spirit :: qi: passing inherited attribute reference to phoenix :: function

Question

El siguiente código es una versión optimizada de lo que estoy tratando de hacer. Básicamente, tengo struct (int_holder en el código de juguete), con un miembro de contenedor de datos. Quiero insertar un objeto (int en este caso) y devolver al padre qi :: rule un puntero al objeto recién insertado.

Paso el int_holder a la gramática por referencia, para llenarlo con valores durante el análisis, por lo tanto, el int_holder será un atributo heredado de la gramática. Código:

#include <boost/spirit/include/qi.hpp> 
#include <boost/spirit/include/phoenix_core.hpp> 
#include <boost/spirit/include/phoenix_operator.hpp> 
#include <boost/spirit/include/phoenix_function.hpp> 
#include <vector> 

namespace qi=boost::spirit::qi; 
namespace phoenix=boost::phoenix; 

struct int_holder 
{ 
    int_holder() {} 
    std::vector<int> ints; 
}; 


struct insert_impl 
{ 
    template<class, class> 
    struct result { typedef int* type; }; 
    int* operator() (int_holder& holder, int i) const 
    { 
     holder.ints.push_back (i); 
     return &holder.ints.back(); 
    } 
}; 

template<class Iterator> 
struct my_grammar : qi::grammar<Iterator, int*(int_holder&)> 
{ 
    my_grammar() : my_grammar::base_type (start) 
      , insert (insert_impl()) 
    { 
     using qi::_val; 
     using qi::int_; 
     using qi::_r1; 
     using qi::_1; 

     using phoenix::ref; 

     start = +next(_val) [_val = _1]; 
     next = int_ [_val = insert(_r1, _1)]; 
    } 
    qi::rule<Iterator, int*(int_holder&)> start, next; 
    phoenix::function<insert_impl> insert; 
}; 


int main() 
{ 
    using phoenix::ref; 

    const char* p="1"; 
    int* last; 
    int_holder holder; 
    my_grammar<const char*> g; 
    qi::parse (p, p+1, g(ref(holder)), last); 
} 

El código no compila, con el siguiente mensaje de error:

