PLUS -> "+"
MULT -> "*"
MINUS -> "-"
MOD -> "%"
DIV -> "/"
CB -> ")"
OB -> "("
##
ID -> ([0 - 9])+
##
##
EOL -> \n|\r
SPACE -> \s|\t
##
start -> { global stack result; print <tab>; 
} E {print " =========== "; print <cr>;  print <tab>; print string(pop(result)); }
E -> E  {print <[OP>;} <PLUS>  {print "+"; print <OP]>; print <tab>;} T  { result.push(pop(result)+pop(result));  }
E -> E  {print <[OP>;} <MINUS>  {print "-"; print <OP]>; print <tab>;} T  { result.push(0-(pop(result)-pop(result)));  }
E -> T 
T -> T  {print <[OP>;} <MULT>  {print "*"; print <OP]>; print <tab>; } F { result.push(pop(result)*pop(result));  }
T -> T  {print <[OP>;} <DIV>  {print "/"; print <OP]>; print <tab>; } F {local int temp; temp := pop(result); result.push((pop(result)/temp));  }
T -> T  {print <[OP>;} <MOD>  {print "%"; print <OP]>; print <tab>; } F {local int temp; temp:=pop(result); result.push(pop(result)%temp); }
T -> F
F -> <OB>  E <CB> 
F -> {print <[CONST>;}  <ID> { print lexeme;  print <CONST]>; print <cr>;  result.push(int(lexeme));}