fix: perf regression

lib/util/Queue.js

@@ -5,28 +5,27 @@
 
 "use strict";
 
-/**
- * @template T
- */
-class Node {
-	/**
-	 * @param {T} value the value
-	 */
-	constructor(value) {
-		this.value = value;
-		/** @type {Node<T> | undefined} */
-		this.next = undefined;
-	}
-}
-
 /**
  * @template T
  */
 class Queue {
-	constructor() {
-		this._head = undefined;
-		this._tail = undefined;
-		this._size = 0;
+	/**
+	 * @param {Iterable<T>=} items The initial elements.
+	 */
+	constructor(items) {
+		/**
+		 * @private
+		 * @type {Set<T>}
+		 */
+		this._set = new Set(items);
+	}
+
+	/**
+	 * Returns the number of elements in this queue.
+	 * @returns {number} The number of elements in this queue.
+	 */
+	get length() {
+		return this._set.size;
 	}
 
 	/**
@@ -35,18 +34,7 @@ class Queue {
 	 * @returns {void}
 	 */
 	enqueue(item) {
-		const node = new Node(item);
-
-		if (this._head) {
-			/** @type {Node<T>} */
-			(this._tail).next = node;
-			this._tail = node;
-		} else {
-			this._head = node;
-			this._tail = node;
-		}
-
-		this._size++;
+		this._set.add(item);
 	}
 
 	/**
@@ -54,31 +42,10 @@ class Queue {
 	 * @returns {T | undefined} The head of the queue of `undefined` if this queue is empty.
 	 */
 	dequeue() {
-		const current = this._head;
-		if (!current) {
-			return;
-		}
-
-		this._head = this._head.next;
-		this._size--;
-		return current.value;
-	}
-
-	/**
-	 * Returns the number of elements in this queue.
-	 * @returns {number} The number of elements in this queue.
-	 */
-	get length() {
-		return this._size;
-	}
-
-	*[Symbol.iterator]() {
-		let current = this._head;
-
-		while (current) {
-			yield current.value;
-			current = current.next;
-		}
+		const result = this._set[Symbol.iterator]().next();
+		if (result.done) return;
+		this._set.delete(result.value);
+		return result.value;
 	}
 }