Lazily load extension API schemas

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.
@@ skipping 30 matching lines @@
     api_defs = idl_schema.Load(schema)
   else:
     sys.exit('Did not recognize file extension %s for schema %s' %
              (schema_extension, schema))
   if len(api_defs) != 1:
     sys.exit('File %s has multiple schemas. Files are only allowed to contain a'
              ' single schema.' % schema)
 
   return api_defs
 
+class TypeNamespaceResolver(object):

[not at google - send to devlin, 2013/03/22 22:10:12]

pull into separate file?

[cduvall, 2013/03/22 22:52:29]

Done.

+  '''Resolves a type name into the namespace the type belongs to.
+  '''
+  def __init__(self, api_path):
+    self._api_path = api_path
+
+  def Resolve(self, full_name, default_namespace):
+    name_parts = full_name.rsplit('.', 1)
+    if len(name_parts) == 1:
+      if full_name not in default_namespace.types:
+        return None

[not at google - send to devlin, 2013/03/22 22:10:12]

can this be an assertion?

[cduvall, 2013/03/22 22:52:29]

Still returning None, to be handled in CppTypeGenerator.

+      return default_namespace
+    namespace_name, type_name = name_parts
+    json_name = '%s.json' % namespace_name
+    idl_name = '%s.idl' % namespace_name
+    if os.path.exists(json_name):
+      real_name = json_name
+    elif os.path.exists(idl_name):
+      real_name = idl_name
+    else:
+      return None

[not at google - send to devlin, 2013/03/22 22:10:12]

I think a structure like

real_name = None
for ext in ['json, 'idl']:
  ...
assert(real_name is not None,
       'Cannot find schema for %s' % namespace_name)

or something like that would be a bit nicer.

[cduvall, 2013/03/22 22:52:29]

Done.

+    namespace = Model().AddNamespace(_LoadSchema(real_name)[0],
+                                     os.path.join(self._api_path, real_name))
+    if type_name not in namespace.types:
+      return None

[not at google - send to devlin, 2013/03/22 22:10:12]

can this be an assertion?

[cduvall, 2013/03/22 22:52:29]

Same as above.

+    return namespace
+
 def GenerateSchema(generator,
                    filenames,
                    root,
                    destdir,
                    root_namespace,
                    dart_overrides_dir):
   # Merge the source files into a single list of schemas.
   api_defs = []
   for filename in filenames:
     schema = os.path.normpath(filename)
     schema_filename, schema_extension = os.path.splitext(schema)
     path, short_filename = os.path.split(schema_filename)
     api_def = _LoadSchema(schema)
 
     # If compiling the C++ model code, delete 'nocompile' nodes.
     if generator == 'cpp':
       api_def = json_schema.DeleteNodes(api_def, 'nocompile')
     api_defs.extend(api_def)
 
   api_model = Model()
-
-  # Load type dependencies into the model.
-  #
-  # HACK(kalman): bundle mode doesn't work with dependencies, because not all
-  # schemas work in bundle mode.
-  #
-  # TODO(kalman): load dependencies lazily (get rid of the 'dependencies' list)
-  # and this problem will go away.
-  if generator != 'cpp-bundle':
-    for target_namespace in api_defs:
-      for referenced_schema in target_namespace.get('dependencies', []):
-        split_schema = referenced_schema.split(':', 1)
-        if len(split_schema) > 1:
-          if split_schema[0] != 'api':
-            continue
-          else:
-            referenced_schema = split_schema[1]
-
-        referenced_schema_path = os.path.join(
-            os.path.dirname(schema), '%s.json' % UnixName(referenced_schema))
-        referenced_api_defs = json_schema.Load(referenced_schema_path)
-
-        for namespace in referenced_api_defs:
-          api_model.AddNamespace(
-              namespace,
-              os.path.relpath(referenced_schema_path, root),
-              include_compiler_options=True)
+  type_namespace_resolver = TypeNamespaceResolver(
+      os.path.dirname(os.path.relpath(schema, root)))
 
   # For single-schema compilation make sure that the first (i.e. only) schema
   # is the default one.
   default_namespace = None
 
   # Load the actual namespaces into the model.
   for target_namespace, schema_filename in zip(api_defs, filenames):
     relpath = os.path.relpath(os.path.normpath(schema_filename), root)
     namespace = api_model.AddNamespace(target_namespace,
                                        relpath,
@@ skipping 10 matching lines @@
     if namespace.unix_name != short_filename:
       sys.exit("Filename %s is illegal. Name files using unix_hacker style." %
                schema_filename)
 
     # The output filename must match the input filename for gyp to deal with it
     # properly.
     out_file = namespace.unix_name
 
   # Construct the type generator with all the namespaces in this model.
   type_generator = CppTypeGenerator(api_model,
+                                    type_namespace_resolver,
                                     default_namespace=default_namespace)
 
   if generator == 'cpp-bundle':
     cpp_bundle_generator = CppBundleGenerator(root,
                                               api_model,
                                               api_defs,
                                               type_generator,
                                               root_namespace)
     generators = [
       ('generated_api.cc', cpp_bundle_generator.api_cc_generator),
@@ skipping 52 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