3 files changed, 100 insertions, 1 deletions
diff --git a/node_modules/webpack/lib/util/Semaphore.js b/node_modules/webpack/lib/util/Semaphore.js
new file mode 100644
index 000000000..de9b69dde
--- /dev/null
+++ b/node_modules/webpack/lib/util/Semaphore.js
@@ -0,0 +1,32 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Tobias Koppers @sokra
+*/
+"use strict";
+
+class Semaphore {
+	constructor(available) {
+		this.available = available;
+		this.waiters = [];
+	}
+
+	acquire(callback) {
+		if(this.available > 0) {
+			this.available--;
+			callback();
+		} else {
+			this.waiters.push(callback);
+		}
+	}
+
+	release() {
+		if(this.waiters.length > 0) {
+			const callback = this.waiters.pop();
+			process.nextTick(callback);
+		} else {
+			this.available++;
+		}
+	}
+}
+
+module.exports = Semaphore;
diff --git a/node_modules/webpack/lib/util/SortableSet.js b/node_modules/webpack/lib/util/SortableSet.js
new file mode 100644
index 000000000..15c7ecb87
--- /dev/null
+++ b/node_modules/webpack/lib/util/SortableSet.js
@@ -0,0 +1,45 @@
+"use strict";
+
+module.exports = class SortableSet extends Set {
+
+	constructor(initialIterable, defaultSort) {
+		super(initialIterable);
+		this._sortFn = defaultSort;
+		this._lastActiveSortFn = null;
+	}
+
+	/**
+	 * @param {any} value - value to add to set
+	 * @returns {SortableSet} - returns itself
+	 */
+	add(value) {
+		this._lastActiveSortFn = null;
+		super.add(value);
+		return this;
+	}
+
+	/**
+	 * @param {Function} sortFn - function to sort the set
+	 * @returns {void}
+	 */
+	sortWith(sortFn) {
+		if(this.size === 0 || sortFn === this._lastActiveSortFn) {
+			// already sorted - nothing to do
+			return;
+		}
+
+		const sortedArray = Array.from(this).sort(sortFn);
+		super.clear();
+		for(let i = 0; i < sortedArray.length; i += 1) {
+			this.add(sortedArray[i]);
+		}
+		this._lastActiveSortFn = sortFn;
+	}
+
+	/**
+	 * @returns {void}
+	 */
+	sort() {
+		this.sortWith(this._sortFn);
+	}
+};
diff --git a/node_modules/webpack/lib/util/identifier.js b/node_modules/webpack/lib/util/identifier.js
index b1bcbf5df..82e5b811f 100644
--- a/node_modules/webpack/lib/util/identifier.js
+++ b/node_modules/webpack/lib/util/identifier.js
@@ -7,10 +7,32 @@ const looksLikeAbsolutePath = (maybeAbsolutePath) => {
 
 const normalizePathSeparator = (p) => p.replace(/\\/g, "/");
 
-exports.makePathsRelative = (context, identifier) => {
+const _makePathsRelative = (context, identifier) => {
 	return identifier
 		.split(/([|! ])/)
 		.map(str => looksLikeAbsolutePath(str) ?
 			normalizePathSeparator(path.relative(context, str)) : str)
 		.join("");
 };
+
+exports.makePathsRelative = (context, identifier, cache) => {
+	if(!cache) return _makePathsRelative(context, identifier);
+
+	const relativePaths = cache.relativePaths || (cache.relativePaths = new Map());
+
+	let cachedResult;
+	let contextCache = relativePaths.get(context);
+	if(typeof contextCache === "undefined") {
+		relativePaths.set(context, contextCache = new Map());
+	} else {
+		cachedResult = contextCache.get(identifier);
+	}
+
+	if(typeof cachedResult !== "undefined") {
+		return cachedResult;
+	} else {
+		const relativePath = _makePathsRelative(context, identifier);
+		contextCache.set(identifier, relativePath);
+		return relativePath;
+	}
+};