source: tags/3.3.11/HeuristicLab.ExtLibs/HeuristicLab.NRefactory/5.5.0/NRefactory-5.5.0/TypeSystem/ParameterListComparer.cs @ 13398

// Copyright (c) 2010-2013 AlphaSierraPapa for the SharpDevelop Team
// 
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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.Collections.Generic;
using System.Threading;
using ICSharpCode.NRefactory.TypeSystem.Implementation;

namespace ICSharpCode.NRefactory.TypeSystem
{
  /// <summary>
  /// Compares parameter lists by comparing the types of all parameters.
  /// </summary>
  /// <remarks>
  /// 'ref int' and 'out int' are considered to be equal.
  /// 'object' and 'dynamic' are also equal.
  /// For generic methods, "Method{T}(T a)" and "Method{S}(S b)" are considered equal.
  /// However, "Method(T a)" and "Method(S b)" are not considered equal when the type parameters T and S belong to classes.
  /// </remarks>
  public sealed class ParameterListComparer : IEqualityComparer<IList<IParameter>>
  {
    public static readonly ParameterListComparer Instance = new ParameterListComparer();
    
    sealed class NormalizeTypeVisitor : TypeVisitor
    {
      public override IType VisitTypeParameter(ITypeParameter type)
      {
        if (type.OwnerType == SymbolKind.Method) {
          return DummyTypeParameter.GetMethodTypeParameter(type.Index);
        } else {
          return base.VisitTypeParameter(type);
        }
      }
      
      public override IType VisitTypeDefinition(ITypeDefinition type)
      {
        if (type.KnownTypeCode == KnownTypeCode.Object)
          return SpecialType.Dynamic;
        return base.VisitTypeDefinition(type);
      }
    }
    
    static readonly NormalizeTypeVisitor normalizationVisitor = new NormalizeTypeVisitor();
    
    /// <summary>
    /// Replaces all occurrences of method type parameters in the given type
    /// by normalized type parameters. This allows comparing parameter types from different
    /// generic methods.
    /// </summary>
    [Obsolete("Use DummyTypeParameter.NormalizeMethodTypeParameters instead if you only need to normalize type parameters. Also, consider if you need to normalize object vs. dynamic as well.")]
    public IType NormalizeMethodTypeParameters(IType type)
    {
      return DummyTypeParameter.NormalizeMethodTypeParameters(type);
    }
    
    public bool Equals(IList<IParameter> x, IList<IParameter> y)
    {
      if (x == y)
        return true;
      if (x == null || y == null || x.Count != y.Count)
        return false;
      for (int i = 0; i < x.Count; i++) {
        var a = x[i];
        var b = y[i];
        if (a == null && b == null)
          continue;
        if (a == null || b == null)
          return false;
        
        // We want to consider the parameter lists "Method<T>(T a)" and "Method<S>(S b)" as equal.
        // However, the parameter types are not considered equal, as T is a different type parameter than S.
        // In order to compare the method signatures, we will normalize all method type parameters.
        IType aType = a.Type.AcceptVisitor(normalizationVisitor);
        IType bType = b.Type.AcceptVisitor(normalizationVisitor);
        
        if (!aType.Equals(bType))
          return false;
      }
      return true;
    }
    
    public int GetHashCode(IList<IParameter> obj)
    {
      int hashCode = obj.Count;
      unchecked {
        foreach (IParameter p in obj) {
          hashCode *= 27;
          IType type = p.Type.AcceptVisitor(normalizationVisitor);
          hashCode += type.GetHashCode();
        }
      }
      return hashCode;
    }
  }
  
  /// <summary>
  /// Compares member signatures.
  /// </summary>
  /// <remarks>
  /// This comparer checks for equal short name, equal type parameter count, and equal parameter types (using ParameterListComparer).
  /// </remarks>
  public sealed class SignatureComparer : IEqualityComparer<IMember>
  {
    StringComparer nameComparer;
    
    public SignatureComparer(StringComparer nameComparer)
    {
      if (nameComparer == null)
        throw new ArgumentNullException("nameComparer");
      this.nameComparer = nameComparer;
    }
    
    /// <summary>
    /// Gets a signature comparer that uses an ordinal comparison for the member name.
    /// </summary>
    public static readonly SignatureComparer Ordinal = new SignatureComparer(StringComparer.Ordinal);
    
    public bool Equals(IMember x, IMember y)
    {
      if (x == y)
        return true;
      if (x == null || y == null || x.SymbolKind != y.SymbolKind || !nameComparer.Equals(x.Name, y.Name))
        return false;
      IParameterizedMember px = x as IParameterizedMember;
      IParameterizedMember py = y as IParameterizedMember;
      if (px != null && py != null) {
        IMethod mx = x as IMethod;
        IMethod my = y as IMethod;
        if (mx != null && my != null && mx.TypeParameters.Count != my.TypeParameters.Count)
          return false;
        return ParameterListComparer.Instance.Equals(px.Parameters, py.Parameters);
      } else {
        return true;
      }
    }
    
    public int GetHashCode(IMember obj)
    {
      unchecked {
        int hash = (int)obj.SymbolKind * 33 + nameComparer.GetHashCode(obj.Name);
        IParameterizedMember pm = obj as IParameterizedMember;
        if (pm != null) {
          hash *= 27;
          hash += ParameterListComparer.Instance.GetHashCode(pm.Parameters);
          IMethod m = pm as IMethod;
          if (m != null)
            hash += m.TypeParameters.Count;
        }
        return hash;
      }
    }
  }
}