| |
| // (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 |
| |