| // Copyright (c) 2011, 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. |
| |
| /** |
| * @assertion Future<T> firstWhere ( |
| * bool test(T element), {@deprecated dynamic defaultValue(), T orElse()}) |
| * |
| * Finds the first element of this stream matching test. |
| * |
| * Returns a future that is completed with the first element of this stream that |
| * test returns true for. |
| * |
| * If no such element is found before this stream is done, and a orElse function |
| * is provided, the result of calling orElse becomes the value of the future. If |
| * orElse throws, the returned future is completed with that error. |
| * |
| * If this stream emits an error before the first matching element, the returned |
| * future is completed with that error, and processing stops. |
| * |
| * Stops listening to the stream after the first matching element or error has |
| * been received. |
| * |
| * Internally the method cancels its subscription after the first element that |
| * matches the predicate. This means that single-subscription (non-broadcast) |
| * streams are closed and cannot be reused after a call to this method. |
| * |
| * If an error occurs, or if this stream ends without finding a match and with |
| * no orElse function provided, the returned future is completed with an error. |
| * |
| * The defaultValue parameter is deprecated, and orElse should be used instead. |
| * @description Checks that non broadcast stream can not be listened after |
| * the first element is returned. |
| * @author a.semenov@unipro.ru |
| */ |
| library firstWhere_A04_t01; |
| import "dart:async"; |
| import "../../../Utils/expect.dart"; |
| |
| void check(Stream s) { |
| asyncStart(); |
| s.firstWhere((_) => true).then( |
| (_) { |
| if (!s.isBroadcast){ |
| Expect.throws(() => s.listen((_){})); |
| } |
| asyncEnd(); |
| } |
| ); |
| } |
| |
| void test(CreateStreamFunction create) { |
| check(create([123])); |
| check(create([1,2,3])); |
| } |