     return []  # No generators.
 
+  script_dir = os.path.dirname(os.path.abspath(__file__))
   generators = []
   for generator_name in [s.strip() for s in generators_string.split(",")]:
     # "Built-in" generators:
     if generator_name.lower() == "c++":
       generator_name = os.path.join(script_dir, "generators",
                                     "mojom_cpp_generator.py")
     elif generator_name.lower() == "javascript":
       generator_name = os.path.join(script_dir, "generators",
                                     "mojom_js_generator.py")
     # Specified generator python module:
@@ skipping 71 matching lines @@
   for generator_module in generator_modules:
     generator = generator_module.Generator(module, args.output_dir)
     generator.GenerateFiles()
 
   # Save result.
   _processed_files[filename] = module
   return module
 # pylint: enable=W0102
 
 
-def Main():
+def main():
   parser = argparse.ArgumentParser(
       description="Generate bindings from mojom files.")
   parser.add_argument("filename", nargs="+",
                       help="mojom input file")
   parser.add_argument("-d", "--depth", dest="depth", default=".",
                       help="depth from source root")
   parser.add_argument("-o", "--output_dir", dest="output_dir", default=".",
                       help="output directory for generated files")
   parser.add_argument("-g", "--generators", dest="generators_string",
                       metavar="GENERATORS", default="c++,javascript",
                       help="comma-separated list of generators")
   parser.add_argument("--debug_print_intermediate", action="store_true",
                       help="print the intermediate representation")
+  parser.add_argument("--use_chromium_bundled_pylibs", action="store_true",
+                      help="use Python modules bundled in the Chromium source")
   args = parser.parse_args()
 
   generator_modules = LoadGenerators(args.generators_string)
 
   if not os.path.exists(args.output_dir):
     os.makedirs(args.output_dir)
 
   for filename in args.filename:
     ProcessFile(args, generator_modules, filename)
 
   return 0
 
 
 if __name__ == "__main__":
-  sys.exit(Main())
+  sys.exit(main())