Edit: /usr/include/boost/hana/count_if.hpp (3137B)
/*!
@file
Defines `boost::hana::count_if`.
@copyright Louis Dionne 2013-2017
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
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
BOOST_HANA_NAMESPACE_BEGIN
//! @cond
template
constexpr auto count_if_t::operator()(Xs&& xs, Pred&& pred) const {
using S = typename hana::tag_of::type;
using CountIf = BOOST_HANA_DISPATCH_IF(count_if_impl,
hana::Foldable::value
);
#ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
static_assert(hana::Foldable::value,
"hana::count_if(xs, pred) requires 'xs' to be Foldable");
#endif
return CountIf::apply(static_cast(xs),
static_cast(pred));
}
//! @endcond
namespace detail {
template
struct count_pred {
Pred pred;
template ()))>::value...
>::value
>::type>
constexpr auto operator()(Xs&& ...xs) const {
constexpr bool results[] = {false, // <-- avoid empty array
static_cast(hana::value(xs)))>())...
};
constexpr std::size_t total = detail::count(
results, results + sizeof(results), true
);
return hana::size_c;
}
template ()))>::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)) ? ++total : 0)...};
return total;
}
};
}
template
struct count_if_impl> : default_ {
template
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),
detail::count_pred{&pred}
);
}
};
BOOST_HANA_NAMESPACE_END
#endif // !BOOST_HANA_COUNT_IF_HPP