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ICSharpCode.TextEditor/Project/Src/Undo/UndoStack.cs

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+// <file>
+//     <copyright see="prj:///doc/copyright.txt"/>
+//     <license see="prj:///doc/license.txt"/>
+//     <owner name="Mike Krüger" email="mike@icsharpcode.net"/>
+//     <version>$Revision$</version>
+// </file>
+
+using System;
+using System.Collections.Generic;
+using System.Drawing;
+
+namespace ICSharpCode.TextEditor.Undo
+{
+	/// <summary>
+	/// This class implements an undo stack
+	/// </summary>
+	public class UndoStack
+	{
+		Stack<IUndoableOperation> undostack = new Stack<IUndoableOperation>();
+		Stack<IUndoableOperation> redostack = new Stack<IUndoableOperation>();
+		
+		public TextEditorControlBase TextEditorControl = null;
+		
+		/// <summary>
+		/// </summary>
+		public event EventHandler ActionUndone;
+		/// <summary>
+		/// </summary>
+		public event EventHandler ActionRedone;
+		
+		public event OperationEventHandler OperationPushed;
+		
+		/// <summary>
+		/// Gets/Sets if changes to the document are protocolled by the undo stack.
+		/// Used internally to disable the undo stack temporarily while undoing an action.
+		/// </summary>
+		internal bool AcceptChanges = true;
+		
+		/// <summary>
+		/// Gets if there are actions on the undo stack.
+		/// </summary>
+		public bool CanUndo {
+			get {
+				return undostack.Count > 0;
+			}
+		}
+		
+		/// <summary>
+		/// Gets if there are actions on the redo stack.
+		/// </summary>
+		public bool CanRedo {
+			get {
+				return redostack.Count > 0;
+			}
+		}
+		
+		/// <summary>
+		/// Gets the number of actions on the undo stack.
+		/// </summary>
+		public int UndoItemCount {
+			get {
+				return undostack.Count;
+			}
+		}
+		
+		/// <summary>
+		/// Gets the number of actions on the redo stack.
+		/// </summary>
+		public int RedoItemCount {
+			get {
+				return redostack.Count;
+			}
+		}
+		
+		int undoGroupDepth;
+		int actionCountInUndoGroup;
+		
+		public void StartUndoGroup()
+		{
+			if (undoGroupDepth == 0) {
+				actionCountInUndoGroup = 0;
+			}
+			undoGroupDepth++;
+			//Util.LoggingService.Debug("Open undo group (new depth=" + undoGroupDepth + ")");
+		}
+		
+		public void EndUndoGroup()
+		{
+			if (undoGroupDepth == 0)
+				throw new InvalidOperationException("There are no open undo groups");
+			undoGroupDepth--;
+			//Util.LoggingService.Debug("Close undo group (new depth=" + undoGroupDepth + ")");
+			if (undoGroupDepth == 0 && actionCountInUndoGroup > 1) {
+				UndoQueue op = new UndoQueue(undostack, actionCountInUndoGroup);
+				undostack.Push(op);
+				if (OperationPushed != null) {
+					OperationPushed(this, new OperationEventArgs(op));
+				}
+			}
+		}
+		
+		public void AssertNoUndoGroupOpen()
+		{
+			if (undoGroupDepth != 0) {
+				undoGroupDepth = 0;
+				throw new InvalidOperationException("No undo group should be open at this point");
+			}
+		}
+		
+		/// <summary>
+		/// Call this method to undo the last operation on the stack
+		/// </summary>
+		public void Undo()
+		{
+			AssertNoUndoGroupOpen();
+			if (undostack.Count > 0) {
+				IUndoableOperation uedit = (IUndoableOperation)undostack.Pop();
+				redostack.Push(uedit);
+				uedit.Undo();
+				OnActionUndone();
+			}
+		}
+		
+		/// <summary>
+		/// Call this method to redo the last undone operation
+		/// </summary>
+		public void Redo()
+		{
+			AssertNoUndoGroupOpen();
+			if (redostack.Count > 0) {
+				IUndoableOperation uedit = (IUndoableOperation)redostack.Pop();
+				undostack.Push(uedit);
+				uedit.Redo();
+				OnActionRedone();
+			}
+		}
+		
+		/// <summary>
+		/// Call this method to push an UndoableOperation on the undostack, the redostack
+		/// will be cleared, if you use this method.
+		/// </summary>
+		public void Push(IUndoableOperation operation)
+		{
+			if (operation == null) {
+				throw new ArgumentNullException("operation");
+			}
+			
+			if (AcceptChanges) {
+				StartUndoGroup();
+				undostack.Push(operation);
+				actionCountInUndoGroup++;
+				if (TextEditorControl != null) {
+					undostack.Push(new UndoableSetCaretPosition(this, TextEditorControl.ActiveTextAreaControl.Caret.Position));
+					actionCountInUndoGroup++;
+				}
+				EndUndoGroup();
+				ClearRedoStack();
+			}
+		}
+		
+		/// <summary>
+		/// Call this method, if you want to clear the redo stack
+		/// </summary>
+		public void ClearRedoStack()
+		{
+			redostack.Clear();
+		}
+		
+		/// <summary>
+		/// Clears both the undo and redo stack.
+		/// </summary>
+		public void ClearAll()
+		{
+			AssertNoUndoGroupOpen();
+			undostack.Clear();
+			redostack.Clear();
+			actionCountInUndoGroup = 0;
+		}
+		
+		/// <summary>
+		/// </summary>
+		protected void OnActionUndone()
+		{
+			if (ActionUndone != null) {
+				ActionUndone(null, null);
+			}
+		}
+		
+		/// <summary>
+		/// </summary>
+		protected void OnActionRedone()
+		{
+			if (ActionRedone != null) {
+				ActionRedone(null, null);
+			}
+		}
+		
+		class UndoableSetCaretPosition : IUndoableOperation
+		{
+			UndoStack stack;
+			TextLocation pos;
+			TextLocation redoPos;
+			
+			public UndoableSetCaretPosition(UndoStack stack, TextLocation pos)
+			{
+				this.stack = stack;
+				this.pos = pos;
+			}
+			
+			public void Undo()
+			{
+				redoPos = stack.TextEditorControl.ActiveTextAreaControl.Caret.Position;
+				stack.TextEditorControl.ActiveTextAreaControl.Caret.Position = pos;
+				stack.TextEditorControl.ActiveTextAreaControl.SelectionManager.ClearSelection();
+			}
+			
+			public void Redo()
+			{
+				stack.TextEditorControl.ActiveTextAreaControl.Caret.Position = redoPos;
+				stack.TextEditorControl.ActiveTextAreaControl.SelectionManager.ClearSelection();
+			}
+		}
+	}
+		
+	public class OperationEventArgs : EventArgs
+	{
+		public OperationEventArgs(IUndoableOperation op)
+		{
+			this.op = op;
+		}
+		
+		IUndoableOperation op;
+		
+		public IUndoableOperation Operation {
+			get {
+				return op;
+			}
+		}
+	}
+	
+	public delegate void OperationEventHandler(object sender, OperationEventArgs e);
+}