or even simpler: boost::tuple v; bool r = qi::parse(s.begin(), s.end(), octet >> '.' >> octet >> '.'

...

...

octet >> '.' >> octet, v);

while the following works correctly: boost::fusion::vector v; bool r = qi::parse(s.begin(), s.end(), octet >> '.' >> octet >> '.'

...

...

octet >> '.' >> octet, v);

So, the attribute gets converted to boost::tuple is some strange way...

Well, finally got it. You have to #include to get boost::tuple adapted correctly.

On 07/03/2012 02:02 PM, Allan Nielsen wrote:

Hi,

Sorry for not providing the simplest possible code to reproduce my problem, but I'm still new to spirit, I think I will miss some details in the conversion.

I tried add the inclusion you suggested, but it did not help. In the mean while, I found this page: http://boost-spirit.com/home/2010/01/19/how-to-access-attributes-from-semant... which is a very good match on what I would like to do.

The only problem is that I can not make it work...

Here is my second attempt (simper that the first, but not as simple as you suggested... sorry)

#include<string> #include #include<iostream> #include #include #include

struct Ipv4 { union { uint32_t as_int; uint8_t as_char[4]; } raw; };

Ipv4 make_ipv4(uint8_t i1, uint8_t i2, uint8_t i3, uint8_t i4) { Ipv4 ip; ip.raw.as_char[0] = i1; ip.raw.as_char[1] = i2; ip.raw.as_char[2] = i3; ip.raw.as_char[3] = i4; return ip; }

namespace qi = boost::spirit::qi; qi::uint_parser octet;

struct Ipv4Address : qi::grammar { Ipv4Address() : Ipv4Address::base_type(start) { start = ( octet>> qi::lit('.')>> octet>> qi::lit('.')>> octet>> qi::lit('.')>> octet ) [ //qi::_val = make_ipv4(1, 2, 3, 4) // working qi::_val = make_ipv4(qi::_1, qi::_2, qi::_3, qi::_4) // compile error ] ; } qi::rule start; } ipv4_address;

int main() { Ipv4 ip; const char * s = "1.2.3.4"; bool r = qi::parse(s, s+strlen(s), ipv4_address, ip); std::cout<< r<< " "<< (int)ip.raw.as_char[0]<< "."<< (int)ip.raw.as_char[1]<< "."<< (int)ip.raw.as_char[2]<< "."<< (int)ip.raw.as_char[3]<< std::endl; }

When compiling this I get the following compile error:

/tmp/ip.cxx: In constructor 'Ipv4Address::Ipv4Address()': /tmp/ip.cxx:26:72: error: cannot convert 'const _1_type {aka const boost::phoenix::actor >}' to 'uint8_t {aka unsigned char}' for argument '1' to 'Ipv4 make_ipv4(uint8_t, uint8_t, uint8_t, uint8_t)'

Any hints?

make_ipv4 is an eager function, you need a lazy function, that is only executed when the parsing succeeds. Your commented line works as expected because everything involved in the eager function call has the right type. look into phoenix::bind to make the function call lazy

Best regards Allan W. Nielsen

On Tue, Jul 3, 2012 at 1:10 PM, Igor R wrote:

...

...

or even simpler: boost::tuple v; bool r = qi::parse(s.begin(), s.end(), octet>> '.'>> octet>> '.'

...

...

octet>> '.'>> octet, v); while the following works correctly: boost::fusion::vector v; bool r = qi::parse(s.begin(), s.end(), octet>> '.'>> octet>> '.' octet>> '.'>> octet, v); So, the attribute gets converted to boost::tuple is some strange way...

Well, finally got it. You have to #include to get boost::tuple adapted correctly. _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

---

Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

Thanks, I changed it to a lazy function as suggested, and then it works. Just for the record: struct Ipv4Address : qi::grammar { Ipv4Address() : Ipv4Address::base_type(start) { start = ( octet >> qi::lit('.') >> octet >> qi::lit('.') >> octet >> qi::lit('.') >> octet ) [ qi::_val = phx::bind(&make_ipv4, qi::_1, qi::_2, qi::_3, qi::_4 ) ] ; } qi::rule start; } ipv4_address; On Tue, Jul 3, 2012 at 2:29 PM, Igor R wrote:

...

Sorry for not providing the simplest possible code to reproduce my problem, but I'm still new to spirit, I think I will miss some details in the conversion.

I tried add the inclusion you suggested, but it did not help.

Sorry, although it works for boost::tuple, it won't work for your Ipv4 struct... But a simple workaround can solve this issue: in Ipv4Address grammar change attribute to boost::tuple, and in your parse() function use tuple type as temporary, then copy it to Ipv4 argument (you use a temporary anyway). Like this: bool parse(const const_string& s, Ipv4& i) { boost::tuple _i; const char * iter = s.begin(); bool r = qi::parse(iter, s.end(), ipv4_address, _i);

if( !r || iter != s.end() ) return false;

i = Ipv4(_i); return true; } _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users