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

   1 //
   2 // cpp03/prefer_member_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   object<N> require(prop<N>) const
  25   {
  26     return object<N>();
  27   }
  28 };
  29
  30 namespace boost {
  31 namespace asio {
  32
  33 template<int N, int M>
  34 struct is_applicable_property<object<N>, prop<M> >
  35 {
  36   static const bool value = true;
  37 };
  38
  39 namespace traits {
  40
  41 template<int N, int M>
  42 struct require_member<object<N>, prop<M> >
  43 {
  44   static const bool is_valid = true;
  45   static const bool is_noexcept = true;
  46   typedef object<M> result_type;
  47 };
  48
  49 } // namespace traits
  50 } // namespace asio
  51 } // namespace boost
  52
  53 int main()
  54 {
  55   object<1> o1 = {};
  56   object<2> o2 = boost::asio::prefer(o1, prop<2>());
  57   object<3> o3 = boost::asio::prefer(o1, prop<2>(), prop<3>());
  58   object<4> o4 = boost::asio::prefer(o1, prop<2>(), prop<3>(), prop<4>());
  59   (void)o2;
  60   (void)o3;
  61   (void)o4;
  62
  63   const object<1> o5 = {};
  64   object<2> o6 = boost::asio::prefer(o5, prop<2>());
  65   object<3> o7 = boost::asio::prefer(o5, prop<2>(), prop<3>());
  66   object<4> o8 = boost::asio::prefer(o5, prop<2>(), prop<3>(), prop<4>());
  67   (void)o6;
  68   (void)o7;
  69   (void)o8;
  70 }