Use a semantic predicate rather than syntactic. You possibly need a bated
predicate here too:
{ input.LA(1) == A && input.LA(2) != B}?=>
However, if you need that kind of syntactic predicate, then I suggest you may
be approaching your problem incorrectly.
Jim
From: [email protected]
[mailto:[email protected]] On Behalf Of Naveen Chawla
Sent: Monday, October 05, 2009 7:02 AM
To: [email protected]
Subject: [antlr-interest] How to do "not" in a syntactic predicate?
If I do
(a ~b)=> a
meaning "take this alternative if you encounter an a when not followed by b"
I get a syntax error: unexpected token b
Is it the right syntax to use '~'?
N
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