mpl/aux_/back_impl.hpp

0001
0002 #ifndef BOOST_MPL_AUX_BACK_IMPL_HPP_INCLUDED
0003 #define BOOST_MPL_AUX_BACK_IMPL_HPP_INCLUDED
0004
0005 // Copyright Aleksey Gurtovoy 2000-2004
0006 //
0007 // Distributed under the Boost Software License, Version 1.0.
0008 // (See accompanying file LICENSE_1_0.txt or copy at
0009 // http://www.boost.org/LICENSE_1_0.txt)
0010 //
0011 // See http://www.boost.org/libs/mpl for documentation.
0012
0013 // $Id$
0014 // $Date$
0015 // $Revision$
0016
0017 #include <boost/mpl/begin_end.hpp>
0018 #include <boost/mpl/next_prior.hpp>
0019 #include <boost/mpl/deref.hpp>
0020 #include <boost/mpl/aux_/traits_lambda_spec.hpp>
0021
0022 namespace boost { namespace mpl {
0023
0024 // default implementation, requires at least bi-directional iterators;
0025 // conrete sequences might override it by specializing either the
0026 // 'back_impl' or the primary 'back' template
0027
0028 template< typename Tag >
0029 struct back_impl
0030 {
0031     template< typename Sequence > struct apply
0032     {
0033         typedef typename end<Sequence>::type end_;
0034         typedef typename prior<end_>::type last_;
0035         typedef typename deref<last_>::type type;
0036     };
0037 };
0038
0039 BOOST_MPL_ALGORITM_TRAITS_LAMBDA_SPEC(1, back_impl)
0040
0041 }}
0042
0043 #endif // BOOST_MPL_AUX_BACK_IMPL_HPP_INCLUDED