source: branches/PersistenceReintegration/HeuristicLab.ExtLibs/HeuristicLab.AvalonEdit/5.0.1/AvalonEdit-5.0.1/Folding/FoldingManager.cs @ 15762

// Copyright (c) 2014 AlphaSierraPapa for the SharpDevelop Team
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy of this
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// 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
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using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Windows;

using ICSharpCode.AvalonEdit.Document;
using ICSharpCode.AvalonEdit.Editing;
using ICSharpCode.AvalonEdit.Rendering;
using ICSharpCode.AvalonEdit.Utils;

namespace ICSharpCode.AvalonEdit.Folding
{
  /// <summary>
  /// Stores a list of foldings for a specific TextView and TextDocument.
  /// </summary>
  public class FoldingManager : IWeakEventListener
  {
    internal readonly TextDocument document;
    
    internal readonly List<TextView> textViews = new List<TextView>();
    readonly TextSegmentCollection<FoldingSection> foldings;
    bool isFirstUpdate = true;
    
    #region Constructor
    /// <summary>
    /// Creates a new FoldingManager instance.
    /// </summary>
    public FoldingManager(TextDocument document)
    {
      if (document == null)
        throw new ArgumentNullException("document");
      this.document = document;
      this.foldings = new TextSegmentCollection<FoldingSection>();
      document.VerifyAccess();
      TextDocumentWeakEventManager.Changed.AddListener(document, this);
    }
    #endregion
    
    #region ReceiveWeakEvent
    /// <inheritdoc cref="IWeakEventListener.ReceiveWeakEvent"/>
    protected virtual bool ReceiveWeakEvent(Type managerType, object sender, EventArgs e)
    {
      if (managerType == typeof(TextDocumentWeakEventManager.Changed)) {
        OnDocumentChanged((DocumentChangeEventArgs)e);
        return true;
      }
      return false;
    }
    
    bool IWeakEventListener.ReceiveWeakEvent(Type managerType, object sender, EventArgs e)
    {
      return ReceiveWeakEvent(managerType, sender, e);
    }
    
    void OnDocumentChanged(DocumentChangeEventArgs e)
    {
      foldings.UpdateOffsets(e);
      int newEndOffset = e.Offset + e.InsertionLength;
      // extend end offset to the end of the line (including delimiter)
      var endLine = document.GetLineByOffset(newEndOffset);
      newEndOffset = endLine.Offset + endLine.TotalLength;
      foreach (var affectedFolding in foldings.FindOverlappingSegments(e.Offset, newEndOffset - e.Offset)) {
        if (affectedFolding.Length == 0) {
          RemoveFolding(affectedFolding);
        } else {
          affectedFolding.ValidateCollapsedLineSections();
        }
      }
    }
    #endregion
    
    #region Manage TextViews
    internal void AddToTextView(TextView textView)
    {
      if (textView == null || textViews.Contains(textView))
        throw new ArgumentException();
      textViews.Add(textView);
      foreach (FoldingSection fs in foldings) {
        if (fs.collapsedSections != null) {
          Array.Resize(ref fs.collapsedSections, textViews.Count);
          fs.ValidateCollapsedLineSections();
        }
      }
    }
    
    internal void RemoveFromTextView(TextView textView)
    {
      int pos = textViews.IndexOf(textView);
      if (pos < 0)
        throw new ArgumentException();
      textViews.RemoveAt(pos);
      foreach (FoldingSection fs in foldings) {
        if (fs.collapsedSections != null) {
          var c = new CollapsedLineSection[textViews.Count];
          Array.Copy(fs.collapsedSections, 0, c, 0, pos);
          fs.collapsedSections[pos].Uncollapse();
          Array.Copy(fs.collapsedSections, pos + 1, c, pos, c.Length - pos);
          fs.collapsedSections = c;
        }
      }
    }
    
    internal void Redraw()
    {
      foreach (TextView textView in textViews)
        textView.Redraw();
    }
    
    internal void Redraw(FoldingSection fs)
    {
      foreach (TextView textView in textViews)
        textView.Redraw(fs);
    }
    #endregion
    
    #region Create / Remove / Clear
    /// <summary>
    /// Creates a folding for the specified text section.
    /// </summary>
    public FoldingSection CreateFolding(int startOffset, int endOffset)
    {
      if (startOffset >= endOffset)
        throw new ArgumentException("startOffset must be less than endOffset");
      if (startOffset < 0 || endOffset > document.TextLength)
        throw new ArgumentException("Folding must be within document boundary");
      FoldingSection fs = new FoldingSection(this, startOffset, endOffset);
      foldings.Add(fs);
      Redraw(fs);
      return fs;
    }
    
