| /* |
| * 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 Stream<T> distinct([bool equals(T previous, T next)]) |
| * Skips data events if they are equal to the previous data event. |
| * The returned stream provides the same events as this stream, |
| * except that it never provides two consequtive data events that are equal. |
| * Equality is determined by the provided equals method. |
| * If that is omitted, the '==' operator on the last provided data element is used. |
| * @description Checks that if parameter is present, returned stream filters events |
| * according to the supplied function. |
| * @author kaigorodov |
| */ |
| import "dart:async"; |
| import "../../../Utils/expect.dart"; |
| import "IsolateStream.dart" as IsolateStream; |
| |
| check(Iterable<int> data, bool equals(var previous, var next)) { |
| Stream s = IsolateStream.fromIterable(data); |
| Stream d = s.distinct(equals); |
| bool first = true; |
| var previous; |
| asyncStart(); |
| d.listen((var event) { |
| if (first) { |
| first = false; |
| } else { |
| Expect.isFalse(equals(previous, event), "p=$previous, e=$event"); |
| } |
| previous = event; |
| }, onDone: () { |
| asyncEnd(); |
| }); |
| } |
| |
| int abs(x) => x < 0 ? -x : x; |
| |
| int sign(x) => (x < 0) ? -1 : (x == 0 ? 0 : 1); |
| |
| main() { |
| check([1, 2, 2, 3], (var previous, var next) => previous == next); |
| check([2, 4, 3, 1], (var previous, var next) => previous % 2 == next % 2); |
| check(new Iterable.generate(10, (int index) => index), |
| (var previous, var next) => abs(previous - next) <= 1); |
| check(new Iterable.generate(10, (int index) => -5 + index), |
| (var previous, var next) => sign(previous) == sign(next)); |
| } |