Eric, I can get the type of a proto expression (wrapped in a user-defined skin) using BOOST_TYPEOF, but then I noticed BOOST_PROTO_TYPEOF in context.hpp. Which one is supposed to be used? BOOST_PROTO_TYPEOF fails on me when trying to emulate the way it is used inside context.hpp. Here is code that shows what I'm trying. If BOOST_PROTO_TYPEOF is internal only, just let me know and forget the code below. Regards, Maurizio #include <iostream> #define BOOST_MPL_CFG_NO_PREPROCESSED_HEADERS #define BOOST_PROTO_MAX_ARITY 8 #define BOOST_MPL_LIMIT_METAFUNCTION_ARITY 8 // GCC bug workaround, needs to be at least BOOST_PROTO_MAX_ARITY #include <boost/xpressive/proto/proto.hpp> #include <boost/xpressive/proto/context.hpp> #include <boost/xpressive/proto/extends.hpp> #include <boost/xpressive/proto/transform/arg.hpp> #include <boost/xpressive/proto/transform/construct.hpp> namespace proto=boost::proto; namespace mpl=boost::mpl; using proto::_; struct my_domain : proto::domain<struct my_grammar> {}; //struct my_domain : proto::domain<> {}; template<typename> struct my_context; template <typename Expr> struct my_expr : proto::extends<Expr, my_expr<Expr>, my_domain> { typedef proto::extends<Expr, my_expr<Expr>, my_domain> base_type; my_expr (Expr const& expr = Expr()) : base_type (expr) {}; using base_type::operator =; operator int () const { return static_cast<int>(proto::eval(*this, my_context<Expr> ())); } operator unsigned int () const { return static_cast<unsigned int>(proto::eval(*this, my_context<Expr> ())); } }; template<typename A, typename B, typename C, typename D, typename E, typename F, typename G, typename H> struct number { unsigned int m_data; }; struct my_grammar : proto::or_ < proto::terminal< number<_,_,_,_,_,_,_,_> > , proto::terminal<int>, proto::terminal<unsigned int>, proto::unary_expr<proto::_, my_grammar> , proto::binary_expr<proto::_, my_grammar, my_grammar>
{}; namespace boost { namespace proto { template<typename Expr> struct generate<my_domain, Expr> { typedef my_expr<Expr> type; static type make (Expr const& expr) { return type (expr); } }; } } // end namespace boost::proto template<typename Expr> struct my_context : proto::callable_context<const my_context<Expr> > { typedef unsigned int result_type; template<typename A, typename B, typename C, typename D, typename E, typename F, typename G, typename H> unsigned int operator () (proto::tag::terminal, number<A,B,C,D,E,F,G,H> n) const { return n.m_data; } }; template<int N> struct my_int : my_expr<typename proto::terminal< number<mpl::int_<0>,mpl::int_<0>, mpl::int_<0>, mpl::int_<0>, mpl::int_<0>, mpl::int_<0>, mpl::int_<0>, mpl::int_<0> > >::type> { typedef number<mpl::int_<0>,mpl::int_<0>, mpl::int_<0>, mpl::int_<0>, mpl::int_<0>, mpl::int_<0>, mpl::int_<0>, mpl::int_<0> > number_type; typedef my_expr<typename proto::terminal<number_type>::type> expr_type; my_int () {} my_int (int i) : expr_type (expr_type::type::make (i)) {} template<typename Expr> my_int& operator = (const my_expr<Expr>& e) { proto::arg (*this).m_data = static_cast<int>(proto::eval(e, my_context<Expr> ())); return *this; } template<typename T> my_int& operator = (T value) { proto::arg (*this).m_data = value; return *this; } }; template<typename T> struct dump; #define DUMP(T) typedef dump<T>::type t int main (int,char**) { my_int<6> i4(-22); int i; unsigned int j; i4 = 5; i4 = 5*i4; i = i4/i4+4; j = i4/i4; BOOST_PROTO_TYPEOF (i4+j+2, a_type); DUMP (a_type); // typedef BOOST_TYPEOF (i4*2) another_type; // DUMP(another_type); } /// Local Variables: /// mode:c++ /// comment-column:80 /// fill-column:160 /// compilation-read-command:nil /// compile-command:"g++ -I. -ope1 pe1.cpp" /// End: