| // Copyright 2018 Google Inc. All Rights Reserved. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| import 'dart:async'; |
| |
| import 'clock.dart'; |
| |
| /// The key for the [Zone] value that controls the current implementation of |
| /// [clock]. |
| final _clockKey = new Object(); |
| |
| /// The key for the [Zone] value that controls whether nested zones can override |
| /// [clock]. |
| final _isFinalKey = new Object(); |
| |
| /// The default implementation of [clock] for the current [Zone]. |
| /// |
| /// This defaults to the system clock. It can be set within a zone using |
| /// [withClock]. |
| Clock get clock => Zone.current[_clockKey] ?? const Clock(); |
| |
| /// Runs [callback] with the given value for the top-level [clock] field. |
| /// |
| /// This is [Zone]-scoped, so asynchronous callbacks spawned within [callback] |
| /// will also use the new value for [clock]. |
| /// |
| /// If [isFinal] is `true`, calls to [withClock] within [callback] will throw a |
| /// [StateError]. However, this parameter is deprecated and should be avoided. |
| T withClock<T>(Clock clock, T callback(), {@deprecated bool isFinal: false}) { |
| if (Zone.current[_isFinalKey] ?? false) { |
| throw new StateError( |
| "Cannot call withClock() within a call to withClock(isFinal: true)."); |
| } |
| |
| return runZoned(callback, |
| zoneValues: {_clockKey: clock, _isFinalKey: isFinal}); |
| } |