[antlr-interest] antlr beginner confused over ambiguities
Rick Schumeyer
rschumeyer at gmail.com
Tue Feb 24 11:52:24 PST 2009
I've read through the ambiguity section of the Definitive Reference, but I'm
still confused on what must be a common problem. The following grammar is
supposed to recognize a time in the format hh:mm:ss, while also recognizing
arbitrary strings elsewhere.
If the input string is "12:34:45", then of course antlr returns a STRING
token. I understand why it does that (I think) but I'm not really sure how
to fix that. I'm fuzzy on the difference between a semantic and syntactic
predicate, and whether one of those is what I need.
grammar STest;
line : timestamp;
timestamp
: INT ':' INT ':' INT
;
INT : ('0'..'9')+;
STRING : ('!'..'+' | '-'..'~')+; /* anything but ws or comma */
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.antlr.org/pipermail/antlr-interest/attachments/20090224/534fe21c/attachment.html
More information about the antlr-interest
mailing list