first

node_modules/webpack/lib/util/TupleQueue.js

@@ -0,0 +1,61 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Tobias Koppers @sokra
+*/
+
+"use strict";
+
+const TupleSet = require("./TupleSet");
+
+/**
+ * @template {any[]} T
+ */
+class TupleQueue {
+	/**
+	 * @param {Iterable<T>=} items The initial elements.
+	 */
+	constructor(items) {
+		/** @private @type {TupleSet<T>} */
+		this._set = new TupleSet(items);
+		/** @private @type {Iterator<T>} */
+		this._iterator = this._set[Symbol.iterator]();
+	}
+
+	/**
+	 * Returns the number of elements in this queue.
+	 * @returns {number} The number of elements in this queue.
+	 */
+	get length() {
+		return this._set.size;
+	}
+
+	/**
+	 * Appends the specified element to this queue.
+	 * @param {T} item The element to add.
+	 * @returns {void}
+	 */
+	enqueue(...item) {
+		this._set.add(...item);
+	}
+
+	/**
+	 * Retrieves and removes the head of this queue.
+	 * @returns {T | undefined} The head of the queue of `undefined` if this queue is empty.
+	 */
+	dequeue() {
+		const result = this._iterator.next();
+		if (result.done) {
+			if (this._set.size > 0) {
+				this._iterator = this._set[Symbol.iterator]();
+				const value = this._iterator.next().value;
+				this._set.delete(...value);
+				return value;
+			}
+			return undefined;
+		}
+		this._set.delete(...result.value);
+		return result.value;
+	}
+}
+
+module.exports = TupleQueue;