kparsr_loop_operators

 for (operator in Operators.values()) {
   var position = expression.reversed().lastIndexOf(operator.sign)

   while (position > 0) {
     if (isOperator(operator, expression, position)) {
         ...
         ...
     }
     // check again for same operator till the previous position
     if (position > 0) {
        position = expression.substring(0,position).
                   reversed().lastIndexOf(operator.sign)
     }
   }
}