| // 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.stream_pool; |
| |
| import 'dart:async'; |
| |
| /// A pool of streams whose events are unified and emitted through a central |
| /// stream. |
| class StreamPool<T> { |
| /// The stream through which all events from streams in the pool are emitted. |
| Stream<T> get stream => _controller.stream; |
| final StreamController<T> _controller; |
| |
| /// Subscriptions to the streams that make up the pool. |
| final _subscriptions = new Map<Stream<T>, StreamSubscription<T>>(); |
| |
| /// Creates a new stream pool that only supports a single subscriber. |
| /// |
| /// Any events from broadcast streams in the pool will be buffered until a |
| /// listener is subscribed. |
| StreamPool() |
| // Create the controller as sync so that any sync input streams will be |
| // forwarded synchronously. Async input streams will have their asynchrony |
| // preserved, since _controller.add will be called asynchronously. |
| : _controller = new StreamController<T>(sync: true); |
| |
| /// Creates a new stream pool where [stream] can be listened to more than |
| /// once. |
| /// |
| /// Any events from buffered streams in the pool will be emitted immediately, |
| /// regardless of whether [stream] has any subscribers. |
| StreamPool.broadcast() |
| // Create the controller as sync so that any sync input streams will be |
| // forwarded synchronously. Async input streams will have their asynchrony |
| // preserved, since _controller.add will be called asynchronously. |
| : _controller = new StreamController<T>.broadcast(sync: true); |
| |
| /// Adds [stream] as a member of this pool. |
| /// |
| /// Any events from [stream] will be emitted through [this.stream]. If |
| /// [stream] is sync, they'll be emitted synchronously; if [stream] is async, |
| /// they'll be emitted asynchronously. |
| void add(Stream<T> stream) { |
| if (_subscriptions.containsKey(stream)) return; |
| _subscriptions[stream] = stream.listen(_controller.add, |
| onError: _controller.addError, |
| onDone: () => remove(stream)); |
| } |
| |
| /// Removes [stream] as a member of this pool. |
| void remove(Stream<T> stream) { |
| var subscription = _subscriptions.remove(stream); |
| if (subscription != null) subscription.cancel(); |
| } |
| |
| /// Removes all streams from this pool and closes [stream]. |
| void close() { |
| for (var subscription in _subscriptions.values) { |
| subscription.cancel(); |
| } |
| _subscriptions.clear(); |
| _controller.close(); |
| } |
| } |