Re: Any interest for a parser class?

From: rogeeff (rogeeff_at_[hidden])
Date: 2002-01-17 11:02:34

--- In boost_at_y..., Vladimir Prus <ghost_at_c...> wrote:
> joel de guzman wrote:
> > ----- Original Message -----
> > From: "Vladimir Prus"
> >
> > > The only question is if Spirit will make any much difference 
for users
> > > that will justify making it a requirement. Yes, David Greene 
expressed a
> > > wish for an elaborated command line syntax, but it remains to 
be decided
> > > if it can'be be supported without using full-blown parser.
> >
> > That's exactly what David Held meant by reinventing
> > the wheel. We have the functionality here and now.
> 
> I think we better stop this discussion, as it brings us nowhere. I 
can use 
> YACC, or ANTRL or Spirit or whatever.  I won't use Spirit unless 
I'm shown
> that Spirit is appropriate for the task. So far, no concrete 
examples were 
> shown.
> 
> > > > Also, forgive me but why isn't nondeterministic RD not
> > > > acceptable for parsing command lines?
> > >
> > > Becase command line syntax can be ambiguious. Checking for those
> > > ambiguities and *documented* resolution of those resolvable are 
a must.
> > > Can
> > > nonterministic parsing give me that?
> >
> > I don't see a reason why not. I think you got this one 
incorrectly.
> > You are looking at the parser while instead you should be looking
> > at the parser generated by the parser. Your grammar should be
> > the one to allow / disallow and check / ignore ambiguity.
> 
> "-bar" can be interpreted, depending on the styles user wants 
> as either:
> 1) Three short options
> 2) Short option followed by parameter
> 3) Long option 
> Can you give an *example* of how this can be handled with Spirit.
> 
> - Volodya

Since I still do not see relationship between generic parse and 
Spirit (other than user can use it for custom argument implementation)
I agree an example would be extremly helpful. Here what I would like 
to see:

main.cpp:

#include <boost/spirit/spirit.hpp> // or whatever I need to include
                                   // with current version od Spirit

int main( int argc, char* argv[] )
{
   // Here I would like to see the definition of CLA parser that 
   // will accept following options:
   // -repeat_number <integer value>
   // -roll
   // -help
   // substrings are accepted (i.e. -repeat 3 should pass)
   // -help should automatically generate usage message to std::cout
   // it also should be generated in case of parsing errors like 
   // -rep 3.5 

   // ...

   // Here I would like to see How will I parse using the parser
   // defined
 
   // ...

   // Here I would like to see CLA values access

   // ...
}

In addition I would like to see how would I access CLA value from 
different file in my project:

second.cpp:
#include ??

void foo()
{
   // Here I would like to see CLA values access

   // ...
}

Also it would be helpful to estimate size of headers that will need 
to be inclued and number of template instantiations (approximately at 
least)

Gennadiy.