//  Copyright Daniel James 2005-2006. Use, modification, and distribution are

//  subject to the Boost Software License, Version 1.0. (See accompanying

//  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

//  Based on Peter Dimov's proposal

//  http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2005/n1756.pdf

//  issue 6.18. 

#if !defined(BOOST_FUNCTIONAL_DETAIL_HASH_FLOAT_HEADER)

#define BOOST_FUNCTIONAL_DETAIL_HASH_FLOAT_HEADER

#if defined(_MSC_VER) && (_MSC_VER >= 1020)

# pragma once

#endif

#include <boost/functional/detail/float_functions.hpp>

#include <boost/limits.hpp>

#include <boost/assert.hpp>

#include <errno.h>

// Don't use fpclassify or _fpclass for stlport.

#if !defined(__SGI_STL_PORT) && !defined(_STLPORT_VERSION)

#  if defined(__GLIBCPP__) || defined(__GLIBCXX__)

// GNU libstdc++ 3

#    if (defined(__USE_ISOC99) || defined(_GLIBCXX_USE_C99_MATH)) && \

        !(defined(macintosh) || defined(__APPLE__) || defined(__APPLE_CC__))

#      define BOOST_HASH_USE_FPCLASSIFY

#    endif

#  elif (defined(_YVALS) && !defined(__IBMCPP__)) || defined(_CPPLIB_VER)

// Dinkumware Library, on Visual C++ 

#    if defined(BOOST_MSVC)

#      define BOOST_HASH_USE_FPCLASS

#    endif

#  endif

#endif

namespace boost

{

    namespace hash_detail

    {

        inline void hash_float_combine(std::size_t& seed, std::size_t value)

        {

            seed ^= value + (seed<<6) + (seed>>2);

        }

        template <class T>

        inline std::size_t float_hash_impl(T v)

        {

            int exp = 0;

            errno = 0;

            v = boost::hash_detail::call_frexp(v, &exp);

            if(errno) return 0;

            std::size_t seed = 0;

            std::size_t const length

                = (std::numeric_limits<T>::digits +

                        std::numeric_limits<int>::digits - 1)

                / std::numeric_limits<int>::digits;

            for(std::size_t i = 0; i < length; ++i)

            {

                v = boost::hash_detail::call_ldexp(v, std::numeric_limits<int>::digits);

                int const part = static_cast<int>(v);

                v -= part;

                hash_float_combine(seed, part);

            }

            hash_float_combine(seed, exp);

            return seed;

        }

        template <class T>

        inline std::size_t float_hash_value(T v)

        {

#if defined(BOOST_HASH_USE_FPCLASSIFY)

            using namespace std;

            switch (fpclassify(v)) {

            case FP_ZERO:

                return 0;

            case FP_INFINITE:

                return (std::size_t)(v > 0 ? -1 : -2);

            case FP_NAN:

                return (std::size_t)(-3);

            case FP_NORMAL:

            case FP_SUBNORMAL:

                return float_hash_impl(v);

            default:

                BOOST_ASSERT(0);

                return 0;

            }

#elif defined(BOOST_HASH_USE_FPCLASS)

            switch(_fpclass(v)) {

            case _FPCLASS_NZ:

            case _FPCLASS_PZ:

                return 0;

            case _FPCLASS_PINF:

                return (std::size_t)(-1);

            case _FPCLASS_NINF:

                return (std::size_t)(-2);

            case _FPCLASS_SNAN:

            case _FPCLASS_QNAN:

                return (std::size_t)(-3);

            case _FPCLASS_NN:

            case _FPCLASS_ND:

                return float_hash_impl(v);

            case _FPCLASS_PD:

            case _FPCLASS_PN:

                return float_hash_impl(v);

            default:

                BOOST_ASSERT(0);

                return 0;

            }

#else

            return float_hash_impl(v);

#endif

        }

    }

}

#endif