PixelPerfectEngine.concrete.eventChainSystem source code

1 module PixelPerfectEngine.concrete.eventChainSystem;
2 /**
3  * Defines an undoable event.
4  */
5 public interface UndoableEvent{
6 	public abstract void redo();	///called both when a redo command is initialized or the event is added to the stack.
7 	public abstract void undo();	///called when an undo command is initialized on the stack.
8 }
9 
10 /**
11  * Implements an undoable event list with automatic handling of undo/redo commands
12  */
13 public class UndoableStack{
14 	private UndoableEvent[] events;
15 	private size_t currentPos;
16 
17 	public this(size_t maxElements){
18 		events.length = maxElements;
19 	}
20 	/**
21 	 * Adds an event to the top of the stack. If there are any undone events, they'll be lost. Bottom event is also lost.
22 	 */
23 	public void addToTop(UndoableEvent e){
24 		if(currentPos){
25 			events = events[currentPos..$];
26 		}
27 		e.redo;
28 		for(int i = events.length - 1 ; i > 0 ; i--){
29 			events[i] = events[i - 1];
30 		}
31 		events[0] = e;
32 	}
33 	/**
34 	 * Undos top event.
35 	 */
36 	public void undo(){
37 		if(currentPos < events.length){
38 			if(events[currentPos]){
39 				events[currentPos].undo;
40 				currentPos++;
41 			}
42 		}
43 	}
44 	/**
45 	 * Redos top event.
46 	 */
47 	public void redo(){
48 		if(currentPos > 0){
49 			if(events[currentPos]){
50 				currentPos--;
51 				events[currentPos].redo;
52 			}
53 		}
54 	}
55 }