mirror of
https://github.com/ecency/ecency-mobile.git
synced 2024-12-04 17:33:55 +03:00
93 lines
3.2 KiB
C++
93 lines
3.2 KiB
C++
/*!
|
|
@file
|
|
Defines `boost::hana::count_if`.
|
|
|
|
@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_COUNT_IF_HPP
|
|
#define BOOST_HANA_COUNT_IF_HPP
|
|
|
|
#include <boost/hana/fwd/count_if.hpp>
|
|
|
|
#include <boost/hana/concept/foldable.hpp>
|
|
#include <boost/hana/config.hpp>
|
|
#include <boost/hana/core/dispatch.hpp>
|
|
#include <boost/hana/detail/algorithm.hpp>
|
|
#include <boost/hana/detail/fast_and.hpp>
|
|
#include <boost/hana/integral_constant.hpp>
|
|
#include <boost/hana/unpack.hpp>
|
|
|
|
#include <cstddef>
|
|
#include <type_traits>
|
|
#include <utility>
|
|
|
|
|
|
BOOST_HANA_NAMESPACE_BEGIN
|
|
//! @cond
|
|
template <typename Xs, typename Pred>
|
|
constexpr auto count_if_t::operator()(Xs&& xs, Pred&& pred) const {
|
|
using S = typename hana::tag_of<Xs>::type;
|
|
using CountIf = BOOST_HANA_DISPATCH_IF(count_if_impl<S>,
|
|
hana::Foldable<S>::value
|
|
);
|
|
|
|
#ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
|
|
static_assert(hana::Foldable<S>::value,
|
|
"hana::count_if(xs, pred) requires 'xs' to be Foldable");
|
|
#endif
|
|
|
|
return CountIf::apply(static_cast<Xs&&>(xs),
|
|
static_cast<Pred&&>(pred));
|
|
}
|
|
//! @endcond
|
|
|
|
namespace detail {
|
|
template <typename Pred>
|
|
struct count_pred {
|
|
Pred pred;
|
|
template <typename ...Xs, typename = typename std::enable_if<
|
|
detail::fast_and<
|
|
Constant<decltype((*pred)(std::declval<Xs&&>()))>::value...
|
|
>::value
|
|
>::type>
|
|
constexpr auto operator()(Xs&& ...xs) const {
|
|
constexpr bool results[] = {false, // <-- avoid empty array
|
|
static_cast<bool>(hana::value<decltype((*pred)(static_cast<Xs&&>(xs)))>())...
|
|
};
|
|
constexpr std::size_t total = detail::count(
|
|
results, results + sizeof(results), true
|
|
);
|
|
return hana::size_c<total>;
|
|
}
|
|
|
|
template <typename ...Xs, typename = void, typename = typename std::enable_if<
|
|
!detail::fast_and<
|
|
Constant<decltype((*pred)(std::declval<Xs&&>()))>::value...
|
|
>::value
|
|
>::type>
|
|
constexpr auto operator()(Xs&& ...xs) const {
|
|
std::size_t total = 0;
|
|
using Swallow = std::size_t[];
|
|
(void)Swallow{0, ((*pred)(static_cast<Xs&&>(xs)) ? ++total : 0)...};
|
|
return total;
|
|
}
|
|
};
|
|
}
|
|
|
|
template <typename T, bool condition>
|
|
struct count_if_impl<T, when<condition>> : default_ {
|
|
template <typename Xs, typename Pred>
|
|
static constexpr decltype(auto) apply(Xs&& xs, Pred&& pred) {
|
|
// We use a pointer instead of a reference to avoid a Clang ICE.
|
|
return hana::unpack(static_cast<Xs&&>(xs),
|
|
detail::count_pred<decltype(&pred)>{&pred}
|
|
);
|
|
}
|
|
};
|
|
BOOST_HANA_NAMESPACE_END
|
|
|
|
#endif // !BOOST_HANA_COUNT_IF_HPP
|