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Re: LR(1) Parsing : Error Handling & Recovery

From Evangelos Drikos <drikosev@otenet.gr>
Newsgroups comp.compilers
Subject Re: LR(1) Parsing : Error Handling & Recovery
Date 2014-07-20 00:40 +0300
Organization An OTEnet S.A. customer
Message-ID <14-07-039@comp.compilers> (permalink)
References <14-07-023@comp.compilers> <14-07-024@comp.compilers> <14-07-030@comp.compilers> <14-07-031@comp.compilers> <14-07-038@comp.compilers>

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Hello,

On 7/19/14, 4:29 PM, Hans Aberg wrote:
> A GLR parser splits the parses in face of an ambiguity, which might be
> used instead. Bison supports this, but currently the actions during a
> parse split are not executed, and so cannot set context variables for
> the lexer, until the merge.

A GLR parser splits on conflicts and thus needs two different types of
actions. I recall that DParser uses the terms speculative and final.
In my GLR Builder I use the terms semantic checks & actions.

Semantic checks are not delayed when the parser splits but they should
not have side effects. In general, it is unsafe to notify the scanner
that the parser has just reached a particular state.

In contrast, you can query a symbol table to reject an active parser or
just create a node for the AST of the current parse. BTW, its my
impression that Elkhound and Elsa parse C++ with actions that actually
are immediate; but i have not read their code to be sure.

To conclude, in a deterministic LALR parser semantic actions are both
immediate and final but in a GLR parser this principle doesn't hold.

Hope this helps,
Ev. Drikos

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Thread

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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