1 // Copyright Cromwell D. Enage 2019.
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_AUX_HAS_NESTED_TEMPLATE_FN_HPP
7 #define BOOST_PARAMETER_AUX_HAS_NESTED_TEMPLATE_FN_HPP
8 
9 #include <boost/parameter/aux_/yesno.hpp>
10 #include <boost/parameter/aux_/preprocessor/nullptr.hpp>
11 #include <boost/parameter/config.hpp>
12 
13 #if defined(BOOST_PARAMETER_CAN_USE_MP11)
14 #include <boost/mp11/integral.hpp>
15 #include <boost/mp11/utility.hpp>
16 #else
17 #include <boost/mpl/bool.hpp>
18 #include <boost/mpl/identity.hpp>
19 #endif
20 
21 namespace boost { namespace parameter { namespace aux {
22 
23 #if defined(BOOST_PARAMETER_CAN_USE_MP11)
24     template <template <typename ...> class F>
25     struct has_nested_template_fn_variadic
26     {
27     };
28 #else
29     template <template <typename P0, typename P1> class F>
30     struct has_nested_template_fn_arity_2
31     {
32     };
33 #endif
34 
35     template <typename T>
36     class has_nested_template_fn_impl
37     {
38         template <typename U>
39         static ::boost::parameter::aux::no_tag _check(...);
40 
41 #if defined(BOOST_PARAMETER_CAN_USE_MP11)
42         template <typename U>
43         static ::boost::parameter::aux::yes_tag
44             _check(
45                 ::boost::mp11::mp_identity<U> const volatile*
46               , ::boost::parameter::aux::has_nested_template_fn_variadic<
47                     U::template fn
48                 >* = BOOST_PARAMETER_AUX_PP_NULLPTR
49             );
50 #else
51         template <typename U>
52         static BOOST_CONSTEXPR ::boost::parameter::aux::yes_tag
53             _check(
54                 ::boost::mpl::identity<U> const volatile*
55               , ::boost::parameter::aux::has_nested_template_fn_arity_2<
56                     U::template fn
57                 >* = BOOST_PARAMETER_AUX_PP_NULLPTR
58             );
59 #endif
60 
61      public:
62 #if defined(BOOST_PARAMETER_CAN_USE_MP11)
63         using type = ::boost::mp11::mp_bool<
64 #else
65         typedef ::boost::mpl::bool_<
66 #endif
67             sizeof(
68                 ::boost::parameter::aux::has_nested_template_fn_impl<T>
69                 ::template _check<T>(
70                     static_cast<
71 #if defined(BOOST_PARAMETER_CAN_USE_MP11)
72                         ::boost::mp11::mp_identity<T> const volatile*
73 #else
74                         ::boost::mpl::identity<T> const volatile*
75 #endif
76                     >(BOOST_PARAMETER_AUX_PP_NULLPTR)
77                 )
78             ) == sizeof(::boost::parameter::aux::yes_tag)
79 #if defined(BOOST_PARAMETER_CAN_USE_MP11)
80         >;
81 #else
82         > type;
83 #endif
84     };
85 }}} // namespace boost::parameter::aux
86 
87 #if defined(BOOST_PARAMETER_CAN_USE_MP11)
88 #include <type_traits>
89 #else
90 #include <boost/type_traits/remove_const.hpp>
91 #endif
92 
93 namespace boost { namespace parameter { namespace aux {
94 
95     template <typename T>
96 #if defined(BOOST_PARAMETER_CAN_USE_MP11)
97     using has_nested_template_fn = typename ::boost::parameter::aux
98     ::has_nested_template_fn_impl<typename ::std::remove_const<T>::type>
99     ::type;
100 #else
101     struct has_nested_template_fn
102       : ::boost::parameter::aux::has_nested_template_fn_impl<
103             typename ::boost::remove_const<T>::type
104         >::type
105     {
106     };
107 #endif
108 }}} // namespace boost::parameter::aux
109 
110 #endif  // include guard
111 
112