williamr@2: 
williamr@4: #ifndef BOOST_MPL_AUX_AT_IMPL_HPP_INCLUDED
williamr@4: #define BOOST_MPL_AUX_AT_IMPL_HPP_INCLUDED
williamr@2: 
williamr@4: // Copyright Aleksey Gurtovoy 2000-2004
williamr@2: //
williamr@2: // Distributed under the Boost Software License, Version 1.0. 
williamr@2: // (See accompanying file LICENSE_1_0.txt or copy at 
williamr@2: // http://www.boost.org/LICENSE_1_0.txt)
williamr@2: //
williamr@2: // See http://www.boost.org/libs/mpl for documentation.
williamr@2: 
williamr@4: // $Source: /cvsroot/boost/boost/boost/mpl/aux_/at_impl.hpp,v $
williamr@4: // $Date: 2004/09/02 15:40:43 $
williamr@4: // $Revision: 1.5 $
williamr@2: 
williamr@4: #include <boost/mpl/begin_end.hpp>
williamr@4: #include <boost/mpl/advance.hpp>
williamr@4: #include <boost/mpl/deref.hpp>
williamr@4: #include <boost/mpl/aux_/traits_lambda_spec.hpp>
williamr@2: 
williamr@2: namespace boost { namespace mpl {
williamr@2: 
williamr@4: // default implementation; conrete sequences might override it by 
williamr@4: // specializing either the 'at_impl' or the primary 'at' template
williamr@4: 
williamr@4: template< typename Tag >
williamr@4: struct at_impl
williamr@2: {
williamr@4:     template< typename Sequence, typename N > struct apply
williamr@2:     {
williamr@4:         typedef typename advance<
williamr@4:               typename begin<Sequence>::type
williamr@4:             , N
williamr@4:             >::type iter_;
williamr@4: 
williamr@4:         typedef typename deref<iter_>::type type;
williamr@2:     };
williamr@2: };
williamr@2: 
williamr@4: BOOST_MPL_ALGORITM_TRAITS_LAMBDA_SPEC(2, at_impl)
williamr@4: 
williamr@2: }}
williamr@2: 
williamr@4: #endif // BOOST_MPL_AUX_AT_IMPL_HPP_INCLUDED