alice.mosphere.at
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1// A generic undo manager that stores state snapshots.
2export class UndoManager<T> {
3 private undoStack: T[] = [];
4 private redoStack: T[] = [];
5 private currentState: T;
6 constructor(initialState: T) {
7 this.currentState = this.deepCopy(initialState);
8 }
9 private deepCopy(state: T): T {
10 return JSON.parse(JSON.stringify(state)) as T;
11 }
12 execute(newState: T) {
13 this.undoStack.push(this.deepCopy(this.currentState));
14 this.currentState = this.deepCopy(newState);
15 this.redoStack = []; // clear redo on new action
16 }
17 undo(): T | null {
18 if (!this.undoStack.length) return null;
19 this.redoStack.push(this.deepCopy(this.currentState));
20 this.currentState = this.undoStack.pop()!;
21 return this.deepCopy(this.currentState);
22 }
23 redo(): T | null {
24 if (!this.redoStack.length) return null;
25 this.undoStack.push(this.deepCopy(this.currentState));
26 this.currentState = this.redoStack.pop()!;
27 return this.deepCopy(this.currentState);
28 }
29 getState(): T {
30 return this.deepCopy(this.currentState);
31 }
32 canUndo(): boolean {
33 return this.undoStack.length > 0;
34 }
35 canRedo(): boolean {
36 return this.redoStack.length > 0;
37 }
38}