source: branches/2708_ScopedAlgorithms/HeuristicLab.ExtLibs/HeuristicLab.AvalonEdit/5.0.1/AvalonEdit-5.0.1/Folding/XmlFoldingStrategy.cs

// Copyright (c) 2014 AlphaSierraPapa for the SharpDevelop Team
// 
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// 
// 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.Linq;
using System.Text;
using System.Xml;

using ICSharpCode.AvalonEdit.Document;

namespace ICSharpCode.AvalonEdit.Folding
{
  /// <summary>
  /// Holds information about the start of a fold in an xml string.
  /// </summary>
  sealed class XmlFoldStart : NewFolding
  {
    internal int StartLine;
  }
  
  /// <summary>
  /// Determines folds for an xml string in the editor.
  /// </summary>
  public class XmlFoldingStrategy
  {
    /// <summary>
    /// Flag indicating whether attributes should be displayed on folded
    /// elements.
    /// </summary>
    public bool ShowAttributesWhenFolded { get; set; }
    
    /// <summary>
    /// Create <see cref="NewFolding"/>s for the specified document and updates the folding manager with them.
    /// </summary>
    public void UpdateFoldings(FoldingManager manager, TextDocument document)
    {
      int firstErrorOffset;
      IEnumerable<NewFolding> foldings = CreateNewFoldings(document, out firstErrorOffset);
      manager.UpdateFoldings(foldings, firstErrorOffset);
    }
    
    /// <summary>
    /// Create <see cref="NewFolding"/>s for the specified document.
    /// </summary>
    public IEnumerable<NewFolding> CreateNewFoldings(TextDocument document, out int firstErrorOffset)
    {
      try {
        XmlTextReader reader = new XmlTextReader(document.CreateReader());
        reader.XmlResolver = null; // don't resolve DTDs
        return CreateNewFoldings(document, reader, out firstErrorOffset);
      } catch (XmlException) {
        firstErrorOffset = 0;
        return Enumerable.Empty<NewFolding>();
      }
    }
    
    /// <summary>
    /// Create <see cref="NewFolding"/>s for the specified document.
    /// </summary>
    public IEnumerable<NewFolding> CreateNewFoldings(TextDocument document, XmlReader reader, out int firstErrorOffset)
    {
      Stack<XmlFoldStart> stack = new Stack<XmlFoldStart>();
      List<NewFolding> foldMarkers = new List<NewFolding>();
      try {
        while (reader.Read()) {
          switch (reader.NodeType) {
            case XmlNodeType.Element:
              if (!reader.IsEmptyElement) {
                XmlFoldStart newFoldStart = CreateElementFoldStart(document, reader);
                stack.Push(newFoldStart);
              }
              break;
              
            case XmlNodeType.EndElement:
              XmlFoldStart foldStart = stack.Pop();
              CreateElementFold(document, foldMarkers, reader, foldStart);
              break;
              
            case XmlNodeType.Comment:
              CreateCommentFold(document, foldMarkers, reader);
              break;
          }
        }
        firstErrorOffset = -1;
      } catch (XmlException ex) {
        // ignore errors at invalid positions (prevent ArgumentOutOfRangeException)
        if (ex.LineNumber >= 1 && ex.LineNumber <= document.LineCount)
          firstErrorOffset = document.GetOffset(ex.LineNumber, ex.LinePosition);
        else
          firstErrorOffset = 0;
      }
      foldMarkers.Sort((a,b) => a.StartOffset.CompareTo(b.StartOffset));
      return foldMarkers;
    }
    
    static int GetOffset(TextDocument document, XmlReader reader)
    {
      IXmlLineInfo info = reader as IXmlLineInfo;
      if (info != null && info.HasLineInfo()) {
        return document.GetOffset(info.LineNumber, info.LinePosition);
      } else {
        throw new ArgumentException("XmlReader does not have positioning information.");
      }
    }
    
    /// <summary>
    /// Creates a comment fold if the comment spans more than one line.
    /// </summary>
    /// <remarks>The text displayed when the comment is folded is the first
    /// line of the comment.</remarks>
    static void CreateCommentFold(TextDocument document, List<NewFolding> foldMarkers, XmlReader reader)
    {
      string comment = reader.Value;
      if (comment != null) {
        int firstNewLine = comment.IndexOf('\n');
        if (firstNewLine >= 0) {
          
