source: branches/2990_VariableImpactBasedFeatureSelection/HeuristicLab.ExtLibs/HeuristicLab.NRefactory/5.5.0/NRefactory.Xml-5.5.0/IncrementalParserState.cs

// Copyright (c) 2009-2013 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 System.Collections.Generic;
using System.Diagnostics;
using ICSharpCode.NRefactory.Editor;

namespace ICSharpCode.NRefactory.Xml
{
  /// <summary>
  /// Encapsulates the state of the incremental tag soup parser.
  /// </summary>
  public class IncrementalParserState
  {
    internal readonly int TextLength;
    internal readonly ITextSourceVersion Version;
    internal readonly InternalObject[] Objects;
    
    internal IncrementalParserState(int textLength, ITextSourceVersion version, InternalObject[] objects)
    {
      this.TextLength = textLength;
      this.Version = version;
      this.Objects = objects;
    }
    
    internal List<UnchangedSegment> GetReuseMapTo(ITextSourceVersion newVersion)
    {
      ITextSourceVersion oldVersion = this.Version;
      if (oldVersion == null || newVersion == null)
        return null;
      if (!oldVersion.BelongsToSameDocumentAs(newVersion))
        return null;
      List<UnchangedSegment> reuseMap = new List<UnchangedSegment>();
      reuseMap.Add(new UnchangedSegment(0, 0, this.TextLength));
      foreach (var change in oldVersion.GetChangesTo(newVersion)) {
        bool needsSegmentRemoval = false;
        for (int i = 0; i < reuseMap.Count; i++) {
          UnchangedSegment segment = reuseMap[i];
          if (segment.NewOffset + segment.Length <= change.Offset) {
            // change is completely after this segment
            continue;
          }
          if (change.Offset + change.RemovalLength <= segment.NewOffset) {
            // change is completely before this segment
            segment.NewOffset += change.InsertionLength - change.RemovalLength;
            reuseMap[i] = segment;
            continue;
          }
          // Change is overlapping segment.
          // Split segment into two parts: the part before change, and the part after change.
          var segmentBefore = new UnchangedSegment(segment.OldOffset, segment.NewOffset, change.Offset - segment.NewOffset);
          Debug.Assert(segmentBefore.Length < segment.Length);
          
          int lengthAtEnd = segment.NewOffset + segment.Length - (change.Offset + change.RemovalLength);
          var segmentAfter = new UnchangedSegment(
            segment.OldOffset + segment.Length - lengthAtEnd,
            change.Offset + change.InsertionLength,
            lengthAtEnd);
          Debug.Assert(segmentAfter.Length < segment.Length);
          Debug.Assert(segmentBefore.Length + segmentAfter.Length <= segment.Length);
          Debug.Assert(segmentBefore.NewOffset + segmentBefore.Length <= segmentAfter.NewOffset);
          Debug.Assert(segmentBefore.OldOffset + segmentBefore.Length <= segmentAfter.OldOffset);
          if (segmentBefore.Length > 0 && segmentAfter.Length > 0) {
            reuseMap[i] = segmentBefore;
            reuseMap.Insert(++i, segmentAfter);
          } else if (segmentBefore.Length > 0) {
            reuseMap[i] = segmentBefore;
          } else {
            reuseMap[i] = segmentAfter;
            if (segmentAfter.Length <= 0)
              needsSegmentRemoval = true;
          }
        }
        if (needsSegmentRemoval)
          reuseMap.RemoveAll(s => s.Length <= 0);
      }
      return reuseMap;
    }
  }
  
  struct UnchangedSegment
  {
    public int OldOffset;
    public int NewOffset;
    public int Length;
    
    public UnchangedSegment(int oldOffset, int newOffset, int length)
    {
      this.OldOffset = oldOffset;
      this.NewOffset = newOffset;
      this.Length = length;
    }
    
    public override string ToString()
    {
      return string.Format("[UnchangedSegment OldOffset={0}, NewOffset={1}, Length={2}]", OldOffset, NewOffset, Length);
    }
  }
}