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Re: Reductions during Bison error handling
From: |
Paul Hilfinger |
Subject: |
Re: Reductions during Bison error handling |
Date: |
Fri, 10 May 2002 20:58:27 -0700 |
Ah! Now I see what problem the yyerrdefault code-suppression was
trying to fix. So now I can amend my comment to say that I think a
different fix might be indicated.
Here's the issue. If our erroneous configuration is
Parse Stack: s1 s2 ... sk ... sn <-top Lookahead: X
we pop back to sk, and if the indicated action is "reduce", we take
the reduction and proceed normally. Now, if that reduction is a
non-defaulted reduction (again, I don't mean default ACTION, but
default reduction, mediated by yydefact), we are guaranteed that X can
eventually be shifted. If, however, the default reduction was used
because X is an erroneous symbol in state sk, then we will eventually
return to the error-recovery code, throw away X *and then continue to
pop the stack*, turning mere "panic-mode" into "full-fledged
rout-mode".
Again, however, the anomalies reported earlier still exist. We might
therefore consider actually using the documented error recovery
procedure. Or we might consider a different technique for throwing
away input.
Paul Hilfinger
- Re: Reductions during Bison error handling, (continued)
- Re: Reductions during Bison error handling, Paul Hilfinger, 2002/05/13
- Re: Reductions during Bison error handling, Hans Aberg, 2002/05/14
- Re: Reductions during Bison error handling, Paul Hilfinger, 2002/05/14
- Re: Reductions during Bison error handling, Hans Aberg, 2002/05/14
- Re: Reductions during Bison error handling, Paul Hilfinger, 2002/05/14
- Re: Reductions during Bison error handling, Hans Aberg, 2002/05/15
- Re: Reductions during Bison error handling, Akim Demaille, 2002/05/20
- Re: Reductions during Bison error handling, Paul Hilfinger, 2002/05/21
- Re: Reductions during Bison error handling, Akim Demaille, 2002/05/20
Re: Reductions during Bison error handling, Paul Hilfinger, 2002/05/10
Re: Reductions during Bison error handling,
Paul Hilfinger <=
Re: Reductions during Bison error handling, Akim Demaille, 2002/05/20
- Re: Reductions during Bison error handling, Richard Stallman, 2002/05/20
- Re: Reductions during Bison error handling, Paul Hilfinger, 2002/05/20
- Re: Reductions during Bison error handling, Richard Stallman, 2002/05/21
- Re: Reductions during Bison error handling, Hans Aberg, 2002/05/21
- Re: Reductions during Bison error handling, Richard Stallman, 2002/05/23
- Re: Reductions during Bison error handling, Akim Demaille, 2002/05/24