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ICSharpCode.TextEditor/Project/Src/Document/TextAnchor.cs

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+// <file>
+//     <copyright see="prj:///doc/copyright.txt"/>
+//     <license see="prj:///doc/license.txt"/>
+//     <owner name="Daniel Grunwald" email="daniel@danielgrunwald.de"/>
+//     <version>$Revision$</version>
+// </file>
+
+using System;
+
+namespace ICSharpCode.TextEditor.Document
+{
+	public enum AnchorMovementType
+	{
+		/// <summary>
+		/// Behaves like a start marker - when text is inserted at the anchor position, the anchor will stay
+		/// before the inserted text.
+		/// </summary>
+		BeforeInsertion,
+		/// <summary>
+		/// Behave like an end marker - when text is insered at the anchor position, the anchor will move
+		/// after the inserted text.
+		/// </summary>
+		AfterInsertion
+	}
+	
+	/// <summary>
+	/// An anchor that can be put into a document and moves around when the document is changed.
+	/// </summary>
+	public sealed class TextAnchor
+	{
+		static Exception AnchorDeletedError()
+		{
+			return new InvalidOperationException("The text containing the anchor was deleted");
+		}
+		
+		LineSegment lineSegment;
+		int columnNumber;
+		
+		public LineSegment Line {
+			get {
+				if (lineSegment == null) throw AnchorDeletedError();
+				return lineSegment;
+			}
+			internal set {
+				lineSegment = value;
+			}
+		}
+		
+		public bool IsDeleted {
+			get {
+				return lineSegment == null;
+			}
+		}
+		
+		public int LineNumber {
+			get {
+				return this.Line.LineNumber;
+			}
+		}
+		
+		public int ColumnNumber {
+			get {
+				if (lineSegment == null) throw AnchorDeletedError();
+				return columnNumber;
+			}
+			internal set {
+				columnNumber = value;
+			}
+		}
+		
+		public TextLocation Location {
+			get {
+				return new TextLocation(this.ColumnNumber, this.LineNumber);
+			}
+		}
+		
+		public int Offset {
+			get {
+				return this.Line.Offset + columnNumber;
+			}
+		}
+		
+		/// <summary>
+		/// Controls how the anchor moves.
+		/// </summary>
+		public AnchorMovementType MovementType { get; set; }
+		
+		public event EventHandler Deleted;
+		
+		internal void Delete(ref DeferredEventList deferredEventList)
+		{
+			// we cannot fire an event here because this method is called while the LineManager adjusts the
+			// lineCollection, so an event handler could see inconsistent state
+			lineSegment = null;
+			deferredEventList.AddDeletedAnchor(this);
+		}
+		
+		internal void RaiseDeleted()
+		{
+			if (Deleted != null)
+				Deleted(this, EventArgs.Empty);
+		}
+		
+		internal TextAnchor(LineSegment lineSegment, int columnNumber)
+		{
+			this.lineSegment = lineSegment;
+			this.columnNumber = columnNumber;
+		}
+		
+		public override string ToString()
+		{
+			if (this.IsDeleted)
+				return "[TextAnchor (deleted)]";
+			else
+				return "[TextAnchor " + this.Location.ToString() + "]";
+		}
+	}
+}