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https://github.com/laurent22/joplin.git
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104 lines
2.2 KiB
TypeScript
104 lines
2.2 KiB
TypeScript
import AsyncActionQueue from '../AsyncActionQueue';
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const EventEmitter = require('events');
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class UndoQueue {
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private inner_:any[] = [];
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private size_:number = 20;
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pop() {
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return this.inner_.pop();
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}
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push(e:any) {
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this.inner_.push(e);
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while (this.length > this.size_) {
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this.inner_.splice(0,1);
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}
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}
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get length():number {
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return this.inner_.length;
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}
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at(index:number):any {
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return this.inner_[index];
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}
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}
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export default class UndoRedoService {
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private pushAsyncQueue:AsyncActionQueue = new AsyncActionQueue(700);
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private undoStates:UndoQueue = new UndoQueue();
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private redoStates:UndoQueue = new UndoQueue();
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private eventEmitter:any = new EventEmitter();
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private isUndoing:boolean = false;
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constructor() {
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this.push = this.push.bind(this);
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}
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on(eventName:string, callback:Function) {
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return this.eventEmitter.on(eventName, callback);
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}
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off(eventName:string, callback:Function) {
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return this.eventEmitter.removeListener(eventName, callback);
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}
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push(state:any) {
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this.undoStates.push(state);
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this.redoStates = new UndoQueue();
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this.eventEmitter.emit('stackChange');
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}
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schedulePush(state:any) {
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this.pushAsyncQueue.push(async () => {
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this.push(state);
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});
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}
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async undo(redoState:any) {
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if (this.isUndoing) return;
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if (!this.canUndo) throw new Error('Nothing to undo');
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this.isUndoing = true;
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await this.pushAsyncQueue.processAllNow();
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const state = this.undoStates.pop();
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this.redoStates.push(redoState);
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this.eventEmitter.emit('stackChange');
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this.isUndoing = false;
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return state;
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}
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async redo(undoState:any) {
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if (this.isUndoing) return;
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if (!this.canRedo) throw new Error('Nothing to redo');
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this.isUndoing = true;
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await this.pushAsyncQueue.processAllNow();
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const state = this.redoStates.pop();
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this.undoStates.push(undoState);
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this.eventEmitter.emit('stackChange');
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this.isUndoing = false;
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return state;
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}
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async reset() {
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this.undoStates = new UndoQueue();
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this.redoStates = new UndoQueue();
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this.isUndoing = false;
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const output = this.pushAsyncQueue.reset();
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this.eventEmitter.emit('stackChange');
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return output;
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}
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get canUndo():boolean {
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return !!this.undoStates.length;
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}
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get canRedo():boolean {
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return !!this.redoStates.length;
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}
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}
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