66 lines
1.7 KiB
JavaScript
66 lines
1.7 KiB
JavaScript
|
/**
|
||
|
|
* Copyright (c) 2013-present, Facebook, Inc.
|
||
|
|
* All rights reserved.
|
||
|
|
*
|
||
|
|
* This source code is licensed under the BSD-style license found in the
|
||
|
|
* LICENSE file in the root directory of this source tree. An additional grant
|
||
|
|
* of patent rights can be found in the PATENTS file in the same directory.
|
||
|
|
*
|
||
|
|
*
|
||
|
|
*/
|
||
|
|
|
||
|
|
'use strict';
|
||
|
|
|
||
|
|
var enumerate = require('./enumerate');
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Checks if two iterables are equal. A custom areEqual function may be provided
|
||
|
|
* as an optional third argument.
|
||
|
|
*/
|
||
|
|
function equalsIterable(one, two, areEqual) {
|
||
|
|
if (one === two) {
|
||
|
|
return true;
|
||
|
|
}
|
||
|
|
|
||
|
|
// We might be able to short circuit by using the size or length fields.
|
||
|
|
var oneSize = maybeGetSize(one);
|
||
|
|
var twoSize = maybeGetSize(two);
|
||
|
|
if (oneSize != null && twoSize != null && oneSize !== twoSize) {
|
||
|
|
return false;
|
||
|
|
}
|
||
|
|
|
||
|
|
// Otherwise use the iterators to check equality. Here we cannot use for-of
|
||
|
|
// because we need to advance the iterators at the same time.
|
||
|
|
var oneIterator = enumerate(one);
|
||
|
|
var oneItem = oneIterator.next();
|
||
|
|
var twoIterator = enumerate(two);
|
||
|
|
var twoItem = twoIterator.next();
|
||
|
|
var safeAreEqual = areEqual || referenceEquality;
|
||
|
|
while (!(oneItem.done || twoItem.done)) {
|
||
|
|
if (!safeAreEqual(oneItem.value, twoItem.value)) {
|
||
|
|
return false;
|
||
|
|
}
|
||
|
|
oneItem = oneIterator.next();
|
||
|
|
twoItem = twoIterator.next();
|
||
|
|
}
|
||
|
|
return oneItem.done === twoItem.done;
|
||
|
|
}
|
||
|
|
|
||
|
|
function maybeGetSize(o) {
|
||
|
|
if (o == null) {
|
||
|
|
return null;
|
||
|
|
}
|
||
|
|
if (typeof o.size === 'number') {
|
||
|
|
return o.size;
|
||
|
|
}
|
||
|
|
if (typeof o.length === 'number') {
|
||
|
|
return o.length;
|
||
|
|
}
|
||
|
|
return null;
|
||
|
|
}
|
||
|
|
|
||
|
|
function referenceEquality(one, two) {
|
||
|
|
return one === two;
|
||
|
|
}
|
||
|
|
|
||
|
|
module.exports = equalsIterable;
|