/*! @file Defines `boost::hana::for_each`. @copyright Louis Dionne 2013-2017 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_HANA_FOR_EACH_HPP #define BOOST_HANA_FOR_EACH_HPP #include <boost/hana/fwd/for_each.hpp> #include <boost/hana/concept/foldable.hpp> #include <boost/hana/config.hpp> #include <boost/hana/core/dispatch.hpp> #include <boost/hana/unpack.hpp> BOOST_HANA_NAMESPACE_BEGIN //! @cond template <typename Xs, typename F> constexpr void for_each_t::operator()(Xs&& xs, F&& f) const { using S = typename hana::tag_of<Xs>::type; using ForEach = BOOST_HANA_DISPATCH_IF(for_each_impl<S>, hana::Foldable<S>::value ); #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS static_assert(hana::Foldable<S>::value, "hana::for_each(xs, f) requires 'xs' to be Foldable"); #endif return ForEach::apply(static_cast<Xs&&>(xs), static_cast<F&&>(f)); } //! @endcond namespace detail { template <typename F> struct on_each { F f; template <typename ...Xs> constexpr void operator()(Xs&& ...xs) const { using Swallow = int[]; (void)Swallow{0, ((void)(*f)(static_cast<Xs&&>(xs)), 0)...}; } }; } template <typename T, bool condition> struct for_each_impl<T, when<condition>> : default_ { template <typename Xs, typename F> static constexpr void apply(Xs&& xs, F&& f) { // We use a pointer instead of a reference to avoid a Clang ICE. hana::unpack(static_cast<Xs&&>(xs), detail::on_each<decltype(&f)>{&f}); } }; BOOST_HANA_NAMESPACE_END #endif // !BOOST_HANA_FOR_EACH_HPP