source: branches/PersistentDataStructures/HeuristicLab.CodeEditor/3.4/LanguageFeatures/CodeFolding/CSharp/FoldingVisitor.cs

// 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;
using System.Collections.Generic;
using System.Linq;

using ICSharpCode.AvalonEdit.Folding;
using ICSharpCode.NRefactory;
using ICSharpCode.NRefactory.CSharp;
using ICSharpCode.NRefactory.Editor;

namespace CSharpBinding.Parser
{
  // TODO: move this class + NewFolding to NRefactory
  class FoldingVisitor : DepthFirstAstVisitor
  {
    internal List<NewFolding> foldings = new List<NewFolding> ();
    internal IDocument document;
    
    int GetOffset(TextLocation location)
    {
      return document.GetOffset(location);
    }
    
    NewFolding AddFolding(TextLocation start, TextLocation end, bool isDefinition = false)
    {
      if (end.Line <= start.Line || start.IsEmpty || end.IsEmpty)
        return null;
      NewFolding folding = new NewFolding(GetOffset(start), GetOffset(end));
      folding.IsDefinition = isDefinition;
      foldings.Add(folding);
      return folding;
    }
    
    TextLocation GetEndOfPrev(AstNode node)
    {
      do {
        node = node.GetPrevNode();
      } while (node.NodeType == NodeType.Whitespace);
      return node.EndLocation;
    }
    
    #region usings
    void AddUsings (AstNode parent)
    {
      var firstChild = parent.Children.FirstOrDefault (child => child is UsingDeclaration || child is UsingAliasDeclaration);
      var node = firstChild;
      while (node != null) {
        var next = node.GetNextNode ();
        if (next is UsingDeclaration || next is UsingAliasDeclaration) {
          node = next;
        } else {
          break;
        }
      }
      if (firstChild != node) {
        NewFolding folding = AddFolding(firstChild.StartLocation, node.EndLocation);
        if (folding != null) {
          folding.Name = "using...";
          folding.DefaultClosed = true;
        }
      }
    }
    public override void VisitSyntaxTree (SyntaxTree unit)
    {
      AddUsings (unit);
      base.VisitSyntaxTree (unit);
    }

    public override void VisitNamespaceDeclaration (NamespaceDeclaration namespaceDeclaration)
    {
      AddUsings (namespaceDeclaration);
      if (!namespaceDeclaration.RBraceToken.IsNull)
        AddFolding (namespaceDeclaration.LBraceToken.GetPrevNode ().EndLocation, namespaceDeclaration.RBraceToken.EndLocation);
      base.VisitNamespaceDeclaration (namespaceDeclaration);
    }
    #endregion
    
    #region Entity Declarations
    public override void VisitTypeDeclaration (TypeDeclaration typeDeclaration)
    {
      if (!typeDeclaration.RBraceToken.IsNull)
        AddFolding (GetEndOfPrev(typeDeclaration.LBraceToken), typeDeclaration.RBraceToken.EndLocation);
      base.VisitTypeDeclaration (typeDeclaration);
    }
    
    public override void VisitMethodDeclaration (MethodDeclaration methodDeclaration)
    {
      if (!methodDeclaration.Body.IsNull) {
        AddFolding (GetEndOfPrev(methodDeclaration.Body.LBraceToken),
                    methodDeclaration.Body.RBraceToken.EndLocation, true);
      }
      base.VisitMethodDeclaration (methodDeclaration);
    }
    
    public override void VisitConstructorDeclaration (ConstructorDeclaration constructorDeclaration)
    {
      if (!constructorDeclaration.Body.IsNull)
        AddFolding (GetEndOfPrev(constructorDeclaration.Body.LBraceToken),
                    constructorDeclaration.Body.RBraceToken.EndLocation, true);
      base.VisitConstructorDeclaration (constructorDeclaration);
    }
    
    public override void VisitDestructorDeclaration (DestructorDeclaration destructorDeclaration)
    {
      if (!destructorDeclaration.Body.IsNull)
        AddFolding (GetEndOfPrev(destructorDeclaration.Body.LBraceToken),
                    destructorDeclaration.Body.RBraceToken.EndLocation, true);
      base.VisitDestructorDeclaration (destructorDeclaration);
    }
    
    public override void VisitOperatorDeclaration (OperatorDeclaration operatorDeclaration)
    {
      if (!operatorDeclaration.Body.IsNull)
        AddFolding (GetEndOfPrev(operatorDeclaration.Body.LBraceToken),
                    operatorDeclaration.Body.RBraceToken.EndLocation, true);
      base.VisitOperatorDeclaration (operatorDeclaration);
    }
    
