public static Set<String> getOperators() {
Set<String> set = new HashSet<>();
for (NaryOperation exp : values()) {
set.add(exp.getOperator());
}
return set;
}
public static boolean contains(String operator) {
for (NaryOperation e : values()) {
if (e.getOperator().equalsIgnoreCase(operator)) {
return true;
}
}
return false;
}