In file included from  
/opt/local/include/boost/fusion/sequence/intrinsic/detail/segmented_begin.hpp:16:0, 
     from /opt/local/include/boost/fusion/sequence/intrinsic/begin.hpp:17, from 
     /opt/local/include/boost/fusion/iterator/segmented_iterator.hpp:12, from 
     /opt/local/include/boost/fusion/sequence/intrinsic/detail/segmented_end.hpp:11, from 
     /opt/local/include/boost/fusion/sequence/intrinsic/end.hpp:17, from 
     /opt/local/include/boost/fusion/sequence/intrinsic/back.hpp:11, from 
     /opt/local/include/boost/fusion/sequence/intrinsic.hpp:11, from 
     /opt/local/include/boost/fusion/include/intrinsic.hpp:10, from 
     /opt/local/include/boost/proto/fusion.hpp:22, from 
     /opt/local/include/boost/proto/core.hpp:21, from 
     /opt/local/include/boost/proto/proto.hpp:12, from 
     /opt/local/include/boost/spirit/home/support/meta_compiler.hpp:19, from 
     /opt/local/include/boost/spirit/home/qi/meta_compiler.hpp:14, from 
     /opt/local/include/boost/spirit/home/qi/action/action.hpp:14, from 
     /opt/local/include/boost/spirit/home/qi/action.hpp:14, from 
     /opt/local/include/boost/spirit/home/qi.hpp:14, from 
     /opt/local/include/boost/spirit/include/qi.hpp:16, from test_qi.cpp:1: 
     /opt/local/include/boost/fusion/container/list/cons.hpp: In instantiation of 
     'boost::fusion::cons<Car, Cdr>::cons(const boost::fusion::cons<Car2, Cdr2>&) [with Car2 = 
     int*&; Cdr2 = boost::fusion::nil; Car = int_holder&; Cdr = boost::fusion::nil]': 
     /opt/local/include/boost/spirit/home/support/context.hpp:117:20: required from 
     'boost::spirit::context<Attributes, Locals>::context(typename Attributes::car_type, const 
     Args&, Context&) [with Args = 
     boost::fusion::vector<boost::phoenix::actor<boost::spirit::attribute<0> >, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, 
     boost::fusion::void_>; Context = boost::spirit::context<boost::fusion::cons<int*&, 
     boost::fusion::cons<int_holder&, boost::fusion::nil> >, boost::fusion::vector0<> >; 
     Attributes = boost::fusion::cons<int*&, boost::fusion::cons<int_holder&, 
     boost::fusion::nil> >; Locals = boost::fusion::vector0<>; typename Attributes::car_type = 
     int*&]' /opt/local/include/boost/spirit/home/qi/nonterminal/rule.hpp:343:67: required 
     from 'bool boost::spirit::qi::rule<Iterator, T1, T2, T3, T4>::parse(Iterator&, const 
     Iterator&, Context&, const Skipper&, Attribute&, const Params&) const [with Context = 
     boost::spirit::context<boost::fusion::cons<int*&, boost::fusion::cons<int_holder&, 
     boost::fusion::nil> >, boost::fusion::vector0<> >; Skipper = boost::spirit::unused_type; 
     Attribute = int*; Params = 
     boost::fusion::vector<boost::phoenix::actor<boost::spirit::attribute<0> >, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, 
     boost::fusion::void_>; Iterator = const char*; T1 = int*(int_holder&); T2 = 
     boost::spirit::unused_type; T3 = boost::spirit::unused_type; T4 = 
     boost::spirit::unused_type]' 
     /opt/local/include/boost/spirit/home/qi/nonterminal/detail/parameterized.hpp:48:79: 
     required from 'bool boost::spirit::qi::parameterized_nonterminal<Subject, 
     Params>::parse(Iterator&, const Iterator&, Context&, const Skipper&, Attribute&) const 
     [with Iterator = const char*; Context = boost::spirit::context<boost::fusion::cons<int*&, 
     boost::fusion::cons<int_holder&, boost::fusion::nil> >, boost::fusion::vector0<> >; 
     Skipper = boost::spirit::unused_type; Attribute = int*; Subject = 
     boost::spirit::qi::rule<const char*, int*(int_holder&), boost::spirit::unused_type, 
     boost::spirit::unused_type, boost::spirit::unused_type>; Params = 
     boost::fusion::vector<boost::phoenix::actor<boost::spirit::attribute<0> >, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, 
     boost::fusion::void_>]' /opt/local/include/boost/spirit/home/qi/action/action.hpp:65:13: 
     required from 'bool boost::spirit::qi::action<Subject, Action>::parse(Iterator&, const 
     Iterator&, Context&, const Skipper&, Attribute&) const [with Iterator = const char*; 
     Context = boost::spirit::context<boost::fusion::cons<int*&, 
     boost::fusion::cons<int_holder&, boost::fusion::nil> >, boost::fusion::vector0<> >; 
     Skipper = boost::spirit::unused_type; Attribute = boost::spirit::unused_type; Subject = 
     boost::spirit::qi::parameterized_nonterminal<boost::spirit::qi::rule<const char*, 
     int*(int_holder&), boost::spirit::unused_type, boost::spirit::unused_type, 
