/*============================================================================= | |
Copyright (c) 2001-2006 Joel de Guzman | |
Distributed under the Boost Software License, Version 1.0. (See accompanying | |
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | |
==============================================================================*/ | |
#if !defined(FUSION_EMPTY_09162005_0335) | |
#define FUSION_EMPTY_09162005_0335 | |
#include <boost/fusion/sequence/intrinsic/size.hpp> | |
#include <boost/mpl/bool.hpp> | |
#include <boost/fusion/support/tag_of.hpp> | |
namespace boost { namespace fusion | |
{ | |
// Special tags: | |
struct sequence_facade_tag; | |
struct mpl_sequence_tag; // mpl sequence tag | |
namespace extension | |
{ | |
template <typename Tag> | |
struct empty_impl | |
{ | |
template <typename Sequence> | |
struct apply | |
: mpl::bool_<(result_of::size<Sequence>::value == 0)> | |
{}; | |
}; | |
template <> | |
struct empty_impl<sequence_facade_tag> | |
{ | |
template <typename Sequence> | |
struct apply : Sequence::template empty<Sequence> {}; | |
}; | |
template <> | |
struct empty_impl<mpl_sequence_tag>; | |
} | |
namespace result_of | |
{ | |
template <typename Sequence> | |
struct empty | |
: extension::empty_impl<typename detail::tag_of<Sequence>::type>:: | |
template apply<Sequence> | |
{}; | |
} | |
template <typename Sequence> | |
inline typename result_of::empty<Sequence>::type | |
empty(Sequence const&) | |
{ | |
typedef typename result_of::empty<Sequence>::type result; | |
return result(); | |
} | |
}} | |
#endif |