source: stable/HeuristicLab.ExtLibs/HeuristicLab.NRefactory/5.5.0/NRefactory.CSharp-5.5.0/Resolver/FindReferences.cs

// Copyright (c) 2010-2013 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
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// DEALINGS IN THE SOFTWARE.

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Threading;
using ICSharpCode.NRefactory.CSharp;
using ICSharpCode.NRefactory.CSharp.Refactoring;
using ICSharpCode.NRefactory.CSharp.TypeSystem;
using ICSharpCode.NRefactory.Semantics;
using ICSharpCode.NRefactory.TypeSystem;
using ICSharpCode.NRefactory.Utils;

namespace ICSharpCode.NRefactory.CSharp.Resolver
{
  public delegate void FoundReferenceCallback(AstNode astNode, ResolveResult result);
  
  /// <summary>
  /// 'Find references' implementation.
  /// </summary>
  /// <remarks>
  /// This class is thread-safe.
  /// The intended multi-threaded usage is to call GetSearchScopes() once, and then
  /// call FindReferencesInFile() concurrently on multiple threads (parallel foreach over all interesting files).
  /// </remarks>
  public sealed class FindReferences
  {
    #region Properties
    /// <summary>
    /// Specifies whether to find type references even if an alias is being used.
    /// Aliases may be <c>var</c> or <c>using Alias = ...;</c>.
    /// </summary>
    public bool FindTypeReferencesEvenIfAliased { get; set; }
    
    /// <summary>
    /// Specifies whether find references should only look for specialized matches
    /// with equal type parameter substitution to the member we are searching for.
    /// </summary>
    public bool FindOnlySpecializedReferences { get; set; }
    
    /// <summary>
    /// If this option is enabled, find references on a overridden member
    /// will find calls to the base member.
    /// </summary>
    public bool FindCallsThroughVirtualBaseMethod { get; set; }
    
    /// <summary>
    /// If this option is enabled, find references on a member implementing
    /// an interface will also find calls to the interface.
    /// </summary>
    public bool FindCallsThroughInterface { get; set; }
    
    /// <summary>
    /// If this option is enabled, find references will look for all references
    /// to the virtual method slot.
    /// </summary>
    public bool WholeVirtualSlot { get; set; }
    
    //public bool FindAllOverloads { get; set; }
    
    /// <summary>
    /// Specifies whether to look for references in documentation comments.
    /// This will find entity references in <c>cref</c> attributes and
    /// parameter references in <c>&lt;param&gt;</c> and <c>&lt;paramref&gt;</c> tags.
    /// TODO: implement this feature.
    /// </summary>
    public bool SearchInDocumentationComments { get; set; }
    #endregion
    
    #region GetEffectiveAccessibility
    /// <summary>
    /// Gets the effective accessibility of the specified entity -
    /// that is, the accessibility viewed from the top level.
    /// </summary>
    /// <remarks>
    /// internal member in public class -> internal
    /// public member in internal class -> internal
    /// protected member in public class -> protected
    /// protected member in internal class -> protected and internal
    /// </remarks>
    public static Accessibility GetEffectiveAccessibility(IEntity entity)
    {
      if (entity == null)
        throw new ArgumentNullException("entity");
      Accessibility a = entity.Accessibility;
      for (ITypeDefinition declType = entity.DeclaringTypeDefinition; declType != null; declType = declType.DeclaringTypeDefinition) {
        a = MergeAccessibility(declType.Accessibility, a);
      }
      return a;
    }
    
    static Accessibility MergeAccessibility(Accessibility outer, Accessibility inner)
    {
      if (outer == inner)
        return inner;
      if (outer == Accessibility.None || inner == Accessibility.None)
        return Accessibility.None;
      if (outer == Accessibility.Private || inner == Accessibility.Private)
        return Accessibility.Private;
      if (outer == Accessibility.Public)
        return inner;
      if (inner == Accessibility.Public)
        return outer;
      // Inner and outer are both in { protected, internal, protected and internal, protected or internal }
      // (but they aren't both the same)
      if (outer == Accessibility.ProtectedOrInternal)
        return inner;
      if (inner == Accessibility.ProtectedOrInternal)
        return outer;
      // Inner and outer are both in { protected, internal, protected and internal },
      // but aren't both the same, so the result is protected and internal.
      return Accessibility.ProtectedAndInternal;
    }
    #endregion
    
    #region class SearchScope
    sealed class SearchScope : IFindReferenceSearchScope
    {
      readonly Func<ICompilation, FindReferenceNavigator> factory;
      
      public SearchScope(Func<ICompilation, FindReferenceNavigator> factory)
      {
        this.factory = factory;
      }
      
      public SearchScope(string searchTerm, Func<ICompilation, FindReferenceNavigator> factory)
      {
        this.searchTerm = searchTerm;
        this.factory = factory;
      }
      
      internal string searchTerm;
      internal FindReferences findReferences;
      internal ICompilation declarationCompilation;
      internal Accessibility accessibility;
      internal ITypeDefinition topLevelTypeDefinition;
      internal string fileName;
      
      IResolveVisitorNavigator IFindReferenceSearchScope.GetNavigator(ICompilation compilation, FoundReferenceCallback callback)
      {
        FindReferenceNavigator n = factory(compilation);
        if (n != null) {
          n.callback = callback;
          n.findReferences = findReferences;
          return n;
        } else {
          return new ConstantModeResolveVisitorNavigator(ResolveVisitorNavigationMode.Skip, null);
        }
      }
      
      ICompilation IFindReferenceSearchScope.Compilation {
        get { return declarationCompilation; }
      }
      
      string IFindReferenceSearchScope.SearchTerm {
        get { return searchTerm; }
      }
      
      Accessibility IFindReferenceSearchScope.Accessibility {
        get { return accessibility; }
      }
      
      ITypeDefinition IFindReferenceSearchScope.TopLevelTypeDefinition {
        get { return topLevelTypeDefinition; }
      }
      
      string IFindReferenceSearchScope.FileName {
        get { return fileName; }
      }
    }
    
    abstract class FindReferenceNavigator : IResolveVisitorNavigator
    {
      internal FoundReferenceCallback callback;
      internal FindReferences findReferences;
      
      internal abstract bool CanMatch(AstNode node);
      internal abstract bool IsMatch(ResolveResult rr);
      
      ResolveVisitorNavigationMode IResolveVisitorNavigator.Scan(AstNode node)
      {
        if (CanMatch(node))
          return ResolveVisitorNavigationMode.Resolve;
        else
          return ResolveVisitorNavigationMode.Scan;
      }
      
      void IResolveVisitorNavigator.Resolved(AstNode node, ResolveResult result)
      {
        if (CanMatch(node) && IsMatch(result)) {
          ReportMatch(node, result);
        }
      }
      
      public virtual void ProcessConversion(Expression expression, ResolveResult result, Conversion conversion, IType targetType)
      {
      }
      
      protected void ReportMatch(AstNode node, ResolveResult result)
      {
        if (callback != null)
          callback(node, result);
      }
      
      internal virtual void NavigatorDone(CSharpAstResolver resolver, CancellationToken cancellationToken)
      {
      }
    }
    #endregion
    
