33 lines
896 B
C++
33 lines
896 B
C++
/*!
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@file
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Forward declares `boost::hana::difference`.
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@copyright Louis Dionne 2013-2017
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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_FWD_DIFFERENCE_HPP
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#define BOOST_HANA_FWD_DIFFERENCE_HPP
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#include <boost/hana/config.hpp>
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#include <boost/hana/core/when.hpp>
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namespace boost { namespace hana {
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// Note: This function is documented per datatype/concept only.
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//! @cond
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template <typename S, typename = void>
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struct difference_impl : difference_impl<S, when<true>> { };
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//! @endcond
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struct difference_t {
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template <typename Xs, typename Ys>
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constexpr auto operator()(Xs&&, Ys&&) const;
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};
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BOOST_HANA_INLINE_VARIABLE constexpr difference_t difference{};
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}} // end namespace boost::hana
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#endif // !BOOST_HANA_FWD_DIFFERENCE_HPP
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