120 lines
3.6 KiB
Plaintext
120 lines
3.6 KiB
Plaintext
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// (C) Copyright John Maddock 2000.
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// Use, modification and distribution are subject to the Boost Software License,
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// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt).
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//
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// See http://www.boost.org/libs/type_traits for most recent version including documentation.
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#ifndef BOOST_TT_ALIGNMENT_OF_HPP_INCLUDED
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#define BOOST_TT_ALIGNMENT_OF_HPP_INCLUDED
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#include <boost/config.hpp>
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#include <cstddef>
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#include <boost/type_traits/intrinsics.hpp>
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#include <boost/type_traits/integral_constant.hpp>
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#ifdef BOOST_MSVC
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# pragma warning(push)
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# pragma warning(disable: 4121 4512) // alignment is sensitive to packing
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#endif
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#if defined(__BORLANDC__) && (__BORLANDC__ < 0x600)
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#pragma option push -Vx- -Ve-
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#endif
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namespace boost {
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template <typename T> struct alignment_of;
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// get the alignment of some arbitrary type:
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namespace detail {
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#ifdef BOOST_MSVC
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#pragma warning(push)
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#pragma warning(disable:4324) // structure was padded due to __declspec(align())
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#endif
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template <typename T>
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struct alignment_of_hack
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{
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char c;
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T t;
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alignment_of_hack();
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};
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#ifdef BOOST_MSVC
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#pragma warning(pop)
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#endif
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template <unsigned A, unsigned S>
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struct alignment_logic
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{
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BOOST_STATIC_CONSTANT(std::size_t, value = A < S ? A : S);
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};
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template< typename T >
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struct alignment_of_impl
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{
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#if defined(BOOST_MSVC) && (BOOST_MSVC >= 1400)
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//
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// With MSVC both the native __alignof operator
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// and our own logic gets things wrong from time to time :-(
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// Using a combination of the two seems to make the most of a bad job:
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//
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BOOST_STATIC_CONSTANT(std::size_t, value =
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(::boost::detail::alignment_logic<
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sizeof(::boost::detail::alignment_of_hack<T>) - sizeof(T),
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__alignof(T)
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>::value));
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#elif !defined(BOOST_ALIGNMENT_OF)
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BOOST_STATIC_CONSTANT(std::size_t, value =
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(::boost::detail::alignment_logic<
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sizeof(::boost::detail::alignment_of_hack<T>) - sizeof(T),
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sizeof(T)
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>::value));
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#else
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//
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// We put this here, rather than in the definition of
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// alignment_of below, because MSVC's __alignof doesn't
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// always work in that context for some unexplained reason.
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// (See type_with_alignment tests for test cases).
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//
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BOOST_STATIC_CONSTANT(std::size_t, value = BOOST_ALIGNMENT_OF(T));
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#endif
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};
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} // namespace detail
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template <class T> struct alignment_of : public integral_constant<std::size_t, ::boost::detail::alignment_of_impl<T>::value>{};
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// references have to be treated specially, assume
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// that a reference is just a special pointer:
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template <typename T> struct alignment_of<T&> : public alignment_of<T*>{};
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#ifdef __BORLANDC__
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// long double gives an incorrect value of 10 (!)
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// unless we do this...
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struct long_double_wrapper{ long double ld; };
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template<> struct alignment_of<long double> : public alignment_of<long_double_wrapper>{};
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#endif
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// void has to be treated specially:
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template<> struct alignment_of<void> : integral_constant<std::size_t, 0>{};
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#ifndef BOOST_NO_CV_VOID_SPECIALIZATIONS
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template<> struct alignment_of<void const> : integral_constant<std::size_t, 0>{};
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template<> struct alignment_of<void const volatile> : integral_constant<std::size_t, 0>{};
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template<> struct alignment_of<void volatile> : integral_constant<std::size_t, 0>{};
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#endif
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} // namespace boost
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#if defined(__BORLANDC__) && (__BORLANDC__ < 0x600)
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#pragma option pop
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#endif
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#ifdef BOOST_MSVC
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# pragma warning(pop)
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#endif
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#endif // BOOST_TT_ALIGNMENT_OF_HPP_INCLUDED
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