import LinkedList from '../linked-list/LinkedList'; export default class Stack { constructor() { this.linkedList = new LinkedList(); } /** * @return {boolean} */ isEmpty() { return !this.linkedList.tail; } /** * @return {*} */ peek() { if (this.isEmpty()) { return null; } return this.linkedList.tail.value; } /** * @param {*} value */ push(value) { this.linkedList.append(value); } /** * @return {*} */ pop() { const removedTail = this.linkedList.deleteTail(); return removedTail ? removedTail.value : null; } /** * @return {*[]} */ toArray() { return this.linkedList .toArray() .map(linkedListNode => linkedListNode.value) .reverse(); } /** * @param {function} [callback] * @return {string} */ toString(callback) { return this.linkedList.toString(callback); } }