1 | // Copyright Daniel Wallin, David Abrahams 2005. |
2 | // Copyright Cromwell D. Enage 2017. |
3 | // Distributed under the Boost Software License, Version 1.0. |
4 | // (See accompanying file LICENSE_1_0.txt or copy at |
5 | // http://www.boost.org/LICENSE_1_0.txt) |
6 | |
7 | #ifndef BOOST_PARAMETER_AUX_UNWRAP_CV_REFERENCE_HPP |
8 | #define BOOST_PARAMETER_AUX_UNWRAP_CV_REFERENCE_HPP |
9 | |
10 | namespace boost { |
11 | |
12 | template <typename T> |
13 | class reference_wrapper; |
14 | } // namespace boost |
15 | |
16 | #include <boost/parameter/aux_/yesno.hpp> |
17 | |
18 | namespace boost { namespace parameter { namespace aux { |
19 | |
20 | // |
21 | // reference_wrapper support -- if perfect forwarding is unsupported, |
22 | // then when passing arguments positionally by non-const reference, |
23 | // we ask users of named parameter interfaces to use ref(x) to wrap them. |
24 | // |
25 | |
26 | template <typename U> |
27 | ::boost::parameter::aux::yes_tag |
28 | is_cv_reference_wrapper_check( |
29 | ::boost::reference_wrapper<U> const volatile* |
30 | ); |
31 | |
32 | ::boost::parameter::aux::no_tag is_cv_reference_wrapper_check(...); |
33 | }}} // namespace boost::parameter::aux |
34 | |
35 | #include <boost/parameter/config.hpp> |
36 | |
37 | #if !defined(BOOST_NO_CXX11_HDR_FUNCTIONAL) |
38 | #include <functional> |
39 | |
40 | namespace boost { namespace parameter { namespace aux { |
41 | |
42 | // Support for std::ref(x) -- Cromwell D. Enage |
43 | template <typename U> |
44 | ::boost::parameter::aux::yes_tag |
45 | is_cv_reference_wrapper_check( |
46 | ::std::reference_wrapper<U> const volatile* |
47 | ); |
48 | }}} // namespace boost::parameter::aux |
49 | #endif |
50 | |
51 | #include <boost/parameter/aux_/preprocessor/nullptr.hpp> |
52 | |
53 | #if defined(BOOST_PARAMETER_CAN_USE_MP11) && !( \ |
54 | BOOST_WORKAROUND(BOOST_MSVC, >= 1900) && \ |
55 | BOOST_WORKAROUND(BOOST_MSVC, < 1910) \ |
56 | ) |
57 | #include <boost/mp11/integral.hpp> |
58 | #include <boost/mp11/utility.hpp> |
59 | #include <type_traits> |
60 | #else // !defined(BOOST_PARAMETER_CAN_USE_MP11) || MSVC-14.0 |
61 | #include <boost/mpl/bool.hpp> |
62 | #include <boost/type_traits/remove_reference.hpp> |
63 | #if !BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x564)) && \ |
64 | !BOOST_WORKAROUND(BOOST_GCC, < 40000) |
65 | #include <boost/mpl/eval_if.hpp> |
66 | #endif |
67 | #endif // BOOST_PARAMETER_CAN_USE_MP11 && not MSVC-14.0 |
68 | |
69 | namespace boost { namespace parameter { namespace aux { |
70 | |
71 | #if defined(BOOST_PARAMETER_CAN_USE_MP11) && !( \ |
72 | BOOST_WORKAROUND(BOOST_MSVC, >= 1900) && \ |
73 | BOOST_WORKAROUND(BOOST_MSVC, < 1910) \ |
74 | ) |
75 | // This metafunction returns mp11::mp_true if T is of type |
76 | // reference_wrapper<U> cv. |
77 | template <typename T> |
78 | using is_cv_reference_wrapper = ::boost::mp11::mp_bool< |
79 | sizeof( |
80 | ::boost::parameter::aux::is_cv_reference_wrapper_check( |
81 | static_cast< |
82 | typename ::std::remove_reference<T>::type* |
83 | >(BOOST_PARAMETER_AUX_PP_NULLPTR) |
84 | ) |
85 | ) == sizeof(::boost::parameter::aux::yes_tag) |
86 | >; |
87 | |
