forked from zhurui/management
36 lines
1.1 KiB
JavaScript
36 lines
1.1 KiB
JavaScript
|
/*
|
||
|
|
MIT License http://www.opensource.org/licenses/mit-license.php
|
||
|
|
Author Tobias Koppers @sokra
|
||
|
|
*/
|
||
|
|
"use strict";
|
||
|
|
|
||
|
|
const mergeCache = new WeakMap();
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Merges two given objects and caches the result to avoid computation if same objects passed as arguments again.
|
||
|
|
* @example
|
||
|
|
* // performs Object.assign(first, second), stores the result in WeakMap and returns result
|
||
|
|
* cachedMerge({a: 1}, {a: 2})
|
||
|
|
* {a: 2}
|
||
|
|
* // when same arguments passed, gets the result from WeakMap and returns it.
|
||
|
|
* cachedMerge({a: 1}, {a: 2})
|
||
|
|
* {a: 2}
|
||
|
|
* @param {object} first first object
|
||
|
|
* @param {object} second second object
|
||
|
|
* @returns {object} merged object of first and second object
|
||
|
|
*/
|
||
|
|
const cachedMerge = (first, second) => {
|
||
|
|
let innerCache = mergeCache.get(first);
|
||
|
|
if (innerCache === undefined) {
|
||
|
|
innerCache = new WeakMap();
|
||
|
|
mergeCache.set(first, innerCache);
|
||
|
|
}
|
||
|
|
const prevMerge = innerCache.get(second);
|
||
|
|
if (prevMerge !== undefined) return prevMerge;
|
||
|
|
const newMerge = Object.assign({}, first, second);
|
||
|
|
innerCache.set(second, newMerge);
|
||
|
|
return newMerge;
|
||
|
|
};
|
||
|
|
|
||
|
|
module.exports = cachedMerge;
|