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 22 namespace 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 27 template< typename Tag > 28 struct 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 39 BOOST_MPL_ALGORITM_TRAITS_LAMBDA_SPEC(1,empty_impl) 40 41 }} 42 43 #endif // BOOST_MPL_AUX_EMPTY_IMPL_HPP_INCLUDED 44