mirror of
https://github.com/ecency/ecency-mobile.git
synced 2024-12-22 12:51:42 +03:00
56 lines
1.7 KiB
C++
56 lines
1.7 KiB
C++
/*!
|
|
@file
|
|
Defines `boost::hana::then`.
|
|
|
|
@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_THEN_HPP
|
|
#define BOOST_HANA_THEN_HPP
|
|
|
|
#include <boost/hana/fwd/then.hpp>
|
|
|
|
#include <boost/hana/chain.hpp>
|
|
#include <boost/hana/concept/monad.hpp>
|
|
#include <boost/hana/config.hpp>
|
|
#include <boost/hana/core/dispatch.hpp>
|
|
#include <boost/hana/functional/always.hpp>
|
|
|
|
|
|
BOOST_HANA_NAMESPACE_BEGIN
|
|
//! @cond
|
|
template <typename Before, typename Xs>
|
|
constexpr decltype(auto) then_t::operator()(Before&& before, Xs&& xs) const {
|
|
using M = typename hana::tag_of<Before>::type;
|
|
using Then = BOOST_HANA_DISPATCH_IF(then_impl<M>,
|
|
hana::Monad<M>::value &&
|
|
hana::Monad<Xs>::value
|
|
);
|
|
|
|
#ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
|
|
static_assert(hana::Monad<M>::value,
|
|
"hana::then(before, xs) requires 'before' to be a Monad");
|
|
|
|
static_assert(hana::Monad<Xs>::value,
|
|
"hana::then(before, xs) requires 'xs' to be a Monad");
|
|
#endif
|
|
|
|
return Then::apply(static_cast<Before&&>(before),
|
|
static_cast<Xs&&>(xs));
|
|
}
|
|
//! @endcond
|
|
|
|
template <typename M, bool condition>
|
|
struct then_impl<M, when<condition>> : default_ {
|
|
template <typename Xs, typename Ys>
|
|
static constexpr decltype(auto) apply(Xs&& xs, Ys&& ys) {
|
|
return hana::chain(static_cast<Xs&&>(xs),
|
|
hana::always(static_cast<Ys&&>(ys)));
|
|
}
|
|
};
|
|
BOOST_HANA_NAMESPACE_END
|
|
|
|
#endif // !BOOST_HANA_THEN_HPP
|