52 lines
1.6 KiB
C++
52 lines
1.6 KiB
C++
/*!
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@file
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Defines `boost::hana::monadic_compose`.
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@copyright Louis Dionne 2013-2016
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Distributed under the Boost Software License, Version 1.0.
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(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
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*/
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#ifndef BOOST_HANA_MONADIC_COMPOSE_HPP
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#define BOOST_HANA_MONADIC_COMPOSE_HPP
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#include <boost/hana/fwd/monadic_compose.hpp>
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#include <boost/hana/chain.hpp>
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#include <boost/hana/concept/monad.hpp>
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#include <boost/hana/config.hpp>
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#include <boost/hana/core/dispatch.hpp>
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#include <boost/hana/functional/partial.hpp>
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BOOST_HANA_NAMESPACE_BEGIN
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namespace detail {
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struct monadic_compose_helper {
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template <typename F, typename G, typename X>
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constexpr decltype(auto) operator()(F&& f, G&& g, X&& x) const {
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using M = typename hana::tag_of<decltype(g(x))>::type;
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#ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
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static_assert(hana::Monad<M>::value,
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"hana::monadic_compose(f, g) requires 'g' to return a monadic value");
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#endif
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return hana::chain(static_cast<G&&>(g)(static_cast<X&&>(x)),
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static_cast<F&&>(f));
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}
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};
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}
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//! @cond
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template <typename F, typename G>
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constexpr auto monadic_compose_t::operator()(F&& f, G&& g) const {
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return hana::partial(detail::monadic_compose_helper{},
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static_cast<F&&>(f),
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static_cast<G&&>(g)
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);
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}
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//! @endcond
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BOOST_HANA_NAMESPACE_END
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#endif // !BOOST_HANA_MONADIC_COMPOSE_HPP
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