Re: GDB/MI Output Syntax ambiguity

[Bob Rossi <bob at brasko dot net>]

On Mon, Aug 23, 2004 at 05:09:24PM -0400, Daniel Jacobowitz wrote:
> On Mon, Aug 23, 2004 at 05:03:14PM -0400, Bob Rossi wrote:
> > Hi,
> > 
> > I am generating a bottom up parser for 'GDB/MI Output Syntax' using
> > bison. Unfortunately, I think that I found an ambiguity, which makes it
> > not easily parsable. Please correct me if I am wrong.
> > 
> > output                  -> ( out-of-band-record )* [ result-record ] "(gdb)" nl
> > result-record           -> [ token ] "^" result-class ( "," result )* nl
> > out-of-band-record      -> async-record | stream-record
> > async-record            -> exec-async-output | status-async-output | notify-asyn
> > exec-async-output       -> [ token ] "*" async-output
> > status-async-output     -> [ token ] "+" async-output
> > notify-async-output     -> [ token ] "=" async-output
> > 
> > I am assuming that the grammar above for 'output' means that there can
> > be 0 or more 'out-of-band-record', followed by 0 or 1 'result-record',
> > followed by '(gdb)' and then a newline.
> 
> This is easily solved.  For instance, factor the optional token out of
> async-record and result-record, and handle output as:
>  output     -> [token] ( out-of-band-record-1 [token] )* [ result-record ] "(gdb)" nl
> 
> 
> I'm not sure how faithful to the documented grammar GDB is... but
> that's a separate problem.

Thanks! Hopefully it won't be to long before I'm done :)
Bob Rossi