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// |reftest| shell-option(--enable-iterator-sequencing) skip-if(!Iterator.concat||!xulRuntime.shell) -- iterator-sequencing is not enabled unconditionally, requires shell-options
// Copyright (C) 2024 André Bargull. All rights reserved.
// This code is governed by the BSD license found in the LICENSE file.
/*---
esid: sec-iterator.concat
description: >
Gets the iterator method from the input iterables only once.
info: |
Iterator.concat ( ...items )
1. Let iterables be a new empty List.
2. For each element item of items, do
a. If item is not an Object, throw a TypeError exception.
b. Let method be ? GetMethod(item, %Symbol.iterator%).
c. If method is undefined, throw a TypeError exception.
d. Append the Record { [[OpenMethod]]: method, [[Iterable]]: item } to iterables.
...
features: [iterator-sequencing]
includes: [compareArray.js]
---*/
let iteratorGets = 0;
let iteratorCalls = 0;
let array = [1, 2, 3];
class CountingIterable {
get [Symbol.iterator]() {
++iteratorGets;
return function () {
++iteratorCalls;
return array[Symbol.iterator]();
};
}
}
let iterable = new CountingIterable();
assert.sameValue(iteratorGets, 0);
assert.sameValue(iteratorCalls, 0);
let iter = Iterator.concat(iterable);
assert.sameValue(iteratorGets, 1);
assert.sameValue(iteratorCalls, 0);
let result = [...iter];
assert.sameValue(iteratorGets, 1);
assert.sameValue(iteratorCalls, 1);
assert.compareArray(result, array);
reportCompare(0, 0);