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

   1 //
   2 // System.Collections.CaseInsensitiveComparer.cs
   3 //
   4 // Authors:
   5 //   Sergey Chaban (serge@wildwestsoftware.com)
   6 //   Eduardo Garcia Cebollero (kiwnix@yahoo.es)
   7 //   Andreas Nahr (ClassDevelopment@A-SoftTech.com)
   8 //
   9
  10 using System.Globalization;
  11
  12 namespace System.Collections
  13 {
  14         [Serializable]
  15         public class CaseInsensitiveComparer : IComparer
  16         {
  17                 private static CaseInsensitiveComparer defaultComparer = new CaseInsensitiveComparer ();
  18                 private static CaseInsensitiveComparer defaultInvariantComparer = new CaseInsensitiveComparer (true);
  19
  20                 private CultureInfo culture;
  21
  22                 // Public instance constructor
  23                 public CaseInsensitiveComparer ()
  24                 {
  25                         //LAMESPEC: This seems to be encoded while the object is created while Comparer does this at runtime.
  26                         culture = CultureInfo.CurrentCulture;
  27                 }
  28
  29                 private CaseInsensitiveComparer (bool invariant)
  30                 {
  31                         // leave culture == null
  32                 }
  33
  34                 public CaseInsensitiveComparer (CultureInfo culture)
  35                 {
  36                         if (culture == null)
  37                                 throw new ArgumentNullException ("culture");
  38
  39                         if (culture.LCID != CultureInfo.InvariantCulture.LCID)
  40                                 this.culture = culture;
  41                         // else leave culture == null
  42                 }
  43
  44                 //
  45                 // Public static properties
  46                 //
  47                 public static CaseInsensitiveComparer Default {
  48                         get {
  49                                 return defaultComparer;
  50                         }
  51                 }
  52
  53 #if NET_1_1
  54                 public
  55 #else
  56                 internal
  57 #endif
  58                 static CaseInsensitiveComparer DefaultInvariant {
  59                         get {
  60                                 return defaultInvariantComparer;
  61                         }
  62                 }
  63
  64                 //
  65                 // IComparer
  66                 //
  67                 public int Compare (object a, object b)
  68                 {
  69                         string sa = a as string;
  70                         string sb = b as string;
  71
  72                         if ((sa != null) && (sb != null)) {
  73                                 if (culture != null)
  74                                         return culture.CompareInfo.Compare (sa, sb, CompareOptions.IgnoreCase);
  75                                 else
  76                                         // FIXME: We should call directly into an invariant compare once available in string
  77                                         return CultureInfo.InvariantCulture.CompareInfo.Compare (sa, sb, CompareOptions.IgnoreCase);
  78                         }
  79                         else
  80                                 return Comparer.Default.Compare (a, b);
  81                 }
  82         }
  83 }