    /// <summary>
    /// Removes a folding section from this manager.
    /// </summary>
    public void RemoveFolding(FoldingSection fs)
    {
      if (fs == null)
        throw new ArgumentNullException("fs");
      fs.IsFolded = false;
      foldings.Remove(fs);
      Redraw(fs);
    }
    
    /// <summary>
    /// Removes all folding sections.
    /// </summary>
    public void Clear()
    {
      document.VerifyAccess();
      foreach (FoldingSection s in foldings)
        s.IsFolded = false;
      foldings.Clear();
      Redraw();
    }
    #endregion
    
    #region Get...Folding
    /// <summary>
    /// Gets all foldings in this manager.
    /// The foldings are returned sorted by start offset;
    /// for multiple foldings at the same offset the order is undefined.
    /// </summary>
    public IEnumerable<FoldingSection> AllFoldings {
      get { return foldings; }
    }
    
    /// <summary>
    /// Gets the first offset greater or equal to <paramref name="startOffset"/> where a folded folding starts.
    /// Returns -1 if there are no foldings after <paramref name="startOffset"/>.
    /// </summary>
    public int GetNextFoldedFoldingStart(int startOffset)
    {
      FoldingSection fs = foldings.FindFirstSegmentWithStartAfter(startOffset);
      while (fs != null && !fs.IsFolded)
        fs = foldings.GetNextSegment(fs);
      return fs != null ? fs.StartOffset : -1;
    }
    
    /// <summary>
    /// Gets the first folding with a <see cref="TextSegment.StartOffset"/> greater or equal to
    /// <paramref name="startOffset"/>.
    /// Returns null if there are no foldings after <paramref name="startOffset"/>.
    /// </summary>
    public FoldingSection GetNextFolding(int startOffset)
    {
      // TODO: returns the longest folding instead of any folding at the first position after startOffset
      return foldings.FindFirstSegmentWithStartAfter(startOffset);
    }
    
    /// <summary>
    /// Gets all foldings that start exactly at <paramref name="startOffset"/>.
    /// </summary>
    public ReadOnlyCollection<FoldingSection> GetFoldingsAt(int startOffset)
    {
      List<FoldingSection> result = new List<FoldingSection>();
      FoldingSection fs = foldings.FindFirstSegmentWithStartAfter(startOffset);
      while (fs != null && fs.StartOffset == startOffset) {
        result.Add(fs);
        fs = foldings.GetNextSegment(fs);
      }
      return result.AsReadOnly();
    }
    
    /// <summary>
    /// Gets all foldings that contain <paramref name="offset" />.
    /// </summary>
    public ReadOnlyCollection<FoldingSection> GetFoldingsContaining(int offset)
    {
      return foldings.FindSegmentsContaining(offset);
    }
    #endregion
    
    #region UpdateFoldings
    /// <summary>
    /// Updates the foldings in this <see cref="FoldingManager"/> using the given new foldings.
    /// This method will try to detect which new foldings correspond to which existing foldings; and will keep the state
    /// (<see cref="FoldingSection.IsFolded"/>) for existing foldings.
    /// </summary>
    /// <param name="newFoldings">The new set of foldings. These must be sorted by starting offset.</param>
    /// <param name="firstErrorOffset">The first position of a parse error. Existing foldings starting after
    /// this offset will be kept even if they don't appear in <paramref name="newFoldings"/>.
    /// Use -1 for this parameter if there were no parse errors.</param>
    public void UpdateFoldings(IEnumerable<NewFolding> newFoldings, int firstErrorOffset)
    {
      if (newFoldings == null)
        throw new ArgumentNullException("newFoldings");
      
      if (firstErrorOffset < 0)
        firstErrorOffset = int.MaxValue;
      
      var oldFoldings = this.AllFoldings.ToArray();
      int oldFoldingIndex = 0;
      int previousStartOffset = 0;
      // merge new foldings into old foldings so that sections keep being collapsed
      // both oldFoldings and newFoldings are sorted by start offset
      foreach (NewFolding newFolding in newFoldings) {
        // ensure newFoldings are sorted correctly
        if (newFolding.StartOffset < previousStartOffset)
          throw new ArgumentException("newFoldings must be sorted by start offset");
        previousStartOffset = newFolding.StartOffset;
        
        int startOffset = newFolding.StartOffset.CoerceValue(0, document.TextLength);
        int endOffset = newFolding.EndOffset.CoerceValue(0, document.TextLength);
        
        if (newFolding.StartOffset == newFolding.EndOffset)
          continue; // ignore zero-length foldings
        