    #region GetSearchScopes
    public IList<IFindReferenceSearchScope> GetSearchScopes(ISymbol symbol)
    {
      if (symbol == null)
        throw new ArgumentNullException("symbol");
      switch (symbol.SymbolKind) {
        case SymbolKind.Namespace:
          return new[] { GetSearchScopeForNamespace((INamespace)symbol) };
        case SymbolKind.TypeParameter:
          return new[] { GetSearchScopeForTypeParameter((ITypeParameter)symbol) };
      }
      SearchScope scope;
      SearchScope additionalScope = null;
      IEntity entity = null;

      if (symbol.SymbolKind == SymbolKind.Variable) {
        var variable = (IVariable) symbol;
        scope = GetSearchScopeForLocalVariable(variable);
      } else if (symbol.SymbolKind == SymbolKind.Parameter) {
        var par = (IParameter)symbol;
        scope = GetSearchScopeForParameter(par);
        entity = par.Owner;
      } else {
        entity = symbol as IEntity;
        if (entity == null)
          throw new NotSupportedException("Unsupported symbol type");
        if (entity is IMember)
          entity = NormalizeMember((IMember)entity);
        switch (entity.SymbolKind) {
          case SymbolKind.TypeDefinition:
            scope = FindTypeDefinitionReferences((ITypeDefinition)entity, this.FindTypeReferencesEvenIfAliased, out additionalScope);
            break;
          case SymbolKind.Field:
            if (entity.DeclaringTypeDefinition != null && entity.DeclaringTypeDefinition.Kind == TypeKind.Enum)
              scope = FindMemberReferences(entity, m => new FindEnumMemberReferences((IField)m));
            else
              scope = FindMemberReferences(entity, m => new FindFieldReferences((IField)m));
            break;
          case SymbolKind.Property:
            scope = FindMemberReferences(entity, m => new FindPropertyReferences((IProperty)m));
            if (entity.Name == "Current")
              additionalScope = FindEnumeratorCurrentReferences((IProperty)entity);
            else if (entity.Name == "IsCompleted")
              additionalScope = FindAwaiterIsCompletedReferences((IProperty)entity);
            break;
          case SymbolKind.Event:
            scope = FindMemberReferences(entity, m => new FindEventReferences((IEvent)m));
            break;
          case SymbolKind.Method:
            scope = GetSearchScopeForMethod((IMethod)entity);
            break;
          case SymbolKind.Indexer:
            scope = FindIndexerReferences((IProperty)entity);
            break;
          case SymbolKind.Operator:
            scope = GetSearchScopeForOperator((IMethod)entity);
            break;
          case SymbolKind.Constructor:
            IMethod ctor = (IMethod)entity;
            scope = FindObjectCreateReferences(ctor);
            additionalScope = FindChainedConstructorReferences(ctor);
            break;
          case SymbolKind.Destructor:
            scope = GetSearchScopeForDestructor((IMethod)entity);
            break;
          default:
            throw new ArgumentException("Unknown entity type " + entity.SymbolKind);
        }
      }
      var effectiveAccessibility = entity != null ? GetEffectiveAccessibility(entity) : Accessibility.Private;
      var topLevelTypeDefinition = GetTopLevelTypeDefinition(entity);

      if (scope.accessibility == Accessibility.None)
        scope.accessibility = effectiveAccessibility;
      scope.declarationCompilation = entity != null ? entity.Compilation : null;
      scope.topLevelTypeDefinition = topLevelTypeDefinition;
      scope.findReferences = this;
      if (additionalScope != null) {
        if (additionalScope.accessibility == Accessibility.None)
          additionalScope.accessibility = effectiveAccessibility;
        additionalScope.declarationCompilation = scope.declarationCompilation;
        additionalScope.topLevelTypeDefinition = topLevelTypeDefinition;
        additionalScope.findReferences = this;
        return new[] { scope, additionalScope };
      } else {
        return new[] { scope };
      }
    }

    public IList<IFindReferenceSearchScope> GetSearchScopes(IEnumerable<ISymbol> symbols)
    {
      if (symbols == null)
        throw new ArgumentNullException("symbols");
      return symbols.SelectMany(GetSearchScopes).ToList();
    }
    
    static ITypeDefinition GetTopLevelTypeDefinition(IEntity entity)
    {
      if (entity == null)
        return null;
      ITypeDefinition topLevelTypeDefinition = entity.DeclaringTypeDefinition;
      while (topLevelTypeDefinition != null && topLevelTypeDefinition.DeclaringTypeDefinition != null)
        topLevelTypeDefinition = topLevelTypeDefinition.DeclaringTypeDefinition;
      return topLevelTypeDefinition;
    }
    #endregion
    
    #region GetInterestingFileNames
    /// <summary>
    /// Gets the file names that possibly contain references to the element being searched for.
    /// </summary>
    public IEnumerable<CSharpUnresolvedFile> GetInterestingFiles(IFindReferenceSearchScope searchScope, ICompilation compilation)
    {
      if (searchScope == null)
        throw new ArgumentNullException("searchScope");
      if (compilation == null)
        throw new ArgumentNullException("compilation");
      var pc = compilation.MainAssembly.UnresolvedAssembly as IProjectContent;
      if (pc == null)
        throw new ArgumentException("Main assembly is not a project content");
      if (searchScope.TopLevelTypeDefinition != null) {
        ITypeDefinition topLevelTypeDef = compilation.Import(searchScope.TopLevelTypeDefinition);
        if (topLevelTypeDef == null) {
          // This compilation cannot have references to the target entity.
          return EmptyList<CSharpUnresolvedFile>.Instance;
        }
        switch (searchScope.Accessibility) {
          case Accessibility.None:
          case Accessibility.Private:
            if (topLevelTypeDef.ParentAssembly == compilation.MainAssembly)
              return topLevelTypeDef.Parts.Select(p => p.UnresolvedFile).OfType<CSharpUnresolvedFile>().Distinct();
            else
              return EmptyList<CSharpUnresolvedFile>.Instance;
          case Accessibility.Protected:
            return GetInterestingFilesProtected(topLevelTypeDef);
          case Accessibility.Internal:
            if (topLevelTypeDef.ParentAssembly.InternalsVisibleTo(compilation.MainAssembly))
              return pc.Files.OfType<CSharpUnresolvedFile>();
            else
              return EmptyList<CSharpUnresolvedFile>.Instance;
          case Accessibility.ProtectedAndInternal:
            if (topLevelTypeDef.ParentAssembly.InternalsVisibleTo(compilation.MainAssembly))
              return GetInterestingFilesProtected(topLevelTypeDef);
            else
              return EmptyList<CSharpUnresolvedFile>.Instance;
          case Accessibility.ProtectedOrInternal:
            if (topLevelTypeDef.ParentAssembly.InternalsVisibleTo(compilation.MainAssembly))
              return pc.Files.OfType<CSharpUnresolvedFile>();
            else
              return GetInterestingFilesProtected(topLevelTypeDef);
          default:
            return pc.Files.OfType<CSharpUnresolvedFile>();
        }
      } else {
        if (searchScope.FileName == null)
          return pc.Files.OfType<CSharpUnresolvedFile>();
        else
          return pc.Files.OfType<CSharpUnresolvedFile>().Where(f => f.FileName == searchScope.FileName);
      }
    }
    
    IEnumerable<CSharpUnresolvedFile> GetInterestingFilesProtected(ITypeDefinition referencedTypeDefinition)
    {
      return (from typeDef in referencedTypeDefinition.Compilation.MainAssembly.GetAllTypeDefinitions()
              where typeDef.IsDerivedFrom(referencedTypeDefinition)
              from part in typeDef.Parts
              select part.UnresolvedFile
             ).OfType<CSharpUnresolvedFile>().Distinct();
    }
    #endregion
    
