private void convertToDFA(NFA nfa) {
DFAState curr, temp;
List<String> tokens = new ArrayList<String>();
LinkedList<DFAState> queue = new LinkedList<DFAState>();
findStart(nfa);
queue.add(start);
MAINWHILE:
while (!queue.isEmpty()) {
curr = queue.removeFirst();
for (DFAState sta : checked) {
if (curr.equals(sta)) {
// System.out.println("NOPE");
continue MAINWHILE;
}
}
checked.add(curr);
// Pull out all keys
for (State s : curr.getStates()) {
for (String k : s.getTransitionTable().keySet()) {
tokens.add(k);
// System.out.println(tokens);
}
}
// Iterate over all possible iterations and link states together
for (String j : tokens) {
if (!j.equals("")) {
temp = goTo(curr, j);
queue.add(temp);
}
}
}
}
// Calculates epsilon transition states
private DFAState closure(DFAState s) {
HashSet<State> ret = new HashSet<State>();
HashSet<State> toAdd;
boolean isAccept = false;
String name = "";
DFAState output;
// Add all input states to output
for (State i : s.getStates()) {
ret.add(i);
}
while (true) {
toAdd = new HashSet<State>();
// Iterate over all states currently in ret
for (State r : ret) {
if (r.getTransitionTable().containsKey("")) {
for (State t : r.getTransitionTable().get("")) {
if (!ret.contains(t)) {
toAdd.add(t);
}
}
}
}
if (toAdd.isEmpty()) {
break;
}
for (State a : toAdd) {
ret.add(a);
}
}
// Determine if new state is accept
for (State t : ret) {
if (t.isAccept()) {
isAccept = true;
name = t.getName();
break;
}
}
// Create new DFAState
output = new DFAState(name, isAccept, ret, new HashMap<String, DFAState>());
for (DFAState sta : states) {
if (output.equals(sta)) {
output = sta;
break;
}
}
// if(states.contains(output)){
// System.out.println("NOOO");
// }
states.add(output);
if (output.isAccept()) {
accept.add(output);
}
return output;
}
// This calculates all of the transitions out of a state
// for a given transition string
private DFAState goTo(DFAState s, String token) {
HashSet<State> ret = new HashSet<State>();
DFAState dummy, output;
for (State i : s.getStates()) {
if (i.getTransitionTable().containsKey(token)) {
for (State t : i.getTransitionTable().get(token)) {
ret.add(t);
}
}
}
// Create dummy DFAState to pass to closure()
dummy = new DFAState("", false, ret, new HashMap<String, DFAState>());
output = closure(dummy);
s.getTransitions().put(token, output);
System.out.println(s.getTransitions());
return output;
}
// Calculates the start state of the DFA
private void findStart(NFA nfa) {
DFAState dummy = new DFAState("", false, new HashSet<State>(), new HashMap<String, DFAState>());
dummy.addState(nfa.getStart());
start = closure(dummy);
}