        // remove old foldings that were skipped
        while (oldFoldingIndex < oldFoldings.Length && newFolding.StartOffset > oldFoldings[oldFoldingIndex].StartOffset) {
          this.RemoveFolding(oldFoldings[oldFoldingIndex++]);
        }
        FoldingSection section;
        // reuse current folding if its matching:
        if (oldFoldingIndex < oldFoldings.Length && newFolding.StartOffset == oldFoldings[oldFoldingIndex].StartOffset) {
          section = oldFoldings[oldFoldingIndex++];
          section.Length = newFolding.EndOffset - newFolding.StartOffset;
        } else {
          // no matching current folding; create a new one:
          section = this.CreateFolding(newFolding.StartOffset, newFolding.EndOffset);
          // auto-close #regions only when opening the document
          if (isFirstUpdate) {
            section.IsFolded = newFolding.DefaultClosed;
            isFirstUpdate = false;
          }
          section.Tag = newFolding;
        }
        section.Title = newFolding.Name;
      }
      // remove all outstanding old foldings:
      while (oldFoldingIndex < oldFoldings.Length) {
        FoldingSection oldSection = oldFoldings[oldFoldingIndex++];
        if (oldSection.StartOffset >= firstErrorOffset)
          break;
        this.RemoveFolding(oldSection);
      }
    }
    #endregion
    
    #region Install
    /// <summary>
    /// Adds Folding support to the specified text area.
    /// Warning: The folding manager is only valid for the text area's current document. The folding manager
    /// must be uninstalled before the text area is bound to a different document.
    /// </summary>
    /// <returns>The <see cref="FoldingManager"/> that manages the list of foldings inside the text area.</returns>
    public static FoldingManager Install(TextArea textArea)
    {
      if (textArea == null)
        throw new ArgumentNullException("textArea");
      return new FoldingManagerInstallation(textArea);
    }
    
    /// <summary>
    /// Uninstalls the folding manager.
    /// </summary>
    /// <exception cref="ArgumentException">The specified manager was not created using <see cref="Install"/>.</exception>
    public static void Uninstall(FoldingManager manager)
    {
      if (manager == null)
        throw new ArgumentNullException("manager");
      FoldingManagerInstallation installation = manager as FoldingManagerInstallation;
      if (installation != null) {
        installation.Uninstall();
      } else {
        throw new ArgumentException("FoldingManager was not created using FoldingManager.Install");
      }
    }
    
    sealed class FoldingManagerInstallation : FoldingManager
    {
      TextArea textArea;
      FoldingMargin margin;
      FoldingElementGenerator generator;
      
      public FoldingManagerInstallation(TextArea textArea) : base(textArea.Document)
      {
        this.textArea = textArea;
        margin = new FoldingMargin() { FoldingManager = this };
        generator = new FoldingElementGenerator() { FoldingManager = this };
        textArea.LeftMargins.Add(margin);
        textArea.TextView.Services.AddService(typeof(FoldingManager), this);
        // HACK: folding only works correctly when it has highest priority
        textArea.TextView.ElementGenerators.Insert(0, generator);
        textArea.Caret.PositionChanged += textArea_Caret_PositionChanged;
      }
      
      /*
      void DemoMode()
      {
        foldingGenerator = new FoldingElementGenerator() { FoldingManager = fm };
        foldingMargin = new FoldingMargin { FoldingManager = fm };
        foldingMarginBorder = new Border {
          Child = foldingMargin,
          Background = new LinearGradientBrush(Colors.White, Colors.Transparent, 0)
        };
        foldingMarginBorder.SizeChanged += UpdateTextViewClip;
        textEditor.TextArea.TextView.ElementGenerators.Add(foldingGenerator);
        textEditor.TextArea.LeftMargins.Add(foldingMarginBorder);
      }
      
      void UpdateTextViewClip(object sender, SizeChangedEventArgs e)
      {
        textEditor.TextArea.TextView.Clip = new RectangleGeometry(
          new Rect(-foldingMarginBorder.ActualWidth,
                   0,
                   textEditor.TextArea.TextView.ActualWidth + foldingMarginBorder.ActualWidth,
                   textEditor.TextArea.TextView.ActualHeight));
      }
       */
      
      public void Uninstall()
      {
        Clear();
        if (textArea != null) {
          textArea.Caret.PositionChanged -= textArea_Caret_PositionChanged;
          textArea.LeftMargins.Remove(margin);
          textArea.TextView.ElementGenerators.Remove(generator);
          textArea.TextView.Services.RemoveService(typeof(FoldingManager));
          margin = null;
          generator = null;
          textArea = null;
        }
      }
      
      void textArea_Caret_PositionChanged(object sender, EventArgs e)
      {
        // Expand Foldings when Caret is moved into them.
        int caretOffset = textArea.Caret.Offset;
        foreach (FoldingSection s in GetFoldingsContaining(caretOffset)) {
          if (s.IsFolded && s.StartOffset < caretOffset && caretOffset < s.EndOffset) {
            s.IsFolded = false;
          }
        }
      }
    }
    #endregion
  }
}