1 // 2 // cpp11/require_concept_static.cpp 3 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 4 // 5 // Copyright (c) 2003-2020 Christopher M. Kohlhoff (chris at kohlhoff dot com) 6 // 7 // Distributed under the Boost Software License, Version 1.0. (See accompanying 8 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 9 // 10 11 #include <boost/asio/require_concept.hpp> 12 #include <cassert> 13 14 template <int> 15 struct prop 16 { 17 static constexpr bool is_requirable_concept = true; 18 }; 19 20 template <int> 21 struct object 22 { 23 }; 24 25 namespace boost { 26 namespace asio { 27 28 template<int N, int M> 29 struct is_applicable_property<object<N>, prop<M> > 30 { 31 static constexpr bool value = true; 32 }; 33 34 namespace traits { 35 36 template<int N> 37 struct static_require_concept<object<N>, prop<N> > 38 { 39 static constexpr bool is_valid = true; 40 }; 41 42 } // namespace traits 43 } // namespace asio 44 } // namespace boost 45 main()46int main() 47 { 48 object<1> o1 = {}; 49 const object<1>& o2 = boost::asio::require_concept(o1, prop<1>()); 50 assert(&o1 == &o2); 51 (void)o2; 52 53 const object<1> o3 = {}; 54 const object<1>& o4 = boost::asio::require_concept(o3, prop<1>()); 55 assert(&o3 == &o4); 56 (void)o4; 57 58 constexpr object<1> o5 = boost::asio::require_concept(object<1>(), prop<1>()); 59 (void)o5; 60 } 61