[antlr-interest] lexer problem

[Robert Soule]

Hi,

I was hoping someone might be able to help me out. I have the following
grammar:

grammar Test;
start: '[' AB ']' | A;
A: '[a]';
AB: ('a' | 'b')+;

In English, there is a keyword in my language '[a]', and
all other statements are of the form: [(a|b)+]. I tried this
with two test cases:

test [ab] fails unexpectedly (no viable alternative)
test [ba] succeeds

I believe that the lexer sees a '[' character followed by
an 'a' characters, and expects a ']' next, even though
'a' or 'b' could also be valid next input characters. Has
anyone had any experience with this type of issue?

thank you,
Robert Soule