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+#ifndef BOOST_METAPARSE_V1_FOLDL_HPP
+#define BOOST_METAPARSE_V1_FOLDL_HPP
+
+// Copyright Abel Sinkovics (abel@sinkovics.hu) 2011.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+#include <boost/metaparse/v1/accept.hpp>
+#include <boost/metaparse/v1/is_error.hpp>
+#include <boost/metaparse/v1/get_position.hpp>
+#include <boost/metaparse/v1/get_result.hpp>
+#include <boost/metaparse/v1/get_remaining.hpp>
+
+#include <boost/mpl/eval_if.hpp>
+
+namespace boost
+{
+ namespace metaparse
+ {
+ namespace v1
+ {
+ template <class P, class State, class ForwardOp>
+ struct foldl
+ {
+ private:
+ template <class Res>
+ struct apply_unchecked :
+ // foldl never returns error
+ // I need to use apply_wrap, and not apply, because apply would
+ // build a metafunction class from foldl<P, State, ForwardOp>
+ // when ForwardOp is a lambda expression.
+ foldl<
+ P,
+ typename ForwardOp::template apply<
+ typename State::type,
+ typename get_result<Res>::type
+ >,
+ ForwardOp
+ >::template apply<
+ typename get_remaining<Res>::type,
+ typename get_position<Res>::type
+ >
+ {};
+
+ template <class S, class Pos>
+ struct next_iteration : accept<typename State::type, S, Pos> {};
+ public:
+ typedef foldl type;
+
+ template <class S, class Pos>
+ struct apply :
+ boost::mpl::eval_if<
+ typename is_error<typename P::template apply<S, Pos> >::type,
+ next_iteration<S, Pos>,
+ apply_unchecked<typename P::template apply<S, Pos> >
+ >
+ {};
+ };
+ }
+ }
+}
+
+#endif
+