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 /*
  * Copyright (C) 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  *
  */
 
 #ifndef WTF_HashTraits_h
 #define WTF_HashTraits_h
 
 #include <wtf/Assertions.h>
 #include <wtf/HashFunctions.h>
 #include <utility>
 #include <limits>
 
 namespace WTF
 {
 
 using std::pair;
 using std::make_pair;
 
 template<typename T> struct IsInteger           {
     static const bool value = false;
 };
 template<> struct IsInteger<bool>               {
     static const bool value = true;
 };
 template<> struct IsInteger<char>               {
     static const bool value = true;
 };
 template<> struct IsInteger<signed char>        {
     static const bool value = true;
 };
 template<> struct IsInteger<unsigned char>      {
     static const bool value = true;
 };
 template<> struct IsInteger<short>              {
     static const bool value = true;
 };
 template<> struct IsInteger<unsigned short>     {
     static const bool value = true;
 };
 template<> struct IsInteger<int>                {
     static const bool value = true;
 };
 template<> struct IsInteger<unsigned int>       {
     static const bool value = true;
 };
 template<> struct IsInteger<long>               {
     static const bool value = true;
 };
 template<> struct IsInteger<unsigned long>      {
     static const bool value = true;
 };
 template<> struct IsInteger<long long>          {
     static const bool value = true;
 };
 template<> struct IsInteger<unsigned long long> {
     static const bool value = true;
 };
 
 #if !defined(WTF_COMPILER_MSVC) || defined(_NATIVE_WCHAR_T_DEFINED)
 template<> struct IsInteger<wchar_t>            {
     static const bool value = true;
 };
 #endif
 
 COMPILE_ASSERT(IsInteger<bool>::value, WTF_IsInteger_bool_true)
 COMPILE_ASSERT(IsInteger<char>::value, WTF_IsInteger_char_true)
 COMPILE_ASSERT(IsInteger<signed char>::value, WTF_IsInteger_signed_char_true)
 COMPILE_ASSERT(IsInteger<unsigned char>::value, WTF_IsInteger_unsigned_char_true)
 COMPILE_ASSERT(IsInteger<short>::value, WTF_IsInteger_short_true)
 COMPILE_ASSERT(IsInteger<unsigned short>::value, WTF_IsInteger_unsigned_short_true)
 COMPILE_ASSERT(IsInteger<int>::value, WTF_IsInteger_int_true)
 COMPILE_ASSERT(IsInteger<unsigned int>::value, WTF_IsInteger_unsigned_int_true)
 COMPILE_ASSERT(IsInteger<long>::value, WTF_IsInteger_long_true)
 COMPILE_ASSERT(IsInteger<unsigned long>::value, WTF_IsInteger_unsigned_long_true)
 COMPILE_ASSERT(IsInteger<long long>::value, WTF_IsInteger_long_long_true)
 COMPILE_ASSERT(IsInteger<unsigned long long>::value, WTF_IsInteger_unsigned_long_long_true)
 
 #if !defined(WTF_COMPILER_MSVC) || defined(_NATIVE_WCHAR_T_DEFINED)
 COMPILE_ASSERT(IsInteger<wchar_t>::value, WTF_IsInteger_wchar_t_true)
 #endif
 
 COMPILE_ASSERT(!IsInteger<char *>::value, WTF_IsInteger_char_pointer_false)
 COMPILE_ASSERT(!IsInteger<const char * >::value, WTF_IsInteger_const_char_pointer_false)
 COMPILE_ASSERT(!IsInteger<volatile char * >::value, WTF_IsInteger_volatile_char_pointer__false)
 COMPILE_ASSERT(!IsInteger<double>::value, WTF_IsInteger_double_false)
 COMPILE_ASSERT(!IsInteger<float>::value, WTF_IsInteger_float_false)
 
 template<typename T> struct HashTraits;
 
 template<bool isInteger, typename T> struct GenericHashTraitsBase;
 
 template<typename T> struct GenericHashTraitsBase<false, T> {
     static const bool emptyValueIsZero = false;
     static const bool needsDestruction = true;
 };
 
 // default integer traits disallow both 0 and -1 as keys (max value instead of -1 for unsigned)
 template<typename T> struct GenericHashTraitsBase<true, T> {
     static const bool emptyValueIsZero = true;
     static const bool needsDestruction = false;
     static void constructDeletedValue(T *slot)
     {
         *slot = static_cast<T>(-1);
     }
     static bool isDeletedValue(T value)
     {
         return value == static_cast<T>(-1);
     }
 };
 
 template<typename T> struct GenericHashTraits : GenericHashTraitsBase<IsInteger<T>::value, T> {
     typedef T TraitType;
     static T emptyValue()
     {
         return T();
     }
 };
 
 template<typename T> struct HashTraits : GenericHashTraits<T> { };
 
 template<typename T> struct FloatHashTraits : GenericHashTraits<T> {
     static const bool needsDestruction = false;
     static T emptyValue()
     {
         return std::numeric_limits<T>::infinity();
     }
     static void constructDeletedValue(T *slot)
     {
         *slot = -std::numeric_limits<T>::infinity();
     }
     static bool isDeletedValue(T value)
     {
         return value == -std::numeric_limits<T>::infinity();
     }
 };
 
 template<> struct HashTraits<float> : FloatHashTraits<float> { };
 template<> struct HashTraits<double> : FloatHashTraits<double> { };
 
 template<typename P> struct HashTraits<P *> : GenericHashTraits<P *> {
     static const bool emptyValueIsZero = true;
     static const bool needsDestruction = false;
     static void constructDeletedValue(P **slot)
     {
         *slot = reinterpret_cast<P *>(-1);
     }
     static bool isDeletedValue(P *value)
     {
         return value == reinterpret_cast<P *>(-1);
     }
 };
 
 template<typename P> struct HashTraits<RefPtr<P> > : GenericHashTraits<RefPtr<P> > {
     static const bool emptyValueIsZero = true;
     static void constructDeletedValue(RefPtr<P> *slot)
     {
         new(slot) RefPtr<P>(HashTableDeletedValue);
     }
     static bool isDeletedValue(const RefPtr<P> &value)
     {
         return value.isHashTableDeletedValue();
     }
 };
 
 // special traits for pairs, helpful for their use in HashMap implementation
 
 template<typename FirstTraitsArg, typename SecondTraitsArg>
 struct PairHashTraits : GenericHashTraits<pair<typename FirstTraitsArg::TraitType, typename SecondTraitsArg::TraitType> > {
     typedef FirstTraitsArg FirstTraits;
     typedef SecondTraitsArg SecondTraits;
     typedef pair<typename FirstTraits::TraitType, typename SecondTraits::TraitType> TraitType;
 
     static const bool emptyValueIsZero = FirstTraits::emptyValueIsZero && SecondTraits::emptyValueIsZero;
     static TraitType emptyValue()
     {
         return make_pair(FirstTraits::emptyValue(), SecondTraits::emptyValue());
     }
 
     static const bool needsDestruction = FirstTraits::needsDestruction || SecondTraits::needsDestruction;
 
     static void constructDeletedValue(TraitType *slot)
     {
         FirstTraits::constructDeletedValue(&slot->first);
     }
     static bool isDeletedValue(const TraitType &value)
     {
         return FirstTraits::isDeletedValue(value.first);
     }
 };
 
 template<typename First, typename Second>
 struct HashTraits<pair<First, Second> > : public PairHashTraits<HashTraits<First>, HashTraits<Second> > { };
 
 } // namespace WTF
 
 using WTF::HashTraits;
 using WTF::PairHashTraits;
 
 #endif // WTF_HashTraits_h