Thanks Mikael, I've also found left recursion to be less of a problem as I focused on the grammar. The details, and especially the division of tasks between lexer and parser in Antlr is what is tricky, as you've also pointed out.
I decided to keep working on my version without peeking at any other work, to see what comes out of that (probably lots of things to laugh at). There is now already an Antlr grammar out there, thanks to Marand, but I find the idea of having multiple works out there very exciting. 2012 has certainly started well for the openEHR community! Best regards Seref 2012/1/13 Mikael Nystr?m <mikael.nystrom at liu.se> > Hi,**** > > ** ** > > I used the standard approach for rewriting left recursion to non left > recursion described in computer grammar books (and in Wikipedia > http://en.wikipedia.org/wiki/Left_recursion). It was a quite straight > forward translation, but it was necessary to be careful with all the > details. :-) We will share the grammar when we have cleaned up the file a > little more.**** > > ** ** > > Regards,**** > > Mikael**** > > ** ** > > ** ** > > *From:* openehr-technical-bounces at openehr.org [mailto: > openehr-technical-bounces at openehr.org] *On Behalf Of *Erik Sundvall > *Sent:* den 5 januari 2012 11:12 > *To:* For openEHR technical discussions > *Subject:* Re: Did anybody implement AQL with a LL parser framework?**** > > ** ** > > Hi!**** > > ** ** > > We implemented an AQL parser using JavaCC. My colleague Mikael Nystr?m > made some transformations to make the published AQL grammar work in JavaCC. > Mikael is on vacation right now, but I'm sure he does not mind sharing his > experiences once he gets back. **** > > ** ** > > I do think it would be interesting to switch to ANTLR sooner or later in > order to share efforts between projects with different > implementation/target-languages and because the ANTLRWorks environment > http://www.antlr.org/works/index.html looks promising compared to the > pretty bad JavaCC-plugin in e.g. Eclipse.**** > > ** ** > > Our parser (and thus also the modified grammar) will soon be open sourced > so you are free to use it. So if you are not in an extreme hurry I'd > suggest using or getting inspiration from what we have already done.**** > > ** ** > > Best regards, > Erik Sundvall > erik.sundvall at liu.se http://www.imt.liu.se/~erisu/ Tel: +46-13-286733 > > **** > > On Wed, Jan 4, 2012 at 16:37, Seref Arikan < > serefarikan at kurumsalteknoloji.com> 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. > > > Kind regards > Seref**** > > _______________________________________________ > 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/20120113/29cece22/attachment.html>
