Re: [Boost-users] boost-spirit: need help with simple parser

Subject: Re: [Boost-users] boost-spirit: need help with simple parser
From: Allan Nielsen (a_at_[hidden])
Date: 2012-07-03 08:39:49

Thanks, I changed it to a lazy function as suggested, and then it works.

Just for the record:
struct Ipv4Address : qi::grammar<const char *, Ipv4()> {
    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<const char *, Ipv4()> start;
} ipv4_address;

On Tue, Jul 3, 2012 at 2:29 PM, Igor R <boost.lists_at_[hidden]> 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<uint8_t, uint8_t, uint8_t, uint8_t>,
> 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<uint8_t, uint8_t, uint8_t, uint8_t> _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;
> }
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