public override void VisitVariableElement(VariableElement element){
if(mVariableMap.ContainsKey(element.getText())){
int element_value = (int) mVariableMap[element.getText()];
mStack.Push(element_value);
} else {
//lets assume that the syntax has been checked for this example because I don't like the exception
//propegation that will happen if I throw here
//throw new Exception("Variable " + element.getText() + " not defined.");
}
}
public override void VisitIntegerElement(IntegerElement element){
