"use strict";
|
|
/**
|
* @template T
|
*/
|
class Queue {
|
/**
|
* @param {Iterable<T>=} items The initial elements.
|
*/
|
constructor(items) {
|
/** @private @type {Set<T>} */
|
this.set = new Set(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) return undefined;
|
this.set.delete(result.value);
|
return result.value;
|
}
|
}
|
|
module.exports = Queue;
|
