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 189 matching lines @@
     return c
 
 class _SchemasHGenerator(object):
   """Generates a code.Code object for the generated schemas .h file"""
   def __init__(self, cpp_bundle):
     self._bundle = cpp_bundle
 
   def Generate(self, namespace):
     c = code.Code()
     c.Append('#include <map>')
+    c.Append('#include <set>')
     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('// Puts names for all the schemas in |schemas|.')
+    c.Append('static void GetNames(std::set<std::string>* names);')
+    c.Append('// Determines if schema named |name| is generated.')
+    c.Append('static bool IsGenerated(std::string name);')
+    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)
 
 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()
     c.Append('// static')
-    c.Sblock('void GeneratedSchemas::Get('
-                 'std::map<std::string, base::StringPiece>* schemas) {')
+    c.Sblock('void GeneratedSchemas::GetNames(std::set<std::string>* names) {')
+    for api in self._bundle._api_defs:
+      namespace = self._bundle._model.namespaces[api.get('namespace')]
+      c.Append('names->insert("%s");' % namespace.name)
+    c.Eblock('}')
+    c.Append()
+    c.Append('// static')
+    c.Sblock('bool GeneratedSchemas::IsGenerated(std::string name) {')
+    for api in self._bundle._api_defs:
+      namespace = self._bundle._model.namespaces[api.get('namespace')]
+      c.Append('if (name == "%s")' % namespace.name)
+      c.Append('  return true;')
+    c.Append('return false;')
+    c.Eblock('}')
+    c.Append()
+    c.Append('// static')
+    c.Sblock('base::StringPiece GeneratedSchemas::Get('
+                  'const std::string& name) {')

[not at google - send to devlin, 2013/05/20 17:19:04]

This is all a bit inefficient:
1 - GetNames returning a new set is O(log n) insertion, if it were a vector it'd
be O(1). it also recreates the set each time when it's a constant value.
2 - IsGenerated looks to be O(n), if it were a binary search it'd be O(log n).

... I actually wrote a long comment here about GetNames etc but now I realise
that we shouldn't need this method at all; ExtensionAPI::GetAllAPINames can be
entirely implemented from the features file. I guess you need a way to express
that something in the file isn't an API but rather a method of one - but that's
doable.

While we're here though; you're right that ::Get should just return a
StringPiece. I think that this class needs to be a LazyInstance which holds onto
its schema in a std::map and returns from it, rather than creating a bunch of
data each time.

[cduvall, 2013/05/22 03:19:56]

I made a lazily initialized map of name -> schema (as a const char[]), and the
map is then accessed for ::Get and ::IsGenerated.

     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.Sblock('if (name == "%s") {' % namespace.name)
+      c.Append('return "%s";' % json_content)
+      c.Eblock('}')
+    c.Append('return "";');
     c.Eblock('}')
     c.Append()
     c.Concat(cpp_util.CloseNamespace(self._bundle._cpp_namespace))
     c.Append()
     return c