net/systemeD/halcyon/connection/MainUndoStack.as

   1 package net.systemeD.halcyon.connection {
   2
   3     import flash.events.*;
   4
   5     public class MainUndoStack extends EventDispatcher {
   6         private static const GLOBAL_INSTANCE:MainUndoStack = new MainUndoStack();
   7
   8         public static function getGlobalStack():MainUndoStack {
   9             return GLOBAL_INSTANCE;
  10         }
  11
  12         private var undoActions:Array = [];
  13         private var redoActions:Array = [];
  14
  15         /*
  16          * Performs the action, then puts it on the undo stack.
  17          *
  18          * If you want to delay execution don't put it on this
  19          * stack -- find another one.
  20          */
  21         public function addAction(action:UndoableAction):void {
  22             var result:uint = action.doAction();
  23
  24             switch ( result ) {
  25
  26             case UndoableAction.FAIL:
  27                 throw new Error("Failure performing "+action);
  28
  29             case UndoableAction.NO_CHANGE:
  30                 // nothing to do, and don't add to stack
  31                 break;
  32
  33             case UndoableAction.SUCCESS:
  34             default:
  35                 if ( undoActions.length > 0 ) {
  36                     var previous:UndoableAction = undoActions[undoActions.length - 1];
  37                     var isMerged:Boolean = action.mergePrevious(previous);
  38                     if ( isMerged ) {
  39                                                 UndoableEntityAction(action).wasDirty = UndoableEntityAction(previous).wasDirty;
  40                                                 UndoableEntityAction(action).connectionWasDirty = UndoableEntityAction(previous).connectionWasDirty;
  41                         undoActions.pop();
  42                                         }
  43                 }
  44                 undoActions.push(action);
  45                 redoActions = [];
  46                 dispatchEvent(new Event("new_undo_item"));
  47                 dispatchEvent(new Event("new_redo_item"));
  48                 break;
  49
  50             }
  51         }
  52
  53         /*
  54          * Call to kill the undo queue -- the user will not be able to undo
  55          * anything they previously did after this is called.
  56          */
  57         public function breakUndo():void {
  58             undoActions = [];
  59             redoActions = [];
  60         }
  61
  62         [Bindable(event="new_undo_item")]
  63         public function canUndo():Boolean {
  64             return undoActions.length > 0;
  65         }
  66
  67         [Bindable(event="new_redo_item")]
  68         public function canRedo():Boolean {
  69             return redoActions.length > 0;
  70         }
  71
  72         public function undo():void {
  73                         if (!undoActions.length) { return; }
  74             var action:UndoableAction = undoActions.pop();
  75             action.undoAction();
  76             redoActions.push(action);
  77             dispatchEvent(new Event("new_undo_item"));
  78             dispatchEvent(new Event("new_redo_item"));
  79         }
  80
  81         public function redo():void {
  82                         if (!redoActions.length) { return; }
  83             var action:UndoableAction = redoActions.pop();
  84             action.doAction();
  85             undoActions.push(action);
  86             dispatchEvent(new Event("new_undo_item"));
  87             dispatchEvent(new Event("new_redo_item"));
  88         }
  89
  90     }
  91 }