undoqueue.cs

c#精彩编程百例（源代码）

//  UndoQueue.cs 
//  Copyright (c) 2000 Mike Krueger
//
//  This program is free software; you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation; either version 2 of the License, or
//  (at your option) any later version.
//
//  This program is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  along with this program; if not, write to the Free Software
//  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

using System;
using System.Diagnostics;
using System.Collections;
using SharpDevelop.Internal.Text;

namespace SharpDevelop.Internal.Undo {
	
	/// <summary>
	/// This class stacks the last x operations from the undostack and makes
	/// one undo/redo operation from it.
	/// </summary>
	public class UndoQueue : UndoableOperation
	{
		ArrayList undolist = new ArrayList();
		
		public UndoQueue(UndoStack stack, int numops)
		{
			if (stack == null) 
				throw new ArgumentNullException("UndoQueue(UndoStack stack, int numops) : buffer can't be null");
			
			Debug.Assert(numops > 0 , "SharpDevelop.Internal.Undo.UndoQueue : numops should be > 0");
			
			for (int i = 0; i < numops; ++i) {
				if (stack._UndoStack.Count > 0) {
					undolist.Add(stack._UndoStack.Pop());
				}
			}
		}
		
		public void Undo()
		{
			for (int i = 0; i < undolist.Count; ++i) 
				((UndoableOperation)undolist[i]).Undo();
		}
		
		public void Redo()
		{
			for (int i = 0; i < undolist.Count; ++i) 
				((UndoableOperation)undolist[i]).Redo();
		}
	}
}