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/*!
@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
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