| // 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 if this stream ends without finding a match and with |
| /// no [orElse] function provided, the future will receive an error. |
| /// @author kaigorodov |
| |
| import "dart:async"; |
| import "../../../Utils/expect.dart"; |
| import "IsolateStream.dart" as IsolateStream; |
| |
| check(Iterable data, bool test(var element)) { |
| Stream s = IsolateStream.fromIterable(data); |
| asyncStart(); |
| s.firstWhere(test).then((data) { |
| Expect.fail("data passed: $data"); |
| }, onError: (error) { |
| Expect.isTrue(error is Error); |
| asyncEnd(); |
| }); |
| } |
| |
| main() { |
| check([], (var element) => true); |
| check([1, 2, 3], (var element) => element == null); |
| check([null, null], (var element) => element != null); |
| check(new Iterable.generate(0, (int index) => index), (var element) => false); |
| check( |
| new Iterable.generate(10, (int index) => index), (var element) => false); |
| check(new Iterable.generate(10, (int index) => index * 5), |
| (var element) => element < 0); |
| check(new Iterable.generate(10, (int index) => index * 5), |
| (var element) => element == 300); |
| } |