| 1 | // Copyright Louis Dionne 2013-2022 |
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| 2 | // Distributed under the Boost Software License, Version 1.0. |
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| 3 | // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt) |
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| 4 | |
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| 5 | #ifndef BOOST_HANA_TEST_STRUCT_MINIMAL_STRUCT_HPP |
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| 6 | #define BOOST_HANA_TEST_STRUCT_MINIMAL_STRUCT_HPP |
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| 7 | |
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| 8 | #include <boost/hana/at.hpp> |
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| 9 | #include <boost/hana/fwd/accessors.hpp> |
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| 10 | #include <boost/hana/pair.hpp> |
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| 11 | #include <boost/hana/range.hpp> |
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| 12 | #include <boost/hana/tuple.hpp> |
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| 13 | #include <boost/hana/unpack.hpp> |
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| 14 | |
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| 15 | |
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| 16 | template <int N> |
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| 17 | struct minimal_struct_tag; |
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| 18 | |
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| 19 | template <typename ...Members> |
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| 20 | struct minimal_struct_t { |
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| 21 | boost::hana::tuple<Members...> members; |
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| 22 | using hana_tag = minimal_struct_tag<sizeof...(Members)>; |
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| 23 | }; |
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| 24 | |
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| 25 | struct obj_t { |
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| 26 | template <typename ...Members> |
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| 27 | constexpr minimal_struct_t<Members...> operator()(Members ...members) const { |
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| 28 | return {{static_cast<Members&&>(members)...}}; |
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| 29 | } |
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| 30 | }; |
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| 31 | constexpr obj_t obj{}; |
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| 32 | |
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| 33 | namespace boost { namespace hana { |
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| 34 | template <int N> |
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| 35 | struct accessors_impl<minimal_struct_tag<N>> { |
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| 36 | template <typename K> |
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| 37 | struct get_member { |
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| 38 | template <typename Struct> |
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| 39 | constexpr decltype(auto) operator()(Struct&& s) const { |
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| 40 | return hana::at_c<K::value>(static_cast<Struct&&>(s).members); |
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| 41 | } |
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| 42 | }; |
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| 43 | |
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| 44 | static auto apply() { |
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| 45 | return hana::unpack(hana::range_c<int, 0, N>, [](auto ...k) { |
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| 46 | return hana::make_tuple( |
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| 47 | hana::make_pair(k, get_member<decltype(k)>{})... |
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| 48 | ); |
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| 49 | }); |
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| 50 | } |
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| 51 | }; |
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| 52 | }} |
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| 53 | |
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| 54 | #endif // !BOOST_HANA_TEST_STRUCT_MINIMAL_STRUCT_HPP |
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| 55 | |
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