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Groups > comp.compilers > #1314
| From | Ivan Godard <ivan@ootbcomp.com> |
|---|---|
| Newsgroups | comp.compilers |
| Subject | Re: LR(1) Parsing : Error Handling & Recovery |
| Date | 2014-07-16 16:39 -0400 |
| Organization | A noiseless patient Spider |
| Message-ID | <14-07-024@comp.compilers> (permalink) |
| References | <14-07-023@comp.compilers> |
On 7/9/2014 5:00 PM, Seima Rao wrote: > How far is impressive error handling & recovery possible by LR(1) > parsers ? > > What would be good references for the subject? > > As an aside, do the famous compilers use LR(1) parsing ? LR1 was an experiment. The way to get apt error messages out of one is to add error production rules. Unfortunately that process explodes the state space, resulting in generally poor quality compilers. As a practical matter, natural languages are pretty much LL1 (German verbs excepted) so people are reasonably familiar to quasi-linear parsing. A recursive descent LL1 parser can be written in less time than a LR1 grammar for the same language can be debugged, if it ever is. For those that really really believe in parser-generators, high-quality generators exist for LL1 too. Nearly all languages yield to LL1 techniques (the formal proofs that a language is not LL1 are irrelevant), often by introducing a few union-productions into the lexer; examples have been shown here, such as DOI=1 in Fortran. The great advantage of a recursive-descent parser is that you can do most semantic analysis on the fly while you are at it, and can emit apt and copious error messages at the point where the source first goes off the rails. You can even do a decent job of recovery: for example, an unrecognized identifier can be used to search for an approximate match in the current dictionary (also built on the fly) to fix a typo, thereby avoiding the cascade of irrelevant diagnostics typical of YACC parsers. FWIW, I recall hearing that GCC switched from LR1 (LALR?) to recursive-descent a few years back. You couldn't pay me to work on a YACC-based front end.
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LR(1) Parsing : Error Handling & Recovery Seima Rao <seimarao@gmail.com> - 2014-07-10 05:30 +0530
Re: LR(1) Parsing : Error Handling & Recovery Ivan Godard <ivan@ootbcomp.com> - 2014-07-16 16:39 -0400
Re: LR(1) Parsing : Error Handling & Recovery Evangelos Drikos <drikosev@otenet.gr> - 2014-07-17 20:15 +0300
Re: LR(1) Parsing : Error Handling & Recovery Ivan Godard <ivan@ootbcomp.com> - 2014-07-17 13:03 -0700
Re: LR(1) Parsing : Error Handling & Recovery Ivan Godard <ivan@ootbcomp.com> - 2014-07-17 13:57 -0700
Re: LR(1) Parsing : Error Handling & Recovery wclodius@earthlink.net (William Clodius) - 2014-07-18 13:41 -0600
Re: LR(1) Parsing : Error Handling & Recovery Stefan Monnier <monnier@iro.umontreal.ca> - 2014-07-18 21:09 -0400
Re: LR(1) Parsing : Error Handling & Recovery Hans-Peter Diettrich <DrDiettrich1@aol.com> - 2014-07-19 12:04 +0200
Re: LR(1) Parsing : Error Handling & Recovery Stefan Monnier <monnier@iro.umontreal.ca> - 2014-07-20 10:28 -0400
Re: LR(1) Parsing : Error Handling & Recovery Hans-Peter Diettrich <DrDiettrich1@netscape.net> - 2014-07-21 10:46 +0200
Re: LR(1) Parsing : Error Handling & Recovery Stefan Monnier <monnier@iro.umontreal.ca> - 2014-08-06 21:32 -0400
Re: LR(1) Parsing : Error Handling & Recovery arnold@skeeve.com (Aharon Robbins) - 2014-07-20 06:05 +0000
Re: LR(1) Parsing : Error Handling & Recovery George Neuner <gneuner2@comcast.net> - 2014-07-17 18:49 -0400
Re: LR(1) Parsing : Error Handling & Recovery wclodius@earthlink.net (William Clodius) - 2014-07-18 13:41 -0600
Re: LR(1) Parsing : Error Handling & Recovery Hans Aberg <haberg-news@telia.com> - 2014-07-19 15:29 +0200
Re: LR(1) Parsing : Error Handling & Recovery Evangelos Drikos <drikosev@otenet.gr> - 2014-07-20 00:40 +0300
Re: LR(1) Parsing : Error Handling & Recovery Hans Aberg <haberg-news@telia.com> - 2014-07-20 01:38 +0200
Re: LR(1) Parsing : Error Handling & Recovery Evangelos Drikos <drikosev@otenet.gr> - 2014-07-21 15:20 +0300
Re: LR(1) Parsing : Error Handling & Recovery Hans Aberg <haberg-news@telia.com> - 2014-07-21 18:39 +0200
Re: LR(1) Parsing : Error Handling & Recovery Evangelos Drikos <drikosev@otenet.gr> - 2014-08-26 13:44 +0300
Re: LR(1) Parsing : Error Handling & Recovery Hans Aberg <haberg-news@telia.com> - 2014-08-29 11:13 +0200
Re: split tokens; was LR(1) Parsing : Error Handling & Recovery Evangelos Drikos <drikosev@otenet.gr> - 2014-09-03 16:57 +0300
Re: LR(1) Parsing : Error Handling & Recovery Hans Aberg <haberg-news@telia.com> - 2014-09-03 19:07 +0200
Re: LR(1) Parsing : Error Handling & Recovery George Neuner <gneuner2@comcast.net> - 2014-07-20 01:19 -0400
Re: LR(1) Parsing : Error Handling & Recovery wclodius@earthlink.net (William Clodius) - 2014-07-20 21:43 -0600
Re: LR(1) Parsing : Error Handling & Recovery wclodius@earthlink.net (William Clodius) - 2014-07-21 21:44 -0600
Re: LR(1) Parsing : Error Handling & Recovery Chris Dodd <cdodd@acm.org> - 2014-07-21 06:07 +0000
Re: LR(1) Parsing : Error Handling & Recovery George Neuner <gneuner2@comcast.net> - 2014-07-25 21:58 -0400
Re: LR(1) Parsing : Error Handling & Recovery Chris Dodd <cdodd@acm.org> - 2014-07-26 21:16 +0000
Re: LR(1) Parsing : Error Handling & Recovery Hans-Peter Diettrich <DrDiettrich1@netscape.net> - 2014-07-28 14:43 +0200
Re: LR(1) Parsing : Error Handling & Recovery Chris Dodd <cdodd@acm.org> - 2014-07-29 19:38 +0000
Re: LR(1) Parsing : Error Handling & Recovery Eric <news@fx29.iad.highwinds-media.com> - 2014-07-16 16:40 -0400
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