    public override void VisitPropertyDeclaration (PropertyDeclaration propertyDeclaration)
    {
      if (!propertyDeclaration.LBraceToken.IsNull)
        AddFolding (GetEndOfPrev(propertyDeclaration.LBraceToken),
                    propertyDeclaration.RBraceToken.EndLocation, true);
      base.VisitPropertyDeclaration (propertyDeclaration);
    }
    
    public override void VisitIndexerDeclaration (IndexerDeclaration indexerDeclaration)
    {
      if (!indexerDeclaration.LBraceToken.IsNull)
        AddFolding (GetEndOfPrev(indexerDeclaration.LBraceToken),
                    indexerDeclaration.RBraceToken.EndLocation, true);
      base.VisitIndexerDeclaration (indexerDeclaration);
    }
    
    public override void VisitCustomEventDeclaration (CustomEventDeclaration eventDeclaration)
    {
      if (!eventDeclaration.LBraceToken.IsNull)
        AddFolding (GetEndOfPrev(eventDeclaration.LBraceToken),
                    eventDeclaration.RBraceToken.EndLocation, true);
      base.VisitCustomEventDeclaration (eventDeclaration);
    }
    #endregion
    
    #region Statements
    public override void VisitSwitchStatement (SwitchStatement switchStatement)
    {
      if (!switchStatement.RBraceToken.IsNull)
        AddFolding (GetEndOfPrev(switchStatement.LBraceToken),
                    switchStatement.RBraceToken.EndLocation);
      base.VisitSwitchStatement (switchStatement);
    }
    
    public override void VisitBlockStatement (BlockStatement blockStatement)
    {
      if (!(blockStatement.Parent is EntityDeclaration) && blockStatement.EndLocation.Line - blockStatement.StartLocation.Line > 2) {
        AddFolding (GetEndOfPrev(blockStatement), blockStatement.EndLocation);
      }

      base.VisitBlockStatement (blockStatement);
    }
    #endregion
    
    #region Preprocessor directives
    Stack<NewFolding> regions = new Stack<NewFolding>();
    
    public override void VisitPreProcessorDirective(PreProcessorDirective preProcessorDirective)
    {
      switch (preProcessorDirective.Type) {
        case PreProcessorDirectiveType.Region:
          NewFolding folding = new NewFolding();
          folding.DefaultClosed = true;
          folding.Name = preProcessorDirective.Argument;
          folding.StartOffset = GetOffset(preProcessorDirective.StartLocation);
          regions.Push(folding);
          break;
        case PreProcessorDirectiveType.Endregion:
          if (regions.Count > 0) {
            folding = regions.Pop();
            folding.EndOffset = GetOffset(preProcessorDirective.EndLocation);
            foldings.Add(folding);
          }
          break;
      }
    }
    #endregion
    
    #region Comments
    public override void VisitComment(Comment comment)
    {
      if (comment.CommentType == CommentType.InactiveCode)
        return; // don't fold the inactive code comment; instead fold the preprocessor directives
      if (AreTwoSinglelineCommentsInConsecutiveLines(comment.PrevSibling as Comment, comment))
        return; // already handled by previous comment
      Comment lastComment = comment;
      Comment nextComment;
      while (true) {
        nextComment = lastComment.NextSibling as Comment;
        if (!AreTwoSinglelineCommentsInConsecutiveLines(lastComment, nextComment))
          break;
        lastComment = nextComment;
      }
      if (lastComment.EndLocation.Line - comment.StartLocation.Line > 2) {
        var folding = AddFolding(comment.StartLocation, lastComment.EndLocation);
        if (folding != null) {
          switch (comment.CommentType) {
            case CommentType.SingleLine:
              folding.Name = "// ...";
              break;
            case CommentType.MultiLine:
              folding.Name = "/* ... */";
              break;
            case CommentType.Documentation:
              folding.Name = "/// ...";
              break;
            case CommentType.MultiLineDocumentation:
              folding.Name = "/** ... */";
              break;
          }
        }
      }
    }
    
    bool AreTwoSinglelineCommentsInConsecutiveLines(Comment comment1, Comment comment2)
    {
      if (comment1 == null || comment2 == null)
        return false;
      return comment1.CommentType == comment2.CommentType
        && comment1.StartLocation.Line == comment1.EndLocation.Line
        && comment1.EndLocation.Line + 1 == comment2.StartLocation.Line
        && comment1.StartLocation.Column == comment2.StartLocation.Column
        && comment2.StartLocation.Line == comment2.EndLocation.Line;
    }
    #endregion
  }
}