/*============================================================================= Copyright (c) 2016 Lee Clagett Copyright (c) 2018 Kohei Takahashi Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) ==============================================================================*/ #ifndef FUSION_AND_07152016_1625 #define FUSION_AND_07152016_1625 #include <boost/config.hpp> #include <boost/config/workaround.hpp> #include <boost/type_traits/integral_constant.hpp> #if defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) #error fusion::detail::and_ requires variadic templates #endif namespace boost { namespace fusion { namespace detail { #if defined(BOOST_NO_CXX17_FOLD_EXPRESSIONS) \ || BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1913)) template<typename ...Cond> struct and_impl : false_type {}; template<typename ...T> struct and_impl<integral_constant<T, true>...> : true_type {}; // This specialization is necessary to avoid MSVC-12 variadics bug. template<bool ...Cond> struct and_impl1 : and_impl<integral_constant<bool, Cond>...> {}; /* fusion::detail::and_ differs from mpl::and_ in the following ways: - The empty set is valid and returns true - A single element set is valid and returns the identity - There is no upper bound on the set size - The conditions are evaluated at once, and are not short-circuited. This reduces instantations when returning true; the implementation is not recursive. */ template<typename ...Cond> struct and_ : and_impl1<Cond::value...> {}; #else template <typename ...Cond> struct and_ : integral_constant<bool, ((bool)Cond::value && ...)> {}; #endif }}} #endif // FUSION_AND_07152016_1625