| // Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| |
| library barback.utils.cancelable_future; |
| |
| import 'dart:async'; |
| |
| /// A wrapper for [Future] that can be cancelled. |
| /// |
| /// When this is cancelled, that means it won't complete either successfully or |
| /// with an error, regardless of whether the wrapped Future completes. |
| /// Cancelling this won't stop whatever code is feeding the wrapped future from |
| /// running. |
| class CancelableFuture<T> implements Future<T> { |
| bool _canceled = false; |
| final _completer = new Completer<T>.sync(); |
| |
| CancelableFuture(Future<T> inner) { |
| inner.then((result) { |
| if (_canceled) return; |
| _completer.complete(result); |
| }).catchError((error, stackTrace) { |
| if (_canceled) return; |
| _completer.completeError(error, stackTrace); |
| }); |
| } |
| |
| Stream<T> asStream() => _completer.future.asStream(); |
| Future<T> catchError(Function onError, {bool test(Object error)}) => |
| _completer.future.catchError(onError, test: test); |
| Future<S> then<S>(FutureOr<S> onValue(T value), {Function onError}) => |
| _completer.future.then(onValue, onError: onError); |
| Future<T> whenComplete(action()) => _completer.future.whenComplete(action); |
| Future<T> timeout(Duration timeLimit, {void onTimeout()}) => |
| _completer.future.timeout(timeLimit, onTimeout: onTimeout); |
| |
| /// Cancels this future. |
| void cancel() { |
| _canceled = true; |
| } |
| } |