/*	Copyright (c) 2004-2006, The Dojo Foundation	All Rights Reserved.	Licensed under the Academic Free License version 2.1 or above OR the	modified BSD license. For more information on Dojo licensing, see:		http://dojotoolkit.org/community/licensing.shtml*/dojo.provide("dojo.undo.Manager");dojo.require("dojo.lang");dojo.undo.Manager = function(parent) {	this.clear();	this._parent = parent;};dojo.lang.extend(dojo.undo.Manager, {	_parent: null,	_undoStack: null,	_redoStack: null,	_currentManager: null,	canUndo: false,	canRedo: false,	isUndoing: false,	isRedoing: false,	// these events allow you to hook in and update your code (UI?) as necessary	onUndo: function(manager, item) {},	onRedo: function(manager, item) {},	// fired when you do *any* undo action, which means you'll have one for every item	// in a transaction. this is usually only useful for debugging	onUndoAny: function(manager, item) {},	onRedoAny: function(manager, item) {},	_updateStatus: function() {		this.canUndo = this._undoStack.length > 0;		this.canRedo = this._redoStack.length > 0;	},	clear: function() {		this._undoStack = [];		this._redoStack = [];		this._currentManager = this;		this.isUndoing = false;		this.isRedoing = false;		this._updateStatus();	},	undo: function() {		if(!this.canUndo) { return false; }		this.endAllTransactions();		this.isUndoing = true;		var top = this._undoStack.pop();		if(top instanceof dojo.undo.Manager){			top.undoAll();		}else{			top.undo();		}		if(top.redo){			this._redoStack.push(top);		}		this.isUndoing = false;		this._updateStatus();		this.onUndo(this, top);		if(!(top instanceof dojo.undo.Manager)){			this.getTop().onUndoAny(this, top);		}		return true;	},	redo: function() {		if(!this.canRedo){ return false; }		this.isRedoing = true;		var top = this._redoStack.pop();		if(top instanceof dojo.undo.Manager){			top.redoAll();		}else{			top.redo();		}		this._undoStack.push(top);		this.isRedoing = false;		this._updateStatus();		this.onRedo(this, top);		if(!(top instanceof dojo.undo.Manager)){			this.getTop().onRedoAny(this, top);		}		return true;	},	undoAll: function() {		while(this._undoStack.length > 0) {			this.undo();		}	},	redoAll: function() {		while(this._redoStack.length > 0) {			this.redo();		}	},	push: function(undo, redo /* optional */, description /* optional */) {		if(!undo) { return; }		if(this._currentManager == this) {			this._undoStack.push({				undo: undo,				redo: redo,				description: description			});		} else {			this._currentManager.push.apply(this._currentManager, arguments);		}		// adding a new undo-able item clears out the redo stack		this._redoStack = [];		this._updateStatus();	},	concat: function(manager) {		if ( !manager ) { return; }		if (this._currentManager == this ) {			for(var x=0; x < manager._undoStack.length; x++) {				this._undoStack.push(manager._undoStack[x]);			}			// adding a new undo-able item clears out the redo stack			this._redoStack = [];			this._updateStatus();		} else {			this._currentManager.concat.apply(this._currentManager, arguments);		}	},	beginTransaction: function(description /* optional */) {		if(this._currentManager == this) {			var mgr = new dojo.undo.Manager(this);			mgr.description = description ? description : "";			this._undoStack.push(mgr);			this._currentManager = mgr;			return mgr;		} else {			//for nested transactions need to make sure the top level _currentManager is set			this._currentManager = this._currentManager.beginTransaction.apply(this._currentManager, arguments);		}	},	endTransaction: function(flatten /* optional */) {		if(this._currentManager == this) {			if(this._parent) {				this._parent._currentManager = this._parent;				// don't leave empty transactions hangin' around				if(this._undoStack.length == 0 || flatten) {					var idx = dojo.lang.find(this._parent._undoStack, this);					if (idx >= 0) {						this._parent._undoStack.splice(idx, 1);						//add the current transaction to parents undo stack						if (flatten) {							for(var x=0; x < this._undoStack.length; x++){								this._parent._undoStack.splice(idx++, 0, this._undoStack[x]);							}							this._updateStatus();						}					}				}				return this._parent;			}		} else {			//for nested transactions need to make sure the top level _currentManager is set			this._currentManager = this._currentManager.endTransaction.apply(this._currentManager, arguments);		}	},	endAllTransactions: function() {		while(this._currentManager != this) {			this.endTransaction();		}	},	// find the top parent of an undo manager	getTop: function() {		if(this._parent) {			return this._parent.getTop();		} else {			return this;		}	}});