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using System; | |
using System.Collections.Generic; | |
public class CharacterComparer : IEqualityComparer<char>, IEqualityComparer<string> | |
{ | |
public static readonly CharacterComparer Ordinal = new CharacterComparer(StringComparer.Ordinal); | |
public static readonly CharacterComparer OrdinalIgnoreCase = new CharacterComparer(StringComparer.OrdinalIgnoreCase); | |
public static readonly CharacterComparer CurrentCulture = new CharacterComparer(StringComparer.CurrentCulture); | |
public static readonly CharacterComparer CurrentCultureIgnoreCase = new CharacterComparer(StringComparer.CurrentCultureIgnoreCase); | |
public static readonly CharacterComparer InvariantCulture = new CharacterComparer(StringComparer.InvariantCulture); | |
public static readonly CharacterComparer InvariantCultureIgnoreCase = new CharacterComparer(StringComparer.InvariantCultureIgnoreCase); | |
private readonly IEqualityComparer<char> _charComparer; | |
private readonly IEqualityComparer<string> _stringComparer; | |
public CharacterComparer(IEqualityComparer<string> stringComparer) | |
{ | |
if (stringComparer == null) throw new ArgumentNullException("stringComparer"); | |
var wrappingComparer = stringComparer as CharacterComparer; | |
if (wrappingComparer != null) | |
{ | |
_stringComparer = wrappingComparer._stringComparer; | |
_charComparer = wrappingComparer._charComparer; | |
} | |
else | |
{ | |
_stringComparer = stringComparer; | |
_charComparer = stringComparer as IEqualityComparer<char>; | |
} | |
} | |
public CharacterComparer(IEqualityComparer<char> charComparer) | |
{ | |
if (charComparer == null) throw new ArgumentNullException("charComparer"); | |
var wrappingComparer = charComparer as CharacterComparer; | |
if (wrappingComparer != null) | |
{ | |
_stringComparer = wrappingComparer._stringComparer; | |
_charComparer = wrappingComparer._charComparer; | |
} | |
else | |
{ | |
_charComparer = charComparer; | |
_stringComparer = charComparer as IEqualityComparer<string>; | |
} | |
} | |
public bool Equals(char x, char y) | |
{ | |
if (_charComparer != null) | |
return _charComparer.Equals(x, y); | |
var s1 = x.ToString(); | |
var s2 = y.ToString(); | |
return _stringComparer.Equals(s1, s2); | |
} | |
public int GetHashCode(char c) | |
{ | |
if (_charComparer != null) | |
return _charComparer.GetHashCode(c); | |
var s = c.ToString(); | |
return _stringComparer.GetHashCode(s); | |
} | |
public bool Equals(string x, string y) | |
{ | |
if (_stringComparer != null) | |
return _stringComparer.Equals(x, y); | |
if (ReferenceEquals(x, y)) return true; | |
if (ReferenceEquals(x, null)) return false; | |
if (ReferenceEquals(y, null)) return false; | |
if (x.Length != y.Length) return false; | |
var it1 = x.GetEnumerator(); | |
var it2 = y.GetEnumerator(); | |
while (true) | |
{ | |
var m1 = it1.MoveNext(); | |
var m2 = it2.MoveNext(); | |
if (m1 ^ m2) | |
// should not be possible because of length check above | |
return false; | |
if (!m1) | |
return true; | |
if (!_charComparer.Equals(it1.Current, it2.Current)) | |
return false; | |
} | |
} | |
public int GetHashCode(string s) | |
{ | |
if (_stringComparer != null) | |
return _stringComparer.GetHashCode(s); | |
unchecked | |
{ | |
var it = s.GetEnumerator(); | |
if (!it.MoveNext()) | |
return _charComparer.GetHashCode(default(char)); | |
var hashCode = _charComparer.GetHashCode(it.Current); | |
while (it.MoveNext()) | |
hashCode = (hashCode * 397) ^ _charComparer.GetHashCode(it.Current); | |
return hashCode; | |
} | |
} | |
} |
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