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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 /** | 5 /// Import `async.dart` instead. |
6 * Help for combining multiple streams into a single stream. | 6 @Deprecated("Will be removed in async 2.0.0.") |
7 */ | |
8 library dart.pkg.async.stream_zip; | 7 library dart.pkg.async.stream_zip; |
9 | 8 |
10 import "dart:async"; | 9 export "src/stream_zip.dart"; |
11 | |
12 /** | |
13 * A stream that combines the values of other streams. | |
14 */ | |
15 class StreamZip extends Stream<List> { | |
16 final Iterable<Stream> _streams; | |
17 StreamZip(Iterable<Stream> streams) : _streams = streams; | |
18 | |
19 StreamSubscription<List> listen(void onData(List data), { | |
20 Function onError, | |
21 void onDone(), | |
22 bool cancelOnError}) { | |
23 cancelOnError = identical(true, cancelOnError); | |
24 List<StreamSubscription> subscriptions = <StreamSubscription>[]; | |
25 StreamController controller; | |
26 List current; | |
27 int dataCount = 0; | |
28 | |
29 /// Called for each data from a subscription in [subscriptions]. | |
30 void handleData(int index, data) { | |
31 current[index] = data; | |
32 dataCount++; | |
33 if (dataCount == subscriptions.length) { | |
34 List data = current; | |
35 current = new List(subscriptions.length); | |
36 dataCount = 0; | |
37 for (int i = 0; i < subscriptions.length; i++) { | |
38 if (i != index) subscriptions[i].resume(); | |
39 } | |
40 controller.add(data); | |
41 } else { | |
42 subscriptions[index].pause(); | |
43 } | |
44 } | |
45 | |
46 /// Called for each error from a subscription in [subscriptions]. | |
47 /// Except if [cancelOnError] is true, in which case the function below | |
48 /// is used instead. | |
49 void handleError(Object error, StackTrace stackTrace) { | |
50 controller.addError(error, stackTrace); | |
51 } | |
52 | |
53 /// Called when a subscription has an error and [cancelOnError] is true. | |
54 /// | |
55 /// Prematurely cancels all subscriptions since we know that we won't | |
56 /// be needing any more values. | |
57 void handleErrorCancel(Object error, StackTrace stackTrace) { | |
58 for (int i = 0; i < subscriptions.length; i++) { | |
59 subscriptions[i].cancel(); | |
60 } | |
61 controller.addError(error, stackTrace); | |
62 } | |
63 | |
64 void handleDone() { | |
65 for (int i = 0; i < subscriptions.length; i++) { | |
66 subscriptions[i].cancel(); | |
67 } | |
68 controller.close(); | |
69 } | |
70 | |
71 try { | |
72 for (Stream stream in _streams) { | |
73 int index = subscriptions.length; | |
74 subscriptions.add(stream.listen( | |
75 (data) { handleData(index, data); }, | |
76 onError: cancelOnError ? handleError : handleErrorCancel, | |
77 onDone: handleDone, | |
78 cancelOnError: cancelOnError)); | |
79 } | |
80 } catch (e) { | |
81 for (int i = subscriptions.length - 1; i >= 0; i--) { | |
82 subscriptions[i].cancel(); | |
83 } | |
84 rethrow; | |
85 } | |
86 | |
87 current = new List(subscriptions.length); | |
88 | |
89 controller = new StreamController<List>( | |
90 onPause: () { | |
91 for (int i = 0; i < subscriptions.length; i++) { | |
92 // This may pause some subscriptions more than once. | |
93 // These will not be resumed by onResume below, but must wait for the | |
94 // next round. | |
95 subscriptions[i].pause(); | |
96 } | |
97 }, | |
98 onResume: () { | |
99 for (int i = 0; i < subscriptions.length; i++) { | |
100 subscriptions[i].resume(); | |
101 } | |
102 }, | |
103 onCancel: () { | |
104 for (int i = 0; i < subscriptions.length; i++) { | |
105 // Canceling more than once is safe. | |
106 subscriptions[i].cancel(); | |
107 } | |
108 } | |
109 ); | |
110 | |
111 if (subscriptions.isEmpty) { | |
112 controller.close(); | |
113 } | |
114 return controller.stream.listen(onData, | |
115 onError: onError, | |
116 onDone: onDone, | |
117 cancelOnError: cancelOnError); | |
118 } | |
119 } | |
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