Re: Is there an error correcting parser generator out there?

johnm@po.EECS.Berkeley.EDU (John D. Mitchell) writes:
>... It is generally the
>case that LR generators are much harder to get good error recovery out of.
>LL generators tend to make this a good bit easier...


This seems to be the current `conventional wisdom' (among a lot of folks I
know anyway), but is it really true? Where's the irrefutable evidence to
support this view?


(You'll have to excuse me, but I'm an unabashed believer in both automated
techniques, e.g. LALR parser generators, and in formality when it comes
to grammar specifications... and I have been for a long long time. These
days however, everyone seems to be saying that recursive descent is better
for error recovery, and that's rather disconcerting to me. I mean... I mean...
what if they're right?? Would that imply that all that time I spent in
school learning about LALR table generators, and all those nights I've
spent YACC'ing things was all wasted effort?)


-- Ron Guilmette, Sunnyvale, CA ---------- RG Consulting -------------------
---- domain addr: rfg@netcom.com ----------- Purveyors of Compiler Test ----
---- uucp addr: ...!uunet!netcom!rfg ------- Suites and Bullet-Proof Shoes -
[One thing that has considerably clouded the issue is that for the first
10 years or so of yacc's existence, there was a subtle bug in the way that
error rules were handled that made error recovery not work. Lots of us gave
up assuming the problem was hopeless, not realizing we'd just tripped over
a bug. -John]
--

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