1
2#ifndef BOOST_MPL_AUX_AT_IMPL_HPP_INCLUDED
3#define BOOST_MPL_AUX_AT_IMPL_HPP_INCLUDED
4
5// Copyright Aleksey Gurtovoy 2000-2004
6//
7// Distributed under the Boost Software License, Version 1.0.
8// (See accompanying file LICENSE_1_0.txt or copy at
9// http://www.boost.org/LICENSE_1_0.txt)
10//
11// See http://www.boost.org/libs/mpl for documentation.
12
13// $Id$
14// $Date$
15// $Revision$
16
17#include <boost/mpl/begin_end.hpp>
18#include <boost/mpl/advance.hpp>
19#include <boost/mpl/deref.hpp>
20#include <boost/mpl/aux_/traits_lambda_spec.hpp>
21
22namespace boost { namespace mpl {
23
24// default implementation; conrete sequences might override it by
25// specializing either the 'at_impl' or the primary 'at' template
26
27template< typename Tag >
28struct at_impl
29{
30 template< typename Sequence, typename N > struct apply
31 {
32 typedef typename advance<
33 typename begin<Sequence>::type
34 , N
35 >::type iter_;
36
37 typedef typename deref<iter_>::type type;
38 };
39};
40
41BOOST_MPL_ALGORITM_TRAITS_LAMBDA_SPEC(2, at_impl)
42
43}}
44
45#endif // BOOST_MPL_AUX_AT_IMPL_HPP_INCLUDED
46