// In header: <boost/proto/transform/env.hpp>


struct _env :  proto::transform<_env> {
  // member classes/structs/unions
  
  struct impl :  proto::transform_impl<Expr, State, Data> {
    // types
    typedef Data result_type;

    // public member functions
    result_type operator()(typename impl::expr_param, 
                           typename impl::state_param, 
                           typename impl::data_param) const;
  };
};