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

   1 /*!
   2 @file
   3 Defines `boost::hana::replicate`.
   4
   5 @copyright Louis Dionne 2013-2017
   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     //! @cond
  29     template <typename M>
  30     template <typename X, typename N>
  31     constexpr auto replicate_t<M>::operator()(X&& x, N const& n) const {
  32         using Replicate = BOOST_HANA_DISPATCH_IF(replicate_impl<M>,
  33             hana::MonadPlus<M>::value &&
  34             hana::IntegralConstant<N>::value
  35         );
  36
  37     #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
  38         static_assert(hana::MonadPlus<M>::value,
  39         "hana::replicate<M>(x, n) requires 'M' to be a MonadPlus");
  40
  41         static_assert(hana::IntegralConstant<N>::value,
  42         "hana::replicate<M>(x, n) requires 'n' to be an IntegralConstant");
  43     #endif
  44
  45         return Replicate::apply(static_cast<X&&>(x), n);
  46     }
  47     //! @endcond
  48
  49     template <typename M, bool condition>
  50     struct replicate_impl<M, when<condition>> : default_ {
  51         template <typename X, typename N>
  52         static constexpr auto apply(X&& x, N const& n) {
  53             return hana::cycle(hana::lift<M>(static_cast<X&&>(x)), n);
  54         }
  55     };
  56
  57     template <typename S>
  58     struct replicate_impl<S, when<Sequence<S>::value>> {
  59         template <typename X, std::size_t ...i>
  60         static constexpr auto replicate_helper(X&& x, std::index_sequence<i...>)
  61         { return hana::make<S>(((void)i, x)...); }
  62
  63         template <typename X, typename N>
  64         static constexpr auto apply(X&& x, N const&) {
  65             constexpr std::size_t n = N::value;
  66             return replicate_helper(static_cast<X&&>(x),
  67                                     std::make_index_sequence<n>{});
  68         }
  69     };
  70 BOOST_HANA_NAMESPACE_END
  71
  72 #endif // !BOOST_HANA_REPLICATE_HPP