    #region FindReferencesInFile
    /// <summary>
    /// Finds all references in the given file.
    /// </summary>
    /// <param name="searchScope">The search scope for which to look.</param>
    /// <param name="resolver">AST resolver for the file to search in.</param>
    /// <param name="callback">Callback used to report the references that were found.</param>
    /// <param name="cancellationToken">CancellationToken that may be used to cancel the operation.</param>
    public void FindReferencesInFile(IFindReferenceSearchScope searchScope, CSharpAstResolver resolver,
                                     FoundReferenceCallback callback, CancellationToken cancellationToken)
    {
      if (resolver == null)
        throw new ArgumentNullException("resolver");
      FindReferencesInFile(searchScope, resolver.UnresolvedFile, (SyntaxTree)resolver.RootNode, resolver.Compilation, callback, cancellationToken);
    }
    
    /// <summary>
    /// Finds all references in the given file.
    /// </summary>
    /// <param name="searchScopes">The search scopes for which to look.</param>
    /// <param name="resolver">AST resolver for the file to search in.</param>
    /// <param name="callback">Callback used to report the references that were found.</param>
    /// <param name="cancellationToken">CancellationToken that may be used to cancel the operation.</param>
    public void FindReferencesInFile(IList<IFindReferenceSearchScope> searchScopes, CSharpAstResolver resolver,
                                     FoundReferenceCallback callback, CancellationToken cancellationToken)
    {
      if (resolver == null)
        throw new ArgumentNullException("resolver");
      FindReferencesInFile(searchScopes, resolver.UnresolvedFile, (SyntaxTree)resolver.RootNode, resolver.Compilation, callback, cancellationToken);
    }
    
    /// <summary>
    /// Finds all references in the given file.
    /// </summary>
    /// <param name="searchScope">The search scope for which to look.</param>
    /// <param name="unresolvedFile">The type system representation of the file being searched.</param>
    /// <param name="syntaxTree">The syntax tree of the file being searched.</param>
    /// <param name="compilation">The compilation for the project that contains the file.</param>
    /// <param name="callback">Callback used to report the references that were found.</param>
    /// <param name="cancellationToken">CancellationToken that may be used to cancel the operation.</param>
    public void FindReferencesInFile(IFindReferenceSearchScope searchScope, CSharpUnresolvedFile unresolvedFile, SyntaxTree syntaxTree,
                                     ICompilation compilation, FoundReferenceCallback callback, CancellationToken cancellationToken)
    {
      if (searchScope == null)
        throw new ArgumentNullException("searchScope");
      FindReferencesInFile(new[] { searchScope }, unresolvedFile, syntaxTree, compilation, callback, cancellationToken);
    }
    
    /// <summary>
    /// Finds all references in the given file.
    /// </summary>
    /// <param name="searchScopes">The search scopes for which to look.</param>
    /// <param name="unresolvedFile">The type system representation of the file being searched.</param>
    /// <param name="syntaxTree">The syntax tree of the file being searched.</param>
    /// <param name="compilation">The compilation for the project that contains the file.</param>
    /// <param name="callback">Callback used to report the references that were found.</param>
    /// <param name="cancellationToken">CancellationToken that may be used to cancel the operation.</param>
    public void FindReferencesInFile(IList<IFindReferenceSearchScope> searchScopes, CSharpUnresolvedFile unresolvedFile, SyntaxTree syntaxTree,
                                     ICompilation compilation, FoundReferenceCallback callback, CancellationToken cancellationToken)
    {
      if (searchScopes == null)
        throw new ArgumentNullException("searchScopes");
      if (syntaxTree == null)
        throw new ArgumentNullException("syntaxTree");
      if (compilation == null)
        throw new ArgumentNullException("compilation");
      if (callback == null)
        throw new ArgumentNullException("callback");
      
      if (searchScopes.Count == 0)
        return;
      var navigators = new IResolveVisitorNavigator[searchScopes.Count];
      for (int i = 0; i < navigators.Length; i++) {
        navigators[i] = searchScopes[i].GetNavigator(compilation, callback);
      }
      IResolveVisitorNavigator combinedNavigator;
      if (searchScopes.Count == 1) {
        combinedNavigator = navigators[0];
      } else {
        combinedNavigator = new CompositeResolveVisitorNavigator(navigators);
      }
      
      cancellationToken.ThrowIfCancellationRequested();
      combinedNavigator = new DetectSkippableNodesNavigator(combinedNavigator, syntaxTree);
      cancellationToken.ThrowIfCancellationRequested();
      CSharpAstResolver resolver = new CSharpAstResolver(compilation, syntaxTree, unresolvedFile);
      resolver.ApplyNavigator(combinedNavigator, cancellationToken);
      foreach (var n in navigators) {
        var frn = n as FindReferenceNavigator;
        if (frn != null)
          frn.NavigatorDone(resolver, cancellationToken);
      }
    }
    #endregion
    
    #region RenameReferencesInFile

    public static AstNode GetNodeToReplace(AstNode node)
    {
      if (node is ConstructorInitializer)
        return null;
      if (node is ObjectCreateExpression)
        node = ((ObjectCreateExpression)node).Type;

      if (node is InvocationExpression)
        node = ((InvocationExpression)node).Target;

      if (node is MemberReferenceExpression)
        node = ((MemberReferenceExpression)node).MemberNameToken;

      if (node is SimpleType)
        node = ((SimpleType)node).IdentifierToken;

      if (node is MemberType)
        node = ((MemberType)node).MemberNameToken;

      if (node is NamespaceDeclaration) {
//        var nsd = ((NamespaceDeclaration)node);
//        node = nsd.Identifiers.LastOrDefault (n => n.Name == memberName) ?? nsd.Identifiers.FirstOrDefault ();
//        if (node == null)
        return null;
      }

      if (node is TypeDeclaration)
        node = ((TypeDeclaration)node).NameToken;
      if (node is DelegateDeclaration)
        node = ((DelegateDeclaration)node).NameToken;

      if (node is EntityDeclaration)
        node = ((EntityDeclaration)node).NameToken;

      if (node is ParameterDeclaration)
        node = ((ParameterDeclaration)node).NameToken;
      if (node is ConstructorDeclaration)
        node = ((ConstructorDeclaration)node).NameToken;
      if (node is DestructorDeclaration)
        node = ((DestructorDeclaration)node).NameToken;
      if (node is NamedArgumentExpression)
        node = ((NamedArgumentExpression)node).NameToken;
      if (node is NamedExpression)
        node = ((NamedExpression)node).NameToken;
      if (node is VariableInitializer)
        node = ((VariableInitializer)node).NameToken;

      if (node is IdentifierExpression) {
        node = ((IdentifierExpression)node).IdentifierToken;
      }
      return node;
    }

    public void RenameReferencesInFile(IList<IFindReferenceSearchScope> searchScopes, string newName, CSharpAstResolver resolver,
                                       Action<RenameCallbackArguments> callback, Action<Error> errorCallback, CancellationToken cancellationToken = default (CancellationToken))
    {
      FindReferencesInFile(
        searchScopes,
        resolver,
        delegate(AstNode astNode, ResolveResult result) {
          var nodeToReplace = GetNodeToReplace(astNode);
          if (nodeToReplace == null) {
            errorCallback (new Error (ErrorType.Error, "no node to replace found."));
            return;
          }
          callback (new RenameCallbackArguments(nodeToReplace, Identifier.Create(newName)));
        },
        cancellationToken);
    }
    #endregion
    
