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Diffstat (limited to 'boost/hana/chain.hpp')
-rw-r--r-- | boost/hana/chain.hpp | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/boost/hana/chain.hpp b/boost/hana/chain.hpp new file mode 100644 index 0000000000..da9de375f2 --- /dev/null +++ b/boost/hana/chain.hpp @@ -0,0 +1,50 @@ +/*! +@file +Defines `boost::hana::chain`. + +@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_CHAIN_HPP +#define BOOST_HANA_CHAIN_HPP + +#include <boost/hana/fwd/chain.hpp> + +#include <boost/hana/concept/monad.hpp> +#include <boost/hana/config.hpp> +#include <boost/hana/core/dispatch.hpp> +#include <boost/hana/flatten.hpp> +#include <boost/hana/transform.hpp> + + +BOOST_HANA_NAMESPACE_BEGIN + //! @cond + template <typename Xs, typename F> + constexpr decltype(auto) chain_t::operator()(Xs&& xs, F&& f) const { + using M = typename hana::tag_of<Xs>::type; + using Chain = BOOST_HANA_DISPATCH_IF(chain_impl<M>, + hana::Monad<M>::value + ); + + #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS + static_assert(hana::Monad<M>::value, + "hana::chain(xs, f) requires 'xs' to be a Monad"); + #endif + + return Chain::apply(static_cast<Xs&&>(xs), static_cast<F&&>(f)); + } + //! @endcond + + template <typename M, bool condition> + struct chain_impl<M, when<condition>> : default_ { + template <typename Xs, typename F> + static constexpr auto apply(Xs&& xs, F&& f) { + return hana::flatten(hana::transform(static_cast<Xs&&>(xs), + static_cast<F&&>(f))); + } + }; +BOOST_HANA_NAMESPACE_END + +#endif // !BOOST_HANA_CHAIN_HPP |