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

   1 //
   2 // System.Collections.CaseInsensitiveHashCodeProvider.cs
   3 //
   4 // Authors:
   5 //   Sergey Chaban (serge@wildwestsoftware.com)
   6 //   Andreas Nahr (ClassDevelopment@A-SoftTech.com)
   7 //
   8
   9 //
  10 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
  11 //
  12 // Permission is hereby granted, free of charge, to any person obtaining
  13 // a copy of this software and associated documentation files (the
  14 // "Software"), to deal in the Software without restriction, including
  15 // without limitation the rights to use, copy, modify, merge, publish,
  16 // distribute, sublicense, and/or sell copies of the Software, and to
  17 // permit persons to whom the Software is furnished to do so, subject to
  18 // the following conditions:
  19 //
  20 // The above copyright notice and this permission notice shall be
  21 // included in all copies or substantial portions of the Software.
  22 //
  23 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  24 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  25 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  26 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  27 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  28 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  29 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  30 //
  31
  32 using System.Globalization;
  33
  34 namespace System.Collections
  35 {
  36         [Serializable]
  37         [MonoTODO ("Fix serialization compatibility with MS.NET")]
  38         public class CaseInsensitiveHashCodeProvider : IHashCodeProvider
  39         {
  40                 static readonly CaseInsensitiveHashCodeProvider singleton = new CaseInsensitiveHashCodeProvider ();
  41                 static readonly CaseInsensitiveHashCodeProvider singletonInvariant = new CaseInsensitiveHashCodeProvider (true);
  42
  43                 CultureInfo culture;
  44
  45                 // Public instance constructor
  46                 public CaseInsensitiveHashCodeProvider ()
  47                 {
  48                         culture = CultureInfo.CurrentCulture;
  49                 }
  50
  51                 private CaseInsensitiveHashCodeProvider (bool invariant)
  52                 {
  53                         // leave culture == null
  54                 }
  55
  56                 public CaseInsensitiveHashCodeProvider (CultureInfo culture)
  57                 {
  58                         if (culture == null)
  59                                 throw new ArgumentNullException ("culture");
  60                         if (culture.LCID != CultureInfo.InvariantCulture.LCID)
  61                                 this.culture = culture;
  62                         // else leave culture == null
  63                 }
  64
  65                 //
  66                 // Public static properties
  67                 //
  68
  69                 public static CaseInsensitiveHashCodeProvider Default {
  70                         get {
  71                                 return singleton;
  72                         }
  73                 }
  74
  75 #if NET_1_1
  76                 public
  77 #else
  78                 internal
  79 #endif
  80                 static CaseInsensitiveHashCodeProvider DefaultInvariant {
  81                         get {
  82                                 return singletonInvariant;
  83                         }
  84                 }
  85
  86                 //
  87                 // IHashCodeProvider
  88                 //
  89
  90                 public int GetHashCode (object obj)
  91                 {
  92                         if (obj == null)
  93                                 throw new ArgumentNullException ("obj");
  94
  95                         string str = obj as string;
  96
  97                         if (str == null)
  98                                 return obj.GetHashCode ();
  99
 100                         int h = 0;
 101                         char c;
 102
 103                         if (culture != null && culture.LCID != CultureInfo.InvariantCulture.LCID) {
 104                                 str = str.ToLower (culture);
 105                                 for (int i = 0; i < str.Length; i++) {
 106                                         c = str [i];
 107                                         h = h * 31 + c;
 108                                 }
 109                         }
 110                         else {
 111                                 for (int i = 0; i < str.Length; i++) {
 112                                         c = Char.ToLowerInvariant (str [i]);
 113                                         h = h * 31 + c;
 114                                 }
 115                         }
 116                         return h;
 117                 }
 118         }
 119 }