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1 | ||
2 | // (C) Copyright John Maddock 2000. | |
3 | // Use, modification and distribution are subject to the Boost Software License, | |
4 | // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at | |
5 | // http://www.boost.org/LICENSE_1_0.txt). | |
6 | // | |
7 | // See http://www.boost.org/libs/type_traits for most recent version including documentation. | |
8 | ||
9 | #ifndef BOOST_TT_ALIGNMENT_OF_HPP_INCLUDED | |
10 | #define BOOST_TT_ALIGNMENT_OF_HPP_INCLUDED | |
11 | ||
12 | #include <boost/config.hpp> | |
13 | #include <cstddef> | |
14 | ||
15 | #include <boost/type_traits/intrinsics.hpp> | |
16 | #include <boost/type_traits/integral_constant.hpp> | |
17 | ||
18 | #ifdef BOOST_MSVC | |
19 | # pragma warning(push) | |
20 | # pragma warning(disable: 4121 4512) // alignment is sensitive to packing | |
21 | #endif | |
22 | #if defined(__BORLANDC__) && (__BORLANDC__ < 0x600) | |
23 | #pragma option push -Vx- -Ve- | |
24 | #endif | |
25 | ||
26 | namespace boost { | |
27 | ||
28 | template <typename T> struct alignment_of; | |
29 | ||
30 | // get the alignment of some arbitrary type: | |
31 | namespace detail { | |
32 | ||
33 | #ifdef BOOST_MSVC | |
34 | #pragma warning(push) | |
35 | #pragma warning(disable:4324) // structure was padded due to __declspec(align()) | |
36 | #endif | |
37 | template <typename T> | |
38 | struct alignment_of_hack | |
39 | { | |
40 | char c; | |
41 | T t; | |
42 | alignment_of_hack(); | |
43 | }; | |
44 | #ifdef BOOST_MSVC | |
45 | #pragma warning(pop) | |
46 | #endif | |
47 | ||
48 | template <unsigned A, unsigned S> | |
49 | struct alignment_logic | |
50 | { | |
51 | BOOST_STATIC_CONSTANT(std::size_t, value = A < S ? A : S); | |
52 | }; | |
53 | ||
54 | ||
55 | template< typename T > | |
56 | struct alignment_of_impl | |
57 | { | |
58 | #if defined(BOOST_MSVC) && (BOOST_MSVC >= 1400) | |
59 | // | |
60 | // With MSVC both the native __alignof operator | |
61 | // and our own logic gets things wrong from time to time :-( | |
62 | // Using a combination of the two seems to make the most of a bad job: | |
63 | // | |
64 | BOOST_STATIC_CONSTANT(std::size_t, value = | |
65 | (::boost::detail::alignment_logic< | |
66 | sizeof(::boost::detail::alignment_of_hack<T>) - sizeof(T), | |
67 | __alignof(T) | |
68 | >::value)); | |
69 | #elif !defined(BOOST_ALIGNMENT_OF) | |
70 | BOOST_STATIC_CONSTANT(std::size_t, value = | |
71 | (::boost::detail::alignment_logic< | |
72 | sizeof(::boost::detail::alignment_of_hack<T>) - sizeof(T), | |
73 | sizeof(T) | |
74 | >::value)); | |
75 | #else | |
76 | // | |
77 | // We put this here, rather than in the definition of | |
78 | // alignment_of below, because MSVC's __alignof doesn't | |
79 | // always work in that context for some unexplained reason. | |
80 | // (See type_with_alignment tests for test cases). | |
81 | // | |
82 | BOOST_STATIC_CONSTANT(std::size_t, value = BOOST_ALIGNMENT_OF(T)); | |
83 | #endif | |
84 | }; | |
85 | ||
86 | } // namespace detail | |
87 | ||
88 | template <class T> struct alignment_of : public integral_constant<std::size_t, ::boost::detail::alignment_of_impl<T>::value>{}; | |
89 | ||
90 | // references have to be treated specially, assume | |
91 | // that a reference is just a special pointer: | |
92 | template <typename T> struct alignment_of<T&> : public alignment_of<T*>{}; | |
93 | ||
94 | #ifdef __BORLANDC__ | |
95 | // long double gives an incorrect value of 10 (!) | |
96 | // unless we do this... | |
97 | struct long_double_wrapper{ long double ld; }; | |
98 | template<> struct alignment_of<long double> : public alignment_of<long_double_wrapper>{}; | |
99 | #endif | |
100 | ||
101 | // void has to be treated specially: | |
102 | template<> struct alignment_of<void> : integral_constant<std::size_t, 0>{}; | |
103 | #ifndef BOOST_NO_CV_VOID_SPECIALIZATIONS | |
104 | template<> struct alignment_of<void const> : integral_constant<std::size_t, 0>{}; | |
105 | template<> struct alignment_of<void const volatile> : integral_constant<std::size_t, 0>{}; | |
106 | template<> struct alignment_of<void volatile> : integral_constant<std::size_t, 0>{}; | |
107 | #endif | |
108 | ||
109 | } // namespace boost | |
110 | ||
111 | #if defined(__BORLANDC__) && (__BORLANDC__ < 0x600) | |
112 | #pragma option pop | |
113 | #endif | |
114 | #ifdef BOOST_MSVC | |
115 | # pragma warning(pop) | |
116 | #endif | |
117 | ||
118 | #endif // BOOST_TT_ALIGNMENT_OF_HPP_INCLUDED | |
119 |