mcs/class/corlib/System.Collections/Comparer.cs

   1 //
   2 // System.Collections.Comparer.cs
   3 //
   4 // Author:
   5 //   Sergey Chaban (serge@wildwestsoftware.com)
   6 //
   7
   8 using System.Globalization;
   9
  10 namespace System.Collections
  11 {
  12         [Serializable]
  13         public sealed class Comparer : IComparer
  14         {
  15                 public static readonly Comparer Default = new Comparer ();
  16 #if NET_1_1
  17                 public
  18 #else
  19                 internal
  20 #endif
  21                 static readonly Comparer DefaultInvariant = new Comparer (CultureInfo.InvariantCulture);
  22
  23                 CultureInfo _culture;
  24
  25                 private Comparer ()
  26                 {
  27                         //LAMESPEC: This seems to be encoded at runtime while CaseInsensitiveComparer does at creation
  28                 }
  29
  30 #if NET_1_1
  31                 public
  32 #else
  33                 internal
  34 #endif
  35                 Comparer (CultureInfo culture)
  36                 {
  37                         if (culture == null)
  38                                 throw new ArgumentNullException ("culture");
  39
  40                         _culture = culture;
  41                 }
  42
  43
  44                 // IComparer
  45                 public int Compare (object a, object b)
  46                 {
  47                         if (a == b)
  48                                 return 0;
  49                         else if (a == null)
  50                                 return -1;
  51                         else if (b == null)
  52                                 return 1;
  53
  54                         if (_culture != null) {
  55                                 string sa = a as string;
  56                                 string sb = b as string;
  57                                 if (sa != null && sb != null)
  58                                         return _culture.CompareInfo.Compare (sa, sb);
  59                         }
  60
  61                         if (a is IComparable)
  62                                 return (a as IComparable).CompareTo (b);
  63                         else if (b is IComparable)
  64                                 return -(b as IComparable).CompareTo (a);
  65
  66                         throw new ArgumentException (Locale.GetText ("Neither a nor b Comparable."));
  67                 }
  68         }
  69 }