Current File : /home/opti/workflow/node_modules/generic-pool/lib/Deque.js
"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;
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