aux_/pack/make_items.hpp

0001 // Copyright David Abrahams, Daniel Wallin 2003.
0002 // Distributed under the Boost Software License, Version 1.0.
0003 // (See accompanying file LICENSE_1_0.txt or copy at
0004 // http://www.boost.org/LICENSE_1_0.txt)
0005
0006 #ifndef BOOST_PARAMETER_AUX_PACK_MAKE_ITEMS_HPP
0007 #define BOOST_PARAMETER_AUX_PACK_MAKE_ITEMS_HPP
0008
0009 #include <boost/parameter/aux_/void.hpp>
0010 #include <boost/parameter/aux_/pack/item.hpp>
0011 #include <boost/parameter/config.hpp>
0012
0013 #if defined(BOOST_PARAMETER_CAN_USE_MP11)
0014 #include <boost/mp11/utility.hpp>
0015 #include <type_traits>
0016 #else
0017 #include <boost/mpl/eval_if.hpp>
0018 #include <boost/mpl/identity.hpp>
0019 #include <boost/type_traits/is_same.hpp>
0020 #endif
0021
0022 namespace boost { namespace parameter { namespace aux {
0023
0024     // Creates a item typelist.
0025     template <typename Spec, typename Arg, typename Tail>
0026 #if defined(BOOST_PARAMETER_CAN_USE_MP11)
0027     using make_items = ::boost::mp11::mp_if<
0028         ::std::is_same<Arg,::boost::parameter::void_>
0029       , ::boost::mp11::mp_identity< ::boost::parameter::void_>
0030       , ::boost::parameter::aux::make_item<Spec,Arg,Tail>
0031     >;
0032 #else
0033     struct make_items
0034       : ::boost::mpl::eval_if<
0035             ::boost::is_same<Arg,::boost::parameter::void_>
0036           , ::boost::mpl::identity< ::boost::parameter::void_>
0037           , ::boost::parameter::aux::make_item<Spec,Arg,Tail>
0038         >
0039     {
0040     };
0041 #endif
0042 }}} // namespace boost::parameter::aux
0043
0044 #endif  // include guard
0045