v1/cpp11/one_of.hpp

0001 #ifndef BOOST_METAPARSE_V1_CPP11_ONE_OF_HPP
0002 #define BOOST_METAPARSE_V1_CPP11_ONE_OF_HPP
0003
0004 // Copyright Abel Sinkovics (abel@sinkovics.hu)  2017.
0005 // Distributed under the Boost Software License, Version 1.0.
0006 //    (See accompanying file LICENSE_1_0.txt or copy at
0007 //          http://www.boost.org/LICENSE_1_0.txt)
0008
0009 #include <boost/metaparse/v1/is_error.hpp>
0010 #include <boost/metaparse/v1/fail.hpp>
0011 #include <boost/metaparse/v1/cpp11/impl/eval_later_result.hpp>
0012 #include <boost/metaparse/v1/error/none_of_the_expected_cases_found.hpp>
0013
0014 #include <boost/mpl/eval_if.hpp>
0015
0016 namespace boost
0017 {
0018   namespace metaparse
0019   {
0020     namespace v1
0021     {
0022       template <class... Ps>
0023       struct one_of;
0024
0025       template <class P, class... Ps>
0026       struct one_of<P, Ps...>
0027       {
0028         typedef one_of type;
0029
0030         template <class S, class Pos>
0031         struct apply :
0032           boost::mpl::eval_if<
0033             typename is_error<typename P::template apply<S, Pos>>::type,
0034             boost::mpl::eval_if<
0035               typename is_error<
0036                 typename one_of<Ps...>::template apply<S, Pos>
0037               >::type,
0038               impl::eval_later_result<
0039                 typename P::template apply<S, Pos>,
0040                 typename one_of<Ps...>::template apply<S, Pos>
0041               >,
0042               typename one_of<Ps...>::template apply<S, Pos>
0043             >,
0044             typename P::template apply<S, Pos>
0045           >
0046         {};
0047       };
0048
0049       template <>
0050       struct one_of<> : fail<error::none_of_the_expected_cases_found> {};
0051     }
0052   }
0053 }
0054
0055 #endif
0056