...
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|---|
grammar Pred;
prog: stat+ ;
stat: keyIF expr stat
| keyCALL ID ';'
| ';'
;
expr: ID
;
keyIF : {input.LT(1).getText().equals("if")}? ID ;
keyCALL : {input.LT(1).getText().equals("call")}? ID ;
ID : 'a'..'z'+ ;
WS : (' '|'\n')+ {$channel=HIDDEN;} ;
|
The other alternative is to do something like this
| No Format |
|---|
identifier : KEY1 | KEY2 | ... | ID ;
|
which is a set comparison and should be faster.