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import { LinkedListApi, NodeType, DataType } from "./helper.d.ts";import { SinglyNode } from "./singlyNode.ts";import {	addGenerator,	updateGenerator,	searchGenerator,	iteratorGenerator} from "./generators.ts"
export class SinglyLinkedList implements LinkedListApi {	#head: null|NodeType	#tail: null|NodeType	public size: number
	constructor() {		this.#head = null		this.#tail = null		this.size = 0	}
	static createSL() {		return new this();	}
	// insert in the head	prepend(data: DataType<any>) {		if (this.#head === null) {			const newNode = new SinglyNode(data);			this.#head = newNode			this.#tail = newNode			return true;		}
		const currentNode = this.#head		this.#head = new SinglyNode(data)		this.#head.next = currentNode		if (currentNode.next === null) {			this.#tail = currentNode		}		this.size++
		return true;	}
	// inset in the tail	append(data: DataType<any>) {		const newNode = new SinglyNode(data);		if (this.#head === null) {			this.#head = newNode			this.#tail = newNode			return true;		}
		this.#tail!.next = newNode		this.#tail = newNode		this.size++
		return false;	}
	// // add anywhere of the linked list except head & tail	add(data: DataType<any>, position: number) {		if (position === 0) {			console.error("Use `prepend()` method to insert data at Head.");			return false;		} else if (position === this.size) {			console.error("Use `append()` method to insert data at Tail.");			return false;		} else if (position > this.size && position != this.size + 1) {			console.error(`Out of range. Size of the linkedList is ${this.size}`);			return false;		}			let currentNode = this.#head		// generator function that returns an iterator		const iterator = addGenerator(currentNode, data, position)		const iteratorNext = iterator.next()		if (iteratorNext.value) {			this.size++			return true		}
		return false;	}
	getFromHead() {		if (this.#head === null) {			return false		}
		return this.#head.data;	}
	getFromTail() {		if (this.#tail === null) {			return false		}
		return this.#tail.data	}
	log() {		let currentNode = this.#head		while (currentNode !== null) {			console.log(currentNode.data);			currentNode = currentNode.next		}	}
	remove(key: string|number) {		if (this.#head === null) {			return false;		} else if (this.#head!.next === null) {			this.#tail = null		}		if (this.#head.data.key === key) {			const prevHeadData = this.#head.data			this.#head = this.#head.next			if (this.#head!.next === null) this.#tail = this.#head
			this.size--			if (this.#head === null) this.size = 0			return true;		}
		// two pointer approach		let previousNode: NodeType = null;		let currentNode: NodeType = this.#head		while (currentNode !== null) {			if (key === currentNode.data.key) {				const temp = currentNode.data				previousNode!.next = currentNode.next				if (currentNode!.next === null) this.#tail = previousNode
				this.size--				return true;			}
			previousNode = currentNode			currentNode = currentNode.next		}
		return false;	}
	update(key: string|number, newValue: any) {		if (this.#head === null) {			return false;		}
		if (this.#head.data.key === key) {			this.#head.data.value = newValue			return this.#head.data;		}		if (this.#tail!.data.key === key) {			this.#tail!.data.value = newValue			return this.#tail!.data;		}
		let currentNode = this.#head.next		// generator function that returns an iterator		const iterator = updateGenerator(key, currentNode, newValue)		const iteratorNext = iterator.next()		if (iteratorNext.value) {			return iteratorNext.value		}
		return false;	}
	search(key: string|number) {		if (this.#head === null) {			return false;		}
		if (this.#head.data.key === key) {			return this.#head.data;		}		if (this.#tail!.data.key === key) {			return this.#tail!.data		}
		let currentNode = this.#head.next		// generator function that returns an iterator		const iterator = searchGenerator(key, currentNode)		const iteratorNext = iterator.next()		if (iteratorNext.value) {			return iteratorNext.value		}
		return false;	}
	iterator() {		const currentNode = this.#head		// generator function that returns an iterator		const iterator = iteratorGenerator(currentNode)		return iterator	}}