Swap lines command

ICSharpCode.AvalonEdit/AvalonEditCommands.cs

@@ -45,6 +45,26 @@ public static class AvalonEditCommands
 				new KeyGesture(Key.D, ModifierKeys.Control)
 			});
 
+		/// <summary>
+		/// Swap the current line and the previous line.
+		/// The default shortcut is Alt+Up.
+		/// </summary>
+		public static readonly RoutedCommand SwapLinesUp = new RoutedCommand(
+			"SwapLinesUp", typeof(TextEditor),
+			new InputGestureCollection {
+				new KeyGesture(Key.Up, ModifierKeys.Alt)
+			});
+
+		/// <summary>
+		/// Swap the current line and the next line.
+		/// The default shortcut is Alt+Down.
+		/// </summary>
+		public static readonly RoutedCommand SwapLinesDown = new RoutedCommand(
+			"SwapLinesDown", typeof(TextEditor),
+			new InputGestureCollection {
+				new KeyGesture(Key.Down, ModifierKeys.Alt)
+			});
+
 		/// <summary>
 		/// Removes leading whitespace from the selected lines (or the whole document if the selection is empty).
 		/// </summary>

ICSharpCode.AvalonEdit/Editing/CaretSelectionPreserver.cs

@@ -0,0 +1,121 @@
+// Copyright (c) 2014 AlphaSierraPapa for the SharpDevelop Team
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this
+// software and associated documentation files (the "Software"), to deal in the Software
+// without restriction, including without limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+// to whom the Software is furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+using System;
+using ICSharpCode.AvalonEdit.Document;
+
+namespace ICSharpCode.AvalonEdit.Editing
+{
+	/// <summary>
+	/// Base class used by the CaretPreserver and SelectionPreserver
+	/// </summary>
+	abstract class CaretSelectionPreserver
+			: IDisposable
+	{
+		protected CaretSelectionPreserver(TextArea _textArea)
+		{
+			isDisposed = false;
+			textArea = _textArea;
+		}
+
+		public static CaretSelectionPreserver Create(TextArea textArea)
+		{
+			if (textArea.Selection.IsEmpty) {
+				return new CaretPreserver(textArea);
+			} else {
+				return new SelectionPreserver(textArea);
+			}
+		}
+
+		public void Dispose()
+		{
+			if (isDisposed) return;
+			isDisposed = true;
+			Restore();
+		}
+
+		public abstract void Restore();
+		public abstract void MoveLine(int i);
+
+		private bool isDisposed;
+
+		private TextArea textArea;
+		public TextArea TextArea { get { return textArea; } }
+	}
+
+	/// <summary>
+	/// This class moves the current caret position when a line is moved up or down
+	/// </summary>
+	class CaretPreserver
+		: CaretSelectionPreserver
+	{
+		public CaretPreserver(TextArea textArea)
+			: base(textArea)
+		{
+			caretLocation = textArea.Caret.Location;
+		}
+
+		public override void Restore()
+		{
+			TextArea.Caret.Location = caretLocation;
+		}
+
+		public override void MoveLine(int i)
+		{
+			caretLocation = new TextLocation(caretLocation.Line + i, caretLocation.Column);
+		}
+
+		TextLocation caretLocation;
+	}
+
+	/// <summary>
+	/// This class moves the current selection when the lines containing that selection
+	/// are moved up or down.
+	///
+	/// NOTE: The SelectionPreserver must inherit from the CaretPreserver as if the caret 
+	/// is not within the selection then the selection is not considered valid and is 
+	/// cleared. By inheriting from the CaretPreserver we move both the selection and 
+	/// the caret at the same time.
+	/// </summary> 
+	class SelectionPreserver
+		: CaretPreserver
+	{
+		public SelectionPreserver(TextArea textArea)
+			: base(textArea)
+		{
+			startLocation = textArea.Selection.StartPosition.Location;
+			endLocation = textArea.Selection.EndPosition.Location;
+		}
+
+		public override void Restore()
+		{
+			base.Restore();
+			TextArea.Selection = Selection.Create(TextArea, new TextViewPosition(startLocation), new TextViewPosition(endLocation));
+		}
+
+
+		public override void MoveLine(int i)
+		{
+			base.MoveLine(i);
+			startLocation = new TextLocation(startLocation.Line + i, startLocation.Column);
+			endLocation = new TextLocation(endLocation.Line + i, endLocation.Column);
+		}
+
+		TextLocation startLocation, endLocation;
+	}
+}

ICSharpCode.AvalonEdit/Editing/EditingCommandHandler.cs

@@ -78,6 +78,9 @@ static EditingCommandHandler()
 			CommandBindings.Add(new CommandBinding(AvalonEditCommands.ToggleOverstrike, OnToggleOverstrike));
 			CommandBindings.Add(new CommandBinding(AvalonEditCommands.DeleteLine, OnDeleteLine));
 
