/////////////////////////////////////////////////////////////////////////////// /// \file at.hpp /// Proto callables Fusion at // // Copyright 2010 Eric Niebler. 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) #ifndef BOOST_PROTO_FUNCTIONAL_FUSION_AT_HPP_EAN_11_27_2010 #define BOOST_PROTO_FUNCTIONAL_FUSION_AT_HPP_EAN_11_27_2010 #include <boost/type_traits/add_const.hpp> #include <boost/type_traits/remove_const.hpp> #include <boost/type_traits/remove_reference.hpp> #include <boost/fusion/include/at.hpp> #include <boost/proto/proto_fwd.hpp> namespace boost { namespace proto { namespace functional { /// \brief A PolymorphicFunctionObject type that invokes the /// \c fusion::at() accessor on its argument. /// /// A PolymorphicFunctionObject type that invokes the /// \c fusion::at() accessor on its argument. struct at { BOOST_PROTO_CALLABLE() template<typename Sig> struct result; template<typename This, typename Seq, typename N> struct result<This(Seq, N)> : fusion::result_of::at< typename boost::remove_reference<Seq>::type , typename boost::remove_const<typename boost::remove_reference<N>::type>::type > {}; template<typename Seq, typename N> typename fusion::result_of::at<Seq, N>::type operator ()(Seq &seq, N const & BOOST_PROTO_DISABLE_IF_IS_CONST(Seq)) const { return fusion::at<N>(seq); } template<typename Seq, typename N> typename fusion::result_of::at<Seq const, N>::type operator ()(Seq const &seq, N const &) const { return fusion::at<N>(seq); } }; }}} #endif