/// <summary>
/// Convert NFATable to DFATable.
/// </summary>
/// <returns> A DFATable. </returns>
public DFATable ToDFATable()
{
// Helper function to check if this DFAState is final.
Func <DFAState, bool> IsFinal = x => {
foreach (int s in x)
{
if (finals.Contains(s))
{
return(true);
}
}
return(false);
};
DFATable dfa = new DFATable(map, revMap);
// Map DFAState to the actual state ID in DFATable.
Dictionary <DFAState, int> dict = new Dictionary <DFAState, int>(DFAState.CreateSetComparer());
Stack <DFAState> unmarked = new Stack <DFAState>();
// Initialize the first DFA state.
DFAState closure = FindEpsilonClosure(new HashSet <int> {
0
});
dict.Add(closure, dfa.AddState());
unmarked.Push(closure);
if (IsFinal(closure))
{
dfa.SetStateFinal(dict[closure]);
}
// Build the DFA by simulating NFA.
while (unmarked.Count() > 0)
{
DFAState T = unmarked.Pop();
for (int i = 0; i < revMap.Count(); ++i)
{
// Find move(T, i).
DFAState move = new DFAState();
foreach (int s in T)
{
move.UnionWith(table[s][i]);
}
// U = epsilon-closure(move).
DFAState U = FindEpsilonClosure(move);
if (!dict.ContainsKey(U))
{
// This is a new DFAState.
dict.Add(U, dfa.AddState());
unmarked.Push(U);
if (IsFinal(U))
{
dfa.SetStateFinal(dict[U]);
}
}
// Add transition from T to U with i.
dfa.AddTransition(dict[T], dict[U], revMap[i]);
}
}
return(dfa.Minimize());
}