+			CommandBindings.Add(new CommandBinding(AvalonEditCommands.SwapLinesUp, OnSwapLinesUp));
+			CommandBindings.Add(new CommandBinding(AvalonEditCommands.SwapLinesDown, OnSwapLinesDown));
+
 			CommandBindings.Add(new CommandBinding(AvalonEditCommands.RemoveLeadingWhitespace, OnRemoveLeadingWhitespace));
 			CommandBindings.Add(new CommandBinding(AvalonEditCommands.RemoveTrailingWhitespace, OnRemoveTrailingWhitespace));
 			CommandBindings.Add(new CommandBinding(AvalonEditCommands.ConvertToUppercase, OnConvertToUpperCase));
@@ -521,6 +524,94 @@ static void OnDeleteLine(object target, ExecutedRoutedEventArgs args)
 		}
 		#endregion
 
+		#region SwapLines
+		static void OnSwapLinesUp(object target, ExecutedRoutedEventArgs args)
+		{
+			TextArea textArea = GetTextArea(target);
+			if (textArea != null && textArea.Document != null) {
+				using (var caretSelectionPreserver = CaretSelectionPreserver.Create(textArea)) {
+					var selectionFirstLine = textArea.Selection.IsEmpty ? textArea.Caret.Line : textArea.Selection.StartPosition.Line;
+					var selectionLastLine = textArea.Selection.IsEmpty ? textArea.Caret.Line : textArea.Selection.EndPosition.Line;
+					// we cannot move up if the selection is on the first line
+					if (selectionFirstLine == 1) return;
+
+					DocumentLine movedLine = textArea.Document.GetLineByNumber(selectionFirstLine - 1);
+					DocumentLine lastLine = textArea.Document.GetLineByNumber(selectionLastLine);
+
+					using (textArea.Document.RunUpdate()) {
+						textArea.Selection = Selection.Create(textArea, movedLine.Offset, movedLine.Offset + movedLine.TotalLength);
+						string movedLineText = textArea.Selection.GetText();
+						if (lastLine.NextLine == null) {
+							movedLineText = movedLineText.RotateTailLinebreak();
+						}
+						textArea.Document.Insert(lastLine.Offset + lastLine.TotalLength, movedLineText);
+						textArea.RemoveSelectedText();
+						caretSelectionPreserver.MoveLine(-1);
+					}
+				}
+				args.Handled = true;
+			}
+		}
+
+		static void OnSwapLinesDown(object target, ExecutedRoutedEventArgs args)
+		{
+			TextArea textArea = GetTextArea(target);
+			if (textArea != null && textArea.Document != null) {
+				using (var caretSelectionPreserver = CaretSelectionPreserver.Create(textArea)) {
+					var selectionFirstLine = textArea.Selection.IsEmpty ? textArea.Caret.Line : textArea.Selection.StartPosition.Line;
+					var selectionLastLine = textArea.Selection.IsEmpty ? textArea.Caret.Line : textArea.Selection.EndPosition.Line;
+					// we cannot move down if the selection is on the last line
+					if (selectionLastLine == textArea.Document.LineCount) return;
+
+					DocumentLine firstLine = textArea.Document.GetLineByNumber(selectionFirstLine);
+					DocumentLine lastLine = textArea.Document.GetLineByNumber(selectionLastLine);
+					DocumentLine movedLine = textArea.Document.GetLineByNumber(selectionLastLine + 1);
+
+					using (textArea.Document.RunUpdate()) {
+						textArea.Selection = Selection.Create(textArea, lastLine.EndOffset, movedLine.EndOffset);
+						string movedLineText = textArea.Selection.GetText().RotateHeadLinebreak();
+						textArea.Document.Insert(firstLine.Offset, movedLineText);
+						textArea.RemoveSelectedText();
+						caretSelectionPreserver.MoveLine(+1);
+					}
+				}
+				args.Handled = true;
+			}
+		}
+
+		/// <summary>
+		/// Move the leading linebreak to the end.
+		/// </summary>
+		/// <param name="self">A string which starts with one or more linebreaks.</param>
+		/// <returns></returns>
+		private static string RotateHeadLinebreak(this string self)
+		{
+			int len = self.Length;
+			// check if the line break is /n or /r/n
+			string linebreak =
+				(len >= 2 && self.Substring(0, 2) == "\r\n")
+				? "\r\n"
+				: self.Substring(0, 1);
+			return self.Remove(0, linebreak.Length) + linebreak;
+		}
+
+		/// <summary>
+		/// Move the tailing linebreak to the head.
+		/// </summary>
+		/// <param name="self">A string which ends with one or more linebreaks.</param>
+		/// <returns></returns>
+		private static string RotateTailLinebreak(this string self)
+		{
+			int len = self.Length;
+			// check if the line break is /n or /r/n
+			string linebreak =
+				(len >= 2 && self.Substring(len - 2, 2) == "\r\n")
+				? "\r\n"
+				: self.Substring(len - 1, 1);
+			return linebreak + self.Remove(len - linebreak.Length);
+		}
+		#endregion
+
 		#region Remove..Whitespace / Convert Tabs-Spaces
 		static void OnRemoveLeadingWhitespace(object target, ExecutedRoutedEventArgs args)
 		{