85 lines
2.9 KiB
C++
85 lines
2.9 KiB
C++
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/*!
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@file
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Defines `boost::hana::is_subset`.
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@copyright Louis Dionne 2013-2016
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Distributed under the Boost Software License, Version 1.0.
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(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
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*/
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#ifndef BOOST_HANA_IS_SUBSET_HPP
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#define BOOST_HANA_IS_SUBSET_HPP
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#include <boost/hana/fwd/is_subset.hpp>
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#include <boost/hana/all_of.hpp>
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#include <boost/hana/concept/searchable.hpp>
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#include <boost/hana/config.hpp>
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#include <boost/hana/contains.hpp>
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#include <boost/hana/core/common.hpp>
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#include <boost/hana/core/to.hpp>
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#include <boost/hana/core/dispatch.hpp>
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#include <boost/hana/detail/has_common_embedding.hpp>
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#include <boost/hana/functional/partial.hpp>
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BOOST_HANA_NAMESPACE_BEGIN
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//! @cond
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template <typename Xs, typename Ys>
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constexpr auto is_subset_t::operator()(Xs&& xs, Ys&& ys) const {
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using S1 = typename hana::tag_of<Xs>::type;
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using S2 = typename hana::tag_of<Ys>::type;
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using IsSubset = BOOST_HANA_DISPATCH_IF(
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decltype(is_subset_impl<S1, S2>{}),
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hana::Searchable<S1>::value &&
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hana::Searchable<S2>::value &&
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!is_default<is_subset_impl<S1, S2>>::value
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);
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#ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
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static_assert(hana::Searchable<S1>::value,
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"hana::is_subset(xs, ys) requires 'xs' to be Searchable");
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static_assert(hana::Searchable<S2>::value,
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"hana::is_subset(xs, ys) requires 'ys' to be Searchable");
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static_assert(!is_default<is_subset_impl<S1, S2>>::value,
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"hana::is_subset(xs, ys) requires 'xs' and 'ys' to be embeddable "
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"in a common Searchable");
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#endif
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return IsSubset::apply(static_cast<Xs&&>(xs), static_cast<Ys&&>(ys));
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}
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//! @endcond
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template <typename S1, typename S2, bool condition>
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struct is_subset_impl<S1, S2, when<condition>> : default_ {
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template <typename ...Args>
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static constexpr auto apply(Args&& ...) = delete;
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};
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template <typename S, bool condition>
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struct is_subset_impl<S, S, when<condition>> {
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template <typename Xs, typename Ys>
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static constexpr decltype(auto) apply(Xs&& xs, Ys&& ys) {
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return hana::all_of(static_cast<Xs&&>(xs),
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hana::partial(hana::contains, static_cast<Ys&&>(ys)));
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}
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};
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// Cross-type overload
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template <typename S1, typename S2>
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struct is_subset_impl<S1, S2, when<
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detail::has_nontrivial_common_embedding<Searchable, S1, S2>::value
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>> {
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using C = typename common<S1, S2>::type;
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template <typename Xs, typename Ys>
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static constexpr decltype(auto) apply(Xs&& xs, Ys&& ys) {
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return hana::is_subset(hana::to<C>(static_cast<Xs&&>(xs)),
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hana::to<C>(static_cast<Ys&&>(ys)));
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}
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};
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BOOST_HANA_NAMESPACE_END
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#endif // !BOOST_HANA_IS_SUBSET_HPP
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