1
2#ifndef BOOST_MPL_AUX_EMPTY_IMPL_HPP_INCLUDED
3#define BOOST_MPL_AUX_EMPTY_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/empty_fwd.hpp>
18#include <boost/mpl/begin_end.hpp>
19#include <boost/mpl/aux_/traits_lambda_spec.hpp>
20#include <boost/type_traits/is_same.hpp>
21
22namespace boost { namespace mpl {
23
24// default implementation; conrete sequences might override it by
25// specializing either the 'empty_impl' or the primary 'empty' template
26
27template< typename Tag >
28struct empty_impl
29{
30 template< typename Sequence > struct apply
31 : is_same<
32 typename begin<Sequence>::type
33 , typename end<Sequence>::type
34 >
35 {
36 };
37};
38
39BOOST_MPL_ALGORITM_TRAITS_LAMBDA_SPEC(1,empty_impl)
40
41}}
42
43#endif // BOOST_MPL_AUX_EMPTY_IMPL_HPP_INCLUDED
44

source code of include/boost/mpl/aux_/empty_impl.hpp