source: branches/RemoveBackwardsCompatibility/HeuristicLab.ExtLibs/HeuristicLab.NRefactory/5.5.0/NRefactory.CSharp-5.5.0/Resolver/MethodGroupResolveResult.cs @ 14815

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// 
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// substantial portions of the Software.
// 
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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.Collections.Generic;
using System.Collections.ObjectModel;
using System.Diagnostics;
using System.Linq;
using System.Text;
using ICSharpCode.NRefactory.CSharp.TypeSystem;
using ICSharpCode.NRefactory.Semantics;
using ICSharpCode.NRefactory.TypeSystem;
using ICSharpCode.NRefactory.TypeSystem.Implementation;

namespace ICSharpCode.NRefactory.CSharp.Resolver
{
  /// <summary>
  /// A method list that belongs to a declaring type.
  /// </summary>
  public class MethodListWithDeclaringType : List<IParameterizedMember>
  {
    readonly IType declaringType;
    
    /// <summary>
    /// The declaring type.
    /// </summary>
    /// <remarks>
    /// Not all methods in this list necessarily have this as their declaring type.
    /// For example, this program:
    /// <code>
    ///  class Base {
    ///    public virtual void M() {}
    ///  }
    ///  class Derived : Base {
    ///    public override void M() {}
    ///    public void M(int i) {}
    ///  }
    /// </code>
    /// results in two lists:
    ///  <c>new MethodListWithDeclaringType(Base) { Derived.M() }</c>,
    ///  <c>new MethodListWithDeclaringType(Derived) { Derived.M(int) }</c>
    /// </remarks>
    public IType DeclaringType {
      get { return declaringType; }
    }
    
    public MethodListWithDeclaringType(IType declaringType)
    {
      this.declaringType = declaringType;
    }
    
    public MethodListWithDeclaringType(IType declaringType, IEnumerable<IParameterizedMember> methods)
      : base(methods)
    {
      this.declaringType = declaringType;
    }
  }
  
  /// <summary>
  /// Represents a group of methods.
  /// A method reference used to create a delegate is resolved to a MethodGroupResolveResult.
  /// The MethodGroupResolveResult has no type.
  /// To retrieve the delegate type or the chosen overload, look at the method group conversion.
  /// </summary>
  public class MethodGroupResolveResult : ResolveResult
  {
    readonly IList<MethodListWithDeclaringType> methodLists;
    readonly IList<IType> typeArguments;
    readonly ResolveResult targetResult;
    readonly string methodName;
    
    public MethodGroupResolveResult(ResolveResult targetResult, string methodName, IList<MethodListWithDeclaringType> methods, IList<IType> typeArguments) : base(SpecialType.UnknownType)
    {
      if (methods == null)
        throw new ArgumentNullException("methods");
      this.targetResult = targetResult;
      this.methodName = methodName;
      this.methodLists = methods;
      this.typeArguments = typeArguments ?? EmptyList<IType>.Instance;
    }
    
    /// <summary>
    /// Gets the resolve result for the target object.
    /// </summary>
    public ResolveResult TargetResult {
      get { return targetResult; }
    }
    
    /// <summary>
    /// Gets the type of the reference to the target object.
    /// </summary>
    public IType TargetType {
      get { return targetResult != null ? targetResult.Type : SpecialType.UnknownType; }
    }
    
    /// <summary>
    /// Gets the name of the methods in this group.
    /// </summary>
    public string MethodName {
      get { return methodName; }
    }
    
    /// <summary>
    /// Gets the methods that were found.
    /// This list does not include extension methods.
    /// </summary>
    public IEnumerable<IMethod> Methods {
      get { return methodLists.SelectMany(m => m.Cast<IMethod>()); }
    }
    
    /// <summary>
    /// Gets the methods that were found, grouped by their declaring type.
    /// This list does not include extension methods.
    /// Base types come first in the list.
    /// </summary>
    public IEnumerable<MethodListWithDeclaringType> MethodsGroupedByDeclaringType {
      get { return methodLists; }
    }
    
    /// <summary>
    /// Gets the type arguments that were explicitly provided.
    /// </summary>
    public IList<IType> TypeArguments {
      get { return typeArguments; }
    }
    
    /// <summary>
    /// List of extension methods, used to avoid re-calculating it in ResolveInvocation() when it was already
    /// calculated by ResolveMemberAccess().
    /// </summary>
    internal List<List<IMethod>> extensionMethods;
    
    // the resolver is used to fetch extension methods on demand
    internal CSharpResolver resolver;
    
    /// <summary>
    /// Gets all candidate extension methods.
    /// Note: this includes candidates that are not eligible due to an inapplicable
    /// this argument.
    /// The candidates will only be specialized if the type arguments were provided explicitly.
    /// </summary>
    /// <remarks>
    /// The results are stored in nested lists because they are grouped by using scope.
    /// That is, for "using SomeExtensions; namespace X { using MoreExtensions; ... }",
    /// the return value will be
    /// new List {
    ///    new List { all extensions from MoreExtensions },
    ///    new List { all extensions from SomeExtensions }
    /// }
    /// </remarks>
    public IEnumerable<IEnumerable<IMethod>> GetExtensionMethods()
    {
      if (resolver != null) {
        Debug.Assert(extensionMethods == null);
        try {
          extensionMethods = resolver.GetExtensionMethods(methodName, typeArguments);
        } finally {
          resolver = null;
        }
      }
      return extensionMethods ?? Enumerable.Empty<IEnumerable<IMethod>>();
    }
    
