PixelPerfectEngine.concrete.eventChainSystem source code

1 module PixelPerfectEngine.concrete.eventChainSystem;
2 
3 import collections.linkedlist;
4 /**
5  * Defines an undoable event.
6  */
7 public interface UndoableEvent{
8 	public void redo();	///called both when a redo command is initialized or the event is added to the stack.
9 	public void undo();	///called when an undo command is initialized on the stack.
10 }
11 
12 /**
13  * Implements an undoable event list with automatic handling of undo/redo commands
14  */
15 public class UndoableStack{
16 	alias EventStack = LinkedList!(UndoableEvent);
17 	protected EventStack events;
18 	protected size_t currentPos, currentCap, maxLength;
19 
20 	public this(size_t maxElements) @safe pure nothrow{
21 		maxLength = maxElements;
22 		//events.length = maxElements;
23 	}
24 	/**
25 	 * Adds an event to the top of the stack. If there are any undone events, they'll be lost. Bottom event is always lost.
26 	 */
27 	public void addToTop(UndoableEvent e){
28 		while(currentPos) {
29 			events.remove(0);
30 			currentPos--;
31 		}
32 		events.insertAt(e, 0);
33 		e.redo;
34 		while(events.length > maxLength) events.remove(maxLength);
35 	}
36 	/**
37 	 * Undos top event.
38 	 */
39 	public void undo(){
40 		if(currentPos < events.length){
41 			events[currentPos].undo;
42 			currentPos++;
43 		}
44 	}
45 	/**
46 	 * Redos top event.
47 	 */
48 	public void redo() {
49 		if(currentPos >= 0){
50 			currentPos--;
51 			events[currentPos].redo;
52 		}
53 	}
54 	/**
55 	 * Returns the length of the current stack
56 	 */
57 	public size_t length() {
58 		return events.length;
59 	}
60 }