ceph/src/boost/boost/metaparse/v1/foldl.hpp

   1 #ifndef BOOST_METAPARSE_V1_FOLDL_HPP
   2 #define BOOST_METAPARSE_V1_FOLDL_HPP
   3
   4 // Copyright Abel Sinkovics (abel@sinkovics.hu)  2011.
   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/accept.hpp>
  10 #include <boost/metaparse/v1/is_error.hpp>
  11 #include <boost/metaparse/v1/get_position.hpp>
  12 #include <boost/metaparse/v1/get_result.hpp>
  13 #include <boost/metaparse/v1/get_remaining.hpp>
  14
  15 #include <boost/mpl/eval_if.hpp>
  16
  17 namespace boost
  18 {
  19   namespace metaparse
  20   {
  21     namespace v1
  22     {
  23       template <class P, class State, class ForwardOp>
  24       struct foldl
  25       {
  26       private:
  27         template <class Res>
  28         struct apply_unchecked :
  29           // foldl never returns error
  30           // I need to use apply_wrap, and not apply, because apply would
  31           // build a metafunction class from foldl<P, State, ForwardOp>
  32           // when ForwardOp is a lambda expression.
  33           foldl<
  34             P,
  35             typename ForwardOp::template apply<
  36               typename State::type,
  37               typename get_result<Res>::type
  38             >,
  39             ForwardOp
  40           >::template apply<
  41             typename get_remaining<Res>::type,
  42             typename get_position<Res>::type
  43           >
  44         {};
  45
  46         template <class S, class Pos>
  47         struct next_iteration : accept<typename State::type, S, Pos> {};
  48       public:
  49         typedef foldl type;
  50
  51         template <class S, class Pos>
  52         struct apply :
  53           boost::mpl::eval_if<
  54             typename is_error<typename P::template apply<S, Pos> >::type,
  55             next_iteration<S, Pos>,
  56             apply_unchecked<typename P::template apply<S, Pos> >
  57           >
  58         {};
  59       };
  60     }
  61   }
  62 }
  63
  64 #endif
  65