Daniel Imms
edb0e1ceb3
- Merge ScrollableElement into SmoothScrollableElement - Prune unused helpers FastDomNode, Widget LinkedList - Make internal exports non-exported - Remove redundant guards/aliases
93 lines
2.3 KiB
TypeScript
93 lines
2.3 KiB
TypeScript
/*---------------------------------------------------------------------------------------------
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* Copyright (c) Microsoft Corporation. All rights reserved.
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* Licensed under the MIT License. See License.txt in the project root for license information.
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*--------------------------------------------------------------------------------------------*/
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class Node<E> {
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public static readonly Undefined = new Node<any>(undefined);
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public element: E;
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public next: Node<E>;
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public prev: Node<E>;
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public constructor(element: E) {
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this.element = element;
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this.next = Node.Undefined;
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this.prev = Node.Undefined;
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}
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}
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export class LinkedList<E> {
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private _first: Node<E> = Node.Undefined;
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private _last: Node<E> = Node.Undefined;
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public push(element: E): () => void {
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return this._insert(element, true);
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}
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private _insert(element: E, atTheEnd: boolean): () => void {
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const newNode = new Node(element);
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if (this._first === Node.Undefined) {
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this._first = newNode;
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this._last = newNode;
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} else if (atTheEnd) {
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// push
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const oldLast = this._last;
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this._last = newNode;
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newNode.prev = oldLast;
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oldLast.next = newNode;
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} else {
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// unshift
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const oldFirst = this._first;
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this._first = newNode;
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newNode.next = oldFirst;
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oldFirst.prev = newNode;
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}
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let didRemove = false;
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return () => {
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if (!didRemove) {
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didRemove = true;
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this._remove(newNode);
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}
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};
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}
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private _remove(node: Node<E>): void {
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if (node.prev !== Node.Undefined && node.next !== Node.Undefined) {
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// middle
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const anchor = node.prev;
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anchor.next = node.next;
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node.next.prev = anchor;
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} else if (node.prev === Node.Undefined && node.next === Node.Undefined) {
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// only node
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this._first = Node.Undefined;
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this._last = Node.Undefined;
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} else if (node.next === Node.Undefined) {
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// last
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this._last = this._last.prev!;
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this._last.next = Node.Undefined;
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} else if (node.prev === Node.Undefined) {
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// first
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this._first = this._first.next!;
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this._first.prev = Node.Undefined;
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}
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// done
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}
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public *[Symbol.iterator](): Iterator<E> {
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let node = this._first;
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while (node !== Node.Undefined) {
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yield node.element;
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node = node.next;
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}
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}
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}
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