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Diffstat (limited to 'boost/hana/is_subset.hpp')
-rw-r--r-- | boost/hana/is_subset.hpp | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/boost/hana/is_subset.hpp b/boost/hana/is_subset.hpp new file mode 100644 index 0000000000..546bc9baa5 --- /dev/null +++ b/boost/hana/is_subset.hpp @@ -0,0 +1,84 @@ +/*! +@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 |