| // Copyright (c) 2016, 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 Execution of a statement s of the form yield* e; proceeds as |
| * follows: |
| * First, the expression e is evaluated to an object o. |
| * If the immediately enclosing function m is marked sync*, then: |
| * 1. It is a dynamic error if the class of o does not implement Iterable. |
| * Otherwise |
| * 2. The method iterator is invoked upon o returning an object i. |
| * 3. The moveNext method of i is invoked on it with no arguments. If moveNext |
| * returns false execution of s is complete. Otherwise |
| * 4. The getter current is invoked on i. If the invocation raises an |
| * exception ex, execution of s throws ex. Otherwise, the result x of the |
| * getter invocation is added to the iterable associated with m. Execution of |
| * the function m immediately enclosing s is suspended until the nullary method |
| * moveNext() is invoked upon the iterator used to initiate the current |
| * invocation of m, at which point execution of s continues at 3. |
| * 5. The current call to moveNext() returns true. |
| * |
| * @description Check that method iterator is invoked upon o |
| * |
| * @author a.semenov@unipro.ru |
| */ |
| import '../../../../Utils/expect.dart'; |
| |
| class IterableWrapper<E> extends Iterable<E> { |
| |
| late int _iteratorCallCount; |
| late Iterable<E> _iterable; |
| |
| IterableWrapper(Iterable<E> iterable) { |
| _iterable = iterable; |
| _iteratorCallCount = 0; |
| } |
| |
| Iterator<E> get iterator { |
| _iteratorCallCount++; |
| return _iterable.iterator; |
| } |
| |
| int get iteratorCallCount => _iteratorCallCount; |
| } |
| |
| Iterable generator(Iterable iterable) sync* { |
| yield* iterable; |
| } |
| |
| main() { |
| IterableWrapper<int> it1 = new IterableWrapper<int>([1]); |
| Expect.equals(1, generator(it1).first); |
| Expect.equals(1, it1.iteratorCallCount); |
| |
| IterableWrapper<String> it2 = new IterableWrapper<String>(['a', 'b']); |
| Expect.equals('a', generator(it2).first); |
| Expect.equals(1, it2.iteratorCallCount); |
| Expect.equals('b', generator(it2).last); |
| Expect.equals(2, it2.iteratorCallCount); |
| } |