mirror of
https://github.com/ecency/ecency-mobile.git
synced 2024-12-23 05:13:04 +03:00
132 lines
4.9 KiB
C++
132 lines
4.9 KiB
C++
/*!
|
|
@file
|
|
Defines `boost::hana::monadic_fold_right`.
|
|
|
|
@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_MONADIC_FOLD_RIGHT_HPP
|
|
#define BOOST_HANA_MONADIC_FOLD_RIGHT_HPP
|
|
|
|
#include <boost/hana/fwd/monadic_fold_right.hpp>
|
|
|
|
#include <boost/hana/chain.hpp>
|
|
#include <boost/hana/concept/foldable.hpp>
|
|
#include <boost/hana/concept/monad.hpp>
|
|
#include <boost/hana/config.hpp>
|
|
#include <boost/hana/core/dispatch.hpp>
|
|
#include <boost/hana/detail/decay.hpp>
|
|
#include <boost/hana/fold_left.hpp>
|
|
#include <boost/hana/functional/curry.hpp>
|
|
#include <boost/hana/functional/partial.hpp>
|
|
#include <boost/hana/lift.hpp>
|
|
|
|
#include <type_traits>
|
|
|
|
|
|
BOOST_HANA_NAMESPACE_BEGIN
|
|
template <typename M>
|
|
struct monadic_fold_right_t {
|
|
#ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
|
|
static_assert(hana::Monad<M>::value,
|
|
"hana::monadic_fold_right<M> requires 'M' to be a Monad");
|
|
#endif
|
|
|
|
template <typename Xs, typename State, typename F>
|
|
constexpr decltype(auto) operator()(Xs&& xs, State&& state, F&& f) const {
|
|
using S = typename hana::tag_of<Xs>::type;
|
|
using MonadicFoldRight = BOOST_HANA_DISPATCH_IF(monadic_fold_right_impl<S>,
|
|
hana::Foldable<S>::value
|
|
);
|
|
|
|
#ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
|
|
static_assert(hana::Foldable<S>::value,
|
|
"hana::monadic_fold_right<M>(xs, state, f) requires 'xs' to be Foldable");
|
|
#endif
|
|
|
|
return MonadicFoldRight::template apply<M>(static_cast<Xs&&>(xs),
|
|
static_cast<State&&>(state),
|
|
static_cast<F&&>(f));
|
|
}
|
|
|
|
template <typename Xs, typename F>
|
|
constexpr decltype(auto) operator()(Xs&& xs, F&& f) const {
|
|
using S = typename hana::tag_of<Xs>::type;
|
|
using MonadicFoldRight = BOOST_HANA_DISPATCH_IF(monadic_fold_right_impl<S>,
|
|
hana::Foldable<S>::value
|
|
);
|
|
|
|
#ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
|
|
static_assert(hana::Foldable<S>::value,
|
|
"hana::monadic_fold_right<M>(xs, f) requires 'xs' to be Foldable");
|
|
#endif
|
|
return MonadicFoldRight::template apply<M>(static_cast<Xs&&>(xs),
|
|
static_cast<F&&>(f));
|
|
}
|
|
};
|
|
|
|
namespace detail {
|
|
struct foldrM_helper {
|
|
template <typename F, typename K, typename X, typename Z>
|
|
constexpr decltype(auto) operator()(F&& f, K&& k, X&& x, Z&& z) const {
|
|
return hana::chain(
|
|
static_cast<F&&>(f)(
|
|
static_cast<X&&>(x),
|
|
static_cast<Z&&>(z)
|
|
),
|
|
static_cast<K&&>(k)
|
|
);
|
|
}
|
|
};
|
|
|
|
template <typename End, typename M, typename F>
|
|
struct monadic_foldr1_helper {
|
|
F f;
|
|
template <typename X, typename Y>
|
|
constexpr decltype(auto) operator()(X&& x, Y&& y) const
|
|
{ return f(static_cast<X&&>(x), static_cast<Y&&>(y)); }
|
|
template <typename X>
|
|
constexpr decltype(auto) operator()(X&& x, End) const
|
|
{ return hana::lift<M>(static_cast<X&&>(x)); }
|
|
};
|
|
}
|
|
|
|
template <typename T, bool condition>
|
|
struct monadic_fold_right_impl<T, when<condition>> : default_ {
|
|
// with state
|
|
template <typename M, typename Xs, typename S, typename F>
|
|
static constexpr decltype(auto) apply(Xs&& xs, S&& s, F&& f) {
|
|
return hana::fold_left(
|
|
static_cast<Xs&&>(xs),
|
|
hana::lift<M>,
|
|
hana::curry<3>(hana::partial(
|
|
detail::foldrM_helper{}, static_cast<F&&>(f)
|
|
))
|
|
)(static_cast<S&&>(s));
|
|
}
|
|
|
|
// without state
|
|
template <typename M, typename Xs, typename F>
|
|
static constexpr decltype(auto) apply(Xs&& xs, F&& f) {
|
|
struct end { };
|
|
using G = detail::monadic_foldr1_helper<end, M, typename detail::decay<F>::type>;
|
|
decltype(auto) result = hana::monadic_fold_right<M>(
|
|
static_cast<Xs&&>(xs),
|
|
end{},
|
|
G{static_cast<F&&>(f)}
|
|
);
|
|
|
|
static_assert(!std::is_same<
|
|
std::remove_reference_t<decltype(result)>,
|
|
decltype(hana::lift<M>(end{}))
|
|
>{},
|
|
"hana::monadic_fold_right<M>(xs, f) requires 'xs' to be non-empty");
|
|
return result;
|
|
}
|
|
};
|
|
BOOST_HANA_NAMESPACE_END
|
|
|
|
#endif // !BOOST_HANA_MONADIC_FOLD_RIGHT_HPP
|