| 1 | /*! |
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| 2 | @file |
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| 3 | Defines `boost::hana::union`. |
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| 4 | |
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| 5 | Copyright Louis Dionne 2013-2022 |
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| 6 | Distributed under the Boost Software License, Version 1.0. |
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| 7 | (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt) |
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| 8 | */ |
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| 9 | |
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| 10 | #ifndef BOOST_HANA_UNION_HPP |
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| 11 | #define BOOST_HANA_UNION_HPP |
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| 12 | |
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| 13 | #include <boost/hana/fwd/union.hpp> |
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| 14 | |
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| 15 | #include <boost/hana/config.hpp> |
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| 16 | #include <boost/hana/core/dispatch.hpp> |
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| 17 | |
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| 18 | |
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| 19 | namespace boost { namespace hana { |
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| 20 | //! @cond |
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| 21 | template <typename Xs, typename Ys> |
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| 22 | constexpr auto union_t::operator()(Xs&& xs, Ys&& ys) const { |
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| 23 | using S = typename hana::tag_of<Xs>::type; |
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| 24 | using Union = BOOST_HANA_DISPATCH_IF(union_impl<S>, |
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| 25 | true |
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| 26 | ); |
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| 27 | |
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| 28 | return Union::apply(static_cast<Xs&&>(xs), static_cast<Ys&&>(ys)); |
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| 29 | } |
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| 30 | //! @endcond |
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| 31 | |
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| 32 | template <typename S, bool condition> |
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| 33 | struct union_impl<S, when<condition>> : default_ { |
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| 34 | template <typename ...Args> |
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| 35 | static constexpr auto apply(Args&& ...) = delete; |
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| 36 | }; |
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| 37 | }} // end namespace boost::hana |
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| 38 | |
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| 39 | #endif // !BOOST_HANA_UNION_HPP |
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| 40 | |
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