source: branches/2990_VariableImpactBasedFeatureSelection/HeuristicLab.ExtLibs/HeuristicLab.NRefactory/5.5.0/NRefactory.CSharp-5.5.0/Refactoring/LocalReferenceFinder.cs

//
// LocalReferenceFinder.cs
//
// Author:
//       Simon Lindgren <simon.n.lindgren@gmail.com>
//
// Copyright (c) 2012 Simon Lindgren
//
// 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.Collections.Generic;
using System.Linq;
using ICSharpCode.NRefactory.CSharp.Resolver;
using ICSharpCode.NRefactory.Semantics;
using ICSharpCode.NRefactory.TypeSystem;
using ICSharpCode.NRefactory.Utils;
using System.Diagnostics;

namespace ICSharpCode.NRefactory.CSharp.Refactoring
{

  /// <summary>
  /// Finds references to <see cref="IVariable">IVariables</see>.
  /// </summary>
  /// <remarks>
  /// This class is more efficient than <see cref="FindReferences"/>
  /// if there is already a resolved tree or if multiple searches needs
  /// to be performed.
  /// </remarks>    
  public class LocalReferenceFinder
  {
    LocalReferenceLocator locator;

    MultiDictionary<IVariable, ReferenceResult> references = new MultiDictionary<IVariable, ReferenceResult>();
    
    HashSet<AstNode> visitedRoots = new HashSet<AstNode>();
    
    public LocalReferenceFinder(CSharpAstResolver resolver)
    {
      locator = new LocalReferenceLocator(resolver, this);
    }

    public LocalReferenceFinder(BaseRefactoringContext context) : this(context.Resolver)
    {
    }

    void VisitIfNeccessary(AstNode rootNode)
    {
      // If any of the parent nodes are recorded as visited,
      // we don't need to traverse rootNode this time.
      var tmpRoot = rootNode;
      while(tmpRoot != null){
        if (visitedRoots.Contains(tmpRoot))
          return;
        tmpRoot = tmpRoot.Parent;
      }

      locator.ProccessRoot (rootNode);
    }

    /// <summary>
    /// Finds the references to <paramref name="variable"/>.
    /// </summary>
    /// <param name='rootNode'>
    /// Root node for the search.
    /// </param>
    /// <param name='variable'>
    /// The variable to find references for.
    /// </param>
    /// <remarks>
    /// When a single <see cref="LocalReferenceFinder"/> is reused for multiple
    /// searches, which references outside of <paramref name="rootNode"/> are
    /// or are not reported is undefined.
    /// </remarks>
    public IList<ReferenceResult> FindReferences(AstNode rootNode, IVariable variable)
    {
      lock (locator) {
        VisitIfNeccessary(rootNode);
        var lookup = (ILookup<IVariable, ReferenceResult>)references;
        if (!lookup.Contains(variable))
          return new List<ReferenceResult>();
        // Clone the list for thread safety
        return references[variable].ToList();
      }
    }

    class LocalReferenceLocator : DepthFirstAstVisitor
    {
      CSharpAstResolver resolver;

      LocalReferenceFinder referenceFinder;

      public LocalReferenceLocator(CSharpAstResolver resolver, LocalReferenceFinder referenceFinder)
      {
        this.resolver = resolver;
        this.referenceFinder = referenceFinder;
      }

      IList<IVariable> processedVariables = new List<IVariable>();

      public void ProccessRoot (AstNode rootNode)
      {
        rootNode.AcceptVisitor(this);
        referenceFinder.visitedRoots.Add(rootNode);
      }

      public override void VisitCSharpTokenNode(CSharpTokenNode token)
      {
        // Nothing
      }

      protected override void VisitChildren(AstNode node)
      {
        if (referenceFinder.visitedRoots.Contains(node))
          return;
        var localResolveResult = resolver.Resolve(node) as LocalResolveResult;
        if (localResolveResult != null && !processedVariables.Contains(localResolveResult.Variable)) {
          referenceFinder.references.Add(localResolveResult.Variable, new ReferenceResult(node, localResolveResult));

          processedVariables.Add(localResolveResult.Variable);
          base.VisitChildren(node);
          Debug.Assert(processedVariables.Contains(localResolveResult.Variable), "Variable should still be in the list of processed variables.");
          processedVariables.Remove(localResolveResult.Variable);
        } else {
          base.VisitChildren(node);
        }
      }
    }
  }

  public class ReferenceResult
  {
    public ReferenceResult (AstNode node, LocalResolveResult resolveResult)
    {
      Node = node;
      ResolveResult = resolveResult;
    }

    public AstNode Node { get; private set; }

    public LocalResolveResult ResolveResult { get; private set; }
  }
}