grammar Calc
addSub

addSub return [v : int]
            : mulDiv addSub2(<mulDiv.v>)
              <$v = addSub2.v;>
            ;

addSub2 (left : int) return [v : int]
            : ADD mulDiv    <int next = left + mulDiv.v;>
              addSub2(next) <$v = addSub2.v;>
            | SUB mulDiv    <int next = left - mulDiv.v;>
              addSub2(next) <$v = addSub2.v;>
            | <$v = left;>
            ;

mulDiv return [v : int]
            : scope mulDiv2(<scope.v>) <$v = mulDiv2.v;>
            ;

mulDiv2 (left : int) return [v : int]
            : MUL scope mulDiv2(<left * scope.v>) <$v = mulDiv2.v;>
            | DIV scope mulDiv2(<left / scope.v>) <$v = mulDiv2.v;>
            | <$v = left;>
            ;

factorial return [v : int]
            : OP addSub CP <$v = addSub.v;>
            | NUM          <$v = Integer.valueOf(NUM);>
            ;

maybe return [v : char]
            : FAC <$v = '!';>
            | "" <$v = 'N';>
            ;


scope return [v : int]
            : OP addSub CP maybe <if(maybe.v == 'N')$v = addSub.v; else $v = addSub.v * 40;>
            | SUB scope <$v = -scope.v;>
            | NUM  maybe     <if(maybe.v == 'N')$v = Integer.valueOf(NUM); else $v = Integer.valueOf(NUM) * 40;>
            ;

ADD : "+";
SUB : "-";
MUL : "*";
FAC : "!";
DIV : "/";
OP  : "(";
CP  : ")";
NUM $ "([1-9][0-9]*)|(0)";
skip -> "[ \n\r\t]+";
EMP : "";