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(BOOST_BORLANDC) && (BOOST_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 BOOST_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(BOOST_BORLANDC) && (BOOST_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 | |
120 | |