Re: Domain name label length

On Thu, Dec 28, 2017 at 12:27 AM, Joel de Guzman <[email protected]> wrote:
> On 26/12/2017 11:38 AM, Michael Powell wrote:
>>
>> Hello,
>>
>> So, a domain name label looks something like this, in general, right?
>>
>> _label = _let >> *(_let | _dig | _hyp) >> (_let | _dig);
>>
>> However, another stipulation is that its length must be <=63 according
>> to the RFC:
>>
>> https://tools.ietf.org/html/rfc1034#section-3.5
>>
>> So... Is there a way to constrain that using Qi?
>
>
> Yes, but if I were you, I'd probably avoid having too much smarts in
> the parser and have those checks post-hoc.

Yes, of course. The rule thus far is pretty straightforward, to do
with length and length only. It would be inappropriate to embed
anything that was so application specific.

template<typename Iterator>
struct MyParser : qi::grammar<Iterator, Ast::Address()> {

    struct validate_label_length {
        template<typename Context>
        void operator()(std::string& l, Context&, bool& pass) {
            pass = l.length() <= 63;
        }
    };

    // ...

    ... _label = raw[_let >> -(*(_let | _dig | _hyp) >> (_let |
_dig))][validate_label_length()];
    ... _address = _label % dot_;

    ... _start = _address >> eoi;
};

But this is yielding compiler errors. I'm not sure I need to include
something Fusion related?

#include <boost/spirit/home/qi.hpp>
#include "ast/domain_name.hpp"

The structure is nested, defined in the scope of my template Parser.

Severity Code Description Project File Line Suppression State
Error C2893 Failed to specialize function template
'action_dispatch<Subject>::fwd_storage<unknown-type,boost::spirit::traits::action_dispatch<Subject>::fwd_none>::type
boost::spirit::traits::action_dispatch<Subject>::do_call(F &&,...)'
Rfc3986_Uri_RegexSyntaxVerification
G:\Source\Boost.Installs\boost_1_65_1\boost\spirit\home\support\action_dispatch.hpp
142
Error C2672 'boost::spirit::traits::action_dispatch<Subject>::do_call':
no matching overloaded function found
Rfc3986_Uri_RegexSyntaxVerification
G:\Source\Boost.Installs\boost_1_65_1\boost\spirit\home\support\action_dispatch.hpp
142
Error C2893 Failed to specialize function template
'action_dispatch<Subject>::fwd_storage<unknown-type,boost::spirit::traits::action_dispatch<Subject>::fwd_attrib_context_pass>::type
boost::spirit::traits::action_dispatch<Subject>::do_call(F
&&,boost::spirit::traits::action_dispatch<Subject>::fwd_tag<A>,boost::spirit::traits::action_dispatch<Subject>::fwd_tag<B>,boost::spirit::traits::action_dispatch<Subject>::fwd_tag<C>,...)'
Rfc3986_Uri_RegexSyntaxVerification
G:\Source\Boost.Installs\boost_1_65_1\boost\spirit\home\support\action_dispatch.hpp
142
Error C2893 Failed to specialize function template
'action_dispatch<Subject>::fwd_storage<unknown-type,boost::spirit::traits::action_dispatch<Subject>::fwd_attrib_context>::type
boost::spirit::traits::action_dispatch<Subject>::do_call(F
&&,boost::spirit::traits::action_dispatch<Subject>::fwd_tag<A>,boost::spirit::traits::action_dispatch<Subject>::fwd_tag<B>,...)'
Rfc3986_Uri_RegexSyntaxVerification
G:\Source\Boost.Installs\boost_1_65_1\boost\spirit\home\support\action_dispatch.hpp
142
Error C2893 Failed to specialize function template
'action_dispatch<Subject>::fwd_storage<unknown-type,boost::spirit::traits::action_dispatch<Subject>::fwd_attrib>::type
boost::spirit::traits::action_dispatch<Subject>::do_call(F
&&,boost::spirit::traits::action_dispatch<Subject>::fwd_tag<A>,...)'
Rfc3986_Uri_RegexSyntaxVerification
G:\Source\Boost.Installs\boost_1_65_1\boost\spirit\home\support\action_dispatch.hpp
142

> Regards,
> --
> Joel de Guzman
> http://www.ciere.com
> http://boost-spirit.com
> http://www.cycfi.com/
>
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