          // Take off 4 chars to get the actual comment start (takes
          // into account the <!-- chars.
          
          int startOffset = GetOffset(document, reader) - 4;
          int endOffset = startOffset + comment.Length + 7;
          
          string foldText = String.Concat("<!--", comment.Substring(0, firstNewLine).TrimEnd('\r') , "-->");
          foldMarkers.Add(new NewFolding(startOffset, endOffset) { Name = foldText } );
        }
      }
    }
    
    /// <summary>
    /// Creates an XmlFoldStart for the start tag of an element.
    /// </summary>
    XmlFoldStart CreateElementFoldStart(TextDocument document, XmlReader reader)
    {
      // Take off 1 from the offset returned
      // from the xml since it points to the start
      // of the element name and not the beginning
      // tag.
      //XmlFoldStart newFoldStart = new XmlFoldStart(reader.Prefix, reader.LocalName, reader.LineNumber - 1, reader.LinePosition - 2);
      XmlFoldStart newFoldStart = new XmlFoldStart();
      
      IXmlLineInfo lineInfo = (IXmlLineInfo)reader;
      newFoldStart.StartLine = lineInfo.LineNumber;
      newFoldStart.StartOffset = document.GetOffset(newFoldStart.StartLine, lineInfo.LinePosition - 1);
      
      if (this.ShowAttributesWhenFolded && reader.HasAttributes) {
        newFoldStart.Name = String.Concat("<", reader.Name, " ", GetAttributeFoldText(reader), ">");
      } else {
        newFoldStart.Name = String.Concat("<", reader.Name, ">");
      }
      
      return newFoldStart;
    }
    
    /// <summary>
    /// Create an element fold if the start and end tag are on
    /// different lines.
    /// </summary>
    static void CreateElementFold(TextDocument document, List<NewFolding> foldMarkers, XmlReader reader, XmlFoldStart foldStart)
    {
      IXmlLineInfo lineInfo = (IXmlLineInfo)reader;
      int endLine = lineInfo.LineNumber;
      if (endLine > foldStart.StartLine) {
        int endCol = lineInfo.LinePosition + reader.Name.Length + 1;
        foldStart.EndOffset = document.GetOffset(endLine, endCol);
        foldMarkers.Add(foldStart);
      }
    }
    
    /// <summary>
    /// Gets the element's attributes as a string on one line that will
    /// be displayed when the element is folded.
    /// </summary>
    /// <remarks>
    /// Currently this puts all attributes from an element on the same
    /// line of the start tag.  It does not cater for elements where attributes
    /// are not on the same line as the start tag.
    /// </remarks>
    static string GetAttributeFoldText(XmlReader reader)
    {
      StringBuilder text = new StringBuilder();
      
      for (int i = 0; i < reader.AttributeCount; ++i) {
        reader.MoveToAttribute(i);
        
        text.Append(reader.Name);
        text.Append("=");
        text.Append(reader.QuoteChar.ToString());
        text.Append(XmlEncodeAttributeValue(reader.Value, reader.QuoteChar));
        text.Append(reader.QuoteChar.ToString());
        
        // Append a space if this is not the
        // last attribute.
        if (i < reader.AttributeCount - 1) {
          text.Append(" ");
        }
      }
      
      return text.ToString();
    }
    
    /// <summary>
    /// Xml encode the attribute string since the string returned from
    /// the XmlTextReader is the plain unencoded string and .NET
    /// does not provide us with an xml encode method.
    /// </summary>
    static string XmlEncodeAttributeValue(string attributeValue, char quoteChar)
    {
      StringBuilder encodedValue = new StringBuilder(attributeValue);
      
      encodedValue.Replace("&", "&amp;");
      encodedValue.Replace("<", "&lt;");
      encodedValue.Replace(">", "&gt;");
      
      if (quoteChar == '"') {
        encodedValue.Replace("\"", "&quot;");
      } else {
        encodedValue.Replace("'", "&apos;");
      }
      
      return encodedValue.ToString();
    }
  }
}