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_ALWAYS_TRUE_PREDICATE_HPP
7 #define BOOST_PARAMETER_AUX_ALWAYS_TRUE_PREDICATE_HPP
8 
9 #include <boost/parameter/config.hpp>
10 #include <boost/mpl/bool.hpp>
11 
12 #if defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
13 #if defined(BOOST_PARAMETER_CAN_USE_MP11)
14 #include <boost/mp11/integral.hpp>
15 #endif
16 #else
17 #include <boost/mpl/always.hpp>
18 #endif
19 
20 namespace boost { namespace parameter { namespace aux {
21 
22 #if defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
23     struct always_true_predicate
24     {
25         template <typename ...>
26         struct apply
27         {
28             typedef ::boost::mpl::true_ type;
29         };
30 
31 #if defined(BOOST_PARAMETER_CAN_USE_MP11)
32         template <typename ...>
33         using fn = ::boost::mp11::mp_true;
34 #endif
35     };
36 #else
37     typedef ::boost::mpl::always< ::boost::mpl::true_> always_true_predicate;
38 #endif  // BOOST_NO_CXX11_VARIADIC_TEMPLATES
39 }}} // namespace boost::parameter::aux
40 
41 #endif  // include guard
42 
43