настройка webpack

node_modules/webpack/lib/util/cleverMerge.js

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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;