features_bundle.py revision 4e180b6a0b4720a9b8e9e959a882386f690f08ff 
1# Copyright 2013 The Chromium Authors. All rights reserved.
2# Use of this source code is governed by a BSD-style license that can be
3# found in the LICENSE file.
4
5import features_utility
6import svn_constants
7from third_party.json_schema_compiler.json_parse import Parse
8
9
10def _AddPlatformsFromDependencies(feature, features_bundle):
11  features_map = {
12    'api': features_bundle.GetAPIFeatures(),
13    'manifest': features_bundle.GetManifestFeatures(),
14    'permission': features_bundle.GetPermissionFeatures()
15  }
16  dependencies = feature.get('dependencies')
17  if dependencies is None:
18    return ['apps', 'extensions']
19  platforms = set()
20  for dependency in dependencies:
21    dep_type, dep_name = dependency.split(':')
22    dependency_features = features_map[dep_type]
23    dependency_feature = dependency_features.get(dep_name)
24    # If the dependency can't be resolved, it is inaccessible and therefore
25    # so is this feature.
26    if dependency_feature is None:
27      return []
28    platforms = platforms.union(dependency_feature['platforms'])
29  feature['platforms'] = list(platforms)
30
31
32class _FeaturesCache(object):
33  def __init__(self, file_system, compiled_fs_factory, *json_paths):
34    self._file_system = file_system
35    self._cache = compiled_fs_factory.Create(
36        file_system, self._CreateCache, type(self))
37    self._json_path = json_paths[0]
38    self._extra_paths = json_paths[1:]
39
40  def _CreateCache(self, _, features_json):
41    features = features_utility.Parse(Parse(features_json))
42    for path in self._extra_paths:
43      extra_json = self._file_system.ReadSingle(path).Get()
44      features = features_utility.MergedWith(
45          features_utility.Parse(Parse(extra_json)), features)
46    return features
47
48  def GetFeatures(self):
49    if self._json_path is None:
50      return {}
51    return self._cache.GetFromFile(self._json_path).Get()
52
53
54class FeaturesBundle(object):
55  '''Provides access to properties of API, Manifest, and Permission features.
56  '''
57  def __init__(self, file_system, compiled_fs_factory, object_store_creator):
58    self._api_cache = _FeaturesCache(
59        file_system,
60        compiled_fs_factory,
61        svn_constants.API_FEATURES_PATH)
62    self._manifest_cache = _FeaturesCache(
63        file_system,
64        compiled_fs_factory,
65        svn_constants.MANIFEST_FEATURES_PATH,
66        svn_constants.MANIFEST_JSON_PATH)
67    self._permission_cache = _FeaturesCache(
68        file_system,
69        compiled_fs_factory,
70        svn_constants.PERMISSION_FEATURES_PATH,
71        svn_constants.PERMISSIONS_JSON_PATH)
72    self._object_store = object_store_creator.Create(_FeaturesCache, 'features')
73
74  def GetPermissionFeatures(self):
75    return self._permission_cache.GetFeatures()
76
77  def GetManifestFeatures(self):
78    return self._manifest_cache.GetFeatures()
79
80  def GetAPIFeatures(self):
81    api_features = self._object_store.Get('api_features').Get()
82    if api_features is None:
83      api_features = self._api_cache.GetFeatures()
84      # TODO(rockot): Handle inter-API dependencies more gracefully.
85      # Not yet a problem because there is only one such case (windows -> tabs).
86      # If we don't store this value before annotating platforms, inter-API
87      # dependencies will lead to infinite recursion.
88      self._object_store.Set('api_features', api_features)
89      for feature in api_features.itervalues():
90        _AddPlatformsFromDependencies(feature, self)
91      self._object_store.Set('api_features', api_features)
92    return api_features
93