59 lines
1.8 KiB
C++
59 lines
1.8 KiB
C++
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/*!
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@file
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Defines `boost::hana::min`.
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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_MIN_HPP
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#define BOOST_HANA_MIN_HPP
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#include <boost/hana/fwd/min.hpp>
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#include <boost/hana/concept/orderable.hpp>
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#include <boost/hana/config.hpp>
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#include <boost/hana/core/dispatch.hpp>
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#include <boost/hana/if.hpp>
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#include <boost/hana/less.hpp>
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BOOST_HANA_NAMESPACE_BEGIN
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//! @cond
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template <typename X, typename Y>
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constexpr decltype(auto) min_t::operator()(X&& x, Y&& y) const {
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using T = typename hana::tag_of<X>::type;
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using U = typename hana::tag_of<Y>::type;
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using Min = BOOST_HANA_DISPATCH_IF(decltype(min_impl<T, U>{}),
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hana::Orderable<T>::value &&
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hana::Orderable<U>::value
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);
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#ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
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static_assert(hana::Orderable<T>::value,
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"hana::min(x, y) requires 'x' to be Orderable");
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static_assert(hana::Orderable<U>::value,
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"hana::min(x, y) requires 'y' to be Orderable");
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#endif
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return Min::apply(static_cast<X&&>(x), static_cast<Y&&>(y));
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}
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//! @endcond
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template <typename T, typename U, bool condition>
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struct min_impl<T, U, when<condition>> : default_ {
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template <typename X, typename Y>
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static constexpr decltype(auto) apply(X&& x, Y&& y) {
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decltype(auto) cond = hana::less(x, y);
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return hana::if_(static_cast<decltype(cond)&&>(cond),
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static_cast<X&&>(x),
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static_cast<Y&&>(y)
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);
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}
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};
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BOOST_HANA_NAMESPACE_END
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#endif // !BOOST_HANA_MIN_HPP
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