dist-javascript-algorithms-and-data-structures/dist/data-structures/queue/Queue.js

Algorithms and data-structures implemented on JavaScript

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = void 0;

var _LinkedList = _interopRequireDefault(require("../linked-list/LinkedList"));

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

class Queue {
  constructor() {
    // We're going to implement Queue based on LinkedList since the two
    // structures are quite similar. Namely, they both operate mostly on
    // the elements at the beginning and the end. Compare enqueue/dequeue
    // operations of Queue with append/deleteHead operations of LinkedList.
    this.linkedList = new _LinkedList.default();
  }
  /**
   * @return {boolean}
   */


  isEmpty() {
    return !this.linkedList.head;
  }
  /**
   * Read the element at the front of the queue without removing it.
   * @return {*}
   */


  peek() {
    if (!this.linkedList.head) {
      return null;
    }

    return this.linkedList.head.value;
  }
  /**
   * Add a new element to the end of the queue (the tail of the linked list).
   * This element will be processed after all elements ahead of it.
   * @param {*} value
   */


  enqueue(value) {
    this.linkedList.append(value);
  }
  /**
   * Remove the element at the front of the queue (the head of the linked list).
   * If the queue is empty, return null.
   * @return {*}
   */


  dequeue() {
    const removedHead = this.linkedList.deleteHead();
    return removedHead ? removedHead.value : null;
  }
  /**
   * @param [callback]
   * @return {string}
   */


  toString(callback) {
    // Return string representation of the queue's linked list.
    return this.linkedList.toString(callback);
  }

}

exports.default = Queue;