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

   1 //\r
   2 // System.Collections.CaseInsensitiveHashCodeProvider\r
   3 //\r
   4 // Author:\r
   5 //   Sergey Chaban (serge@wildwestsoftware.com)\r
   6 //\r
   7 \r
   8 \r
   9 \r
  10 using System;\r
  11 using System.Collections;\r
  12 \r
  13 \r
  14 \r
  15 namespace System.Collections {\r
  16 \r
  17         [Serializable]\r
  18         public class CaseInsensitiveHashCodeProvider : IHashCodeProvider {\r
  19 \r
  20                 private static CaseInsensitiveHashCodeProvider singleton;\r
  21 \r
  22 \r
  23                 // Class constructor\r
  24 \r
  25                 static CaseInsensitiveHashCodeProvider ()\r
  26                 {\r
  27                         singleton=new CaseInsensitiveHashCodeProvider ();\r
  28                 }\r
  29 \r
  30 \r
  31 \r
  32                 // Public instance constructor\r
  33 \r
  34                 public CaseInsensitiveHashCodeProvider ()\r
  35                 {\r
  36                 }\r
  37 \r
  38 \r
  39 \r
  40                 //\r
  41                 // Public static properties\r
  42                 //\r
  43 \r
  44                 public static CaseInsensitiveHashCodeProvider Default {\r
  45                         get {\r
  46                                 return singleton;\r
  47                         }\r
  48                 }\r
  49 \r
  50 \r
  51                 //\r
  52                 // Instance methods\r
  53                 //\r
  54 \r
  55                 //\r
  56                 // IHashCodeProvider\r
  57                 //\r
  58 \r
  59                 [MonoTODO]\r
  60                 public int GetHashCode (object obj)\r
  61                 {\r
  62                         if (obj == null) {\r
  63                                 throw new ArgumentNullException ("obj is null");\r
  64                         }\r
  65 \r
  66                         string str = obj as string;\r
  67 \r
  68                         if (str == null) {\r
  69                                 // FIXME:\r
  70                                 return 0;\r
  71                         }\r
  72 \r
  73                         int h = 0;\r
  74                         char c;\r
  75 \r
  76                         if (str.Length > 0) {\r
  77                                 for (int i = 0;i<str.Length;i++) {\r
  78                                         c = str [i];\r
  79 \r
  80                                         if (Char.IsLetter (c))\r
  81                                                 c = Char.ToLower (c);\r
  82 \r
  83                                         h = h * 31 + c;\r
  84                                 }\r
  85                         }\r
  86 \r
  87                         return h;\r
  88                 }\r
  89 \r
  90         } // CaseInsensitiveHashCodeProvider\r
  91 }\r
  92 \r