source: branches/2893_BNLR/HeuristicLab.ExtLibs/HeuristicLab.NRefactory/5.5.0/NRefactory.CSharp-5.5.0/Resolver/ResolveAtLocation.cs

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// 
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// 
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// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
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using System;
using System.Threading;
using ICSharpCode.NRefactory.CSharp.TypeSystem;
using ICSharpCode.NRefactory.Semantics;
using ICSharpCode.NRefactory.TypeSystem;

namespace ICSharpCode.NRefactory.CSharp.Resolver
{
  /// <summary>
  /// Helper class that resolves the node at a specified location.
  /// Can be used for implementing tool tips.
  /// </summary>
  public static class ResolveAtLocation
  {
    public static ResolveResult Resolve (ICompilation compilation, CSharpUnresolvedFile unresolvedFile, SyntaxTree syntaxTree, TextLocation location,
                                        CancellationToken cancellationToken = default(CancellationToken))
    {
      return Resolve (new Lazy<ICompilation>(() => compilation), unresolvedFile, syntaxTree, location, cancellationToken);
    }
    public static ResolveResult Resolve(Lazy<ICompilation> compilation, CSharpUnresolvedFile unresolvedFile, SyntaxTree syntaxTree, TextLocation location,
                                        CancellationToken cancellationToken = default(CancellationToken))
    {
      AstNode node;
      return Resolve(compilation, unresolvedFile, syntaxTree, location, out node, cancellationToken);
    }
    
    public static ResolveResult Resolve (ICompilation compilation, CSharpUnresolvedFile unresolvedFile, SyntaxTree syntaxTree, TextLocation location, out AstNode node,
                                        CancellationToken cancellationToken = default(CancellationToken))
    {
      return Resolve (new Lazy<ICompilation>(() => compilation), unresolvedFile, syntaxTree, location, out node, cancellationToken);
    }
    public static ResolveResult Resolve(Lazy<ICompilation> compilation, CSharpUnresolvedFile unresolvedFile, SyntaxTree syntaxTree, TextLocation location, out AstNode node,
                                        CancellationToken cancellationToken = default(CancellationToken))
    {
      node = syntaxTree.GetNodeAt(location);
      if (node == null || node is ArrayInitializerExpression)
        return null;
      if (node.Parent is UsingAliasDeclaration && node.Role == UsingAliasDeclaration.AliasRole) {
        var r = new CSharpAstResolver(compilation.Value, syntaxTree, unresolvedFile);
        return r.Resolve(((UsingAliasDeclaration)node.Parent).Import, cancellationToken);
      }
      if (CSharpAstResolver.IsUnresolvableNode(node)) {
        if (node is Identifier) {
          node = node.Parent;
        } else if (node.NodeType == NodeType.Token) {
          if (node.Parent is IndexerExpression || node.Parent is ConstructorInitializer || node.Role == IndexerDeclaration.ThisKeywordRole) {
            // There's no other place where one could hover to see the indexer's tooltip,
            // so we need to resolve it when hovering over the '[' or ']'.
            // For constructor initializer, the same applies to the 'base'/'this' token.
            node = node.Parent;
          } else if (node.Parent is BinaryOperatorExpression || node.Parent is UnaryOperatorExpression) {
            // Resolve user-defined operator
            node = node.Parent;
          } else {
            return null;
          }
        } else {
          // don't resolve arbitrary nodes - we don't want to show tooltips for everything
          return null;
        }
      } else {
        // It's a resolvable node.
        // However, we usually don't want to show the tooltip everywhere
        // For example, hovering with the mouse over an empty line between two methods causes
        // node==TypeDeclaration, but we don't want to show any tooltip.
        
        if (!node.GetChildByRole(Roles.Identifier).IsNull) {
          // We'll suppress the tooltip for resolvable nodes if there is an identifier that
          // could be hovered over instead:
          return null;
        }
      }

      if (node == null)
        return null;
      if (node.Parent is ObjectCreateExpression && node.Role == Roles.Type) {
        node = node.Parent;
      } else if (node is ThisReferenceExpression && node.Parent is IndexerExpression) {
        node = node.Parent;
      }

      InvocationExpression parentInvocation = null;
      if ((node is IdentifierExpression || node is MemberReferenceExpression || node is PointerReferenceExpression) && node.Role != Roles.Argument) {
        // we also need to resolve the invocation
        parentInvocation = node.Parent as InvocationExpression;
      }
      
      // TODO: I think we should provide an overload so that an existing CSharpAstResolver can be reused
      CSharpAstResolver resolver = new CSharpAstResolver(compilation.Value, syntaxTree, unresolvedFile);
      ResolveResult rr = resolver.Resolve(node, cancellationToken);
      MethodGroupResolveResult mgrr = rr as MethodGroupResolveResult;
      if (mgrr != null) {
        // For method groups, resolve the parent invocation instead.
        if (parentInvocation != null)
          return resolver.Resolve(parentInvocation);
        if (node is Expression) {
          // If it's not an invocation, try if it's a conversion to a delegate type:
          Conversion c = resolver.GetConversion((Expression)node, cancellationToken);
          if (c.IsMethodGroupConversion)
            return new MemberResolveResult(mgrr.TargetResult, c.Method);
        }
      }
      return rr;
    }
  }
}