Redis

"use strict"; const DoublyLinkedList = require("./DoublyLinkedList"); const DequeIterator = require("./DequeIterator"); /** * DoublyLinkedList backed double ended queue * implements just enough to keep the Pool */ class Deque { constructor() { this._list = new DoublyLinkedList(); } /** * removes and returns the first element from the queue * @return {any} [description] */ shift() { if (this.length === 0) { return undefined; } const node = this._list.head; this._list.remove(node); return node.data; } /** * adds one elemts to the beginning of the queue * @param {any} element [description] * @return {any} [description] */ unshift(element) { const node = DoublyLinkedList.createNode(element); this._list.insertBeginning(node); } /** * adds one to the end of the queue * @param {any} element [description] * @return {any} [description] */ push(element) { const node = DoublyLinkedList.createNode(element); this._list.insertEnd(node); } /** * removes and returns the last element from the queue */ pop() { if (this.length === 0) { return undefined; } const node = this._list.tail; this._list.remove(node); return node.data; } [Symbol.iterator]() { return new DequeIterator(this._list); } iterator() { return new DequeIterator(this._list); } reverseIterator() { return new DequeIterator(this._list, true); } /** * get a reference to the item at the head of the queue * @return {any} [description] */ get head() { if (this.length === 0) { return undefined; } const node = this._list.head; return node.data; } /** * get a reference to the item at the tail of the queue * @return {any} [description] */ get tail() { if (this.length === 0) { return undefined; } const node = this._list.tail; return node.data; } get length() { return this._list.length; } } module.exports = Deque;