[antlr-interest] [V3] Null Pointer Exception on bad input
containing optional options
parrt at cs.usfca.edu
Wed Aug 9 12:55:01 PDT 2006
On Aug 9, 2006, at 12:47 PM, John B. Brodie wrote:
> the following grammar gets a null pointer exception (rather than a
> nice error message about its ambiguity):
> grammar t;
> foo : JUNK* EOF ;
> JUNK : 'foo' ( 'bar'? 'baz'? )? ;
> did not see anything similar on the wiki's bug list.
> is this the best place to report these things?
> if it matters, i am using:
> ANTLR Parser Generator Early Access Version 3.0b3 (July 21,
> 2006) 1989-2006
Thanks...i fixed this yesterday. now I get:
ANTLR Parser Generator Early Access Version 3.0b4 (??, 2006)
duh.g:5:14: Decision can match input such as "<EOT>" using multiple
alternatives: 1, 2
As a result, alternative(s) 2 were disabled for that input
duh.g:5:14: The following alternatives are unreachable: 2
which is the correct message.
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