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 //   Sebastien Pouliot  <sebastien@ximian.com>
   8 //
   9 // Copyright (C) 2004-2005 Novell, Inc (http://www.novell.com)
  10 //
  11 // Permission is hereby granted, free of charge, to any person obtaining
  12 // a copy of this software and associated documentation files (the
  13 // "Software"), to deal in the Software without restriction, including
  14 // without limitation the rights to use, copy, modify, merge, publish,
  15 // distribute, sublicense, and/or sell copies of the Software, and to
  16 // permit persons to whom the Software is furnished to do so, subject to
  17 // the following conditions:
  18 //
  19 // The above copyright notice and this permission notice shall be
  20 // included in all copies or substantial portions of the Software.
  21 //
  22 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  23 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  24 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  25 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  26 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  27 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  28 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  29 //
  30
  31 using System.Globalization;
  32 using System.Runtime.InteropServices;
  33
  34 namespace System.Collections
  35 {
  36         [Serializable]
  37 #if NET_2_0
  38         [ComVisible(true)]
  39         [Obsolete ("Please use StringComparer instead.")]
  40 #endif
  41         public class CaseInsensitiveHashCodeProvider : IHashCodeProvider
  42         {
  43                 static readonly CaseInsensitiveHashCodeProvider singleton = new CaseInsensitiveHashCodeProvider ();
  44                 static readonly CaseInsensitiveHashCodeProvider singletonInvariant = new CaseInsensitiveHashCodeProvider (true);
  45
  46                 TextInfo m_text; // must match MS name for serialization
  47
  48                 // Public instance constructor
  49                 public CaseInsensitiveHashCodeProvider ()
  50                 {
  51                         m_text = CultureInfo.CurrentCulture.TextInfo;
  52                 }
  53
  54                 private CaseInsensitiveHashCodeProvider (bool invariant)
  55                 {
  56                         // leave m_text == null
  57                 }
  58
  59                 public CaseInsensitiveHashCodeProvider (CultureInfo culture)
  60                 {
  61                         if (culture == null)
  62                                 throw new ArgumentNullException ("culture");
  63                         if (culture.LCID != CultureInfo.InvariantCulture.LCID)
  64                                 m_text = culture.TextInfo;
  65                         // else leave m_text == null
  66                 }
  67
  68                 //
  69                 // Public static properties
  70                 //
  71
  72                 public static CaseInsensitiveHashCodeProvider Default {
  73                         get {
  74                                 return singleton;
  75                         }
  76                 }
  77
  78 #if NET_1_1
  79                 public
  80 #else
  81                 internal
  82 #endif
  83                 static CaseInsensitiveHashCodeProvider DefaultInvariant {
  84                         get {
  85                                 return singletonInvariant;
  86                         }
  87                 }
  88
  89                 //
  90                 // IHashCodeProvider
  91                 //
  92
  93                 public int GetHashCode (object obj)
  94                 {
  95                         if (obj == null)
  96                                 throw new ArgumentNullException ("obj");
  97
  98                         string str = obj as string;
  99
 100                         if (str == null)
 101                                 return obj.GetHashCode ();
 102
 103                         int h = 0;
 104                         char c;
 105
 106                         if ((m_text != null) && (m_text.LCID != CultureInfo.InvariantCulture.LCID)) {
 107                                 str = m_text.ToLower (str);
 108                                 for (int i = 0; i < str.Length; i++) {
 109                                         c = str [i];
 110                                         h = h * 31 + c;
 111                                 }
 112                         } else {
 113                                 for (int i = 0; i < str.Length; i++) {
 114                                         c = Char.ToLowerInvariant (str [i]);
 115                                         h = h * 31 + c;
 116                                 }
 117                         }
 118                         return h;
 119                 }
 120         }
 121 }