aux_/at_impl.hpp

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#ifndef BOOST_MPL_AUX_AT_IMPL_HPP_INCLUDED
#define BOOST_MPL_AUX_AT_IMPL_HPP_INCLUDED
 
// Copyright Aleksey Gurtovoy 2000-2004
//
// 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)
//
// See http://www.boost.org/libs/mpl for documentation.
 
// $Id: at_impl.hpp 13472 2017-08-22 07:53:44Z richean $
// $Date: 2017-08-22 09:53:44 +0200 (Di, 22 Aug 2017) $
// $Revision: 13472 $
 
#include <boost/mpl/begin_end.hpp>
#include <boost/mpl/advance.hpp>
#include <boost/mpl/deref.hpp>
#include <boost/mpl/aux_/traits_lambda_spec.hpp>
 
namespace boost { namespace mpl {
 
// default implementation; conrete sequences might override it by 
// specializing either the 'at_impl' or the primary 'at' template
 
template< typename Tag >
struct at_impl
{
    template< typename Sequence, typename N > struct apply
    {
        typedef typename advance<
              typename begin<Sequence>::type
            , N
            >::type iter_;
 
        typedef typename deref<iter_>::type type;
    };
};
 
BOOST_MPL_ALGORITM_TRAITS_LAMBDA_SPEC(2, at_impl)
 
}}
 
#endif // BOOST_MPL_AUX_AT_IMPL_HPP_INCLUDED