These are fair observations. In fact SIP ABNF is not LL(1) therefore you cannot easily build a parser for it using a parser generator.
The ABNF is context sensitive. If you want to build a parse for it using parser generators, I have built one using antlr but it is so convoluted and slow that I gave up. Best parse sip by hand. Ranga On Wed, Mar 26, 2008 at 5:29 PM, Paul Kyzivat <[EMAIL PROTECTED]> wrote: > You could make the same argument about C or Java. They would (arguably) > be easier to compile if you only allowed whitespace in a much more > restricted set of places. > > I think this is more a matter of how the syntax is described, rather > than what it allows. Most parsers that I know of distinguish lexical > processing from parsing. If you do that, each becomes simpler. But the > 3261 syntax in ABNF encompasses both, and is more complex as a result. > > I think you might find that if you manually transformed the syntax, > splitting off a lexical phase, you wouldn't see the same complexity. > > In any case, the form of the syntax is now institutionalized and won't > be changed any time soon. > > Paul > > > Iñaki Baz Castillo wrote: > > El Wednesday 26 March 2008 14:50:45 Iñaki Baz Castillo escribió: > > > >> Am I the only who thinks that SIP could be really much easier than it's > now > >> just by doing it less permissive? > > > > More things: > > > > > > - Why line folding allows any number of space or tab at the beggining of > the > > line instead of just a single space? > > ------------------------------------------------------- > > Subject: This is the > > subject in > > line > > folding > > ------------------------------------------------------- > > In fact, when it's rebuilt in the UAS any number of spaces at the line > start > > is converted into a single space: > > ------------------------------------------------------- > > Subject: This is the subject in line folding > > ------------------------------------------------------- > > > > > > - Why host:port allows any number of spaces, tabs, CRLF between "host" and > ":" > > and between ":" and "port"? > > ------------------------------------------------------- > > 192.168.1.33 > > : > > 5061 > > ------------------------------------------------------- > > Wouldn't it be much easier if there couldn't be any space between them? > > ------------------------------------------------------- > > 192.168.1.33:5061 > > ------------------------------------------------------- > > > > > > Best regards. > > > > > _______________________________________________ > Sip-implementors mailing list > Sip-implementors@lists.cs.columbia.edu > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > -- M. Ranganathan _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
