65 lines
2.1 KiB
C++
65 lines
2.1 KiB
C++
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/*!
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@file
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Defines `boost::hana::zip_shortest_with`.
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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_ZIP_SHORTEST_WITH_HPP
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#define BOOST_HANA_ZIP_SHORTEST_WITH_HPP
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#include <boost/hana/fwd/zip_shortest_with.hpp>
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#include <boost/hana/concept/sequence.hpp>
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#include <boost/hana/core/dispatch.hpp>
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#include <boost/hana/config.hpp>
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#include <boost/hana/detail/algorithm.hpp>
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#include <boost/hana/detail/fast_and.hpp>
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#include <boost/hana/integral_constant.hpp>
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#include <boost/hana/length.hpp>
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#include <boost/hana/take_front.hpp>
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#include <boost/hana/zip_with.hpp>
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#include <cstddef>
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namespace boost { namespace hana {
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//! @cond
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template <typename F, typename Xs, typename ...Ys>
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constexpr auto
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zip_shortest_with_t::operator()(F&& f, Xs&& xs, Ys&& ...ys) const {
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#ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
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static_assert(detail::fast_and<
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hana::Sequence<Xs>::value, hana::Sequence<Ys>::value...
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>::value,
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"hana::zip_shortest_with(f, xs, ys...) requires 'xs' and 'ys...' to be Sequences");
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#endif
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return zip_shortest_with_impl<typename hana::tag_of<Xs>::type>::apply(
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static_cast<F&&>(f),
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static_cast<Xs&&>(xs),
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static_cast<Ys&&>(ys)...
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);
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}
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//! @endcond
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template <typename S, bool condition>
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struct zip_shortest_with_impl<S, when<condition>> : default_ {
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template <typename F, typename ...Xs>
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static constexpr decltype(auto) apply(F&& f, Xs&& ...xs) {
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constexpr std::size_t lengths[] = {
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decltype(hana::length(xs))::value...
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};
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constexpr std::size_t min_len =
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*detail::min_element(lengths, lengths + sizeof...(xs));
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return hana::zip_with(static_cast<F&&>(f),
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hana::take_front(static_cast<Xs&&>(xs), hana::size_c<min_len>)...
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);
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}
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};
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}} // end namespace boost::hana
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#endif // !BOOST_HANA_ZIP_SHORTEST_WITH_HPP
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