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 Hu Chunming
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/*!
@file
Defines `boost::hana::is_subset`.
Copyright Louis Dionne 2013-2022
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_IS_SUBSET_HPP
#define BOOST_HANA_IS_SUBSET_HPP
#include <boost/hana/fwd/is_subset.hpp>
#include <boost/hana/all_of.hpp>
#include <boost/hana/concept/searchable.hpp>
#include <boost/hana/config.hpp>
#include <boost/hana/contains.hpp>
#include <boost/hana/core/common.hpp>
#include <boost/hana/core/to.hpp>
#include <boost/hana/core/dispatch.hpp>
#include <boost/hana/detail/has_common_embedding.hpp>
#include <boost/hana/functional/partial.hpp>
namespace boost { namespace hana {
//! @cond
template <typename Xs, typename Ys>
constexpr auto is_subset_t::operator()(Xs&& xs, Ys&& ys) const {
using S1 = typename hana::tag_of<Xs>::type;
using S2 = typename hana::tag_of<Ys>::type;
using IsSubset = BOOST_HANA_DISPATCH_IF(
decltype(is_subset_impl<S1, S2>{}),
hana::Searchable<S1>::value &&
hana::Searchable<S2>::value &&
!is_default<is_subset_impl<S1, S2>>::value
);
#ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
static_assert(hana::Searchable<S1>::value,
"hana::is_subset(xs, ys) requires 'xs' to be Searchable");
static_assert(hana::Searchable<S2>::value,
"hana::is_subset(xs, ys) requires 'ys' to be Searchable");
static_assert(!is_default<is_subset_impl<S1, S2>>::value,
"hana::is_subset(xs, ys) requires 'xs' and 'ys' to be embeddable "
"in a common Searchable");
#endif
return IsSubset::apply(static_cast<Xs&&>(xs), static_cast<Ys&&>(ys));
}
//! @endcond
template <typename S1, typename S2, bool condition>
struct is_subset_impl<S1, S2, when<condition>> : default_ {
template <typename ...Args>
static constexpr auto apply(Args&& ...) = delete;
};
template <typename S, bool condition>
struct is_subset_impl<S, S, when<condition>> {
template <typename Xs, typename Ys>
static constexpr decltype(auto) apply(Xs&& xs, Ys&& ys) {
return hana::all_of(static_cast<Xs&&>(xs),
hana::partial(hana::contains, static_cast<Ys&&>(ys)));
}
};
// Cross-type overload
template <typename S1, typename S2>
struct is_subset_impl<S1, S2, when<
detail::has_nontrivial_common_embedding<Searchable, S1, S2>::value
>> {
using C = typename common<S1, S2>::type;
template <typename Xs, typename Ys>
static constexpr decltype(auto) apply(Xs&& xs, Ys&& ys) {
return hana::is_subset(hana::to<C>(static_cast<Xs&&>(xs)),
hana::to<C>(static_cast<Ys&&>(ys)));
}
};
}} // end namespace boost::hana
#endif // !BOOST_HANA_IS_SUBSET_HPP
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