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

   1 /*!
   2 @file
   3 Defines `boost::hana::replicate`.
   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_REPLICATE_HPP
  11 #define BOOST_HANA_REPLICATE_HPP
  12
  13 #include <boost/hana/fwd/replicate.hpp>
  14
  15 #include <boost/hana/concept/integral_constant.hpp>
  16 #include <boost/hana/concept/monad_plus.hpp>
  17 #include <boost/hana/config.hpp>
  18 #include <boost/hana/core/dispatch.hpp>
  19 #include <boost/hana/core/make.hpp>
  20 #include <boost/hana/cycle.hpp>
  21 #include <boost/hana/lift.hpp>
  22
  23 #include <cstddef>
  24 #include <utility>
  25
  26
  27 BOOST_HANA_NAMESPACE_BEGIN
  28     template <typename M>
  29     struct replicate_t {
  30     #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
  31         static_assert(hana::MonadPlus<M>::value,
  32         "hana::replicate<M>(x, n) requires 'M' to be a MonadPlus");
  33     #endif
  34
  35         template <typename X, typename N>
  36         constexpr auto operator()(X&& x, N const& n) const {
  37             using Replicate = BOOST_HANA_DISPATCH_IF(replicate_impl<M>,
  38                 hana::MonadPlus<M>::value &&
  39                 hana::IntegralConstant<N>::value
  40             );
  41
  42         #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
  43             static_assert(hana::IntegralConstant<N>::value,
  44             "hana::replicate<M>(x, n) requires 'n' to be an IntegralConstant");
  45         #endif
  46
  47             return Replicate::apply(static_cast<X&&>(x), n);
  48         }
  49     };
  50
  51     template <typename M, bool condition>
  52     struct replicate_impl<M, when<condition>> : default_ {
  53         template <typename X, typename N>
  54         static constexpr auto apply(X&& x, N const& n) {
  55             return hana::cycle(hana::lift<M>(static_cast<X&&>(x)), n);
  56         }
  57     };
  58
  59     template <typename S>
  60     struct replicate_impl<S, when<Sequence<S>::value>> {
  61         template <typename X, std::size_t ...i>
  62         static constexpr auto replicate_helper(X&& x, std::index_sequence<i...>)
  63         { return hana::make<S>(((void)i, x)...); }
  64
  65         template <typename X, typename N>
  66         static constexpr auto apply(X&& x, N const&) {
  67             constexpr std::size_t n = N::value;
  68             return replicate_helper(static_cast<X&&>(x),
  69                                     std::make_index_sequence<n>{});
  70         }
  71     };
  72 BOOST_HANA_NAMESPACE_END
  73
  74 #endif // !BOOST_HANA_REPLICATE_HPP