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- /*!
- @file
- Defines `boost::hana::is_subset`.
- @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_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>
- BOOST_HANA_NAMESPACE_BEGIN
- //! @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)));
- }
- };
- BOOST_HANA_NAMESPACE_END
- #endif // !BOOST_HANA_IS_SUBSET_HPP
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