    #region Find TypeDefinition References
    SearchScope FindTypeDefinitionReferences(ITypeDefinition typeDefinition, bool findTypeReferencesEvenIfAliased, out SearchScope additionalScope)
    {
      string searchTerm = null;
      additionalScope = null;
      if (!findTypeReferencesEvenIfAliased && KnownTypeReference.GetCSharpNameByTypeCode(typeDefinition.KnownTypeCode) == null) {
        // We can optimize the search by looking only for the type references with the right identifier,
        // but only if it's not a primitive type and we're not looking for indirect references (through an alias)
        searchTerm = typeDefinition.Name;
        if (searchTerm.Length > 9 && searchTerm.EndsWith("Attribute", StringComparison.Ordinal)) {
          // The type might be an attribute, so we also need to look for the short form:
          string shortForm = searchTerm.Substring(0, searchTerm.Length - 9);
          additionalScope = FindTypeDefinitionReferences(typeDefinition, shortForm);
        }
      }
      return FindTypeDefinitionReferences(typeDefinition, searchTerm);
    }
    
    SearchScope FindTypeDefinitionReferences(ITypeDefinition typeDefinition, string searchTerm)
    {
      return new SearchScope(
        searchTerm,
        delegate (ICompilation compilation) {
          ITypeDefinition imported = compilation.Import(typeDefinition);
          if (imported != null)
            return new FindTypeDefinitionReferencesNavigator(imported, searchTerm);
          else
            return null;
        });
    }
    
    sealed class FindTypeDefinitionReferencesNavigator : FindReferenceNavigator
    {
      readonly ITypeDefinition typeDefinition;
      readonly string searchTerm;
      
      public FindTypeDefinitionReferencesNavigator(ITypeDefinition typeDefinition, string searchTerm)
      {
        this.typeDefinition = typeDefinition;
        this.searchTerm = searchTerm;
      }
      
      internal override bool CanMatch(AstNode node)
      {
        IdentifierExpression ident = node as IdentifierExpression;
        if (ident != null)
          return searchTerm == null || ident.Identifier == searchTerm;
        
        MemberReferenceExpression mre = node as MemberReferenceExpression;
        if (mre != null)
          return searchTerm == null || mre.MemberName == searchTerm;
        
        SimpleType st = node as SimpleType;
        if (st != null)
          return searchTerm == null || st.Identifier == searchTerm;
        
        MemberType mt = node as MemberType;
        if (mt != null)
          return searchTerm == null || mt.MemberName == searchTerm;
        
        if (searchTerm == null && node is PrimitiveType)
          return true;
        
        TypeDeclaration typeDecl = node as TypeDeclaration;
        if (typeDecl != null)
          return searchTerm == null || typeDecl.Name == searchTerm;
        
        DelegateDeclaration delegateDecl = node as DelegateDeclaration;
        if (delegateDecl != null)
          return searchTerm == null || delegateDecl.Name == searchTerm;
        
        return false;
      }
      
      internal override bool IsMatch(ResolveResult rr)
      {
        TypeResolveResult trr = rr as TypeResolveResult;
        return trr != null && typeDefinition.Equals(trr.Type.GetDefinition());
      }
    }
    #endregion
    
    #region Find Member References
    SearchScope FindMemberReferences(IEntity member, Func<IMember, FindMemberReferencesNavigator> factory)
    {
      string searchTerm = member.Name;
      return new SearchScope(
        searchTerm,
        delegate(ICompilation compilation) {
          IMember imported = compilation.Import((IMember)member);
          return imported != null ? factory(imported) : null;
        });
    }
    
    class FindMemberReferencesNavigator : FindReferenceNavigator
    {
      readonly IMember member;
      readonly string searchTerm;
      
      public FindMemberReferencesNavigator(IMember member)
      {
        this.member = member;
        this.searchTerm = member.Name;
      }
      
      internal override bool CanMatch(AstNode node)
      {
        IdentifierExpression ident = node as IdentifierExpression;
        if (ident != null)
          return ident.Identifier == searchTerm;
        
        MemberReferenceExpression mre = node as MemberReferenceExpression;
        if (mre != null)
          return mre.MemberName == searchTerm;
        
        PointerReferenceExpression pre = node as PointerReferenceExpression;
        if (pre != null)
          return pre.MemberName == searchTerm;
        
        NamedExpression ne = node as NamedExpression;
        if (ne != null)
          return ne.Name == searchTerm;
        
        return false;
      }
      
      internal override bool IsMatch(ResolveResult rr)
      {
        MemberResolveResult mrr = rr as MemberResolveResult;
        return mrr != null && findReferences.IsMemberMatch(member, mrr.Member, mrr.IsVirtualCall);
      }
    }
    
    IMember NormalizeMember(IMember member)
    {
      if (WholeVirtualSlot && member.IsOverride)
        member = InheritanceHelper.GetBaseMembers(member, false).FirstOrDefault(m => !m.IsOverride) ?? member;
      if (!FindOnlySpecializedReferences)
        member = member.MemberDefinition;
      return member;
    }
    
    bool IsMemberMatch(IMember member, IMember referencedMember, bool isVirtualCall)
    {
      referencedMember = NormalizeMember(referencedMember);
      if (member.Equals(referencedMember))
        return true;
      if (FindCallsThroughInterface && member.DeclaringTypeDefinition != null && member.DeclaringTypeDefinition.Kind == TypeKind.Interface) {
        if (FindOnlySpecializedReferences) {
          return referencedMember.ImplementedInterfaceMembers.Contains(member);
        } else {
          return referencedMember.ImplementedInterfaceMembers.Any(m => m.MemberDefinition.Equals(member));
        }
      }
      if (!isVirtualCall)
        return false;
      bool isInterfaceCall = referencedMember.DeclaringTypeDefinition != null && referencedMember.DeclaringTypeDefinition.Kind == TypeKind.Interface;
      if (FindCallsThroughVirtualBaseMethod && member.IsOverride && !WholeVirtualSlot && !isInterfaceCall) {
        // Test if 'member' overrides 'referencedMember':
        foreach (var baseMember in InheritanceHelper.GetBaseMembers(member, false)) {
          if (FindOnlySpecializedReferences) {
            if (baseMember.Equals(referencedMember))
              return true;
          } else {
            if (baseMember.MemberDefinition.Equals(referencedMember))
              return true;
          }
          if (!baseMember.IsOverride)
            break;
        }
        return false;
      } else if (FindCallsThroughInterface && isInterfaceCall) {
        // Test if 'member' implements 'referencedMember':
        if (FindOnlySpecializedReferences) {
          return member.ImplementedInterfaceMembers.Contains(referencedMember);
        } else {
          return member.ImplementedInterfaceMembers.Any(m => m.MemberDefinition.Equals(referencedMember));
        }
      }
      return false;
    }
    
