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 #if NET_2_0
  31
  32 using System.Collections;
  33 using System.Globalization;
  34 using System.Runtime.InteropServices;
  35 using System.Collections.Generic;
  36
  37 namespace System
  38 {
  39         [Serializable, ComVisible(true)]
  40         public abstract class StringComparer : IComparer, IEqualityComparer, IComparer<string>, IEqualityComparer<string>
  41         {
  42                 static StringComparer invariantCultureIgnoreCase = new CultureAwareComparer (CultureInfo.InvariantCulture, true);
  43                 static StringComparer invariantCulture = new CultureAwareComparer (CultureInfo.InvariantCulture, false);
  44                 static StringComparer ordinalIgnoreCase = new OrdinalComparer (true);
  45                 static StringComparer ordinal = new OrdinalComparer (false);
  46
  47                 // Constructors
  48                 protected StringComparer ()
  49                 {
  50                 }
  51
  52                 // Properties
  53                 public static StringComparer CurrentCulture {
  54                         get {
  55                                 return new CultureAwareComparer (CultureInfo.CurrentCulture, false);
  56                         }
  57                 }
  58
  59                 public static StringComparer CurrentCultureIgnoreCase {
  60                         get {
  61                                 return new CultureAwareComparer (CultureInfo.CurrentCulture, true);
  62                         }
  63                 }
  64
  65                 public static StringComparer InvariantCulture {
  66                         get {
  67                                 return invariantCulture;
  68                         }
  69                 }
  70
  71                 public static StringComparer InvariantCultureIgnoreCase {
  72                         get {
  73                                 return invariantCultureIgnoreCase;
  74                         }
  75                 }
  76
  77                 public static StringComparer Ordinal {
  78                         get { return ordinal; }
  79                 }
  80
  81                 public static StringComparer OrdinalIgnoreCase {
  82                         get { return ordinalIgnoreCase; }
  83                 }
  84
  85                 // Methods
  86                 public static StringComparer Create (CultureInfo culture, bool ignoreCase)
  87                 {
  88                         return new CultureAwareComparer (culture, ignoreCase);
  89                 }
  90
  91                 public int Compare (object x, object y)
  92                 {
  93                         if (x == y)
  94                                 return 0;
  95                         if (x == null)
  96                                 return -1;
  97                         if (y == null)
  98                                 return 1;
  99
 100                         string s_x = x as string;
 101                         if (s_x != null) {
 102                                 string s_y = y as string;
 103                                 if (s_y != null)
 104                                         return Compare (s_x, s_y);
 105                         }
 106
 107                         IComparable ic = x as IComparable;
 108                         if (ic == null)
 109                                 throw new ArgumentException ();
 110
 111                         return ic.CompareTo (y);
 112                 }
 113
 114                 public new bool Equals (object x, object y)
 115                 {
 116                         if (x == y)
 117                                 return true;
 118                         if (x == null || y == null)
 119                                 return false;
 120
 121                         string s_x = x as string;
 122                         if (s_x != null) {
 123                                 string s_y = y as string;
 124                                 if (s_y != null)
 125                                         return Equals (s_x, s_y);
 126                         }
 127                         return x.Equals (y);
 128                 }
 129
 130                 public int GetHashCode (object o)
 131                 {
 132                         if (o == null)
 133                                 throw new ArgumentNullException("o");
 134
 135                         string s = o as string;
 136                         return s == null ? o.GetHashCode (): GetHashCode(s);
 137                 }
 138
 139                 public abstract int Compare (string x, string y);
 140                 public abstract bool Equals (string x, string y);
 141                 public abstract int GetHashCode (string s);
 142         }
 143
 144         [Serializable]
 145         class CultureAwareComparer : StringComparer
 146         {
 147                 readonly bool _ignoreCase;
 148                 readonly CompareInfo _compareInfo;
 149
 150                 public CultureAwareComparer (CultureInfo ci, bool ignore_case)
 151                 {
 152                         _compareInfo = ci.CompareInfo;
 153                         _ignoreCase = ignore_case;
 154                 }
 155
 156                 public override int Compare (string x, string y)
 157                 {
 158                         CompareOptions co = _ignoreCase ? CompareOptions.IgnoreCase :
 159                                 CompareOptions.None;
 160                         return _compareInfo.Compare (x, y, co);
 161                 }
 162
 163                 public override bool Equals (string x, string y)
 164                 {
 165                         return Compare (x, y) == 0;
 166                 }
 167
 168                 public override int GetHashCode (string s)
 169                 {
 170                         if (s == null)
 171                                 throw new ArgumentNullException("s");
 172
 173                         CompareOptions co = _ignoreCase ? CompareOptions.IgnoreCase :
 174                                 CompareOptions.None;
 175                         return _compareInfo.GetSortKey (s, co).GetHashCode ();
 176                 }
 177         }
 178
 179         [Serializable]
 180         internal class OrdinalComparer : StringComparer
 181         {
 182                 public OrdinalComparer (bool ignoreCase)
 183                 {
 184                         _ignoreCase = ignoreCase;
 185                 }
 186
 187                 public override int Compare (string x, string y)
 188                 {
 189                         if (!_ignoreCase)
 190                                 return String.CompareOrdinal (x, y);
 191
 192                         // copied from String.CompareOrdinal()
 193                         if (x == null) {
 194                                 if (y == null)
 195                                         return 0;
 196                                 else
 197                                         return -1;
 198                         }
 199                         else if (y == null) {
 200                                 return 1;
 201                         }
 202
 203                         int max = x.Length > y.Length ? y.Length : x.Length;
 204                         for (int i = 0; i < max; i++) {
 205                                 if (x [i] == y [i])
 206                                         continue;
 207                                 char xc = Char.ToUpperInvariant (x [i]);
 208                                 char yc = Char.ToUpperInvariant (y [i]);
 209                                 if (xc != yc)
 210                                         return xc - yc;
 211                         }
 212                         return max < x.Length ? -1 :
 213                                 max == y.Length ? 0 : 1;
 214                 }
 215
 216                 public override bool Equals (string x, string y)
 217                 {
 218                         if (!_ignoreCase)
 219                                 return x == y;
 220                         return Compare (x, y) == 0;
 221                 }
 222
 223                 public override int GetHashCode (string s)
 224                 {
 225                         if (!_ignoreCase)
 226                                 return s.GetHashCode ();
 227
 228                         return s.GetCaseInsensitiveHashCode ();
 229                 }
 230
 231                 readonly bool _ignoreCase;
 232         }
 233 }
 234
 235 #endif