88 | // Needed for unwrap_cv_reference below. T might be const, so |
89 | // mp_eval_if<> might fail because of deriving from T const on EDG. |
90 | template <typename T> |
91 | using unwrap_cv_reference_impl = typename ::std::remove_reference<T>::type; |
92 | |
93 | // Produces the unwrapped type to hold a reference to in |
94 | // tagged_argument<>. Can't use boost::unwrap_reference<> here |
95 | // because it doesn't handle the case where T = reference_wrapper<U> cv. |
96 | template <typename T> |
97 | using unwrap_cv_reference = ::boost::mp11::mp_eval_if< |
98 | ::boost::parameter::aux::is_cv_reference_wrapper<T> |
99 | , ::boost::parameter::aux::unwrap_cv_reference_impl<T> |
100 | , ::std::remove_reference |
101 | , T |
102 | >; |
103 | #else // !defined(BOOST_PARAMETER_CAN_USE_MP11) || MSVC-14.0 |
104 | // This metafunction returns mpl::true_ if T is of type |
105 | // reference_wrapper<U> cv. |
106 | template <typename T> |
107 | struct is_cv_reference_wrapper |
108 | { |
109 | BOOST_STATIC_CONSTANT( |
110 | bool, value = ( |
111 | sizeof( |
112 | ::boost::parameter::aux::is_cv_reference_wrapper_check( |
113 | static_cast< |
114 | typename ::boost::remove_reference<T>::type* |
115 | >(BOOST_PARAMETER_AUX_PP_NULLPTR) |
116 | ) |
117 | ) == sizeof(::boost::parameter::aux::yes_tag) |
118 | ) |
119 | ); |
120 | |
121 | typedef boost::mpl::bool_< |
122 | #if BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x564)) |
123 | is_cv_reference_wrapper:: |
124 | #endif |
125 | value> type; |
126 | }; |
127 | |
128 | #if BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x564)) || \ |
129 | BOOST_WORKAROUND(BOOST_GCC, < 40000) |
130 | template < |
131 | typename T |
132 | , typename = typename ::boost::parameter::aux |
133 | ::is_cv_reference_wrapper<T>::type |
134 | > |
135 | struct unwrap_cv_reference : ::boost::remove_reference<T> |
136 | { |
137 | }; |
138 | |
139 | template <typename T> |
140 | struct unwrap_cv_reference<T const,::boost::mpl::false_> |
141 | { |
142 | typedef T const type; |
143 | }; |
144 | |
145 | template <typename T> |
146 | struct unwrap_cv_reference<T,::boost::mpl::true_> : T |
147 | { |
148 | }; |
149 | #else // no Borland or GCC 3- workarounds needed |
150 | // Needed for unwrap_cv_reference below. T might be const, so |
151 | // eval_if<> might fail because of deriving from T const on EDG. |
152 | template <typename T> |
153 | struct unwrap_cv_reference_impl : ::boost::remove_reference<T>::type |
154 | { |
155 | }; |
156 | |
157 | // Produces the unwrapped type to hold a reference to in |
158 | // tagged_argument<>. Can't use boost::unwrap_reference<> here |
159 | // because it doesn't handle the case where T = reference_wrapper<U> cv. |
160 | template <typename T> |
161 | struct unwrap_cv_reference |
162 | : ::boost::mpl::eval_if< |
163 | ::boost::parameter::aux::is_cv_reference_wrapper<T> |
164 | , ::boost::parameter::aux::unwrap_cv_reference_impl<T> |
165 | , ::boost::remove_reference<T> |
166 | > |
167 | { |
168 | }; |
169 | #endif // Borland or GCC 3- workarounds needed |
170 | #endif // BOOST_PARAMETER_CAN_USE_MP11 && not MSVC-14.0 |
171 | }}} // namespace boost::parameter::aux |
172 | |
173 | #endif // include guard |
174 | |
175 | |