metaparse/v1/foldr_start_with_parser.hpp

0001 #ifndef BOOST_METAPARSE_V1_FOLDR_START_WITH_PARSER_HPP
0002 #define BOOST_METAPARSE_V1_FOLDR_START_WITH_PARSER_HPP
0003
0004 // Copyright Abel Sinkovics (abel@sinkovics.hu)  2012.
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/accept.hpp>
0010 #include <boost/metaparse/v1/is_error.hpp>
0011 #include <boost/metaparse/v1/get_position.hpp>
0012 #include <boost/metaparse/v1/get_result.hpp>
0013 #include <boost/metaparse/v1/get_remaining.hpp>
0014
0015 #include <boost/mpl/eval_if.hpp>
0016
0017 namespace boost
0018 {
0019   namespace metaparse
0020   {
0021     namespace v1
0022     {
0023       template <class P, class StateP, class BackwardOp>
0024       struct foldr_start_with_parser
0025       {
0026       private:
0027         template <class Res, class Rem>
0028         struct apply_unchecked1 :
0029           accept<
0030             typename BackwardOp::template apply<
0031               typename get_result<Rem>::type,
0032               typename get_result<Res>::type
0033             >::type,
0034             typename get_remaining<Rem>::type,
0035             typename get_position<Rem>::type
0036           >
0037         {};
0038
0039         template <class Res>
0040         struct apply_unchecked;
0041       public:
0042         typedef foldr_start_with_parser type;
0043
0044         template <class S, class Pos>
0045         struct apply :
0046           boost::mpl::eval_if<
0047             typename is_error<typename P::template apply<S, Pos> >::type,
0048             typename StateP::template apply<S, Pos>,
0049             apply_unchecked<typename P::template apply<S, Pos> >
0050           >
0051         {};
0052       private:
0053         template <class Res>
0054         struct apply_unchecked
0055         {
0056         private:
0057           typedef
0058             typename foldr_start_with_parser::template apply<
0059               typename get_remaining<Res>::type,
0060               typename get_position<Res>::type
0061             >
0062             parsed_remaining;
0063         public:
0064           typedef
0065             typename boost::mpl::eval_if<
0066               typename is_error<parsed_remaining>::type,
0067               parsed_remaining,
0068               apply_unchecked1<Res, parsed_remaining>
0069             >::type
0070             type;
0071         };
0072       };
0073     }
0074   }
0075 }
0076
0077 #endif
0078