mcs/tests/gtest-197.cs

   1 using System;
   2 using System.Runtime.InteropServices;
   3
   4 namespace Martin.Collections.Generic {
   5         [Serializable]
   6         public abstract class EqualityComparer <T> : IEqualityComparer <T> {
   7
   8                 static EqualityComparer ()
   9                 {
  10                         if (typeof (IEquatable <T>).IsAssignableFrom (typeof (T)))
  11                                 _default = (EqualityComparer <T>) Activator.CreateInstance (typeof (IEquatableOfTEqualityComparer<>).MakeGenericType (typeof (T)));
  12                         else
  13                                 _default = new DefaultComparer ();
  14                 }
  15
  16
  17                 public abstract int GetHashCode (T obj);
  18                 public abstract bool Equals (T x, T y);
  19
  20                 static readonly EqualityComparer <T> _default;
  21
  22                 public static EqualityComparer <T> Default {
  23                         get {
  24                                 return _default;
  25                         }
  26                 }
  27
  28                 [Serializable]
  29                 class DefaultComparer : EqualityComparer<T> {
  30
  31                         public override int GetHashCode (T obj)
  32                         {
  33                                 return obj.GetHashCode ();
  34                         }
  35
  36                         public override bool Equals (T x, T y)
  37                         {
  38                                 if (x == null)
  39                                         return y == null;
  40
  41                                 return x.Equals (y);
  42                         }
  43                 }
  44         }
  45
  46         [Serializable]
  47         class IEquatableOfTEqualityComparer <T> : EqualityComparer <T> where T : IEquatable <T> {
  48
  49                 public override int GetHashCode (T obj)
  50                 {
  51                         return obj.GetHashCode ();
  52                 }
  53
  54                 public override bool Equals (T x, T y)
  55                 {
  56                         if (x == null)
  57                                 return y == null;
  58
  59                         return x.Equals (y);
  60                 }
  61         }
  62
  63         public interface IEqualityComparer<T> {
  64                 bool Equals (T x, T y);
  65                 int GetHashCode (T obj);
  66         }
  67
  68         class X
  69         {
  70                 public static void Main ()
  71                 { }
  72         }
  73 }