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# Copyright 2019 The Chromium Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
import json5
class RuntimeEnabledFeatures(object):
"""Represents a set of definitions of runtime enabled features."""
_REQUIRE_INIT_MESSAGE = (
"RuntimeEnabledFeatures.init must be called in advance.")
_is_initialized = False
@classmethod
def init(cls, filepaths):
"""
Args:
filepaths: Paths to the definition files of runtime-enabled features
("runtime_enabled_features.json5").
"""
assert not cls._is_initialized
assert isinstance(filepaths, list)
assert all(isinstance(filepath, str) for filepath in filepaths)
cls._features = {}
for filepath in filepaths:
with open(filepath, encoding='utf-8') as file_obj:
datastore = json5.load(file_obj)
for entry in datastore["data"]:
assert entry["name"] not in cls._features
cls._features[entry["name"]] = entry
cls._is_initialized = True
@classmethod
def is_context_dependent(cls, feature_name):
"""Returns True if the feature may be enabled per-context."""
return (cls.is_browser_controlled(feature_name)
or cls.is_origin_trial(feature_name))
@classmethod
def is_browser_controlled(cls, feature_name):
"""Returns True if the feature can be controlled by the browser."""
assert cls._is_initialized, cls._REQUIRE_INIT_MESSAGE
assert isinstance(feature_name, str)
assert feature_name in cls._features, (
"Unknown runtime-enabled feature: {}".format(feature_name))
value = cls._features[feature_name].get(
"browser_process_read_write_access", False)
assert isinstance(value, bool)
return value
@classmethod
def is_origin_trial(cls, feature_name):
"""Returns True if the feature is an origin trial."""
assert cls._is_initialized, cls._REQUIRE_INIT_MESSAGE
assert isinstance(feature_name, str)
assert feature_name in cls._features, (
"Unknown runtime-enabled feature: {}".format(feature_name))
return cls._features[feature_name].get(
"origin_trial_feature_name") is not None
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