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- // (C) Copyright 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_ALIGNMENT_OF_HPP_INCLUDED
- #define BOOST_TT_ALIGNMENT_OF_HPP_INCLUDED
- #include <boost/config.hpp>
- #include <cstddef>
- #include <boost/type_traits/intrinsics.hpp>
- #include <boost/type_traits/integral_constant.hpp>
- #ifdef BOOST_MSVC
- # pragma warning(push)
- # pragma warning(disable: 4121 4512) // alignment is sensitive to packing
- #endif
- #if defined(__BORLANDC__) && (__BORLANDC__ < 0x600)
- #pragma option push -Vx- -Ve-
- #endif
- namespace boost {
- template <typename T> struct alignment_of;
- // get the alignment of some arbitrary type:
- namespace detail {
- #ifdef BOOST_MSVC
- #pragma warning(push)
- #pragma warning(disable:4324) // structure was padded due to __declspec(align())
- #endif
- template <typename T>
- struct alignment_of_hack
- {
- char c;
- T t;
- alignment_of_hack();
- };
- #ifdef BOOST_MSVC
- #pragma warning(pop)
- #endif
- template <unsigned A, unsigned S>
- struct alignment_logic
- {
- BOOST_STATIC_CONSTANT(std::size_t, value = A < S ? A : S);
- };
- template< typename T >
- struct alignment_of_impl
- {
- #if defined(BOOST_MSVC) && (BOOST_MSVC >= 1400)
- //
- // With MSVC both the native __alignof operator
- // and our own logic gets things wrong from time to time :-(
- // Using a combination of the two seems to make the most of a bad job:
- //
- BOOST_STATIC_CONSTANT(std::size_t, value =
- (::boost::detail::alignment_logic<
- sizeof(::boost::detail::alignment_of_hack<T>) - sizeof(T),
- __alignof(T)
- >::value));
- #elif !defined(BOOST_ALIGNMENT_OF)
- BOOST_STATIC_CONSTANT(std::size_t, value =
- (::boost::detail::alignment_logic<
- sizeof(::boost::detail::alignment_of_hack<T>) - sizeof(T),
- sizeof(T)
- >::value));
- #else
- //
- // We put this here, rather than in the definition of
- // alignment_of below, because MSVC's __alignof doesn't
- // always work in that context for some unexplained reason.
- // (See type_with_alignment tests for test cases).
- //
- BOOST_STATIC_CONSTANT(std::size_t, value = BOOST_ALIGNMENT_OF(T));
- #endif
- };
- } // namespace detail
- template <class T> struct alignment_of : public integral_constant<std::size_t, ::boost::detail::alignment_of_impl<T>::value>{};
- // references have to be treated specially, assume
- // that a reference is just a special pointer:
- template <typename T> struct alignment_of<T&> : public alignment_of<T*>{};
- #ifdef __BORLANDC__
- // long double gives an incorrect value of 10 (!)
- // unless we do this...
- struct long_double_wrapper{ long double ld; };
- template<> struct alignment_of<long double> : public alignment_of<long_double_wrapper>{};
- #endif
- // void has to be treated specially:
- template<> struct alignment_of<void> : integral_constant<std::size_t, 0>{};
- #ifndef BOOST_NO_CV_VOID_SPECIALIZATIONS
- template<> struct alignment_of<void const> : integral_constant<std::size_t, 0>{};
- template<> struct alignment_of<void const volatile> : integral_constant<std::size_t, 0>{};
- template<> struct alignment_of<void volatile> : integral_constant<std::size_t, 0>{};
- #endif
- } // namespace boost
- #if defined(__BORLANDC__) && (__BORLANDC__ < 0x600)
- #pragma option pop
- #endif
- #ifdef BOOST_MSVC
- # pragma warning(pop)
- #endif
- #endif // BOOST_TT_ALIGNMENT_OF_HPP_INCLUDED
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