123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113
import { QueueType, DataType, QueueApi, QueueNode } from "./helper.ts"
export class Queue implements QueueApi {	public frontNode: QueueType	private backNode: QueueType	public size: number
	constructor() {		this.frontNode = null		this.backNode = null		this.size = 0	}
	getFront() {		if (this.frontNode === null) return null		return this.frontNode!.data	}
	getBack() {		if (this.frontNode === null) return null		return this.backNode!.data	}
	enqueue(data: DataType<any>) {		const newNode = new QueueNode(data)		if (this.frontNode === null) {			// adding same pointer for frontNode & backNode			this.frontNode = newNode			this.backNode = newNode			return true;		}
		// pointer and it's greatness		// frontNode & backNode both have same reference.		// so backNode.next will also update frontNode.next
		// then in secound insertion frontNode & backNode pointers are changed,		// but frontNode.next & backNode.next pointers are still same.		// so backNode.next will also update frontNode.next		this.backNode!.next = newNode		this.backNode = newNode		this.size++
		return true;	}
	dequeue() {		if (this.frontNode === null) {			return false;		} else if (this.frontNode!.next === null) {			this.backNode = null		}				const node = this.frontNode		this.frontNode = node!.next		this.size--		if (this.frontNode === null) this.size = 0
		return node!.data;	}
	search(key: string|number) {		if (this.frontNode === null) {			return null		}
		if (key === this.frontNode!.data.key) {			return this.frontNode!.data		}		if (key === this.backNode!.data.key) {			return this.backNode!.data		}
		let currentNode = this.frontNode!.next		while (currentNode !== null) {			if (key === currentNode.data.key) {				return currentNode.data			}
			currentNode = currentNode.next		}
		return null	}
	update(key: string|number, newValue: any) {		if (this.frontNode === null) {			return false		}
		if (key === this.frontNode!.data.key) {			this.frontNode!.data.value = newValue			return this.frontNode!.data		}		if (key === this.backNode!.data.key) {			this.backNode!.data.value = newValue			return this.backNode!.data		}
		let currentNode = this.frontNode!.next		while (currentNode !== null) {			if (key === currentNode.data.key) {				currentNode.data.value = newValue				return currentNode.data			}
			currentNode = currentNode.next		}
		return false	}}