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Restore vc6/7 compatibility; reduce template instantiations.

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[SVN r21121]
This commit is contained in:
Dave Abrahams
2003-12-03 13:49:08 +00:00
parent 2ff80eac58
commit fc577f2a2d
1 changed files with 58 additions and 7 deletions
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65
include/boost/type_traits/type_with_alignment.hpp
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@@ -1,4 +1,3 @@
// (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
@@ -57,12 +56,64 @@ typedef int (alignment_dummy::*member_function_ptr)();
BOOST_PP_LIST_APPEND(BOOST_TT_ALIGNMENT_BASE_TYPES, \
BOOST_TT_ALIGNMENT_STRUCT_TYPES)
#define BOOST_TT_CHOOSE_MIN_ALIGNMENT(R,P,I,T) \
typename mpl::if_c< \
(alignment_of< T >::value == target && !BOOST_PP_CAT(found,I)), \
T, char>::type BOOST_PP_CAT(t,I); \
enum { BOOST_PP_CAT(found,BOOST_PP_INC(I)) = \
alignment_of< T >::value == target || BOOST_PP_CAT(found,I) } ;
//
// lower_alignment_helper --
//
// This template gets instantiated a lot, so use partial
// specialization when available to reduce the compiler burden.
//
#ifdef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
template <bool found = true>
struct lower_alignment_helper_impl
{
template <std::size_t, class>
struct apply
{
typedef char type;
enum { value = true };
};
};
template <>
struct lower_alignment_helper_impl<false>
{
template <std::size_t target, class TestType>
struct apply
: mpl::if_c<(alignment_of<TestType>::value == target), TestType, char>
{
enum { value = (alignment_of<TestType>::value == target) };
};
};
template <bool found, std::size_t target, class TestType>
struct lower_alignment_helper
: lower_alignment_helper_impl<found>::template apply<target,TestType>
{
};
#else
template <bool found, std::size_t target, class TestType>
struct lower_alignment_helper
{
typedef char type;
enum { value = true };
};
template <std::size_t target, class TestType>
struct lower_alignment_helper<false,target,TestType>
: mpl::if_c<(alignment_of<TestType>::value == target), TestType, char>
{
enum { value = (alignment_of<TestType>::value == target) };
};
#endif
#define BOOST_TT_CHOOSE_MIN_ALIGNMENT(R,P,I,T) \
typename lower_alignment_helper< \
BOOST_PP_CAT(found,I),target,T \
>::type BOOST_PP_CAT(t,I); \
enum { \
BOOST_PP_CAT(found,BOOST_PP_INC(I)) \
= lower_alignment_helper<BOOST_PP_CAT(found,I),target,T >::value \
};
#define BOOST_TT_CHOOSE_T(R,P,I,T) T BOOST_PP_CAT(t,I);