Path: csiph.com!weretis.net!feeder9.news.weretis.net!border-2.nntp.ord.giganews.com!nntp.giganews.com!news.iecc.com!.POSTED.news.iecc.com!nerds-end From: Chris Clark Newsgroups: comp.compilers Subject: LALR look-ahead sets from item right context grammar? Date: Sat, 31 Jan 2026 01:30:19 +0000 Organization: Compilers Central Sender: johnl%iecc.com Approved: comp.compilers@iecc.com Message-ID: <26-01-007@comp.compilers> References: <26-01-005@comp.compilers> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Injection-Info: gal.iecc.com; posting-host="news.iecc.com:2001:470:1f07:1126:0:676f:7373:6970"; logging-data="10283"; mail-complaints-to="abuse@iecc.com" Keywords: parse, LALR Posted-Date: 31 Jan 2026 17:45:55 EST X-submission-address: compilers@iecc.com X-moderator-address: compilers-request@iecc.com X-FAQ-and-archives: http://compilers.iecc.com Lines: 7 Xref: csiph.com comp.compilers:3712 While I haven't read the book you reference, and thus am not familiar with the details of the "right context grammar", I would suggest you look to verify that in cases where there are nullable non-terminals in the right context grammar, that it would also include the "follow" set and not just the "first' set. We did something similar to that in our version of "Yacc++ and the Language Objects Library" but our algorithm is a non-standard implementation of the technology. Still the LR(0) machine has more information in it than is generally assumed.