Antlr is LL(*), but LL can't handle direct/indirect recursion, which is a matter of grammar rules. Direct recursion is easier to handle, but indirect recursion makes my head hurt :)
On Wed, Jan 4, 2012 at 4:02 PM, Thomas Beale < thomas.beale at oceaninformatics.com> wrote: > On 04/01/2012 15:37, Seref Arikan wrote: > > Greetings, > > The AQL grammar from the wiki has direct and indirect left recursion. > > Which means without changes in the grammar, LL parser generators (both > > JavaCC and Anltr) can't generate parsers for this grammar. > > > > I'm curious if anybody has refactored this grammar for LL parser > > generators. Shinji? Your latest release includes an AQL parser does > > not it? Could you please share your method? I can always look at the > > code, but you'd probably save me time :) > > > > I'm interested in experiences of others too. > > there is no guarantee that the current grammar is the best one, and in > my view, a better grammar could be developed. We just need to make sure > it deals with the typical queries we write, and ones that are already > written (or at least that the latter could safely be translated). > > Other thing to keep in mind: many non-LL grammars are probably > computable as LL grammars with sufficient tokens of lookahead. > > - thomas > > _______________________________________________ > openEHR-technical mailing list > openEHR-technical at openehr.org > http://lists.chime.ucl.ac.uk/mailman/listinfo/openehr-technical > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.openehr.org/mailman/private/openehr-technical_lists.openehr.org/attachments/20120104/06d0c6c7/attachment.html>
