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1 // Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file | 1 // Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file |
2 // for details. All rights reserved. Use of this source code is governed by a | 2 // for details. All rights reserved. Use of this source code is governed by a |
3 // BSD-style license that can be found in the LICENSE file. | 3 // BSD-style license that can be found in the LICENSE file. |
4 | 4 |
5 library barback.utils.stream_pool; | 5 library glob.stream_pool; |
6 | 6 |
7 import 'dart:async'; | 7 import 'dart:async'; |
8 | 8 |
9 /// A pool of streams whose events are unified and emitted through a central | 9 /// A pool of streams whose events are unified and emitted through a central |
10 /// stream. | 10 /// stream. |
11 class StreamPool<T> { | 11 class StreamPool<T> { |
12 /// The stream through which all events from streams in the pool are emitted. | 12 /// The stream through which all events from streams in the pool are emitted. |
13 Stream<T> get stream => _controller.stream; | 13 Stream<T> get stream => _controller.stream; |
14 final StreamController<T> _controller; | 14 final StreamController<T> _controller; |
15 | 15 |
16 /// Subscriptions to the streams that make up the pool. | 16 /// Subscriptions to the streams that make up the pool. |
17 final _subscriptions = new Map<Stream<T>, StreamSubscription<T>>(); | 17 final _subscriptions = new Map<Stream<T>, StreamSubscription<T>>(); |
18 | 18 |
| 19 /// Whether this pool should be closed when it becomes empty. |
| 20 bool _closeWhenEmpty = false; |
| 21 |
19 /// Creates a new stream pool that only supports a single subscriber. | 22 /// Creates a new stream pool that only supports a single subscriber. |
20 /// | 23 /// |
21 /// Any events from broadcast streams in the pool will be buffered until a | 24 /// Any events from broadcast streams in the pool will be buffered until a |
22 /// listener is subscribed. | 25 /// listener is subscribed. |
23 StreamPool() | 26 StreamPool() |
24 // Create the controller as sync so that any sync input streams will be | 27 // Create the controller as sync so that any sync input streams will be |
25 // forwarded synchronously. Async input streams will have their asynchrony | 28 // forwarded synchronously. Async input streams will have their asynchrony |
26 // preserved, since _controller.add will be called asynchronously. | 29 // preserved, since _controller.add will be called asynchronously. |
27 : _controller = new StreamController<T>(sync: true); | 30 : _controller = new StreamController<T>(sync: true); |
28 | 31 |
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46 if (_subscriptions.containsKey(stream)) return; | 49 if (_subscriptions.containsKey(stream)) return; |
47 _subscriptions[stream] = stream.listen(_controller.add, | 50 _subscriptions[stream] = stream.listen(_controller.add, |
48 onError: _controller.addError, | 51 onError: _controller.addError, |
49 onDone: () => remove(stream)); | 52 onDone: () => remove(stream)); |
50 } | 53 } |
51 | 54 |
52 /// Removes [stream] as a member of this pool. | 55 /// Removes [stream] as a member of this pool. |
53 void remove(Stream<T> stream) { | 56 void remove(Stream<T> stream) { |
54 var subscription = _subscriptions.remove(stream); | 57 var subscription = _subscriptions.remove(stream); |
55 if (subscription != null) subscription.cancel(); | 58 if (subscription != null) subscription.cancel(); |
| 59 if (_closeWhenEmpty && _subscriptions.isEmpty) close(); |
56 } | 60 } |
57 | 61 |
58 /// Removes all streams from this pool and closes [stream]. | 62 /// Removes all streams from this pool and closes [stream]. |
59 void close() { | 63 void close() { |
60 for (var subscription in _subscriptions.values) { | 64 for (var subscription in _subscriptions.values) { |
61 subscription.cancel(); | 65 subscription.cancel(); |
62 } | 66 } |
63 _subscriptions.clear(); | 67 _subscriptions.clear(); |
64 _controller.close(); | 68 _controller.close(); |
65 } | 69 } |
| 70 |
| 71 /// The next time this pool becomes empty, close it. |
| 72 void closeWhenEmpty() { |
| 73 if (_subscriptions.isEmpty) close(); |
| 74 _closeWhenEmpty = true; |
| 75 } |
66 } | 76 } |
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