

// (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/ice_or.hpp>

#include <boost/type_traits/config.hpp>

#include <boost/type_traits/intrinsics.hpp>



#ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION

#   include <boost/type_traits/remove_cv.hpp>

#   include <boost/type_traits/is_class.hpp>

#   include <boost/type_traits/add_reference.hpp>

#else

#   include <boost/type_traits/is_reference.hpp>

#   include <boost/type_traits/is_pointer.hpp>

#   include <boost/type_traits/is_member_pointer.hpp>

#   include <boost/type_traits/is_array.hpp>

#   include <boost/type_traits/is_void.hpp>

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

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

#endif



// should be always the last #include directive

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



namespace boost {



namespace detail {



#ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION

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&);

};



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::type_traits::ice_or<

              ::boost::detail::empty_helper<cvt,::boost::is_class<T>::value>::value

              , BOOST_IS_EMPTY(cvt)

            >::value

            ));

};



#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::type_traits::ice_or<

              ::boost::detail::empty_helper<

                  cvt

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

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

              >::value

              , BOOST_IS_EMPTY(cvt)

           >::value));

};



#endif // __BORLANDC__



#else // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION



#ifdef BOOST_MSVC6_MEMBER_TEMPLATES



template <typename T>

struct empty_helper_t1 : public T

{

   empty_helper_t1();

   int i[256];

};



struct empty_helper_t2 { int i[256]; };



template <typename T>

struct empty_helper_base

{

   enum { value = (sizeof(empty_helper_t1<T>) == sizeof(empty_helper_t2)) };

};



template <typename T>

struct empty_helper_nonbase

{

   enum { value = false };

};



template <bool base>

struct empty_helper_chooser

{

   template <typename T> struct result_

   {

      typedef empty_helper_nonbase<T> type;

   };

};



template <>

struct empty_helper_chooser<true>

{

   template <typename T> struct result_

   {

      typedef empty_helper_base<T> type;

   };

};



template <typename T>

struct is_empty_impl

{

   typedef ::boost::detail::empty_helper_chooser<

      ::boost::type_traits::ice_and<

         ::boost::type_traits::ice_not< ::boost::is_reference<T>::value >::value,

         ::boost::type_traits::ice_not< ::boost::is_convertible<T,double>::value >::value,

         ::boost::type_traits::ice_not< ::boost::is_pointer<T>::value >::value,

         ::boost::type_traits::ice_not< ::boost::is_member_pointer<T>::value >::value,

         ::boost::type_traits::ice_not< ::boost::is_array<T>::value >::value,

         ::boost::type_traits::ice_not< ::boost::is_void<T>::value >::value,

         ::boost::type_traits::ice_not<

            ::boost::is_convertible<T,void const volatile*>::value

            >::value

      >::value > chooser;



   typedef typename chooser::template result_<T> result;

   typedef typename result::type eh_type;



   BOOST_STATIC_CONSTANT(bool, value =

      (::boost::type_traits::ice_or<eh_type::value, BOOST_IS_EMPTY(T)>::value));

};



#else



template <typename T> struct is_empty_impl

{

    BOOST_STATIC_CONSTANT(bool, value = BOOST_IS_EMPTY(T));

};



#endif  // BOOST_MSVC6_MEMBER_TEMPLATES



#endif  // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION



// these help when the compiler has no partial specialization support:

BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_empty,void,false)

#ifndef BOOST_NO_CV_VOID_SPECIALIZATIONS

BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_empty,void const,false)

BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_empty,void volatile,false)

BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_empty,void const volatile,false)

#endif



} // namespace detail



BOOST_TT_AUX_BOOL_TRAIT_DEF1(is_empty,T,::boost::detail::is_empty_impl<T>::value)



} // namespace boost



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



#endif // BOOST_TT_IS_EMPTY_HPP_INCLUDED



