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                 class StringCultureComparer: StringComparer
  43                 {
  44                         CompareOptions co;
  45                         CompareInfo ci;
  46
  47                         public StringCultureComparer (CultureInfo ci, bool ignore_case)
  48                         {
  49                                 this.ci = ci.CompareInfo;
  50                                 co = ignore_case ? CompareOptions.IgnoreCase : CompareOptions.None;
  51                         }
  52
  53                         public override int Compare (string x, string y)
  54                         {
  55                                 return ci.Compare (x, y, co);
  56                         }
  57
  58                         public override bool Equals (string x, string y)
  59                         {
  60                                 return Compare (x, y) == 0;
  61                         }
  62
  63                         public override int GetHashCode (string s)
  64                         {
  65                                 if (s == null)
  66                                         throw new ArgumentNullException("s");
  67
  68                                 return ci.GetSortKey (s, co).GetHashCode ();
  69                         }
  70                 }
  71
  72                 class OrdinalComparer : StringComparer
  73                 {
  74                         public OrdinalComparer ()
  75                         {
  76                         }
  77
  78                         public override int Compare (string x, string y)
  79                         {
  80                                 return String.CompareOrdinal (x, y);
  81                         }
  82
  83                         public override bool Equals (string x, string y)
  84                         {
  85                                 return x == y;
  86                         }
  87
  88                         public override int GetHashCode (string s)
  89                         {
  90                                 return s.GetHashCode ();
  91                         }
  92                 }
  93
  94                 class OrdinalIgnoreCaseComparer : StringComparer
  95                 {
  96                         public OrdinalIgnoreCaseComparer ()
  97                         {
  98                         }
  99
 100                         public override int Compare (string x, string y)
 101                         {
 102                                 // copied from String.CompareOrdinal()
 103                                 if (x == null) {
 104                                         if (y == null)
 105                                                 return 0;
 106                                         else
 107                                                 return -1;
 108                                 }
 109                                 else if (y == null) {
 110                                         return 1;
 111                                 }
 112
 113                                 int max = x.Length > y.Length ? y.Length : x.Length;
 114                                 for (int i = 0; i < max; i++) {
 115                                         if (x [i] == y [i])
 116                                                 continue;
 117                                         char xc = Char.ToUpperInvariant (x [i]);
 118                                         char yc = Char.ToUpperInvariant (y [i]);
 119                                         if (xc != yc)
 120                                                 return xc - yc;
 121                                 }
 122                                 return max < x.Length ? -1 :
 123                                         max == y.Length ? 0 : 1;
 124                         }
 125
 126                         public override bool Equals (string x, string y)
 127                         {
 128                                 return Compare (x, y) != 0;
 129                         }
 130
 131                         public override int GetHashCode (string s)
 132                         {
 133                                 return s.ToUpperInvariant ().GetHashCode ();
 134                         }
 135                 }
 136
 137                 static StringComparer invariantCultureIgnoreCase = new StringCultureComparer (CultureInfo.InvariantCulture, true);
 138                 static StringComparer invariantCulture = new StringCultureComparer (CultureInfo.InvariantCulture, false);
 139                 static StringComparer ordinalIgnoreCase =
 140                         new OrdinalIgnoreCaseComparer ();
 141                 static StringComparer ordinal = new OrdinalComparer ();
 142
 143                 // Constructors
 144                 protected StringComparer ()
 145                 {
 146                 }
 147
 148                 // Properties
 149                 public static StringComparer CurrentCulture {
 150                         get {
 151                                 return new StringCultureComparer (CultureInfo.CurrentCulture, false);
 152                         }
 153                 }
 154
 155                 public static StringComparer CurrentCultureIgnoreCase {
 156                         get {
 157                                 return new StringCultureComparer (CultureInfo.CurrentCulture, true);
 158                         }
 159                 }
 160
 161                 public static StringComparer InvariantCulture {
 162                         get {
 163                                 return invariantCulture;
 164                         }
 165                 }
 166
 167                 public static StringComparer InvariantCultureIgnoreCase {
 168                         get {
 169                                 return invariantCultureIgnoreCase;
 170                         }
 171                 }
 172
 173                 public static StringComparer Ordinal {
 174                         get { return ordinal; }
 175                 }
 176
 177                 public static StringComparer OrdinalIgnoreCase {
 178                         get { return ordinalIgnoreCase; }
 179                 }
 180
 181                 // Methods
 182                 public static StringComparer Create (CultureInfo culture, bool ignoreCase)
 183                 {
 184                         return new StringCultureComparer (culture, ignoreCase);
 185                 }
 186
 187                 public int Compare (object x, object y)
 188                 {
 189                         if (x == y)
 190                                 return 0;
 191                         if (x == null)
 192                                 return -1;
 193                         if (y == null)
 194                                 return 1;
 195
 196                         string s_x = x as string;
 197                         if (s_x != null) {
 198                                 string s_y = y as string;
 199                                 if (s_y != null)
 200                                         return Compare (s_x, s_y);
 201                         }
 202
 203                         IComparable ic = x as IComparable;
 204                         if (ic == null)
 205                                 throw new ArgumentException ();
 206
 207                         return ic.CompareTo (y);
 208                 }
 209
 210                 public new bool Equals (object x, object y)
 211                 {
 212                         if (x == y)
 213                                 return true;
 214                         if (x == null || y == null)
 215                                 return false;
 216
 217                         string s_x = x as string;
 218                         if (s_x != null) {
 219                                 string s_y = y as string;
 220                                 if (s_y != null)
 221                                         return Equals (s_x, s_y);
 222                         }
 223                         return x.Equals (y);
 224                 }
 225
 226                 public int GetHashCode (object o)
 227                 {
 228                         if (o == null)
 229                                 throw new ArgumentNullException("o");
 230
 231                         string s = o as string;
 232                         return s == null ? o.GetHashCode (): GetHashCode(s);
 233                 }
 234
 235                 public abstract int Compare (string x, string y);
 236                 public abstract bool Equals (string x, string y);
 237                 public abstract int GetHashCode (string s);
 238         }
 239 }
 240
 241 #endif