/*
 * Copyright (C) 2005, 2006, 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_HashFunctions_h
#define WTF_HashFunctions_h

#include <wtf/RefPtr.h>
#include <kjs/global.h>
#if HAVE_STDINT_H
#include <stdint.h>
#endif

namespace WTF
{

template<size_t size> struct IntTypes;
template<> struct IntTypes<1> {
    typedef int8_t SignedType;
    typedef uint8_t UnsignedType;
};
template<> struct IntTypes<2> {
    typedef int16_t SignedType;
    typedef uint16_t UnsignedType;
};
template<> struct IntTypes<4> {
    typedef int32_t SignedType;
    typedef uint32_t UnsignedType;
};
template<> struct IntTypes<8> {
    typedef int64_t SignedType;
    typedef uint64_t UnsignedType;
};

// integer hash function

// Thomas Wang's 32 Bit Mix Function: http://www.cris.com/~Ttwang/tech/inthash.htm
inline unsigned intHash(uint8_t key8)
{
    unsigned key = key8;
    key += ~(key << 15);
    key ^= (key >> 10);
    key += (key << 3);
    key ^= (key >> 6);
    key += ~(key << 11);
    key ^= (key >> 16);
    return key;
}

// Thomas Wang's 32 Bit Mix Function: http://www.cris.com/~Ttwang/tech/inthash.htm
inline unsigned intHash(uint16_t key16)
{
    unsigned key = key16;
    key += ~(key << 15);
    key ^= (key >> 10);
    key += (key << 3);
    key ^= (key >> 6);
    key += ~(key << 11);
    key ^= (key >> 16);
    return key;
}

// Thomas Wang's 32 Bit Mix Function: http://www.cris.com/~Ttwang/tech/inthash.htm
inline unsigned intHash(uint32_t key)
{
    key += ~(key << 15);
    key ^= (key >> 10);
    key += (key << 3);
    key ^= (key >> 6);
    key += ~(key << 11);
    key ^= (key >> 16);
    return key;
}

// Thomas Wang's 64 bit Mix Function: http://www.cris.com/~Ttwang/tech/inthash.htm
inline unsigned intHash(uint64_t key)
{
    key += ~(key << 32);
    key ^= (key >> 22);
    key += ~(key << 13);
    key ^= (key >> 8);
    key += (key << 3);
    key ^= (key >> 15);
    key += ~(key << 27);
    key ^= (key >> 31);
    return static_cast<unsigned>(key);
}

template<typename T> struct IntHash {
    static unsigned hash(T key)
    {
        return intHash(static_cast<typename IntTypes<sizeof(T)>::UnsignedType>(key));
    }
    static bool equal(T a, T b)
    {
        return a == b;
    }
    static const bool safeToCompareToEmptyOrDeleted = true;
};

template<typename T> struct FloatHash {
    static unsigned hash(T key)
    {
        return intHash(*reinterpret_cast<typename IntTypes<sizeof(T)>::UnsignedType *>(&key));
    }
    static bool equal(T a, T b)
    {
        return a == b;
    }
    static const bool safeToCompareToEmptyOrDeleted = true;
};

// pointer identity hash function

template<typename T> struct PtrHash {
    static unsigned hash(T key)
    {
#if COMPILER(MSVC)
#pragma warning(push)
#pragma warning(disable: 4244) // work around what seems to be a bug in MSVC's conversion warnings
#endif
        return IntHash<uintptr_t>::hash(reinterpret_cast<uintptr_t>(key));
#if COMPILER(MSVC)
#pragma warning(pop)
#endif
    }
    static bool equal(T a, T b)
    {
        return a == b;
    }
    static const bool safeToCompareToEmptyOrDeleted = true;
};
template<typename P> struct PtrHash<RefPtr<P> > : PtrHash<P *> {
    using PtrHash<P *>::hash;
    static unsigned hash(const RefPtr<P> &key)
    {
        return hash(key.get());
    }
    using PtrHash<P *>::equal;
    static bool equal(const RefPtr<P> &a, const RefPtr<P> &b)
    {
        return a == b;
    }
    static bool equal(P *a, const RefPtr<P> &b)
    {
        return a == b;
    }
    static bool equal(const RefPtr<P> &a, P *b)
    {
        return a == b;
    }
};

// default hash function for each type

template<typename T> struct DefaultHash;

template<typename T, typename U> struct PairHash {
    static unsigned hash(const std::pair<T, U> &p)
    {
        return intHash((static_cast<uint64_t>(DefaultHash<T>::Hash::hash(p.first)) << 32 | DefaultHash<U>::Hash::hash(p.second)));
    }
    static bool equal(const std::pair<T, U> &a, const std::pair<T, U> &b)
    {
        return DefaultHash<T>::Hash::equal(a.first, b.first) && DefaultHash<U>::Hash::equal(a.second, b.second);
    }
    static const bool safeToCompareToEmptyOrDeleted = DefaultHash<T>::Hash::safeToCompareToEmptyOrDeleted
            && DefaultHash<U>::Hash::safeToCompareToEmptyOrDeleted;
};

// make IntHash the default hash function for many integer types

template<> struct DefaultHash<short> {
    typedef IntHash<unsigned> Hash;
};
template<> struct DefaultHash<unsigned short> {
    typedef IntHash<unsigned> Hash;
};
template<> struct DefaultHash<int> {
    typedef IntHash<unsigned> Hash;
};
template<> struct DefaultHash<unsigned> {
    typedef IntHash<unsigned> Hash;
};
template<> struct DefaultHash<long> {
    typedef IntHash<unsigned long> Hash;
};
template<> struct DefaultHash<unsigned long> {
    typedef IntHash<unsigned long> Hash;
};
template<> struct DefaultHash<long long> {
    typedef IntHash<unsigned long long> Hash;
};
template<> struct DefaultHash<unsigned long long> {
    typedef IntHash<unsigned long long> Hash;
};

#if !COMPILER(MSVC) || defined(_NATIVE_WCHAR_T_DEFINED)
template<> struct DefaultHash<wchar_t> {
    typedef IntHash<wchar_t> Hash;
};
#endif

template<> struct DefaultHash<float> {
    typedef FloatHash<float> Hash;
};
template<> struct DefaultHash<double> {
    typedef FloatHash<double> Hash;
};

// make PtrHash the default hash function for pointer types that don't specialize

template<typename P> struct DefaultHash<P *> {
    typedef PtrHash<P *> Hash;
};
template<typename P> struct DefaultHash<RefPtr<P> > {
    typedef PtrHash<RefPtr<P> > Hash;
};

template<typename T, typename U> struct DefaultHash<std::pair<T, U> > {
    typedef PairHash<T, U> Hash;
};

} // namespace WTF

using WTF::DefaultHash;
using WTF::IntHash;
using WTF::PtrHash;

#endif // WTF_HashFunctions_h
