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-rw-r--r--boost/hana/is_subset.hpp84
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+/*!
+@file
+Defines `boost::hana::is_subset`.
+
+@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_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