107 lines
2.9 KiB
Plaintext
107 lines
2.9 KiB
Plaintext
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/**
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* Copyright (c) 2013-present, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under the BSD-style license found in the
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* LICENSE file in the root directory of this source tree. An additional grant
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* of patent rights can be found in the PATENTS file in the same directory.
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*
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* @providesModule areEqual
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* @flow
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*/
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const aStackPool = [];
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const bStackPool = [];
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/**
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* Checks if two values are equal. Values may be primitives, arrays, or objects.
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* Returns true if both arguments have the same keys and values.
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*
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* @see http://underscorejs.org
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* @copyright 2009-2013 Jeremy Ashkenas, DocumentCloud Inc.
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* @license MIT
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*/
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function areEqual(a: any, b: any): boolean {
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const aStack = aStackPool.length ? aStackPool.pop() : [];
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const bStack = bStackPool.length ? bStackPool.pop() : [];
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const result = eq(a, b, aStack, bStack);
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aStack.length = 0;
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bStack.length = 0;
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aStackPool.push(aStack);
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bStackPool.push(bStack);
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return result;
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}
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function eq(a: any, b: any, aStack: Array<any>, bStack: Array<any>): boolean {
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if (a === b) {
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// Identical objects are equal. `0 === -0`, but they aren't identical.
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return a !== 0 || 1 / a == 1 / b;
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}
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if (a == null || b == null) {
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// a or b can be `null` or `undefined`
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return false;
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}
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if (typeof a != 'object' || typeof b != 'object') {
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return false;
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}
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const objToStr = Object.prototype.toString;
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const className = objToStr.call(a);
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if (className != objToStr.call(b)) {
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return false;
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}
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switch (className) {
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case '[object String]':
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return a == String(b);
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case '[object Number]':
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return isNaN(a) || isNaN(b) ? false : a == Number(b);
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case '[object Date]':
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case '[object Boolean]':
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return +a == +b;
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case '[object RegExp]':
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return a.source == b.source && a.global == b.global && a.multiline == b.multiline && a.ignoreCase == b.ignoreCase;
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}
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// Assume equality for cyclic structures.
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let length = aStack.length;
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while (length--) {
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if (aStack[length] == a) {
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return bStack[length] == b;
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}
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}
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aStack.push(a);
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bStack.push(b);
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let size = 0;
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// Recursively compare objects and arrays.
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if (className === '[object Array]') {
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size = a.length;
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if (size !== b.length) {
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return false;
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}
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// Deep compare the contents, ignoring non-numeric properties.
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while (size--) {
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if (!eq(a[size], b[size], aStack, bStack)) {
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return false;
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}
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}
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} else {
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if (a.constructor !== b.constructor) {
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return false;
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}
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if (a.hasOwnProperty('valueOf') && b.hasOwnProperty('valueOf')) {
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return a.valueOf() == b.valueOf();
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}
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const keys = Object.keys(a);
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if (keys.length != Object.keys(b).length) {
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return false;
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}
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for (let i = 0; i < keys.length; i++) {
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if (!eq(a[keys[i]], b[keys[i]], aStack, bStack)) {
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return false;
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}
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}
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}
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aStack.pop();
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bStack.pop();
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return true;
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}
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module.exports = areEqual;
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