ceph/src/boost/boost/hana/repeat.hpp

   1 /*!
   2 @file
   3 Defines `boost::hana::repeat`.
   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_REPEAT_HPP
  11 #define BOOST_HANA_REPEAT_HPP
  12
  13 #include <boost/hana/fwd/repeat.hpp>
  14
  15 #include <boost/hana/concept/integral_constant.hpp>
  16 #include <boost/hana/config.hpp>
  17 #include <boost/hana/core/dispatch.hpp>
  18
  19 #include <cstddef>
  20 #include <utility>
  21
  22
  23 BOOST_HANA_NAMESPACE_BEGIN
  24     template <typename I, bool condition>
  25     struct repeat_impl<I, when<condition>> : default_ {
  26         template <typename F, std::size_t ...i>
  27         static constexpr void repeat_helper(F&& f, std::index_sequence<i...>) {
  28             using Swallow = std::size_t[];
  29             (void)Swallow{0, ((void)f(), i)...};
  30         }
  31
  32         template <typename N, typename F>
  33         static constexpr auto apply(N const&, F&& f) {
  34             static_assert(N::value >= 0, "hana::repeat(n, f) requires 'n' to be non-negative");
  35             constexpr std::size_t n = N::value;
  36             repeat_helper(static_cast<F&&>(f), std::make_index_sequence<n>{});
  37         }
  38     };
  39
  40     //! @cond
  41     template <typename N, typename F>
  42     constexpr void repeat_t::operator()(N const& n, F&& f) const {
  43         using I = typename hana::tag_of<N>::type;
  44         using Repeat = BOOST_HANA_DISPATCH_IF(repeat_impl<I>,
  45             hana::IntegralConstant<I>::value
  46         );
  47
  48     #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
  49         static_assert(hana::IntegralConstant<I>::value,
  50         "hana::repeat(n, f) requires 'n' to be an IntegralConstant");
  51     #endif
  52
  53         return Repeat::apply(n, static_cast<F&&>(f));
  54     }
  55     //! @endcond
  56 BOOST_HANA_NAMESPACE_END
  57
  58 #endif // !BOOST_HANA_REPEAT_HPP