Docserver: Consolidate features caching and access.

chrome/common/extensions/docs/server2/api_features.py

+# Copyright 2013 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.
+
+from copy import deepcopy
+
+from features import Features
+import features_utility
+from third_party.json_schema_compiler.json_parse import Parse
+
+def _GetExtensionTypesRecursive(feature, feature_set):
+  extension_types = feature.get('extension_types')
+  if extension_types is None:
+    dependencies = feature.get('dependencies')
+    # No specific constraints == available on all platforms!

[not at google - send to devlin, 2013/09/23 18:31:30]

this... should never happen. but what *can* happen here is an 'all' keyword I
think.

+    if dependencies is None:
+      return set(('platform_app', 'extension'))
+    extension_types = set()
+    for dependency in dependencies:
+      dep_type, dep_name = dependency.split(':')
+      dependency_features = feature_set[dep_type]
+      dependency_feature = dependency_features.get(dep_name)
+      # If the dependency can't be resolved, it is inaccessible and therefore
+      # so is this API feature.
+      if dependency_feature is None:
+        return set()
+      extension_types = extension_types.union(
+          _GetExtensionTypesRecursive(dependency_features.get(dep_name),
+                                      feature_set))
+  return set(extension_types)
+
+class APIFeatures(Features):
+  '''Subclass of Features that can dig into dependencies to deduce the feature's
+  supported extension types.
+  '''
+  def __init__(self,
+               compiled_fs_factory,
+               api_features_path,
+               manifest_features,
+               permission_features):
+    self._manifest_features = manifest_features
+    self._permission_features = permission_features
+    super(APIFeatures, self).__init__(compiled_fs_factory, api_features_path)
+
+  def FilterByPlatform(self, features, platform):
+    '''Filter API features by supported platform using data from feature
+    dependencies if necessary.'''
+    feature_set = {
+      'api': features,
+      'manifest': self._manifest_features.get('all'),
+      'permission': self._permission_features.get('all'),
+    }
+    filtered_features = {}
+    for name, feature in features.iteritems():
+      platforms = features_utility.GetPlatformSetForExtensionTypes(
+          _GetExtensionTypesRecursive(feature, feature_set))
+      if not platform or platform in platforms:
+        filtered_features[name] = deepcopy(feature)
+    return filtered_features