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Diffstat (limited to 'boost/metaparse/v1/accept_when.hpp')
| -rw-r--r-- | boost/metaparse/v1/accept_when.hpp | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/boost/metaparse/v1/accept_when.hpp b/boost/metaparse/v1/accept_when.hpp new file mode 100644 index 0000000000..425064dcd5 --- /dev/null +++ b/boost/metaparse/v1/accept_when.hpp @@ -0,0 +1,59 @@ +#ifndef BOOST_METAPARSE_V1_ACCEPT_WHEN_HPP +#define BOOST_METAPARSE_V1_ACCEPT_WHEN_HPP + +// Copyright Abel Sinkovics (abel@sinkovics.hu) 2009 - 2010. +// 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/get_result.hpp> +#include <boost/metaparse/v1/reject.hpp> +#include <boost/metaparse/v1/is_error.hpp> + +#include <boost/mpl/if.hpp> +#include <boost/mpl/eval_if.hpp> + +namespace boost +{ + namespace metaparse + { + namespace v1 + { + template <class P, class Pred, class Msg> + struct accept_when + { + private: + struct unchecked + { + template <class S, class Pos> + struct apply : + boost::mpl::eval_if< + typename Pred::template apply< + typename get_result<typename P::template apply<S, Pos> >::type + >::type, + typename P::template apply<S, Pos>, + reject<Msg, Pos> + > + {}; + }; + public: + typedef accept_when type; + + template <class S, class Pos> + struct apply : + boost::mpl::if_< + is_error<typename P::template apply<S, Pos> >, + P, + unchecked + >::type::template apply< + S, + Pos + > + {}; + }; + } + } +} + +#endif + |