ceph/src/boost/libs/asio/test/properties/cpp03/can_prefer_not_applicable_free_require.cpp

   1 //
   2 // cpp03/can_prefer_not_applicable_free_require.cpp
   3 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   4 //
   5 // Copyright (c) 2003-2022 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/prefer.hpp>
  12 #include <cassert>
  13
  14 template <int>
  15 struct prop
  16 {
  17   static const bool is_preferable = true;
  18 };
  19
  20 template <int>
  21 struct object
  22 {
  23   template <int N>
  24   friend object<N> require(const object&, prop<N>)
  25   {
  26     return object<N>();
  27   }
  28 };
  29
  30 namespace boost {
  31 namespace asio {
  32 namespace traits {
  33
  34 template<int N, int M>
  35 struct require_free<object<N>, prop<M> >
  36 {
  37   static const bool is_valid = true;
  38   static const bool is_noexcept = true;
  39   typedef object<M> result_type;
  40 };
  41
  42 } // namespace traits
  43 } // namespace asio
  44 } // namespace boost
  45
  46 int main()
  47 {
  48   assert((!boost::asio::can_prefer<object<1>, prop<2> >::value));
  49   assert((!boost::asio::can_prefer<object<1>, prop<2>, prop<3> >::value));
  50   assert((!boost::asio::can_prefer<object<1>, prop<2>, prop<3>, prop<4> >::value));
  51   assert((!boost::asio::can_prefer<const object<1>, prop<2> >::value));
  52   assert((!boost::asio::can_prefer<const object<1>, prop<2>, prop<3> >::value));
  53   assert((!boost::asio::can_prefer<const object<1>, prop<2>, prop<3>, prop<4> >::value));
  54 }