    /*
    bool PerformVirtualLookup(IMember member, IMember referencedMember)
    {
      if (FindCallsThroughVirtualBaseMethod && member.IsOverride && !WholeVirtualSlot)
        return true;
      var typeDef = referencedMember.DeclaringTypeDefinition;
      return FindCallsThroughInterface && typeDef != null && typeDef.Kind == TypeKind.Interface;
    }*/
    
    sealed class FindFieldReferences : FindMemberReferencesNavigator
    {
      public FindFieldReferences(IField field) : base(field)
      {
      }
      
      internal override bool CanMatch(AstNode node)
      {
        if (node is VariableInitializer) {
          return node.Parent is FieldDeclaration;
        }
        return base.CanMatch(node);
      }
    }
    
    sealed class FindEnumMemberReferences : FindMemberReferencesNavigator
    {
      public FindEnumMemberReferences(IField field) : base(field)
      {
      }
      
      internal override bool CanMatch(AstNode node)
      {
        return node is EnumMemberDeclaration || base.CanMatch(node);
      }
    }
    
    sealed class FindPropertyReferences : FindMemberReferencesNavigator
    {
      public FindPropertyReferences(IProperty property) : base(property)
      {
      }
      
      internal override bool CanMatch(AstNode node)
      {
        return node is PropertyDeclaration || base.CanMatch(node);
      }
    }
    
    sealed class FindEventReferences : FindMemberReferencesNavigator
    {
      public FindEventReferences(IEvent ev) : base(ev)
      {
      }
      
      internal override bool CanMatch(AstNode node)
      {
        if (node is VariableInitializer) {
          return node.Parent is EventDeclaration;
        }
        return node is CustomEventDeclaration || base.CanMatch(node);
      }
    }
    #endregion
    
    #region Find References to IEnumerator.Current
    SearchScope FindEnumeratorCurrentReferences(IProperty property)
    {
      return new SearchScope(
        delegate(ICompilation compilation) {
          IProperty imported = compilation.Import(property);
          return imported != null ? new FindEnumeratorCurrentReferencesNavigator(imported) : null;
        });
    }

    SearchScope FindAwaiterIsCompletedReferences(IProperty property)
    {
      return new SearchScope(
        delegate(ICompilation compilation) {
          IProperty imported = compilation.Import(property);
          return imported != null ? new FindAwaiterIsCompletedReferencesNavigator(imported) : null;
        });
    }
    
    sealed class FindEnumeratorCurrentReferencesNavigator : FindReferenceNavigator
    {
      IProperty property;
      
      public FindEnumeratorCurrentReferencesNavigator(IProperty property)
      {
        this.property = property;
      }
      
      internal override bool CanMatch(AstNode node)
      {
        return node is ForeachStatement;
      }
      
      internal override bool IsMatch(ResolveResult rr)
      {
        ForEachResolveResult ferr = rr as ForEachResolveResult;
        return ferr != null && ferr.CurrentProperty != null && findReferences.IsMemberMatch(property, ferr.CurrentProperty, true);
      }
    }

    sealed class FindAwaiterIsCompletedReferencesNavigator : FindReferenceNavigator
    {
      IProperty property;
      
      public FindAwaiterIsCompletedReferencesNavigator(IProperty property)
      {
        this.property = property;
      }
      
      internal override bool CanMatch(AstNode node)
      {
        return node is UnaryOperatorExpression;
      }
      
      internal override bool IsMatch(ResolveResult rr)
      {
        AwaitResolveResult arr = rr as AwaitResolveResult;
        return arr != null && arr.IsCompletedProperty != null && findReferences.IsMemberMatch(property, arr.IsCompletedProperty, true);
      }
    }
    #endregion
    
    #region Find Method References
    SearchScope GetSearchScopeForMethod(IMethod method)
    {
      Type specialNodeType;
      switch (method.Name) {
        case "Add":
          specialNodeType = typeof(ArrayInitializerExpression);
          break;
        case "Where":
          specialNodeType = typeof(QueryWhereClause);
          break;
        case "Select":
          specialNodeType = typeof(QuerySelectClause);
          break;
        case "SelectMany":
          specialNodeType = typeof(QueryFromClause);
          break;
        case "Join":
        case "GroupJoin":
          specialNodeType = typeof(QueryJoinClause);
          break;
        case "OrderBy":
        case "OrderByDescending":
        case "ThenBy":
        case "ThenByDescending":
          specialNodeType = typeof(QueryOrdering);
          break;
        case "GroupBy":
          specialNodeType = typeof(QueryGroupClause);
          break;
        case "Invoke":
          if (method.DeclaringTypeDefinition != null && method.DeclaringTypeDefinition.Kind == TypeKind.Delegate)
            specialNodeType = typeof(InvocationExpression);
          else
            specialNodeType = null;
          break;
        case "GetEnumerator":
        case "MoveNext":
          specialNodeType = typeof(ForeachStatement);
          break;
        case "GetAwaiter":
        case "GetResult":
        case "OnCompleted":
        case "UnsafeOnCompleted":
          specialNodeType = typeof(UnaryOperatorExpression);
          break;
        default:
          specialNodeType = null;
          break;
      }
      // Use searchTerm only if specialNodeType==null
      string searchTerm = (specialNodeType == null) ? method.Name : null;
      return new SearchScope(
        searchTerm,
        delegate (ICompilation compilation) {
          IMethod imported = compilation.Import(method);
          if (imported != null)
            return new FindMethodReferences(imported, specialNodeType);
          else
            return null;
        });
    }
    
    sealed class FindMethodReferences : FindReferenceNavigator
    {
      readonly IMethod method;
      readonly Type specialNodeType;
      HashSet<Expression> potentialMethodGroupConversions = new HashSet<Expression>();
      
      public FindMethodReferences(IMethod method, Type specialNodeType)
      {
        this.method = method;
        this.specialNodeType = specialNodeType;
      }
      
      internal override bool CanMatch(AstNode node)
      {
        if (specialNodeType != null && node.GetType() == specialNodeType)
          return true;
        
        Expression expr = node as Expression;
        if (expr == null)
          return node is MethodDeclaration;
        
        InvocationExpression ie = node as InvocationExpression;
        if (ie != null) {
          Expression target = ParenthesizedExpression.UnpackParenthesizedExpression(ie.Target);
          
          IdentifierExpression ident = target as IdentifierExpression;
          if (ident != null)
            return ident.Identifier == method.Name;
          
          MemberReferenceExpression mre = target as MemberReferenceExpression;
          if (mre != null)
            return mre.MemberName == method.Name;
          
          PointerReferenceExpression pre = target as PointerReferenceExpression;
          if (pre != null)
            return pre.MemberName == method.Name;
        } else if (expr.Role != Roles.TargetExpression) {
          // MemberReferences & Identifiers that aren't used in an invocation can still match the method
          // as delegate name.
          if (expr.GetChildByRole(Roles.Identifier).Name == method.Name)
            potentialMethodGroupConversions.Add(expr);
        }
        return node is MethodDeclaration;
      }
      
      internal override bool IsMatch(ResolveResult rr)
      {
        if (specialNodeType != null) {
          var ferr = rr as ForEachResolveResult;
          if (ferr != null) {
            return IsMatch(ferr.GetEnumeratorCall)
              || (ferr.MoveNextMethod != null && findReferences.IsMemberMatch(method, ferr.MoveNextMethod, true));
          }
          var arr = rr as AwaitResolveResult;
          if (arr != null) {
            return IsMatch(arr.GetAwaiterInvocation)
              || (arr.GetResultMethod != null && findReferences.IsMemberMatch(method, arr.GetResultMethod, true))
              || (arr.OnCompletedMethod != null && findReferences.IsMemberMatch(method, arr.OnCompletedMethod, true));
          }
        }
        var mrr = rr as MemberResolveResult;
        return mrr != null && findReferences.IsMemberMatch(method, mrr.Member, mrr.IsVirtualCall);
      }
      
      internal override void NavigatorDone(CSharpAstResolver resolver, CancellationToken cancellationToken)
      {
        foreach (var expr in potentialMethodGroupConversions) {
          var conversion = resolver.GetConversion(expr, cancellationToken);
          if (conversion.IsMethodGroupConversion && findReferences.IsMemberMatch(method, conversion.Method, conversion.IsVirtualMethodLookup)) {
            IType targetType = resolver.GetExpectedType(expr, cancellationToken);
            ResolveResult result = resolver.Resolve(expr, cancellationToken);
            ReportMatch(expr, new ConversionResolveResult(targetType, result, conversion));
          }
        }
        base.NavigatorDone(resolver, cancellationToken);
      }
    }
    #endregion
    
