1 // (C) Copyright John Maddock 2000.
2 // Use, modification and distribution are subject to the Boost Software License,
3 // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
4 // http://www.boost.org/LICENSE_1_0.txt).
6 // See http://www.boost.org/libs/type_traits for most recent version including documentation.
8 #ifndef BOOST_TT_TYPE_WITH_ALIGNMENT_INCLUDED
9 #define BOOST_TT_TYPE_WITH_ALIGNMENT_INCLUDED
11 #include <boost/mpl/if.hpp>
12 #include <boost/preprocessor/list/for_each_i.hpp>
13 #include <boost/preprocessor/tuple/to_list.hpp>
14 #include <boost/preprocessor/cat.hpp>
15 #include <boost/preprocessor/list/transform.hpp>
16 #include <boost/preprocessor/list/append.hpp>
17 #include <boost/type_traits/alignment_of.hpp>
18 #include <boost/type_traits/is_pod.hpp>
19 #include <boost/static_assert.hpp>
20 #include <boost/config.hpp>
22 // should be the last #include
23 #include <boost/type_traits/detail/bool_trait_def.hpp>
28 # pragma warning(push)
29 # pragma warning(disable: 4121) // alignment is sensitive to packing
38 class alignment_dummy;
39 typedef void (*function_ptr)();
40 typedef int (alignment_dummy::*member_ptr);
41 typedef int (alignment_dummy::*member_function_ptr)();
43 #ifdef BOOST_HAS_LONG_LONG
44 #define BOOST_TT_ALIGNMENT_BASE_TYPES BOOST_PP_TUPLE_TO_LIST( \
46 char, short, int, long, ::boost::long_long_type, float, double, long double \
47 , void*, function_ptr, member_ptr, member_function_ptr))
49 #define BOOST_TT_ALIGNMENT_BASE_TYPES BOOST_PP_TUPLE_TO_LIST( \
51 char, short, int, long, float, double, long double \
52 , void*, function_ptr, member_ptr, member_function_ptr))
55 #define BOOST_TT_HAS_ONE_T(D,Data,T) boost::detail::has_one_T< T >
57 #define BOOST_TT_ALIGNMENT_STRUCT_TYPES \
58 BOOST_PP_LIST_TRANSFORM(BOOST_TT_HAS_ONE_T, \
60 BOOST_TT_ALIGNMENT_BASE_TYPES)
62 #define BOOST_TT_ALIGNMENT_TYPES \
63 BOOST_PP_LIST_APPEND(BOOST_TT_ALIGNMENT_BASE_TYPES, \
64 BOOST_TT_ALIGNMENT_STRUCT_TYPES)
67 // lower_alignment_helper --
69 // This template gets instantiated a lot, so use partial
70 // specialization when available to reduce the compiler burden.
72 #ifdef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
73 template <bool found = true>
74 struct lower_alignment_helper_impl
76 template <std::size_t, class>
80 enum { value = true };
85 struct lower_alignment_helper_impl<false>
87 template <std::size_t target, class TestType>
89 : mpl::if_c<(alignment_of<TestType>::value == target), TestType, char>
91 enum { value = (alignment_of<TestType>::value == target) };
95 template <bool found, std::size_t target, class TestType>
96 struct lower_alignment_helper
97 : lower_alignment_helper_impl<found>::template apply<target,TestType>
101 template <bool found, std::size_t target, class TestType>
102 struct lower_alignment_helper
105 enum { value = true };
108 template <std::size_t target, class TestType>
109 struct lower_alignment_helper<false,target,TestType>
111 enum { value = (alignment_of<TestType>::value == target) };
112 typedef typename mpl::if_c<value, TestType, char>::type type;
116 #define BOOST_TT_CHOOSE_MIN_ALIGNMENT(R,P,I,T) \
117 typename lower_alignment_helper< \
118 BOOST_PP_CAT(found,I),target,T \
119 >::type BOOST_PP_CAT(t,I); \
121 BOOST_PP_CAT(found,BOOST_PP_INC(I)) \
122 = lower_alignment_helper<BOOST_PP_CAT(found,I),target,T >::value \
125 #define BOOST_TT_CHOOSE_T(R,P,I,T) T BOOST_PP_CAT(t,I);
127 template <typename T>
133 template <std::size_t target>
134 union lower_alignment
136 enum { found0 = false };
138 BOOST_PP_LIST_FOR_EACH_I(
139 BOOST_TT_CHOOSE_MIN_ALIGNMENT
141 , BOOST_TT_ALIGNMENT_TYPES
147 BOOST_PP_LIST_FOR_EACH_I(
150 , BOOST_TT_ALIGNMENT_TYPES
154 #undef BOOST_TT_ALIGNMENT_BASE_TYPES
155 #undef BOOST_TT_HAS_ONE_T
156 #undef BOOST_TT_ALIGNMENT_STRUCT_TYPES
157 #undef BOOST_TT_ALIGNMENT_TYPES
158 #undef BOOST_TT_CHOOSE_MIN_ALIGNMENT
159 #undef BOOST_TT_CHOOSE_T
161 template<std::size_t TAlign, std::size_t Align>
164 BOOST_STATIC_CONSTANT(bool,
165 value = (TAlign >= Align) & (TAlign % Align == 0)
169 #ifdef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
