source: branches/2929_PrioritizedGrammarEnumeration/HeuristicLab.ExtLibs/HeuristicLab.AvalonEdit/5.0.1/AvalonEdit-5.0.1/Document/WeakLineTracker.cs @ 16452

// 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;

namespace ICSharpCode.AvalonEdit.Document
{
  /// <summary>
  /// Allows registering a line tracker on a TextDocument using a weak reference from the document to the line tracker.
  /// </summary>
  public sealed class WeakLineTracker : ILineTracker
  {
    TextDocument textDocument;
    WeakReference targetObject;
    
    private WeakLineTracker(TextDocument textDocument, ILineTracker targetTracker)
    {
      this.textDocument = textDocument;
      this.targetObject = new WeakReference(targetTracker);
    }
    
    /// <summary>
    /// Registers the <paramref name="targetTracker"/> as line tracker for the <paramref name="textDocument"/>.
    /// A weak reference to the target tracker will be used, and the WeakLineTracker will deregister itself
    /// when the target tracker is garbage collected.
    /// </summary>
    public static WeakLineTracker Register(TextDocument textDocument, ILineTracker targetTracker)
    {
      if (textDocument == null)
        throw new ArgumentNullException("textDocument");
      if (targetTracker == null)
        throw new ArgumentNullException("targetTracker");
      WeakLineTracker wlt = new WeakLineTracker(textDocument, targetTracker);
      textDocument.LineTrackers.Add(wlt);
      return wlt;
    }
    
    /// <summary>
    /// Deregisters the weak line tracker.
    /// </summary>
    public void Deregister()
    {
      if (textDocument != null) {
        textDocument.LineTrackers.Remove(this);
        textDocument = null;
      }
    }
    
    void ILineTracker.BeforeRemoveLine(DocumentLine line)
    {
      ILineTracker targetTracker = targetObject.Target as ILineTracker;
      if (targetTracker != null)
        targetTracker.BeforeRemoveLine(line);
      else
        Deregister();
    }
    
    void ILineTracker.SetLineLength(DocumentLine line, int newTotalLength)
    {
      ILineTracker targetTracker = targetObject.Target as ILineTracker;
      if (targetTracker != null)
        targetTracker.SetLineLength(line, newTotalLength);
      else
        Deregister();
    }
    
    void ILineTracker.LineInserted(DocumentLine insertionPos, DocumentLine newLine)
    {
      ILineTracker targetTracker = targetObject.Target as ILineTracker;
      if (targetTracker != null)
        targetTracker.LineInserted(insertionPos, newLine);
      else
        Deregister();
    }
    
    void ILineTracker.RebuildDocument()
    {
      ILineTracker targetTracker = targetObject.Target as ILineTracker;
      if (targetTracker != null)
        targetTracker.RebuildDocument();
      else
        Deregister();
    }
    
    void ILineTracker.ChangeComplete(DocumentChangeEventArgs e)
    {
      ILineTracker targetTracker = targetObject.Target as ILineTracker;
      if (targetTracker != null)
        targetTracker.ChangeComplete(e);
      else
        Deregister();
    }
  }
}