Thanks Shinji, In general, Antlr has some convenient features, infinite lookahead being one of them. I've quickly checked, and Treetop does not seem to support left recursion either. So you must have modified the grammar to make it work. I'm referring to grammar rules such as A : A | B;
Tom made the point earlier. At one point it would be good to unify various AQL implementation experiences. I'll check out the papers. Best regards Seref On Thu, Jan 5, 2012 at 2:21 AM, Shinji KOBAYASHI <skoba at moss.gr.jp> wrote: > Hi Seref, > > My ADL parser does not include AQL parsing. > I used Treetop, which is an Ruby implementation of PEG/Packrat parsing > algorithm, > not LL/LR. PEG/Packrat parser algorithm was described in this paper. > http://bford.info/pub/lang/packrat-icfp02/ > > Antlr is an implementation of PEG parser by LL techniques. I do not > know Antlr so much. > > Packrat parser does not need to separate scanner/parser/lexer and is > capable to > infinite look ahead recursive. > > I do not know why are you parsing AQL, but this proceeding about querying > EHR > by archetype might be helpful for your research. > http://web-ext.u-aizu.ac.jp/labs/sw-db/7108/71080109.pdf > > Best regards, > Shinji > > 2012/1/5 Seref Arikan <serefarikan at kurumsalteknoloji.com>: > > 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 > > > _______________________________________________ > 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/20120105/7ab40933/attachment.html>
