Lazily load API schemas from resource files and convert all APIs to features

tools/json_schema_compiler/cpp_bundle_generator.py

 # 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.
 
 import code
 import cpp_util
 from model import Platforms
 from schema_util import CapitalizeFirstLetter
 from schema_util import JsFunctionNameToClassName
 
@@ skipping 197 matching lines @@
     c = code.Code()
     c.Append('#include <map>')
     c.Append('#include <string>')
     c.Append();
     c.Append('#include "base/strings/string_piece.h"')
     c.Append()
     c.Concat(cpp_util.OpenNamespace(self._bundle._cpp_namespace))
     c.Append()
     c.Append('class GeneratedSchemas {')
     c.Sblock(' public:')
-    c.Append('// Puts all API schemas in |schemas|.')
-    c.Append('static void Get('
-                 'std::map<std::string, base::StringPiece>* schemas);')
+    c.Append('// Determines if schema named |name| is generated.')
+    c.Append('static bool IsGenerated(std::string name);')
+    c.Append()
+    c.Append('// Gets the API schema named |name|.')
+    c.Append('static base::StringPiece Get(const std::string& name);')
     c.Eblock('};');
     c.Append()
     c.Concat(cpp_util.CloseNamespace(self._bundle._cpp_namespace))
     return self._bundle._GenerateHeader('generated_schemas', c)
 
+def _FormatNameAsConstant(name):
+  """Formats a name to be a C++ constant of the form kConstantName"""
+  return 'k%s' % re.sub('_[a-z]',
+                        lambda m: m.group(0)[1].upper(),
+                        name.replace('.', '_').capitalize())
+
 class _SchemasCCGenerator(object):
   """Generates a code.Code object for the generated schemas .cc file"""
 
   def __init__(self, cpp_bundle):
     self._bundle = cpp_bundle
 
   def Generate(self, namespace):
     c = code.Code()
     c.Append(cpp_util.CHROMIUM_LICENSE)
     c.Append()
     c.Append('#include "%s"' % (os.path.join(SOURCE_BASE_PATH,
                                              'generated_schemas.h')))
     c.Append()
-    c.Concat(cpp_util.OpenNamespace(self._bundle._cpp_namespace))
+    c.Append('#include "base/lazy_instance.h"')
     c.Append()
-    c.Append('// static')
-    c.Sblock('void GeneratedSchemas::Get('
-                 'std::map<std::string, base::StringPiece>* schemas) {')
+    c.Append('namespace {')
     for api in self._bundle._api_defs:
       namespace = self._bundle._model.namespaces[api.get('namespace')]
       # JSON parsing code expects lists of schemas, so dump a singleton list.
       json_content = json.dumps([_RemoveDescriptions(api)],
                                 separators=(',', ':'))
       # Escape all double-quotes and backslashes. For this to output a valid
       # JSON C string, we need to escape \ and ".
       json_content = json_content.replace('\\', '\\\\').replace('"', '\\"')
-      c.Append('(*schemas)["%s"] = "%s";' % (namespace.name, json_content))
+      c.Append('const char %s[] = "%s";' %
+          (_FormatNameAsConstant(namespace.name), json_content))
+    c.Append('}')
+    c.Concat(cpp_util.OpenNamespace(self._bundle._cpp_namespace))
+    c.Append()
+    c.Sblock('struct Static {')
+    c.Sblock('Static() {')
+    for api in self._bundle._api_defs:
+      namespace = self._bundle._model.namespaces[api.get('namespace')]
+      c.Append('schemas["%s"] = %s;' % (namespace.name,
+                                        _FormatNameAsConstant(namespace.name)))
+    c.Eblock('}');
+    c.Append()
+    c.Append('std::map<std::string, const char*> schemas;')
+    c.Eblock('};');
+    c.Append()
+    c.Append('base::LazyInstance<Static> g_lazy_instance;')
+    c.Append()
+    c.Append('// static')
+    c.Sblock('base::StringPiece GeneratedSchemas::Get('
+                  'const std::string& name) {')
+    c.Append('return IsGenerated(name) ? '
+             'g_lazy_instance.Get().schemas[name] : "";')
+    c.Eblock('}')
+    c.Append()
+    c.Append('// static')
+    c.Sblock('bool GeneratedSchemas::IsGenerated(std::string name) {')
+    c.Append('return g_lazy_instance.Get().schemas.count(name) > 0;')

[not at google - send to devlin, 2013/05/24 19:09:18]

hey could you post on gist what the output generated for this looks like?

[cduvall, 2013/05/30 00:50:51]

https://gist.github.com/anonymous/5667331

     c.Eblock('}')
     c.Append()
     c.Concat(cpp_util.CloseNamespace(self._bundle._cpp_namespace))
     c.Append()
     return c