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1 | // (C) Copyright John Maddock 2015. |
2 | // Use, modification and distribution are subject to the | |
3 | // Boost Software License, Version 1.0. (See accompanying file | |
4 | // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | |
5 | ||
6 | #ifndef BOOST_TYPE_TRAITS_INTEGRAL_CONSTANT_HPP | |
7 | #define BOOST_TYPE_TRAITS_INTEGRAL_CONSTANT_HPP | |
8 | ||
9 | #include <boost/config.hpp> | |
10 | #include <boost/detail/workaround.hpp> | |
11 | ||
12 | #if (BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1400)) \ | |
13 | || BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x610)) \ | |
14 | || BOOST_WORKAROUND(__DMC__, BOOST_TESTED_AT(0x840)) \ | |
15 | || BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3202)) \ | |
16 | || BOOST_WORKAROUND(BOOST_INTEL_CXX_VERSION, BOOST_TESTED_AT(810)) ) | |
17 | ||
18 | ||
19 | namespace boost{ | |
20 | namespace mpl | |
21 | { | |
22 | template <bool B> struct bool_; | |
23 | template <class I, I val> struct integral_c; | |
24 | struct integral_c_tag; | |
25 | } | |
26 | } | |
27 | ||
28 | #else | |
29 | ||
30 | namespace mpl_{ | |
31 | ||
32 | template <bool B> struct bool_; | |
33 | template <class I, I val> struct integral_c; | |
34 | struct integral_c_tag; | |
35 | } | |
36 | ||
37 | namespace boost | |
38 | { | |
39 | namespace mpl | |
40 | { | |
41 | using ::mpl_::bool_; | |
42 | using ::mpl_::integral_c; | |
43 | using ::mpl_::integral_c_tag; | |
44 | } | |
45 | } | |
46 | ||
47 | #endif | |
48 | ||
49 | namespace boost{ | |
50 | ||
51 | template <class T, T val> | |
52 | struct integral_constant | |
53 | { | |
54 | typedef mpl::integral_c_tag tag; | |
55 | typedef T value_type; | |
56 | typedef integral_constant<T, val> type; | |
57 | static const T value = val; | |
58 | // | |
59 | // This helper function is just to disable type-punning | |
60 | // warnings from GCC: | |
61 | // | |
62 | template <class U> | |
63 | static U& dereference(U* p) { return *p; } | |
64 | ||
65 | operator const mpl::integral_c<T, val>& ()const | |
66 | { | |
67 | static const char data[sizeof(long)] = { 0 }; | |
68 | return dereference(reinterpret_cast<const mpl::integral_c<T, val>*>(&data)); | |
69 | } | |
70 | BOOST_CONSTEXPR operator T()const { return val; } | |
71 | }; | |
72 | ||
73 | template <class T, T val> | |
74 | T const integral_constant<T, val>::value; | |
75 | ||
76 | template <bool val> | |
77 | struct integral_constant<bool, val> | |
78 | { | |
79 | typedef mpl::integral_c_tag tag; | |
80 | typedef bool value_type; | |
81 | typedef integral_constant<bool, val> type; | |
82 | static const bool value = val; | |
83 | // | |
84 | // This helper function is just to disable type-punning | |
85 | // warnings from GCC: | |
86 | // | |
87 | template <class T> | |
88 | static T& dereference(T* p) { return *p; } | |
89 | ||
90 | operator const mpl::bool_<val>& ()const | |
91 | { | |
92 | static const char data = 0; | |
93 | return dereference(reinterpret_cast<const mpl::bool_<val>*>(&data)); | |
94 | } | |
95 | BOOST_CONSTEXPR operator bool()const { return val; } | |
96 | }; | |
97 | ||
98 | template <bool val> | |
99 | bool const integral_constant<bool, val>::value; | |
100 | ||
101 | typedef integral_constant<bool, true> true_type; | |
102 | typedef integral_constant<bool, false> false_type; | |
103 | ||
104 | } | |
105 | ||
106 | #endif |