74 lines
2.1 KiB
JavaScript
74 lines
2.1 KiB
JavaScript
/*---------------------------------------------------------------------------------------------
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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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import { ArrayNavigator } from './navigator.js';
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export class HistoryNavigator {
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constructor(history = [], limit = 10) {
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this._initialize(history);
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this._limit = limit;
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this._onChange();
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}
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getHistory() {
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return this._elements;
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}
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add(t) {
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this._history.delete(t);
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this._history.add(t);
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this._onChange();
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}
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next() {
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if (this._currentPosition() !== this._elements.length - 1) {
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return this._navigator.next();
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}
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return null;
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}
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previous() {
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if (this._currentPosition() !== 0) {
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return this._navigator.previous();
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}
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return null;
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}
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current() {
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return this._navigator.current();
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}
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first() {
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return this._navigator.first();
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}
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last() {
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return this._navigator.last();
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}
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has(t) {
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return this._history.has(t);
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}
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_onChange() {
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this._reduceToLimit();
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const elements = this._elements;
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this._navigator = new ArrayNavigator(elements, 0, elements.length, elements.length);
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}
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_reduceToLimit() {
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const data = this._elements;
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if (data.length > this._limit) {
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this._initialize(data.slice(data.length - this._limit));
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}
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}
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_currentPosition() {
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const currentElement = this._navigator.current();
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if (!currentElement) {
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return -1;
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}
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return this._elements.indexOf(currentElement);
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}
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_initialize(history) {
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this._history = new Set();
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for (const entry of history) {
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this._history.add(entry);
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}
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}
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get _elements() {
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const elements = [];
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this._history.forEach(e => elements.push(e));
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return elements;
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}
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}
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