1grammar t057autoAST42; 2options {language=JavaScript;output=AST;} 3a returns [result] : x+=b! x+=b { 4$result = "1st x="+$x[0].toStringTree()+','; 5} ; 6b : ID; 7ID : 'a'..'z'+ ; 8INT : '0'..'9'+; 9WS : (' '|'\n') {$channel=HIDDEN;} ; 10