ceph/src/boost/boost/callable_traits/detail/polyfills/disjunction.hpp

   1 /*
   2 Copyright Barrett Adair 2015-2017
   3
   4 Distributed under the Boost Software License, Version 1.0.
   5 (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
   6
   7 */
   8
   9 #ifndef BOOST_CLBL_TRTS_DETAIL_POLYFILLS_DISJUNCTION_HPP
  10 #define BOOST_CLBL_TRTS_DETAIL_POLYFILLS_DISJUNCTION_HPP
  11
  12 #undef BOOST_CLBL_TRTS_DISJUNCTION
  13 #define BOOST_CLBL_TRTS_DISJUNCTION(...) \
  14     ::boost::callable_traits::detail::disjunction<__VA_ARGS__>
  15
  16 namespace boost { namespace callable_traits { namespace detail {
  17
  18 //polyfill for C++17 std::disjunction
  19 template<typename...>
  20 struct disjunction : std::false_type {};
  21
  22 template<typename T>
  23 struct disjunction<T> : T {};
  24
  25 template<typename T, typename... Ts>
  26 struct disjunction<T, Ts...>
  27     : std::conditional<T::value != false, T, disjunction<Ts...>>::type {};
  28
  29 }}} // namespace boost::callable_traits::detail
  30
  31 #endif // #ifndef BOOST_CLBL_TRTS_DETAIL_POLYFILLS_DISJUNCTION_HPP