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Viewing changes to boost/boost/type_traits/type_with_alignment.hpp

  • Committer: Bazaar Package Importer
  • Author(s): LaMont Jones
  • Date: 2004-08-24 07:25:04 UTC
  • Revision ID: james.westby@ubuntu.com-20040824072504-zf993vnevvisdsvb
Tags: upstream-0.9.1
Import upstream version 0.9.1

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boost/boost/type_traits/type_with_alignment.hpp
 
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// (C) Copyright John Maddock 2000.
 
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// Permission to copy, use, modify, sell and distribute this software is 
 
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// granted provided this copyright notice appears in all copies. This 
 
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// software is provided "as is" without express or implied warranty, 
 
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// and with no claim as to its suitability for any purpose.
 
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#ifndef BOOST_TT_TYPE_WITH_ALIGNMENT_INCLUDED
 
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#define BOOST_TT_TYPE_WITH_ALIGNMENT_INCLUDED
 
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#include "boost/mpl/if.hpp"
 
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#include "boost/preprocessor/list/for_each_i.hpp"
 
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#include "boost/preprocessor/tuple/to_list.hpp"
 
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#include "boost/preprocessor/cat.hpp"
 
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#include "boost/type_traits/alignment_of.hpp"
 
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#include "boost/type_traits/is_pod.hpp"
 
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#include "boost/static_assert.hpp"
 
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#include "boost/config.hpp"
 
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// should be the last #include
 
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#include "boost/type_traits/detail/bool_trait_def.hpp"
 
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#include <cstddef>
 
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#ifdef BOOST_MSVC
 
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#   pragma warning(push)
 
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#   pragma warning(disable: 4121) // alignment is sensitive to packing
 
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#endif
 
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namespace boost {
 
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#ifndef __BORLANDC__
 
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namespace detail {
 
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class alignment_dummy;
 
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typedef void (*function_ptr)();
 
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typedef int (alignment_dummy::*member_ptr);
 
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typedef int (alignment_dummy::*member_function_ptr)();
 
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#define BOOST_TT_ALIGNMENT_TYPES BOOST_PP_TUPLE_TO_LIST( \
 
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        11, ( \
 
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        char, short, int, long, float, double, long double \
 
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        , void*, function_ptr, member_ptr, member_function_ptr))
 
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#define BOOST_TT_CHOOSE_MIN_ALIGNMENT(R,P,I,T) \
 
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        typename mpl::if_c< \
 
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           alignment_of<T>::value <= target, T, char>::type BOOST_PP_CAT(t,I);
 
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#define BOOST_TT_CHOOSE_T(R,P,I,T) T BOOST_PP_CAT(t,I);
 
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template <std::size_t target>
 
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union lower_alignment
 
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{
 
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    BOOST_PP_LIST_FOR_EACH_I(
 
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          BOOST_TT_CHOOSE_MIN_ALIGNMENT
 
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        , ignored
 
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        , BOOST_TT_ALIGNMENT_TYPES
 
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        )
 
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};
 
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union max_align
 
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{
 
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    BOOST_PP_LIST_FOR_EACH_I(
 
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          BOOST_TT_CHOOSE_T
 
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        , ignored
 
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        , BOOST_TT_ALIGNMENT_TYPES
 
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        )
 
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};
 
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#undef BOOST_TT_ALIGNMENT_TYPES
 
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#undef BOOST_TT_CHOOSE_MIN_ALIGNMENT
 
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#undef BOOST_TT_CHOOSE_T
 
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template<int TAlign, int Align>
 
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struct is_aligned
 
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{
 
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    BOOST_STATIC_CONSTANT(bool,
 
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        value = (TAlign >= Align) & (TAlign % Align == 0)
 
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        );
 
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};
 
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BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::max_align,true)
 
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BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::lower_alignment<1> ,true)
 
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BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::lower_alignment<2> ,true)
 
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BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::lower_alignment<4> ,true)
 
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BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::lower_alignment<8> ,true)
 
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BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::lower_alignment<10> ,true)
 
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BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::lower_alignment<16> ,true)
 
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BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::lower_alignment<32> ,true)
 
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} // namespace detail
 
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// This alignment method originally due to Brian Parker, implemented by David
 
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// Abrahams, and then ported here by Doug Gregor. 
 
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template <int Align>
 
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class type_with_alignment
 
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{
 
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    typedef detail::lower_alignment<Align> t1;
 
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    typedef typename mpl::if_c<
 
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          ::boost::detail::is_aligned< ::boost::alignment_of<t1>::value,Align >::value
 
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        , t1
 
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        , detail::max_align
 
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        >::type align_t;
 
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    BOOST_STATIC_CONSTANT(std::size_t, found = alignment_of<align_t>::value);
 
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#ifndef __BORLANDC__
 
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    BOOST_STATIC_ASSERT(found >= Align);
 
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    BOOST_STATIC_ASSERT(found % Align == 0);
 
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#else
 
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    BOOST_STATIC_ASSERT(::boost::type_with_alignment<Align>::found >= Align);
 
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    BOOST_STATIC_ASSERT(::boost::type_with_alignment<Align>::found % Align == 0);
 
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#endif
 
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 public:
 
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    typedef align_t type;
 
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};
 
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#else
 
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//
 
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// Borland specific version, we have this for two reasons:
 
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// 1) The version above doesn't always compile (with the new test cases for example)
 
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// 2) Because of Borlands #pragma option we can create types with alignments that are
 
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//    greater that the largest aligned builtin type.
 
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namespace align{
 
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#pragma option push -a16
 
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struct a2{ short s; };
 
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struct a4{ int s; };
 
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struct a8{ double s; };
 
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struct a16{ long double s; };
 
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#pragma option pop
 
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}
 
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namespace detail {
 
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BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a2,true)
 
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BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a4,true)
 
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BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a8,true)
 
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BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a16,true)
 
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}
 
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template <std::size_t N> struct type_with_alignment
 
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{
 
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   // We should never get to here, but if we do use the maximally
 
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   // aligned type:
 
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   // BOOST_STATIC_ASSERT(0);
 
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   typedef align::a16 type;
 
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};
 
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template <> struct type_with_alignment<1>{ typedef char type; };
 
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template <> struct type_with_alignment<2>{ typedef align::a2 type; };
 
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template <> struct type_with_alignment<4>{ typedef align::a4 type; };
 
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template <> struct type_with_alignment<8>{ typedef align::a8 type; };
 
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template <> struct type_with_alignment<16>{ typedef align::a16 type; };
 
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#endif
 
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} // namespace boost
 
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#ifdef BOOST_MSVC
 
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#   pragma warning(pop)
 
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#endif
 
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#include "boost/type_traits/detail/bool_trait_undef.hpp"
 
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#endif // BOOST_TT_TYPE_WITH_ALIGNMENT_INCLUDED
 
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