Generate externs automatically from json/idl files.

tools/json_schema_compiler/compiler.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.
 """Generator for C++ structs from api json files.
 
 The purpose of this tool is to remove the need for hand-written code that
 converts to and from base::Value types when receiving javascript api calls.
 Originally written for generating code for extension apis. Reference schemas
 are in chrome/common/extensions/api.
 
 Usage example:
   compiler.py --root /home/Work/src --namespace extensions windows.json
     tabs.json
   compiler.py --destdir gen --root /home/Work/src
     --namespace extensions windows.json tabs.json
 """
 
 import optparse
 import os
 import sys
 
 from cpp_bundle_generator import CppBundleGenerator
 from cpp_generator import CppGenerator
 from cpp_type_generator import CppTypeGenerator
 from dart_generator import DartGenerator
+from js_externs_generator import JsExternsGenerator
 import json_schema
 from model import Model, UnixName
 from schema_loader import SchemaLoader
 
 # Names of supported code generators, as specified on the command-line.
 # First is default.
-GENERATORS = ['cpp', 'cpp-bundle', 'dart']
+GENERATORS = ['cpp', 'cpp-bundle', 'dart', 'externs']
 
 def GenerateSchema(generator,
                    filenames,
                    root,
                    destdir,
                    root_namespace,
                    dart_overrides_dir):
   schema_loader = SchemaLoader(os.path.dirname(os.path.relpath(
       os.path.normpath(filenames[0]), root)))
   # Merge the source files into a single list of schemas.
@@ skipping 59 matching lines @@
     cpp_generator = CppGenerator(type_generator, root_namespace)
     generators = [
       ('%s.h' % namespace.unix_name, cpp_generator.h_generator),
       ('%s.cc' % namespace.unix_name, cpp_generator.cc_generator)
     ]
   elif generator == 'dart':
     generators = [
       ('%s.dart' % namespace.unix_name, DartGenerator(
           dart_overrides_dir))
     ]
+  elif generator == 'externs':
+    generators = [
+      ('%s_externs.js' % namespace.unix_name, JsExternsGenerator())
+    ]
   else:
     raise Exception('Unrecognised generator %s' % generator)
 
   output_code = []
   for filename, generator in generators:
     code = generator.Generate(namespace).Render()
     if destdir:
       with open(os.path.join(destdir, namespace.source_file_dir,
           filename), 'w') as f:
         f.write(code)
@@ skipping 27 matching lines @@
   # Unless in bundle mode, only one file should be specified.
   if opts.generator != 'cpp-bundle' and len(filenames) > 1:
     # TODO(sashab): Could also just use filenames[0] here and not complain.
     raise Exception(
         "Unless in bundle mode, only one file can be specified at a time.")
 
   result = GenerateSchema(opts.generator, filenames, opts.root, opts.destdir,
                           opts.namespace, opts.dart_overrides_dir)
   if not opts.destdir:
     print result