    #region Find Indexer References
    SearchScope FindIndexerReferences(IProperty indexer)
    {
      return new SearchScope(
        delegate (ICompilation compilation) {
          IProperty imported = compilation.Import(indexer);
          if (imported != null)
            return new FindIndexerReferencesNavigator(imported);
          else
            return null;
        });
    }
    
    sealed class FindIndexerReferencesNavigator : FindReferenceNavigator
    {
      readonly IProperty indexer;
      
      public FindIndexerReferencesNavigator(IProperty indexer)
      {
        this.indexer = indexer;
      }
      
      internal override bool CanMatch(AstNode node)
      {
        return node is IndexerExpression || node is IndexerDeclaration;
      }
      
      internal override bool IsMatch(ResolveResult rr)
      {
        MemberResolveResult mrr = rr as MemberResolveResult;
        return mrr != null && findReferences.IsMemberMatch(indexer, mrr.Member, mrr.IsVirtualCall);
      }
    }
    #endregion
    
    #region Find Operator References
    SearchScope GetSearchScopeForOperator(IMethod op)
    {
      OperatorType? opType = OperatorDeclaration.GetOperatorType(op.Name);
      if (opType == null)
        return GetSearchScopeForMethod(op);
      switch (opType.Value) {
        case OperatorType.LogicalNot:
          return FindUnaryOperator(op, UnaryOperatorType.Not);
        case OperatorType.OnesComplement:
          return FindUnaryOperator(op, UnaryOperatorType.BitNot);
        case OperatorType.UnaryPlus:
          return FindUnaryOperator(op, UnaryOperatorType.Plus);
        case OperatorType.UnaryNegation:
          return FindUnaryOperator(op, UnaryOperatorType.Minus);
        case OperatorType.Increment:
          return FindUnaryOperator(op, UnaryOperatorType.Increment);
        case OperatorType.Decrement:
          return FindUnaryOperator(op, UnaryOperatorType.Decrement);
        case OperatorType.True:
        case OperatorType.False:
          // TODO: implement search for op_True/op_False correctly
          return GetSearchScopeForMethod(op);
        case OperatorType.Addition:
          return FindBinaryOperator(op, BinaryOperatorType.Add);
        case OperatorType.Subtraction:
          return FindBinaryOperator(op, BinaryOperatorType.Subtract);
        case OperatorType.Multiply:
          return FindBinaryOperator(op, BinaryOperatorType.Multiply);
        case OperatorType.Division:
          return FindBinaryOperator(op, BinaryOperatorType.Divide);
        case OperatorType.Modulus:
          return FindBinaryOperator(op, BinaryOperatorType.Modulus);
        case OperatorType.BitwiseAnd:
          // TODO: an overloaded bitwise operator can also be called using the corresponding logical operator
          // (if op_True/op_False is defined)
          return FindBinaryOperator(op, BinaryOperatorType.BitwiseAnd);
        case OperatorType.BitwiseOr:
          return FindBinaryOperator(op, BinaryOperatorType.BitwiseOr);
        case OperatorType.ExclusiveOr:
          return FindBinaryOperator(op, BinaryOperatorType.ExclusiveOr);
        case OperatorType.LeftShift:
          return FindBinaryOperator(op, BinaryOperatorType.ShiftLeft);
        case OperatorType.RightShift:
          return FindBinaryOperator(op, BinaryOperatorType.ShiftRight);
        case OperatorType.Equality:
          return FindBinaryOperator(op, BinaryOperatorType.Equality);
        case OperatorType.Inequality:
          return FindBinaryOperator(op, BinaryOperatorType.InEquality);
        case OperatorType.GreaterThan:
          return FindBinaryOperator(op, BinaryOperatorType.GreaterThan);
        case OperatorType.LessThan:
          return FindBinaryOperator(op, BinaryOperatorType.LessThan);
        case OperatorType.GreaterThanOrEqual:
          return FindBinaryOperator(op, BinaryOperatorType.GreaterThanOrEqual);
        case OperatorType.LessThanOrEqual:
          return FindBinaryOperator(op, BinaryOperatorType.LessThanOrEqual);
        case OperatorType.Implicit:
          return FindOperator(op, m => new FindImplicitOperatorNavigator(m));
        case OperatorType.Explicit:
          return FindOperator(op, m => new FindExplicitOperatorNavigator(m));
        default:
          throw new InvalidOperationException("Invalid value for OperatorType");
      }
    }
    
    SearchScope FindOperator(IMethod op, Func<IMethod, FindReferenceNavigator> factory)
    {
      return new SearchScope(
        delegate (ICompilation compilation) {
          IMethod imported = compilation.Import(op);
          return imported != null ? factory(imported) : null;
        });
    }
    
    SearchScope FindUnaryOperator(IMethod op, UnaryOperatorType operatorType)
    {
      return FindOperator(op, m => new FindUnaryOperatorNavigator(m, operatorType));
    }
    
    sealed class FindUnaryOperatorNavigator : FindReferenceNavigator
    {
      readonly IMethod op;
      readonly UnaryOperatorType operatorType;
      
      public FindUnaryOperatorNavigator(IMethod op, UnaryOperatorType operatorType)
      {
        this.op = op;
        this.operatorType = operatorType;
      }
      
      internal override bool CanMatch(AstNode node)
      {
        UnaryOperatorExpression uoe = node as UnaryOperatorExpression;
        if (uoe != null) {
          if (operatorType == UnaryOperatorType.Increment)
            return uoe.Operator == UnaryOperatorType.Increment || uoe.Operator == UnaryOperatorType.PostIncrement;
          else if (operatorType == UnaryOperatorType.Decrement)
            return uoe.Operator == UnaryOperatorType.Decrement || uoe.Operator == UnaryOperatorType.PostDecrement;
          else
            return uoe.Operator == operatorType;
        }
        return node is OperatorDeclaration;
      }
      
      internal override bool IsMatch(ResolveResult rr)
      {
        MemberResolveResult mrr = rr as MemberResolveResult;
        return mrr != null && findReferences.IsMemberMatch(op, mrr.Member, mrr.IsVirtualCall);
      }
    }
    