     boost::spirit::unused_type>, 
     boost::fusion::vector<boost::phoenix::actor<boost::spirit::attribute<0> >, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, 
     boost::fusion::void_> >; Action = 
     boost::phoenix::actor<boost::phoenix::composite<boost::phoenix::assign_eval, 
     boost::fusion::vector<boost::spirit::attribute<0>, boost::spirit::argument<0>, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_> > 
     >]' /opt/local/include/boost/spirit/home/qi/detail/fail_function.hpp:38:72: required from 
     'bool boost::spirit::qi::detail::fail_function<Iterator, Context, 
     Skipper>::operator()(const Component&, Attribute&) const [with Component = 
     boost::spirit::qi::action<boost::spirit::qi::parameterized_nonterminal<boost::spirit::qi::rule<const 
     char*, int*(int_holder&), boost::spirit::unused_type, boost::spirit::unused_type, 
     boost::spirit::unused_type>, 
     boost::fusion::vector<boost::phoenix::actor<boost::spirit::attribute<0> >, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, 
     boost::fusion::void_> >, 
     boost::phoenix::actor<boost::phoenix::composite<boost::phoenix::assign_eval, 
     boost::fusion::vector<boost::spirit::attribute<0>, boost::spirit::argument<0>, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_> > 
     > >; Attribute = boost::spirit::unused_type; Iterator = const char*; Context = 
     boost::spirit::context<boost::fusion::cons<int*&, boost::fusion::cons<int_holder&, 
     boost::fusion::nil> >, boost::fusion::vector0<> >; Skipper = boost::spirit::unused_type]' 
     /opt/local/include/boost/spirit/home/qi/detail/pass_container.hpp:263:38: [ skipping 10 
     instantiation contexts ] /opt/local/include/boost/function/function_template.hpp:1042:16: 
     required from 'boost::function<R(T0, T1, T2, T3)>::function(Functor, typename 
     boost::enable_if_c<boost::type_traits::ice_not<boost::is_integral<Functor>::value>::value, 
     int>::type) [with Functor = 
     boost::spirit::qi::detail::parser_binder<boost::spirit::qi::plus<boost::spirit::qi::action<boost::spirit::qi::parameterized_nonterminal<boost::spirit::qi::rule<const 
     char*, int*(int_holder&), boost::spirit::unused_type, boost::spirit::unused_type, 
     boost::spirit::unused_type>, 
     boost::fusion::vector<boost::phoenix::actor<boost::spirit::attribute<0> >, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, 
     boost::fusion::void_> >, 
     boost::phoenix::actor<boost::phoenix::composite<boost::phoenix::assign_eval, 
     boost::fusion::vector<boost::spirit::attribute<0>, boost::spirit::argument<0>, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_> > 
     > > >, mpl_::bool_<false> >; R = bool; T0 = const char*&; T1 = const char* const&; T2 = 
     boost::spirit::context<boost::fusion::cons<int*&, boost::fusion::cons<int_holder&, 
     boost::fusion::nil> >, boost::fusion::vector0<> >&; T3 = const 
     boost::spirit::unused_type&; typename 
     boost::enable_if_c<boost::type_traits::ice_not<boost::is_integral<Functor>::value>::value, 
     int>::type = int]' /opt/local/include/boost/function/function_template.hpp:1083:5: 
     required from 'typename 
     boost::enable_if_c<boost::type_traits::ice_not<boost::is_integral<Functor>::value>::value, 
     boost::function<R(T0, T1, T2, T3)>&>::type boost::function<R(T0, T1, T2, 
     T3)>::operator=(Functor) [with Functor = 
     boost::spirit::qi::detail::parser_binder<boost::spirit::qi::plus<boost::spirit::qi::action<boost::spirit::qi::parameterized_nonterminal<boost::spirit::qi::rule<const 
     char*, int*(int_holder&), boost::spirit::unused_type, boost::spirit::unused_type, 
     boost::spirit::unused_type>, 
     boost::fusion::vector<boost::phoenix::actor<boost::spirit::attribute<0> >, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, 
     boost::fusion::void_> >, 
     boost::phoenix::actor<boost::phoenix::composite<boost::phoenix::assign_eval, 
     boost::fusion::vector<boost::spirit::attribute<0>, boost::spirit::argument<0>, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_> > 
     > > >, mpl_::bool_<false> >; R = bool; T0 = const char*&; T1 = const char* const&; T2 = 
     boost::spirit::context<boost::fusion::cons<int*&, boost::fusion::cons<int_holder&, 
     boost::fusion::nil> >, boost::fusion::vector0<> >&; T3 = const 
     boost::spirit::unused_type&; typename 
     boost::enable_if_c<boost::type_traits::ice_not<boost::is_integral<Functor>::value>::value, 
