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/*
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 cleverMerge(first, second), stores the result in WeakMap and returns result
* cachedCleverMerge({a: 1}, {a: 2})
* {a: 2}
* // when same arguments passed, gets the result from WeakMap and returns it.
* cachedCleverMerge({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 cachedCleverMerge = (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 = cleverMerge(first, second);
innerCache.set(second, newMerge);
return newMerge;
};
/**
* Merges two objects. Objects are not deeply merged.
* TODO webpack 5: merge objects deeply clever.
* Arrays might reference the old value with "..."
* @param {object} first first object
* @param {object} second second object
* @returns {object} merged object of first and second object
*/
const cleverMerge = (first, second) => {
const newObject = Object.assign({}, first);
for (const key of Object.keys(second)) {
if (!(key in newObject)) {
newObject[key] = second[key];
continue;
}
const secondValue = second[key];
if (!Array.isArray(secondValue)) {
newObject[key] = secondValue;
continue;
}
const firstValue = newObject[key];
if (Array.isArray(firstValue)) {
const newArray = [];
for (const item of secondValue) {
if (item === "...") {
for (const item of firstValue) {
newArray.push(item);
}
} else {
newArray.push(item);
}
}
newObject[key] = newArray;
} else {
newObject[key] = secondValue;
}
}
return newObject;
};
exports.cachedCleverMerge = cachedCleverMerge;
exports.cleverMerge = cleverMerge;
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