    SearchScope FindBinaryOperator(IMethod op, BinaryOperatorType operatorType)
    {
      return FindOperator(op, m => new FindBinaryOperatorNavigator(m, operatorType));
    }
    
    sealed class FindBinaryOperatorNavigator : FindReferenceNavigator
    {
      readonly IMethod op;
      readonly BinaryOperatorType operatorType;
      
      public FindBinaryOperatorNavigator(IMethod op, BinaryOperatorType operatorType)
      {
        this.op = op;
        this.operatorType = operatorType;
      }
      
      internal override bool CanMatch(AstNode node)
      {
        BinaryOperatorExpression boe = node as BinaryOperatorExpression;
        if (boe != null) {
          return boe.Operator == operatorType;
        }
        return node is OperatorDeclaration;
      }
      
      internal override bool IsMatch(ResolveResult rr)
      {
        MemberResolveResult mrr = rr as MemberResolveResult;
        return mrr != null && findReferences.IsMemberMatch(op, mrr.Member, mrr.IsVirtualCall);
      }
    }
    
    sealed class FindImplicitOperatorNavigator : FindReferenceNavigator
    {
      readonly IMethod op;
      
      public FindImplicitOperatorNavigator(IMethod op)
      {
        this.op = op;
      }
      
      internal override bool CanMatch(AstNode node)
      {
        return true;
      }
      
      internal override bool IsMatch(ResolveResult rr)
      {
        MemberResolveResult mrr = rr as MemberResolveResult;
        return mrr != null && findReferences.IsMemberMatch(op, mrr.Member, mrr.IsVirtualCall);
      }
      
      public override void ProcessConversion(Expression expression, ResolveResult result, Conversion conversion, IType targetType)
      {
        if (conversion.IsUserDefined && findReferences.IsMemberMatch(op, conversion.Method, conversion.IsVirtualMethodLookup)) {
          ReportMatch(expression, result);
        }
      }
    }
    
    sealed class FindExplicitOperatorNavigator : FindReferenceNavigator
    {
      readonly IMethod op;
      
      public FindExplicitOperatorNavigator(IMethod op)
      {
        this.op = op;
      }
      
      internal override bool CanMatch(AstNode node)
      {
        return node is CastExpression;
      }
      
      internal override bool IsMatch(ResolveResult rr)
      {
        ConversionResolveResult crr = rr as ConversionResolveResult;
        return crr != null && crr.Conversion.IsUserDefined
          && findReferences.IsMemberMatch(op, crr.Conversion.Method, crr.Conversion.IsVirtualMethodLookup);
      }
    }
    #endregion
    
    #region Find Constructor References
    SearchScope FindObjectCreateReferences(IMethod ctor)
    {
      string searchTerm = null;
      if (KnownTypeReference.GetCSharpNameByTypeCode(ctor.DeclaringTypeDefinition.KnownTypeCode) == null) {
        // not a built-in type
        searchTerm = ctor.DeclaringTypeDefinition.Name;
        if (searchTerm.Length > 9 && searchTerm.EndsWith("Attribute", StringComparison.Ordinal)) {
          // we also need to look for the short form
          searchTerm = null;
        }
      }
      return new SearchScope(
        searchTerm,
        delegate (ICompilation compilation) {
          IMethod imported = compilation.Import(ctor);
          if (imported != null)
            return new FindObjectCreateReferencesNavigator(imported);
          else
            return null;
        });
    }
    
    sealed class FindObjectCreateReferencesNavigator : FindReferenceNavigator
    {
      readonly IMethod ctor;
      
      public FindObjectCreateReferencesNavigator(IMethod ctor)
      {
        this.ctor = ctor;
      }
      
      internal override bool CanMatch(AstNode node)
      {
        return node is ObjectCreateExpression || node is ConstructorDeclaration || node is Attribute;
      }
      
      internal override bool IsMatch(ResolveResult rr)
      {
        MemberResolveResult mrr = rr as MemberResolveResult;
        return mrr != null && findReferences.IsMemberMatch(ctor, mrr.Member, mrr.IsVirtualCall);
      }
    }
    
    SearchScope FindChainedConstructorReferences(IMethod ctor)
    {
      SearchScope searchScope = new SearchScope(
        delegate (ICompilation compilation) {
          IMethod imported = compilation.Import(ctor);
          if (imported != null)
            return new FindChainedConstructorReferencesNavigator(imported);
          else
            return null;
        });
      if (ctor.DeclaringTypeDefinition.IsSealed)
        searchScope.accessibility = Accessibility.Private;
      else
        searchScope.accessibility = Accessibility.Protected;
      searchScope.accessibility = MergeAccessibility(GetEffectiveAccessibility(ctor), searchScope.accessibility);
      return searchScope;
    }
    
    sealed class FindChainedConstructorReferencesNavigator : FindReferenceNavigator
    {
      readonly IMethod ctor;
      
      public FindChainedConstructorReferencesNavigator(IMethod ctor)
      {
        this.ctor = ctor;
      }
      
      internal override bool CanMatch(AstNode node)
      {
        return node is ConstructorInitializer;
      }
      
      internal override bool IsMatch(ResolveResult rr)
      {
        MemberResolveResult mrr = rr as MemberResolveResult;
        return mrr != null && findReferences.IsMemberMatch(ctor, mrr.Member, mrr.IsVirtualCall);
      }
    }
    #endregion
    
    #region Find Destructor References
    SearchScope GetSearchScopeForDestructor(IMethod dtor)
    {
      var scope = new SearchScope (
        delegate (ICompilation compilation) {
          IMethod imported = compilation.Import(dtor);
          if (imported != null) {
            return new FindDestructorReferencesNavigator (imported);
          } else {
            return null;
          }
        });
      scope.accessibility = Accessibility.Private;
      return scope;
    }
    
    sealed class FindDestructorReferencesNavigator : FindReferenceNavigator
    {
      readonly IMethod dtor;
      
      public FindDestructorReferencesNavigator (IMethod dtor)
      {
        this.dtor = dtor;
      }
      
      internal override bool CanMatch(AstNode node)
      {
        return node is DestructorDeclaration;
      }
      
      internal override bool IsMatch(ResolveResult rr)
      {
        MemberResolveResult mrr = rr as MemberResolveResult;
        return mrr != null && findReferences.IsMemberMatch(dtor, mrr.Member, mrr.IsVirtualCall);
      }
    }
    #endregion

    #region Find Local Variable References
    /// <summary>
    /// Finds all references of a given variable.
    /// </summary>
    /// <param name="variable">The variable for which to look.</param>
    /// <param name="unresolvedFile">The type system representation of the file being searched.</param>
    /// <param name="syntaxTree">The syntax tree of the file being searched.</param>
    /// <param name="compilation">The compilation.</param>
    /// <param name="callback">Callback used to report the references that were found.</param>
    /// <param name="cancellationToken">Cancellation token that may be used to cancel the operation.</param>
    public void FindLocalReferences(IVariable variable, CSharpUnresolvedFile unresolvedFile, SyntaxTree syntaxTree,
                                    ICompilation compilation, FoundReferenceCallback callback, CancellationToken cancellationToken)
    {
      if (variable == null)
        throw new ArgumentNullException("variable");
      var searchScope = new SearchScope(c => new FindLocalReferencesNavigator(variable));
      searchScope.declarationCompilation = compilation;
      FindReferencesInFile(searchScope, unresolvedFile, syntaxTree, compilation, callback, cancellationToken);
    }
    
