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

   1 #ifndef BOOST_METAPARSE_V1_CPP11_FIRST_OF_HPP
   2 #define BOOST_METAPARSE_V1_CPP11_FIRST_OF_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 namespace boost
  15 {
  16   namespace metaparse
  17   {
  18     namespace v1
  19     {
  20       template <class... Ps>
  21       struct first_of
  22       {
  23         typedef first_of type;
  24
  25         template <class S, class Pos>
  26         struct apply : impl::nth_of_c<0, S, Pos, Ps...> {};
  27       };
  28
  29       template <>
  30       struct first_of<> : fail<error::index_out_of_range<0, -1, 0>> {};
  31     }
  32   }
  33 }
  34
  35 #endif
  36