1 /*=============================================================================
2     Copyright (c) 2007 Tobias Schwinger
3 
4     Distributed under the Boost Software License, Version 1.0. (See accompanying
5     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6 ==============================================================================*/
7 #if !defined(BOOST_FUSION_SEQUENCE_EMPTY_IMPL_HPP_INCLUDED)
8 #define BOOST_FUSION_SEQUENCE_EMPTY_IMPL_HPP_INCLUDED
9 
10 #include <boost/fusion/support/config.hpp>
11 #include <boost/type_traits/is_convertible.hpp>
12 #include <boost/fusion/container/list/nil.hpp>
13 
14 namespace boost { namespace fusion
15 {
16     struct cons_tag;
17 
18     struct nil_;
19 
20     template <typename Car, typename Cdr>
21     struct cons;
22 
23     namespace extension
24     {
25         template <typename Tag>
26         struct empty_impl;
27 
28         template <>
29         struct empty_impl<cons_tag>
30         {
31             template <typename Sequence>
32             struct apply
33                 : boost::is_convertible<Sequence, nil_>
34             {};
35         };
36     }
37 }}
38 
39 #endif
40