disjunction.hpp

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/*
Copyright Barrett Adair 2015-2017
 
Distributed under the Boost Software License, Version 1.0.
(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
 
*/
 
#ifndef BOOST_CLBL_TRTS_DETAIL_POLYFILLS_DISJUNCTION_HPP
#define BOOST_CLBL_TRTS_DETAIL_POLYFILLS_DISJUNCTION_HPP
 
#undef BOOST_CLBL_TRTS_DISJUNCTION
#define BOOST_CLBL_TRTS_DISJUNCTION(...) \
    ::boost::callable_traits::detail::disjunction<__VA_ARGS__>
 
namespace boost { namespace callable_traits { namespace detail {
 
//polyfill for C++17 std::disjunction
template<typename...>
struct disjunction : std::false_type {};
 
template<typename T>
struct disjunction<T> : T {};
 
template<typename T, typename... Ts>
struct disjunction<T, Ts...>
    : std::conditional<T::value != false, T, disjunction<Ts...>>::type {};
 
}}} // namespace boost::callable_traits::detail
 
#endif // #ifndef BOOST_CLBL_TRTS_DETAIL_POLYFILLS_DISJUNCTION_HPP