    SearchScope GetSearchScopeForLocalVariable(IVariable variable)
    {
      var scope = new SearchScope (
        delegate {
          return new FindLocalReferencesNavigator(variable);
        }
      );
      scope.fileName = variable.Region.FileName;
      return scope;
    }
    
    class FindLocalReferencesNavigator : FindReferenceNavigator
    {
      readonly IVariable variable;
      
      public FindLocalReferencesNavigator(IVariable variable)
      {
        this.variable = variable;
      }
      
      internal override bool CanMatch(AstNode node)
      {
        var expr = node as IdentifierExpression;
        if (expr != null)
          return expr.TypeArguments.Count == 0 && variable.Name == expr.Identifier;
        var vi = node as VariableInitializer;
        if (vi != null)
          return vi.Name == variable.Name;
        var pd = node as ParameterDeclaration;
        if (pd != null)
          return pd.Name == variable.Name;
        var id = node as Identifier;
        if (id != null)
          return id.Name == variable.Name;
        return false;
      }
      
      internal override bool IsMatch(ResolveResult rr)
      {
        var lrr = rr as LocalResolveResult;
        return lrr != null && lrr.Variable.Name == variable.Name && lrr.Variable.Region == variable.Region;
      }
    }
    #endregion

    #region Find Type Parameter References
    /// <summary>
    /// Finds all references of a given type parameter.
    /// </summary>
    /// <param name="typeParameter">The type parameter for which to look.</param>
    /// <param name="unresolvedFile">The type system representation of the file being searched.</param>
    /// <param name="syntaxTree">The syntax tree of the file being searched.</param>
    /// <param name="compilation">The compilation.</param>
    /// <param name="callback">Callback used to report the references that were found.</param>
    /// <param name="cancellationToken">Cancellation token that may be used to cancel the operation.</param>
    [Obsolete("Use GetSearchScopes(typeParameter) instead")]
    public void FindTypeParameterReferences(IType typeParameter, CSharpUnresolvedFile unresolvedFile, SyntaxTree syntaxTree,
                                            ICompilation compilation, FoundReferenceCallback callback, CancellationToken cancellationToken)
    {
      if (typeParameter == null)
        throw new ArgumentNullException("typeParameter");
      if (typeParameter.Kind != TypeKind.TypeParameter)
        throw new ArgumentOutOfRangeException("typeParameter", "Only type parameters are allowed");
      var searchScope = new SearchScope(c => new FindTypeParameterReferencesNavigator((ITypeParameter)typeParameter));
      searchScope.declarationCompilation = compilation;
      searchScope.accessibility = Accessibility.Private;
      FindReferencesInFile(searchScope, unresolvedFile, syntaxTree, compilation, callback, cancellationToken);
    }
    
    SearchScope GetSearchScopeForTypeParameter(ITypeParameter tp)
    {
      var searchScope = new SearchScope(c => new FindTypeParameterReferencesNavigator(tp));
      var compilationProvider = tp as ICompilationProvider;
      if (compilationProvider != null)
        searchScope.declarationCompilation = compilationProvider.Compilation;
      searchScope.topLevelTypeDefinition = GetTopLevelTypeDefinition(tp.Owner);
      searchScope.accessibility = Accessibility.Private;
      return searchScope;
    }

    class FindTypeParameterReferencesNavigator : FindReferenceNavigator
    {
      readonly ITypeParameter typeParameter;
      
      public FindTypeParameterReferencesNavigator(ITypeParameter typeParameter)
      {
        this.typeParameter = typeParameter;
      }
      
      internal override bool CanMatch(AstNode node)
      {
        var type = node as SimpleType;
        if (type != null)
          return type.Identifier == typeParameter.Name;
        var declaration = node as TypeParameterDeclaration;
        if (declaration != null)
          return declaration.Name == typeParameter.Name;
        return false;
      }
      
      internal override bool IsMatch(ResolveResult rr)
      {
        var lrr = rr as TypeResolveResult;
        return lrr != null && lrr.Type.Kind == TypeKind.TypeParameter && ((ITypeParameter)lrr.Type).Region == typeParameter.Region;
      }
    }
    #endregion
    
    #region Find Namespace References
    SearchScope GetSearchScopeForNamespace(INamespace ns)
    {
      var scope = new SearchScope (
        delegate (ICompilation compilation) {
          return new FindNamespaceNavigator (ns);
        }
      );
      return scope;
    }

    sealed class FindNamespaceNavigator : FindReferenceNavigator
    {
      readonly INamespace ns;

      public FindNamespaceNavigator (INamespace ns)
      {
        this.ns = ns;
      }

      internal override bool CanMatch(AstNode node)
      {
        var nsd = node as NamespaceDeclaration;
        if (nsd != null && nsd.FullName.StartsWith(ns.FullName, StringComparison.Ordinal))
          return true;

        var ud = node as UsingDeclaration;
        if (ud != null && ud.Namespace == ns.FullName)
          return true;

        var st = node as SimpleType;
        if (st != null && st.Identifier == ns.Name)
          return !st.AncestorsAndSelf.TakeWhile (n => n is AstType).Any (m => m.Role == NamespaceDeclaration.NamespaceNameRole);

        var mt = node as MemberType;
        if (mt != null && mt.MemberName == ns.Name)
          return !mt.AncestorsAndSelf.TakeWhile (n => n is AstType).Any (m => m.Role == NamespaceDeclaration.NamespaceNameRole);

        var identifer = node as IdentifierExpression;
        if (identifer != null && identifer.Identifier == ns.Name)
          return true;

        var mrr = node as MemberReferenceExpression;
        if (mrr != null && mrr.MemberName == ns.Name)
          return true;


        return false;
      }

      internal override bool IsMatch(ResolveResult rr)
      {
        var nsrr = rr as NamespaceResolveResult;
        return nsrr != null && nsrr.NamespaceName.StartsWith(ns.FullName, StringComparison.Ordinal);
      }
    }
    #endregion
    
    #region Find Parameter References

    SearchScope GetSearchScopeForParameter(IParameter parameter)
    {
      var scope = new SearchScope (
        delegate {
          return new FindParameterReferencesNavigator (parameter);
        }
      );
      if (parameter.Owner == null) {
        scope.fileName = parameter.Region.FileName;
      }
      return scope;
    }

    class FindParameterReferencesNavigator : FindReferenceNavigator
    {
      readonly IParameter parameter;

      public FindParameterReferencesNavigator(IParameter parameter)
      {
        this.parameter = parameter;
      }

      internal override bool CanMatch(AstNode node)
      {
        var expr = node as IdentifierExpression;
        if (expr != null)
          return expr.TypeArguments.Count == 0 && parameter.Name == expr.Identifier;
        var vi = node as VariableInitializer;
        if (vi != null)
          return vi.Name == parameter.Name;
        var pd = node as ParameterDeclaration;
        if (pd != null)
          return pd.Name == parameter.Name;
        var id = node as Identifier;
        if (id != null)
          return id.Name == parameter.Name;
        var nae = node as NamedArgumentExpression;
        if (nae != null)
          return nae.Name == parameter.Name;
        return false;
      }

      internal override bool IsMatch(ResolveResult rr)
      {
        var lrr = rr as LocalResolveResult;
        if (lrr != null)
          return lrr.Variable.Name == parameter.Name && lrr.Variable.Region == parameter.Region;

        var nar = rr as NamedArgumentResolveResult;
        return nar != null && nar.Parameter.Name == parameter.Name && nar.Parameter.Region == parameter.Region;
      }
    }
    #endregion
  }
}