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