ceph/src/boost/boost/metaparse/v1/cpp11/nth_of_c.hpp

   1 #ifndef BOOST_METAPARSE_V1_CPP11_NTH_OF_C_HPP
   2 #define BOOST_METAPARSE_V1_CPP11_NTH_OF_C_HPP
   3
   4 // Copyright Abel Sinkovics (abel@sinkovics.hu)  2017.
   5 // Distributed under the Boost Software License, Version 1.0.
   6 //    (See accompanying file LICENSE_1_0.txt or copy at
   7 //          http://www.boost.org/LICENSE_1_0.txt)
   8
   9 #include <boost/metaparse/v1/cpp11/impl/nth_of_c.hpp>
  10
  11 #include <boost/metaparse/v1/fail.hpp>
  12 #include <boost/metaparse/v1/error/index_out_of_range.hpp>
  13
  14 #include <type_traits>
  15
  16 namespace boost
  17 {
  18   namespace metaparse
  19   {
  20     namespace v1
  21     {
  22       template <int N, class... Ps>
  23       struct nth_of_c
  24       {
  25         typedef nth_of_c type;
  26
  27         template <class S, class Pos>
  28         struct apply :
  29           std::conditional<
  30             (0 <= N && N < sizeof...(Ps)),
  31             impl::nth_of_c<N, S, Pos, Ps...>,
  32             typename fail<error::index_out_of_range<0, sizeof...(Ps) - 1, N>>
  33               ::template apply<S, Pos>
  34           >::type
  35         {};
  36       };
  37
  38       template <int N>
  39       struct nth_of_c<N> : fail<error::index_out_of_range<0, -1, N>> {};
  40     }
  41   }
  42 }
  43
  44 #endif
  45