blob: 0246e3636e0851388eadb2a59b767d606e7b85e9 [file] [log] [blame]
// 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 When iteration over the iterable is started, by getting an
* iterator j from the iterable and calling moveNext(), execution of the body
* of f will begin. When f terminates, j is positioned after its last element,
* so that its current value is null and the current call to moveNext() on j
* returns false, as will all further calls.
* Each iterator starts a separate computation. If the sync* function is
* impure, the sequence of values yielded by each iterator may differ.
* One can derive more than one iterator from a given iterable. Note that
* operations on the iterable itself can create distinct iterators. An example
* would be length. It is conceivable that different iterators might yield
* sequences of different length. The same care needs to be taken when writing
* sync* functions as when writing an Iterator class. In particular, it should
* handle multiple simultaneous iterators gracefully. If the iterator depends
* on external state that might change, it should check that the state is still
* valid after every yield (and maybe throw a ConcurrentModificationError if
* it isn’t).
* Each iterator runs with its own shallow copies of all local variables; in
* particular, each iterator has the same initial arguments, even if their
* bindings are modified by the function. Two executions of an iterator
* interact only via state outside the function.
*
* @description Check that each iterator has the shallow copies of initial
* arguments
*
* @author a.semenov@unipro.ru
*/
import '../../../Utils/expect.dart';
class A {
int x;
A(this.x);
}
Iterable generator1(A a) sync* {
yield a;
}
test1() {
A a = new A(0);
Iterable iterable = generator1(a);
for (int i = 0; i < 10; i++) {
Iterator it = iterable.iterator;
Expect.isTrue(it.moveNext());
Expect.identical(a, it.current);
}
}
Iterable generator2(A a) sync* {
yield a.x++;
yield a.x++;
yield a.x++;
yield a.x++;
}
test2() {
Iterable iterable = generator2(new A(0));
Expect.listEquals([0,1,2,3], take(iterable.iterator, 4));
Expect.listEquals([4,5,6,7], take(iterable.iterator, 4));
Expect.listEquals([8,9,10,11], take(iterable.iterator, 4));
}
List take(Iterator iterator, int count) {
List result = [];
while (count-- > 0 && iterator.moveNext()) {
result.add(iterator.current);
}
return result;
}
main() {
test1();
test2();
}