Mojo: Simplify typemap usage.

mojo/public/tools/bindings/generate_type_mappings.py

Index: mojo/public/tools/bindings/generate_type_mappings.py
diff --git a/mojo/public/tools/bindings/generate_type_mappings.py b/mojo/public/tools/bindings/generate_type_mappings.py
new file mode 100644
index 0000000000000000000000000000000000000000..103410d7f4a9961c754ed2a561945359e5db6cd2
--- /dev/null
+++ b/mojo/public/tools/bindings/generate_type_mappings.py
@@ -0,0 +1,57 @@
+# Copyright 2016 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.
+
+import argparse
+import os
+import json
+
+
+def ReadTypemap(path):
+  with open(path) as f:
+    return json.load(f)['c++']
+
+
+def ParseTypemapArgs(args):
+  typemaps = [s for s in '\n'.join(args).split('--start-typemap\n') if s]
+  result = {}
+  for typemap in typemaps:
+    result.update(ParseTypemap(typemap))
+  return result
+
+
+def ParseTypemap(typemap):
+  values = {'type_mappings': [], 'public_headers': [], 'traits_headers': []}
+  for line in typemap.split('\n'):
+    if not line:
+      continue
+    key, _, value = line.partition('=')
+    values[key].append(value.lstrip('/'))
+  result = {}
+  for typename in values['type_mappings']:
+    mojom_type, _, native_type = typename.partition('=')
+    result[mojom_type] = {
+        'typename': native_type,
+        'public_headers': values['public_headers'],
+        'traits_headers': values['traits_headers'],
+    }
+  return result
+
+
+def main():
+  parser = argparse.ArgumentParser()
+  parser.add_argument('--dependency', type=str, action='append', default=[])
+  parser.add_argument('--output', type=str, required=True)
+  params, typemap_params = parser.parse_known_args()
+  typemaps = ParseTypemapArgs(typemap_params)
+  missing = [path for path in params.dependency if not os.path.exists(path)]
+  if missing:
+    raise IOError('Missing dependencies: %s' % ', '.join(missing))
+  for path in params.dependency:
+    typemaps.update(ReadTypemap(path))
+  with open(params.output, 'w') as f:
+    json.dump({'c++': typemaps}, f)
+
+
+if __name__ == '__main__':
+  main()