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LinkedList.js
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LinkedList.js
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import LinkedListNode from './LinkedListNode';
import Comparator from '../../utils/comparator/Comparator';
export default class LinkedList {
/**
* @param {Function} [comparatorFunction]
*/
constructor(comparatorFunction) {
/** @var LinkedListNode */
this.head = null;
/** @var LinkedListNode */
this.tail = null;
this.compare = new Comparator(comparatorFunction);
}
/**
* @param {*} value
* @return {LinkedList}
*/
prepend(value) {
// Make new node to be a head.
this.head = new LinkedListNode(value, this.head);
return this;
}
/**
* @param {*} value
* @return {LinkedList}
*/
append(value) {
const newNode = new LinkedListNode(value);
// If there is no head yet let's make new node a head.
if (!this.head) {
this.head = newNode;
this.tail = newNode;
return this;
}
// Attach new node to the end of linked list.
this.tail.next = newNode;
this.tail = newNode;
return this;
}
/**
* @param {*} value
* @return {LinkedListNode}
*/
delete(value) {
if (!this.head) {
return null;
}
let deletedNode = null;
// If the head must be deleted then make 2nd node to be a head.
if (this.compare.equal(this.head.value, value)) {
deletedNode = this.head;
this.head = this.head.next;
}
let currentNode = this.head;
if (currentNode !== null) {
// If next node must be deleted then make next node to be a next next one.
while (currentNode.next) {
if (this.compare.equal(currentNode.next.value, value)) {
deletedNode = currentNode.next;
currentNode.next = currentNode.next.next;
} else {
currentNode = currentNode.next;
}
}
}
// Check if tail must be deleted.
if (this.compare.equal(this.tail.value, value)) {
this.tail = currentNode;
}
return deletedNode;
}
/**
* @param {Object} findParams
* @param {*} findParams.value
* @param {function} [findParams.callback]
* @return {LinkedListNode}
*/
find({ value = undefined, callback = undefined }) {
if (!this.head) {
return null;
}
let currentNode = this.head;
while (currentNode) {
// If callback is specified then try to find node by callback.
if (callback && callback(currentNode.value)) {
return currentNode;
}
// If value is specified then try to compare by value..
if (value !== undefined && this.compare.equal(currentNode.value, value)) {
return currentNode;
}
currentNode = currentNode.next;
}
return null;
}
/**
* @return {LinkedListNode}
*/
deleteTail() {
if (this.head === this.tail) {
const deletedTail = this.tail;
this.head = null;
this.tail = null;
return deletedTail;
}
const deletedTail = this.tail;
// Rewind to the last node and delete "next" link for the node before the last one.
let currentNode = this.head;
while (currentNode.next) {
if (!currentNode.next.next) {
currentNode.next = null;
} else {
currentNode = currentNode.next;
}
}
this.tail = currentNode;
return deletedTail;
}
/**
* @return {LinkedListNode}
*/
deleteHead() {
if (!this.head) {
return null;
}
const deletedHead = this.head;
if (this.head.next) {
this.head = this.head.next;
} else {
this.head = null;
this.tail = null;
}
return deletedHead;
}
/**
* @return {LinkedListNode[]}
*/
toArray() {
const nodes = [];
let currentNode = this.head;
while (currentNode) {
nodes.push(currentNode);
currentNode = currentNode.next;
}
return nodes;
}
/**
* @param {function} [callback]
* @return {string}
*/
toString(callback) {
return this.toArray().map(node => node.toString(callback)).toString();
}
}