| 1 | /*! |
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| 2 | @file |
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| 3 | Forward declares `boost::hana::reverse`. |
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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_FWD_REVERSE_HPP |
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| 11 | #define BOOST_HANA_FWD_REVERSE_HPP |
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| 12 | |
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| 13 | #include <boost/hana/config.hpp> |
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| 14 | #include <boost/hana/core/when.hpp> |
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| 15 | |
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| 16 | |
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| 17 | namespace boost { namespace hana { |
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| 18 | //! Reverse a sequence. |
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| 19 | //! @ingroup group-Sequence |
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| 20 | //! |
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| 21 | //! Specifically, `reverse(xs)` is a new sequence containing the same |
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| 22 | //! elements as `xs`, except in reverse order. |
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| 23 | //! |
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| 24 | //! |
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| 25 | //! @param xs |
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| 26 | //! The sequence to reverse. |
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| 27 | //! |
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| 28 | //! |
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| 29 | //! Example |
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| 30 | //! ------- |
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| 31 | //! @include example/reverse.cpp |
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| 32 | #ifdef BOOST_HANA_DOXYGEN_INVOKED |
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| 33 | constexpr auto reverse = [](auto&& xs) { |
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| 34 | return tag-dispatched; |
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| 35 | }; |
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| 36 | #else |
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| 37 | template <typename S, typename = void> |
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| 38 | struct reverse_impl : reverse_impl<S, when<true>> { }; |
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| 39 | |
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| 40 | struct reverse_t { |
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| 41 | template <typename Xs> |
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| 42 | constexpr auto operator()(Xs&& xs) const; |
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| 43 | }; |
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| 44 | |
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| 45 | BOOST_HANA_INLINE_VARIABLE constexpr reverse_t reverse{}; |
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| 46 | #endif |
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| 47 | }} // end namespace boost::hana |
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| 48 | |
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| 49 | #endif // !BOOST_HANA_FWD_REVERSE_HPP |
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| 50 | |
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