51 lines
1.2 KiB
C++
51 lines
1.2 KiB
C++
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#ifndef BOOST_METAPARSE_V1_LOOK_AHEAD_HPP
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#define BOOST_METAPARSE_V1_LOOK_AHEAD_HPP
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// Copyright Abel Sinkovics (abel@sinkovics.hu) 2011.
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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#include <boost/metaparse/v1/is_error.hpp>
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#include <boost/metaparse/v1/accept.hpp>
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#include <boost/metaparse/v1/get_result.hpp>
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#include <boost/mpl/eval_if.hpp>
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namespace boost
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{
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namespace metaparse
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{
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namespace v1
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{
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template <class P>
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struct look_ahead
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{
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private:
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template <class S, class Pos>
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struct no_error :
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accept<
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typename get_result<typename P::template apply<S, Pos> >::type,
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S,
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Pos
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>
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{};
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public:
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typedef look_ahead type;
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template <class S, class Pos>
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struct apply :
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boost::mpl::eval_if<
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typename is_error<typename P::template apply<S, Pos> >::type,
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typename P::template apply<S, Pos>,
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no_error<S, Pos>
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>
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{};
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};
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}
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}
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}
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#endif
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