----- Original Message ----- From: "Felipe Magno de Almeida" <felipe.m.almeida@gmail.com> To: <boost@lists.boost.org> Sent: Friday, September 16, 2005 9:40 AM Subject: Re: [boost] Async xpressive, regex and spirit
IMO, it would be needed the possibility to have more than one grammar, one for success and another for failure(Would be interesting to have the possibility for more than two), until no-one has a match continue to wait for more data...
Sorry. Don't follow the duplex grammar idea.
Imagine a SMTP protocol, it has two or more responses for a command, being from success, warning and completely failure. That way is necessary 3 grammars, one for each. If nothing matched, then we probably have a real problem. But one of the three should be matched, in genereal.
I suspect we have different understandings of what a grammar is. Other possible misunderstandings make this confusing, e.g. software that receives SMTP responses never receives the related commands (client vs server) so a grammar that spans these domains does not make sense? Also, are you applying language technology (i.e. grammars) to the overall processing of protocol signals/messages? While I find the idea compelling (my first use of yacc a long time ago was for exactly this) it may not be the most appropriate, e.g. FSMs are "lingua franca" in telephony protocols whereas grammars do not get a mention. But grammars are cool :-) Cheers.