170 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::max_align,true)
171 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::lower_alignment<1> ,true)
172 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::lower_alignment<2> ,true)
173 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::lower_alignment<4> ,true)
174 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::lower_alignment<8> ,true)
175 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::lower_alignment<10> ,true)
176 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::lower_alignment<16> ,true)
177 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::detail::lower_alignment<32> ,true)
180 } // namespace detail
182 #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
183 template<std::size_t Align>
184 struct is_pod< ::boost::detail::lower_alignment<Align> >
186 BOOST_STATIC_CONSTANT(std::size_t, value = true);
190 // This alignment method originally due to Brian Parker, implemented by David
191 // Abrahams, and then ported here by Doug Gregor.
192 template <std::size_t Align>
193 class type_with_alignment
195 typedef ::boost::detail::lower_alignment<Align> t1;
196 typedef typename mpl::if_c<
197 ::boost::detail::is_aligned< ::boost::alignment_of<t1>::value,Align >::value
199 , ::boost::detail::max_align
202 BOOST_STATIC_CONSTANT(std::size_t, found = alignment_of<align_t>::value);
204 BOOST_STATIC_ASSERT(found >= Align);
205 BOOST_STATIC_ASSERT(found % Align == 0);
208 typedef align_t type;
211 #if defined(__GNUC__)
213 struct __attribute__((__aligned__(2))) a2 {};
214 struct __attribute__((__aligned__(4))) a4 {};
215 struct __attribute__((__aligned__(8))) a8 {};
216 struct __attribute__((__aligned__(16))) a16 {};
217 struct __attribute__((__aligned__(32))) a32 {};
220 template<> class type_with_alignment<1> { public: typedef char type; };
221 template<> class type_with_alignment<2> { public: typedef align::a2 type; };
222 template<> class type_with_alignment<4> { public: typedef align::a4 type; };
223 template<> class type_with_alignment<8> { public: typedef align::a8 type; };
224 template<> class type_with_alignment<16> { public: typedef align::a16 type; };
225 template<> class type_with_alignment<32> { public: typedef align::a32 type; };
228 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a2,true)
229 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a4,true)
230 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a8,true)
231 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a16,true)
232 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a32,true)
239 // Borland specific version, we have this for two reasons:
240 // 1) The version above doesn't always compile (with the new test cases for example)
241 // 2) Because of Borlands #pragma option we can create types with alignments that are
242 // greater that the largest aligned builtin type.
245 #pragma option push -a16
246 struct a2{ short s; };
248 struct a8{ double s; };
249 struct a16{ long double s; };
255 typedef ::boost::align::a16 max_align;
257 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a2,true)
258 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a4,true)
259 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a8,true)
260 BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_pod,::boost::align::a16,true)
263 template <std::size_t N> struct type_with_alignment
265 // We should never get to here, but if we do use the maximally
267 // BOOST_STATIC_ASSERT(0);
268 typedef align::a16 type;
270 template <> struct type_with_alignment<1>{ typedef char type; };
271 template <> struct type_with_alignment<2>{ typedef align::a2 type; };
272 template <> struct type_with_alignment<4>{ typedef align::a4 type; };
273 template <> struct type_with_alignment<8>{ typedef align::a8 type; };
274 template <> struct type_with_alignment<16>{ typedef align::a16 type; };
281 # pragma warning(pop)
284 #include <boost/type_traits/detail/bool_trait_undef.hpp>
286 #endif // BOOST_TT_TYPE_WITH_ALIGNMENT_INCLUDED