    /// <summary>
    /// Gets the eligible extension methods.
    /// </summary>
    /// <param name="substituteInferredTypes">
    /// Specifies whether to produce a <see cref="SpecializedMethod"/>
    /// when type arguments could be inferred from <see cref="TargetType"/>.
    /// This setting is only used for inferred types and has no effect if the type parameters are
    /// specified explicitly.
    /// </param>
    /// <remarks>
    /// The results are stored in nested lists because they are grouped by using scope.
    /// That is, for "using SomeExtensions; namespace X { using MoreExtensions; ... }",
    /// the return value will be
    /// new List {
    ///    new List { all extensions from MoreExtensions },
    ///    new List { all extensions from SomeExtensions }
    /// }
    /// </remarks>
    public IEnumerable<IEnumerable<IMethod>> GetEligibleExtensionMethods(bool substituteInferredTypes)
    {
      var result = new List<List<IMethod>>();
      foreach (var methodGroup in GetExtensionMethods()) {
        var outputGroup = new List<IMethod>();
        foreach (var method in methodGroup) {
          IType[] inferredTypes;
          if (CSharpResolver.IsEligibleExtensionMethod(this.TargetType, method, true, out inferredTypes)) {
            if (substituteInferredTypes && inferredTypes != null) {
              outputGroup.Add(method.Specialize(new TypeParameterSubstitution(null, inferredTypes)));
            } else {
              outputGroup.Add(method);
            }
          }
        }
        if (outputGroup.Count > 0)
          result.Add(outputGroup);
      }
      return result;
    }
    
    public override string ToString()
    {
      return string.Format("[{0} with {1} method(s)]", GetType().Name, this.Methods.Count());
    }
    
    public OverloadResolution PerformOverloadResolution(ICompilation compilation, ResolveResult[] arguments, string[] argumentNames = null,
                                                        bool allowExtensionMethods = true,
                                                        bool allowExpandingParams = true, 
                                                        bool allowOptionalParameters = true,
                                                        bool checkForOverflow = false, CSharpConversions conversions = null)
    {
      Log.WriteLine("Performing overload resolution for " + this);
      Log.WriteCollection("  Arguments: ", arguments);
      
      var typeArgumentArray = this.TypeArguments.ToArray();
      OverloadResolution or = new OverloadResolution(compilation, arguments, argumentNames, typeArgumentArray, conversions);
      or.AllowExpandingParams = allowExpandingParams;
      or.AllowOptionalParameters = allowOptionalParameters;
      or.CheckForOverflow = checkForOverflow;
      
      or.AddMethodLists(methodLists);
      
      if (allowExtensionMethods && !or.FoundApplicableCandidate) {
        // No applicable match found, so let's try extension methods.
        
        var extensionMethods = this.GetExtensionMethods();
        
        if (extensionMethods.Any()) {
          Log.WriteLine("No candidate is applicable, trying {0} extension methods groups...", extensionMethods.Count());
          ResolveResult[] extArguments = new ResolveResult[arguments.Length + 1];
          extArguments[0] = new ResolveResult(this.TargetType);
          arguments.CopyTo(extArguments, 1);
          string[] extArgumentNames = null;
          if (argumentNames != null) {
            extArgumentNames = new string[argumentNames.Length + 1];
            argumentNames.CopyTo(extArgumentNames, 1);
          }
          var extOr = new OverloadResolution(compilation, extArguments, extArgumentNames, typeArgumentArray, conversions);
          extOr.AllowExpandingParams = allowExpandingParams;
          extOr.AllowOptionalParameters = allowOptionalParameters;
          extOr.IsExtensionMethodInvocation = true;
          extOr.CheckForOverflow = checkForOverflow;
          
          foreach (var g in extensionMethods) {
            foreach (var method in g) {
              Log.Indent();
              OverloadResolutionErrors errors = extOr.AddCandidate(method);
              Log.Unindent();
              or.LogCandidateAddingResult("  Extension", method, errors);
            }
            if (extOr.FoundApplicableCandidate)
              break;
          }
          // For the lack of a better comparison function (the one within OverloadResolution
          // cannot be used as it depends on the argument set):
          if (extOr.FoundApplicableCandidate || or.BestCandidate == null) {
            // Consider an extension method result better than the normal result only
            // if it's applicable; or if there is no normal result.
            or = extOr;
          }
        }
      }
      Log.WriteLine("Overload resolution finished, best candidate is {0}.", or.GetBestCandidateWithSubstitutedTypeArguments());
      return or;
    }
    
    public override IEnumerable<ResolveResult> GetChildResults()
    {
      if (targetResult != null)
        return new[] { targetResult };
      else
        return Enumerable.Empty<ResolveResult>();
    }
  }
}