77 lines
2.2 KiB
JavaScript
77 lines
2.2 KiB
JavaScript
|
"use strict";
|
||
|
|
(function queuePrivateClosure () {
|
||
|
|
/**
|
||
|
|
* This class is a primitive doubly linked list, I need it to implement a queue
|
||
|
|
* */
|
||
|
|
class Queue {
|
||
|
|
constructor () {
|
||
|
|
this._head = new Node(null);
|
||
|
|
this._tail = this._head;
|
||
|
|
this._head.next = this._tail;
|
||
|
|
this._head.prev = this._tail;
|
||
|
|
this.length = 0;
|
||
|
|
}
|
||
|
|
/**
|
||
|
|
* Check if the queue is empty
|
||
|
|
*
|
||
|
|
* @returns Boolean
|
||
|
|
* */
|
||
|
|
get empty () {return this._head === this._tail;}
|
||
|
|
/**
|
||
|
|
* Adds element to the end of the queue.
|
||
|
|
* Data is not copied, now ownership taken
|
||
|
|
*
|
||
|
|
* @param {any} data - a data you wish to add
|
||
|
|
* */
|
||
|
|
push (data) {
|
||
|
|
const node = new Node(data);
|
||
|
|
node.prev = this._head.prev;
|
||
|
|
node.next = this._head;
|
||
|
|
this._head.prev = node;
|
||
|
|
this._head = node;
|
||
|
|
++this.length;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Removes element from the beginning of the queue and returns it
|
||
|
|
*
|
||
|
|
* @returns {any} - a data from the list
|
||
|
|
* @throws Error if the list was empty
|
||
|
|
* */
|
||
|
|
pop () {
|
||
|
|
if (this.empty)
|
||
|
|
throw new Error("An attempt to pop from an empty queue");
|
||
|
|
|
||
|
|
const node = this._tail.prev;
|
||
|
|
const data = node.data;
|
||
|
|
node.prev.next = node.next;
|
||
|
|
node.next.prev = node.prev;
|
||
|
|
if (this._head === node) {
|
||
|
|
this._head = node.next;
|
||
|
|
}
|
||
|
|
--this.length;
|
||
|
|
return data;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* A helper class for the Queue, just a data structure with getters
|
||
|
|
* */
|
||
|
|
class Node {
|
||
|
|
constructor (data) {
|
||
|
|
this._data = data;
|
||
|
|
this._next = null; //Node
|
||
|
|
this._prev = null; //Node
|
||
|
|
}
|
||
|
|
get data () {return this._data;}
|
||
|
|
get next () {return this._next;}
|
||
|
|
set next (/*Node*/node) {this._next = node;}
|
||
|
|
get prev () {return this._prev;}
|
||
|
|
set prev (/*Node*/node) {this._prev = node;}
|
||
|
|
}
|
||
|
|
|
||
|
|
if (typeof module === 'object' && module.exports)
|
||
|
|
module.exports = Queue;
|
||
|
|
else
|
||
|
|
window.__MimicryQueue__ = Queue;
|
||
|
|
})();
|