ceph/src/boost/libs/hana/test/_include/support/seq.hpp

   1 // Copyright Louis Dionne 2013-2017
   2 // Distributed under the Boost Software License, Version 1.0.
   3 // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
   4
   5 #ifndef TEST_SUPPORT_SEQ_HPP
   6 #define TEST_SUPPORT_SEQ_HPP
   7
   8 #include <boost/hana/fwd/at.hpp>
   9 #include <boost/hana/fwd/concept/sequence.hpp>
  10 #include <boost/hana/fwd/core/make.hpp>
  11 #include <boost/hana/fwd/drop_front.hpp>
  12 #include <boost/hana/fwd/fold_left.hpp>
  13 #include <boost/hana/fwd/is_empty.hpp>
  14 #include <boost/hana/fwd/length.hpp>
  15 #include <boost/hana/tuple.hpp>
  16 #include <boost/hana/unpack.hpp>
  17
  18
  19 struct Seq;
  20
  21 template <typename Storage>
  22 struct seq_type {
  23     explicit constexpr seq_type(Storage s) : storage(s) { }
  24     Storage storage;
  25     using hana_tag = Seq;
  26 };
  27
  28 struct seq_t {
  29     template <typename ...Xs>
  30     constexpr auto operator()(Xs&& ...xs) const {
  31         auto storage = boost::hana::make_tuple(xs...);
  32         return seq_type<decltype(storage)>(storage);
  33     }
  34 };
  35 constexpr seq_t seq{};
  36
  37 namespace boost { namespace hana {
  38     //////////////////////////////////////////////////////////////////////////
  39     // Foldable
  40     //
  41     // Define either one to select which MCD is used:
  42     //  BOOST_HANA_TEST_FOLDABLE_FOLD_LEFT_MCD
  43     //  BOOST_HANA_TEST_FOLDABLE_UNPACK_MCD
  44     //  BOOST_HANA_TEST_FOLDABLE_ITERABLE_MCD
  45     //
  46     // If neither is defined, the MCD used is unspecified.
  47     //////////////////////////////////////////////////////////////////////////
  48 #ifdef BOOST_HANA_TEST_FOLDABLE_FOLD_LEFT_MCD
  49     template <>
  50     struct fold_left_impl<Seq> {
  51         template <typename Xs, typename S, typename F>
  52         static constexpr auto apply(Xs xs, S s, F f) {
  53             return hana::fold_left(xs.storage, s, f);
  54         }
  55
  56         template <typename Xs, typename F>
  57         static constexpr auto apply(Xs xs, F f) {
  58             return hana::fold_left(xs.storage, f);
  59         }
  60     };
  61 #elif defined(BOOST_HANA_TEST_FOLDABLE_ITERABLE_MCD)
  62     template <>
  63     struct length_impl<Seq> {
  64         template <typename Xs>
  65         static constexpr auto apply(Xs const& xs) {
  66             return hana::length(xs.storage);
  67         }
  68     };
  69 #else
  70     template <>
  71     struct unpack_impl<Seq> {
  72         template <typename Xs, typename F>
  73         static constexpr auto apply(Xs xs, F f)
  74         { return hana::unpack(xs.storage, f); }
  75     };
  76 #endif
  77
  78     //////////////////////////////////////////////////////////////////////////
  79     // Iterable
  80     //////////////////////////////////////////////////////////////////////////
  81     template <>
  82     struct at_impl<Seq> {
  83         template <typename Xs, typename N>
  84         static constexpr decltype(auto) apply(Xs&& xs, N&& n) {
  85             return hana::at(static_cast<Xs&&>(xs).storage, n);
  86         }
  87     };
  88
  89     template <>
  90     struct drop_front_impl<Seq> {
  91         template <typename Xs, typename N>
  92         static constexpr auto apply(Xs xs, N n) {
  93             return hana::unpack(hana::drop_front(xs.storage, n), ::seq);
  94         }
  95     };
  96
  97     template <>
  98     struct is_empty_impl<Seq> {
  99         template <typename Xs>
 100         static constexpr auto apply(Xs xs) {
 101             return hana::is_empty(xs.storage);
 102         }
 103     };
 104
 105     //////////////////////////////////////////////////////////////////////////
 106     // Sequence
 107     //////////////////////////////////////////////////////////////////////////
 108     template <>
 109     struct Sequence<Seq> {
 110         static constexpr bool value = true;
 111     };
 112
 113     template <>
 114     struct make_impl<Seq> {
 115         template <typename ...Xs>
 116         static constexpr auto apply(Xs&& ...xs) {
 117             return ::seq(static_cast<Xs&&>(xs)...);
 118         }
 119     };
 120 }} // end namespace boost::hana
 121
 122 #endif // !TEST_SUPPORT_SEQ_HPP