     boost::function<R(T0, T1, T2, T3)>&>::type = boost::function<bool(const char*&, const 
     char* const&, boost::spirit::context<boost::fusion::cons<int*&, 
     boost::fusion::cons<int_holder&, boost::fusion::nil> >, boost::fusion::vector0<> >&, 
     const boost::spirit::unused_type&)>&]' 
     /opt/local/include/boost/spirit/home/qi/nonterminal/rule.hpp:182:13: required from 
     'static void boost::spirit::qi::rule<Iterator, T1, T2, T3, 
     T4>::define(boost::spirit::qi::rule<Iterator, T1, T2, T3, T4>&, const Expr&, mpl_::true_) 
     [with Auto = mpl_::bool_<false>; Expr = 
     boost::proto::exprns_::expr<boost::proto::tagns_::tag::unary_plus, 
     boost::proto::argsns_::list1<const 
     boost::proto::exprns_::expr<boost::proto::tagns_::tag::subscript, 
     boost::proto::argsns_::list2<boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, 
     boost::proto::argsns_::term<boost::spirit::qi::parameterized_nonterminal<boost::spirit::qi::rule<const 
     char*, int*(int_holder&), boost::spirit::unused_type, boost::spirit::unused_type, 
     boost::spirit::unused_type>, 
     boost::fusion::vector<boost::phoenix::actor<boost::spirit::attribute<0> >, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, 
     boost::fusion::void_> > >, 0l>&, 
     boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, 
     boost::proto::argsns_::term<const 
     boost::phoenix::actor<boost::phoenix::composite<boost::phoenix::assign_eval, 
     boost::fusion::vector<boost::spirit::attribute<0>, boost::spirit::argument<0>, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_> > 
     >&>, 0l> >, 2l>&>, 1l>; Iterator = const char*; T1 = int*(int_holder&); T2 = 
     boost::spirit::unused_type; T3 = boost::spirit::unused_type; T4 = 
     boost::spirit::unused_type; boost::spirit::qi::rule<Iterator, T1, T2, T3, T4> = 
     boost::spirit::qi::rule<const char*, int*(int_holder&), boost::spirit::unused_type, 
     boost::spirit::unused_type, boost::spirit::unused_type>; mpl_::true_ = 
     mpl_::bool_<true>]' /opt/local/include/boost/spirit/home/qi/nonterminal/rule.hpp:220:13: 
     required from 'boost::spirit::qi::rule<Iterator, T1, T2, T3, T4>& 
     boost::spirit::qi::rule<Iterator, T1, T2, T3, T4>::operator=(const Expr&) [with Expr = 
     boost::proto::exprns_::expr<boost::proto::tagns_::tag::unary_plus, 
     boost::proto::argsns_::list1<const 
     boost::proto::exprns_::expr<boost::proto::tagns_::tag::subscript, 
     boost::proto::argsns_::list2<boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, 
     boost::proto::argsns_::term<boost::spirit::qi::parameterized_nonterminal<boost::spirit::qi::rule<const 
     char*, int*(int_holder&), boost::spirit::unused_type, boost::spirit::unused_type, 
     boost::spirit::unused_type>, 
     boost::fusion::vector<boost::phoenix::actor<boost::spirit::attribute<0> >, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, 
     boost::fusion::void_> > >, 0l>&, 
     boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, 
     boost::proto::argsns_::term<const 
     boost::phoenix::actor<boost::phoenix::composite<boost::phoenix::assign_eval, 
     boost::fusion::vector<boost::spirit::attribute<0>, boost::spirit::argument<0>, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, 
     boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_> > 
     >&>, 0l> >, 2l>&>, 1l>; Iterator = const char*; T1 = int*(int_holder&); T2 = 
     boost::spirit::unused_type; T3 = boost::spirit::unused_type; T4 = 
     boost::spirit::unused_type; boost::spirit::qi::rule<Iterator, T1, T2, T3, T4> = 
     boost::spirit::qi::rule<const char*, int*(int_holder&), boost::spirit::unused_type, 
     boost::spirit::unused_type, boost::spirit::unused_type>]' test_qi.cpp:41:3: required from 
     'my_grammar<Iterator>::my_grammar() [with Iterator = const char*]' test_qi.cpp:57:26: 
     required from here /opt/local/include/boost/fusion/container/list/cons.hpp:83:40: error: 
     invalid initialization of reference of type 'boost::fusion::cons<int_holder&, 
     boost::fusion::nil>::car_type {aka int_holder&}' from expression of type 'int*' 

es evidente que existe un problema cuando se pasa a la función _r1 el Fénix ::, pero no tengo ni idea de cómo resuélvelo. Gracias por adelantado.

Answer 1

Lo sentimos, Acabo de descubrir el error, la línea de código

start = +next(_val) [_val = _1]; 

necesitaba ser cambiado a

start = +next(_r1) [_val = _1]; 

y entonces funciona. Perdón por perder tu tiempo! ¡Adiós!