mcs/class/corlib/System/StringComparer.cs

   1 //
   2 // System.StringComparer
   3 //
   4 // Authors:
   5 //      Marek Safar (marek.safar@seznam.cz)
   6 //
   7 // (C) 2005 Novell, Inc (http://www.novell.com)
   8 //
   9
  10 // Permission is hereby granted, free of charge, to any person obtaining
  11 // a copy of this software and associated documentation files (the
  12 // "Software"), to deal in the Software without restriction, including
  13 // without limitation the rights to use, copy, modify, merge, publish,
  14 // distribute, sublicense, and/or sell copies of the Software, and to
  15 // permit persons to whom the Software is furnished to do so, subject to
  16 // the following conditions:
  17 //
  18 // The above copyright notice and this permission notice shall be
  19 // included in all copies or substantial portions of the Software.
  20 //
  21 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  22 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  23 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  24 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  25 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  26 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  27 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  28 //
  29
  30 using System.Collections;
  31 using System.Globalization;
  32 using System.Runtime.InteropServices;
  33 using System.Collections.Generic;
  34
  35 namespace System
  36 {
  37         [Serializable, ComVisible(true)]
  38         public abstract class StringComparer : IComparer, IEqualityComparer, IComparer<string>, IEqualityComparer<string>
  39         {
  40                 static class Predefined
  41                 {
  42                         public static readonly StringComparer invariantCultureIgnoreCase = new CultureAwareComparer (CultureInfo.InvariantCulture, true);
  43                         public static readonly StringComparer invariantCulture = new CultureAwareComparer (CultureInfo.InvariantCulture, false);
  44                         public static readonly StringComparer ordinalIgnoreCase = new OrdinalComparer (true);
  45                         public static readonly StringComparer ordinal = new OrdinalComparer (false);
  46                 }
  47
  48                 // Constructors
  49                 protected StringComparer ()
  50                 {
  51                 }
  52
  53                 // Properties
  54                 public static StringComparer CurrentCulture {
  55                         get {
  56                                 return new CultureAwareComparer (CultureInfo.CurrentCulture, false);
  57                         }
  58                 }
  59
  60                 public static StringComparer CurrentCultureIgnoreCase {
  61                         get {
  62                                 return new CultureAwareComparer (CultureInfo.CurrentCulture, true);
  63                         }
  64                 }
  65
  66                 public static StringComparer InvariantCulture {
  67                         get {
  68                                 return Predefined.invariantCulture;
  69                         }
  70                 }
  71
  72                 public static StringComparer InvariantCultureIgnoreCase {
  73                         get {
  74                                 return Predefined.invariantCultureIgnoreCase;
  75                         }
  76                 }
  77
  78                 public static StringComparer Ordinal {
  79                         get { return Predefined.ordinal; }
  80                 }
  81
  82                 public static StringComparer OrdinalIgnoreCase {
  83                         get { return Predefined.ordinalIgnoreCase; }
  84                 }
  85
  86                 // Methods
  87                 public static StringComparer Create (CultureInfo culture, bool ignoreCase)
  88                 {
  89                         if (culture == null)
  90                                 throw new ArgumentNullException ("culture");
  91
  92                         return new CultureAwareComparer (culture, ignoreCase);
  93                 }
  94
  95                 public int Compare (object x, object y)
  96                 {
  97                         if (x == y)
  98                                 return 0;
  99                         if (x == null)
 100                                 return -1;
 101                         if (y == null)
 102                                 return 1;
 103
 104                         string s_x = x as string;
 105                         if (s_x != null) {
 106                                 string s_y = y as string;
 107                                 if (s_y != null)
 108                                         return Compare (s_x, s_y);
 109                         }
 110
 111                         IComparable ic = x as IComparable;
 112                         if (ic == null)
 113                                 throw new ArgumentException ();
 114
 115                         return ic.CompareTo (y);
 116                 }
 117
 118                 public new bool Equals (object x, object y)
 119                 {
 120                         if (x == y)
 121                                 return true;
 122                         if (x == null || y == null)
 123                                 return false;
 124
 125                         string s_x = x as string;
 126                         if (s_x != null) {
 127                                 string s_y = y as string;
 128                                 if (s_y != null)
 129                                         return Equals (s_x, s_y);
 130                         }
 131                         return x.Equals (y);
 132                 }
 133
 134                 public int GetHashCode (object obj)
 135                 {
 136                         if (obj == null)
 137                                 throw new ArgumentNullException("obj");
 138
 139                         string s = obj as string;
 140                         return s == null ? obj.GetHashCode (): GetHashCode(s);
 141                 }
 142
 143                 public abstract int Compare (string x, string y);
 144                 public abstract bool Equals (string x, string y);
 145                 public abstract int GetHashCode (string obj);
 146         }
 147
 148         [Serializable]
 149         sealed class CultureAwareComparer : StringComparer
 150         {
 151                 readonly bool _ignoreCase;
 152                 readonly CompareInfo _compareInfo;
 153
 154                 public CultureAwareComparer (CultureInfo ci, bool ignore_case)
 155                 {
 156                         _compareInfo = ci.CompareInfo;
 157                         _ignoreCase = ignore_case;
 158                 }
 159
 160                 public override int Compare (string x, string y)
 161                 {
 162                         CompareOptions co = _ignoreCase ? CompareOptions.IgnoreCase :
 163                                 CompareOptions.None;
 164                         return _compareInfo.Compare (x, y, co);
 165                 }
 166
 167                 public override bool Equals (string x, string y)
 168                 {
 169                         return Compare (x, y) == 0;
 170                 }
 171
 172                 public override int GetHashCode (string s)
 173                 {
 174                         if (s == null)
 175                                 throw new ArgumentNullException("s");
 176
 177                         CompareOptions co = _ignoreCase ? CompareOptions.IgnoreCase :
 178                                 CompareOptions.None;
 179                         return _compareInfo.GetSortKey (s, co).GetHashCode ();
 180                 }
 181         }
 182
 183         [Serializable]
 184         internal sealed class OrdinalComparer : StringComparer
 185         {
 186                 readonly bool _ignoreCase;
 187
 188                 public OrdinalComparer (bool ignoreCase)
 189                 {
 190                         _ignoreCase = ignoreCase;
 191                 }
 192
 193                 public override int Compare (string x, string y)
 194                 {
 195                         if (_ignoreCase)
 196                                 return String.CompareOrdinalCaseInsensitiveUnchecked (x, 0, Int32.MaxValue, y, 0, Int32.MaxValue);
 197                         else
 198                                 return String.CompareOrdinalUnchecked (x, 0, Int32.MaxValue, y, 0, Int32.MaxValue);
 199                 }
 200
 201                 public override bool Equals (string x, string y)
 202                 {
 203                         if (_ignoreCase)
 204                                 return Compare (x, y) == 0;
 205
 206                         return x == y;
 207                 }
 208
 209                 public override int GetHashCode (string s)
 210                 {
 211                         if (s == null)
 212                                 throw new ArgumentNullException ("s");
 213
 214                         if (_ignoreCase)
 215                                 return s.GetCaseInsensitiveHashCode ();
 216                         else
 217                                 return s.GetHashCode ();
 218                 }
 219         }
 220 }