1 // Copyright David Abrahams 2005.
2 // Distributed under the Boost Software License, Version 1.0.
3 // (See accompanying file LICENSE_1_0.txt or copy at
4 // http://www.boost.org/LICENSE_1_0.txt)
5 
6 #ifndef BOOST_PARAMETER_BINDING_DWA200558_HPP
7 #define BOOST_PARAMETER_BINDING_DWA200558_HPP
8 
9 #include <boost/parameter/aux_/void.hpp>
10 #include <boost/parameter/config.hpp>
11 
12 #if defined(BOOST_PARAMETER_CAN_USE_MP11)
13 #include <boost/mp11/integral.hpp>
14 #include <boost/mp11/list.hpp>
15 #include <boost/mp11/utility.hpp>
16 #include <type_traits>
17 #else
18 #include <boost/mpl/bool.hpp>
19 #include <boost/mpl/if.hpp>
20 #include <boost/mpl/eval_if.hpp>
21 #include <boost/mpl/identity.hpp>
22 #include <boost/mpl/apply_wrap.hpp>
23 #include <boost/mpl/assert.hpp>
24 #include <boost/type_traits/is_same.hpp>
25 #endif
26 
27 namespace boost { namespace parameter {
28 
29     // A metafunction that, given an argument pack, returns the reference type
30     // of the parameter identified by the given keyword.  If no such parameter
31     // has been specified, returns Default
32 
33     template <typename Parameters, typename Keyword, typename Default>
34     struct binding0
35     {
36 #if defined(BOOST_PARAMETER_CAN_USE_MP11)
37         using type = ::boost::mp11::mp_apply_q<
38             typename Parameters::binding
39           , ::boost::mp11::mp_list<Keyword,Default,::boost::mp11::mp_true>
40         >;
41 
42         static_assert(
43             ::boost::mp11::mp_if<
44                 ::std::is_same<Default,::boost::parameter::void_>
45               , ::boost::mp11::mp_if<
46                     ::std::is_same<type,::boost::parameter::void_>
47                   , ::boost::mp11::mp_false
48                   , ::boost::mp11::mp_true
49                 >
50               , ::boost::mp11::mp_true
51             >::value
52           , "required parameters must not result in void_ type"
53         );
54 #else   // !defined(BOOST_PARAMETER_CAN_USE_MP11)
55         typedef typename ::boost::mpl::apply_wrap3<
56             typename Parameters::binding
57           , Keyword
58           , Default
59           , ::boost::mpl::true_
60         >::type type;
61 
62         BOOST_MPL_ASSERT((
63             typename ::boost::mpl::eval_if<
64                 ::boost::is_same<Default,::boost::parameter::void_>
65               , ::boost::mpl::if_<
66                     ::boost::is_same<type,::boost::parameter::void_>
67                   , ::boost::mpl::false_
68                   , ::boost::mpl::true_
69                 >
70               , ::boost::mpl::true_
71             >::type
72         ));
73 #endif  // BOOST_PARAMETER_CAN_USE_MP11
74     };
75 
76 #if defined(BOOST_PARAMETER_CAN_USE_MP11)
77     template <typename Placeholder, typename Keyword, typename Default>
78     struct binding1
79     {
80         using type = ::boost::mp11::mp_apply_q<
81             Placeholder
82           , ::boost::mp11::mp_list<Keyword,Default,::boost::mp11::mp_true>
83         >;
84 
85         static_assert(
86             ::boost::mp11::mp_if<
87                 ::std::is_same<Default,::boost::parameter::void_>
88               , ::boost::mp11::mp_if<
89                     ::std::is_same<type,::boost::parameter::void_>
90                   , ::boost::mp11::mp_false
91                   , ::boost::mp11::mp_true
92                 >
93               , ::boost::mp11::mp_true
94             >::value
95           , "required parameters must not result in void_ type"
96         );
97     };
98 #endif  // BOOST_PARAMETER_CAN_USE_MP11
99 }} // namespace boost::parameter
100 
101 #include <boost/parameter/aux_/is_placeholder.hpp>
102 
103 namespace boost { namespace parameter {
104 
105     template <
106         typename Parameters
107       , typename Keyword
108       , typename Default = ::boost::parameter::void_
109     >
110     struct binding
111 #if !defined(BOOST_PARAMETER_CAN_USE_MP11)
112       : ::boost::mpl::eval_if<
113             ::boost::parameter::aux::is_mpl_placeholder<Parameters>
114           , ::boost::mpl::identity<int>
115           , ::boost::parameter::binding0<Parameters,Keyword,Default>
116         >
117 #endif
118     {
119 #if defined(BOOST_PARAMETER_CAN_USE_MP11)
120         using type = typename ::boost::mp11::mp_if<
121             ::boost::parameter::aux::is_mpl_placeholder<Parameters>
122           , ::boost::mp11::mp_identity<int>
123           , ::boost::mp11::mp_if<
124                 ::boost::parameter::aux::is_mp11_placeholder<Parameters>
125               , ::boost::parameter::binding1<Parameters,Keyword,Default>
126               , ::boost::parameter::binding0<Parameters,Keyword,Default>
127             >
128         >::type;
129 #endif
130     };
131 }} // namespace boost::parameter
132 
133 #include <boost/parameter/aux_/result_of0.hpp>
134 
135 namespace boost { namespace parameter {
136 
137     // A metafunction that, given an argument pack, returns the reference type
138     // of the parameter identified by the given keyword.  If no such parameter
139     // has been specified, returns the type returned by invoking DefaultFn
140     template <typename Parameters, typename Keyword, typename DefaultFn>
141     struct lazy_binding
142     {
143 #if defined(BOOST_PARAMETER_CAN_USE_MP11)
144         using type = ::boost::mp11::mp_apply_q<
145             typename Parameters::binding
146           , ::boost::mp11::mp_list<
147                 Keyword
148               , typename ::boost::parameter::aux::result_of0<DefaultFn>::type
149               , ::boost::mp11::mp_true
150             >
151         >;
152 #else
153         typedef typename ::boost::mpl::apply_wrap3<
154             typename Parameters::binding
155           , Keyword
156           , typename ::boost::parameter::aux::result_of0<DefaultFn>::type
157           , ::boost::mpl::true_
158         >::type type;
159 #endif  // BOOST_PARAMETER_CAN_USE_MP11
160     };
161 }} // namespace boost::parameter
162 
163 #endif  // include guard
164 
165