[antlr-interest] rewrite empty input string to "*"

[Jean-Sebastien Vachon]

Hi All,

What is the best way to rewrite an empty input?

I mean if my input is "" (empty string) how can I rewrite to "*" ?

The desired behaviour is to search everything (*) if the input is empty.

I thought about upgrading my top rule to be:

query
  : (andExpression+ -> andExpression) EOF
  | (SPACE*) EOF -> STAR
  ;

Where STAR and SPACE are defined as:

STAR  : '*';
SPACE : (' ' | '\t' | '\f')+ {$channel=HIDDEN;};

With this set of rules the output of tree in its text form is "STAR" while I was expecting "*"

What am I doing wrong?

Thanks