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/*
* 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);
}