ceph/src/boost/libs/hana/include/boost/hana/zip_shortest_with.hpp

   1 /*!
   2 @file
   3 Defines `boost::hana::zip_shortest_with`.
   4
   5 @copyright Louis Dionne 2013-2016
   6 Distributed under the Boost Software License, Version 1.0.
   7 (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
   8  */
   9
  10 #ifndef BOOST_HANA_ZIP_SHORTEST_WITH_HPP
  11 #define BOOST_HANA_ZIP_SHORTEST_WITH_HPP
  12
  13 #include <boost/hana/fwd/zip_shortest_with.hpp>
  14
  15 #include <boost/hana/concept/sequence.hpp>
  16 #include <boost/hana/core/dispatch.hpp>
  17 #include <boost/hana/config.hpp>
  18 #include <boost/hana/detail/algorithm.hpp>
  19 #include <boost/hana/detail/fast_and.hpp>
  20 #include <boost/hana/integral_constant.hpp>
  21 #include <boost/hana/length.hpp>
  22 #include <boost/hana/take_front.hpp>
  23 #include <boost/hana/zip_with.hpp>
  24
  25 #include <cstddef>
  26
  27
  28 BOOST_HANA_NAMESPACE_BEGIN
  29     //! @cond
  30     template <typename F, typename Xs, typename ...Ys>
  31     constexpr auto
  32     zip_shortest_with_t::operator()(F&& f, Xs&& xs, Ys&& ...ys) const {
  33     #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
  34         static_assert(detail::fast_and<
  35             hana::Sequence<Xs>::value, hana::Sequence<Ys>::value...
  36         >::value,
  37         "hana::zip_shortest_with(f, xs, ys...) requires 'xs' and 'ys...' to be Sequences");
  38     #endif
  39
  40         return zip_shortest_with_impl<typename hana::tag_of<Xs>::type>::apply(
  41             static_cast<F&&>(f),
  42             static_cast<Xs&&>(xs),
  43             static_cast<Ys&&>(ys)...
  44         );
  45     }
  46     //! @endcond
  47
  48     template <typename S, bool condition>
  49     struct zip_shortest_with_impl<S, when<condition>> : default_ {
  50         template <typename F, typename ...Xs>
  51         static constexpr decltype(auto) apply(F&& f, Xs&& ...xs) {
  52             constexpr std::size_t lengths[] = {
  53                 decltype(hana::length(xs))::value...
  54             };
  55             constexpr std::size_t min = *detail::min_element(lengths, lengths + sizeof...(xs));
  56             return hana::zip_with(static_cast<F&&>(f),
  57                 hana::take_front(static_cast<Xs&&>(xs), hana::size_c<min>)...
  58             );
  59         }
  60     };
  61 BOOST_HANA_NAMESPACE_END
  62
  63 #endif // !BOOST_HANA_ZIP_SHORTEST_WITH_HPP