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Diffstat (limited to 'boost/hana/for_each.hpp')
| -rw-r--r-- | boost/hana/for_each.hpp | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/boost/hana/for_each.hpp b/boost/hana/for_each.hpp new file mode 100644 index 0000000000..091b83c38c --- /dev/null +++ b/boost/hana/for_each.hpp @@ -0,0 +1,62 @@ +/*! +@file +Defines `boost::hana::for_each`. + +@copyright Louis Dionne 2013-2016 +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 |