// (C) Copyright Steve Cleary, Beman Dawes, Howard Hinnant & John Maddock 2000.

//  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).

//

//  See http://www.boost.org/libs/type_traits for most recent version including documentation.

#ifndef BOOST_TT_IS_EMPTY_HPP_INCLUDED

#define BOOST_TT_IS_EMPTY_HPP_INCLUDED

#include <boost/type_traits/is_convertible.hpp>

#include <boost/type_traits/detail/config.hpp>

#include <boost/type_traits/intrinsics.hpp>

#include <boost/type_traits/remove_cv.hpp>

#include <boost/type_traits/is_class.hpp>

#include <boost/type_traits/add_reference.hpp>

#ifndef BOOST_INTERNAL_IS_EMPTY

#define BOOST_INTERNAL_IS_EMPTY(T) false

#else

#define BOOST_INTERNAL_IS_EMPTY(T) BOOST_IS_EMPTY(T)

#endif

namespace boost {

namespace detail {

#ifdef BOOST_MSVC

#pragma warning(push)

#pragma warning(disable:4624) // destructor could not be generated

#endif

template <typename T>

struct empty_helper_t1 : public T

{

    empty_helper_t1();  // hh compiler bug workaround

    int i[256];

private:

   // suppress compiler warnings:

   empty_helper_t1(const empty_helper_t1&);

   empty_helper_t1& operator=(const empty_helper_t1&);

};

#ifdef BOOST_MSVC

#pragma warning(pop)

#endif

struct empty_helper_t2 { int i[256]; };

#if !BOOST_WORKAROUND(__BORLANDC__, < 0x600)

template <typename T, bool is_a_class = false>

struct empty_helper

{

    BOOST_STATIC_CONSTANT(bool, value = false);

};

template <typename T>

struct empty_helper<T, true>

{

    BOOST_STATIC_CONSTANT(

        bool, value = (sizeof(empty_helper_t1<T>) == sizeof(empty_helper_t2))

        );

};

template <typename T>

struct is_empty_impl

{

    typedef typename remove_cv<T>::type cvt;

    BOOST_STATIC_CONSTANT(

        bool, 

        value = ( ::boost::detail::empty_helper<cvt,::boost::is_class<T>::value>::value || BOOST_INTERNAL_IS_EMPTY(cvt)));

};

#else // __BORLANDC__

template <typename T, bool is_a_class, bool convertible_to_int>

struct empty_helper

{

    BOOST_STATIC_CONSTANT(bool, value = false);

};

template <typename T>

struct empty_helper<T, true, false>

{

    BOOST_STATIC_CONSTANT(bool, value = (

        sizeof(empty_helper_t1<T>) == sizeof(empty_helper_t2)

        ));

};

template <typename T>

struct is_empty_impl

{

   typedef typename remove_cv<T>::type cvt;

   typedef typename add_reference<T>::type r_type;

   BOOST_STATIC_CONSTANT(

       bool, value = (

              ::boost::detail::empty_helper<

                  cvt

                , ::boost::is_class<T>::value

                , ::boost::is_convertible< r_type,int>::value

              >::value || BOOST_INTERNAL_IS_EMPTY(cvt));

};

#endif // __BORLANDC__

} // namespace detail

template <class T> struct is_empty : integral_constant<bool, ::boost::detail::is_empty_impl<T>::value> {};

} // namespace boost

#undef BOOST_INTERNAL_IS_EMPTY

#endif // BOOST_TT_IS_EMPTY_HPP_INCLUDED