public NFA closure()
{
NFA ret = new NFA(this);
//add new start state
int oldStartState = ret.startState;
int newStartState = ret.addState(false);
ret.startState = newStartState;
ret.connect(newStartState, oldStartState, new EpsilonConnection(0, 0));
//add connections from old end states to old start state
ret.addConnectionToEndStates(oldStartState, new EpsilonConnection(0, 0));
//old start state is a valid end state
ret.endStates.Add(newStartState);
ret.hasEpsilons = true;
return(ret);
}
public NFA or(NFA second)
{
NFA ret = new NFA(this);
//add states
ret.incrementIndices(second.numStates);
foreach (int i in second.endStates)
{
ret.endStates.Add(i);
}
//add connections between newly added states
foreach (Connection c in second.connections)
{
ret.connections.Add(c.copy());
}
//connect new start states with old start state
ret.connect(ret.startState, second.startState, new EpsilonConnection(-1, -1));
ret.hasEpsilons = true;
ret.calculateConnectionPerState();
return(ret);
}
public NFA toDFA()
{
NFA temp = new NFA(this);
NFA ret = new NFA();
temp.deEpsilonate();
List <HashSet <int> > newStates = new List <HashSet <int> >();
newStates.Add(new HashSet <int>());
Queue <HashSet <int> > statesThatNeedProcessing = new Queue <HashSet <int> >();
HashSet <int> startState = new HashSet <int>();
startState.Add(temp.startState);
ret.startState = ret.addState(temp.endStates.Contains(temp.startState));
newStates.Add(startState);
statesThatNeedProcessing.Enqueue(startState);
while (statesThatNeedProcessing.Count > 0)
{
HashSet <int> newState = statesThatNeedProcessing.Dequeue();
int hasState = newStates.FindIndex(h => newState.SetEquals(h));
List <Connection> allConnections = new List <Connection>();
List <Connection> uninterestingConnections = new List <Connection>();
HashSet <int> anyReachable = new HashSet <int>();
foreach (int i in newState)
{
allConnections.AddRange(temp.connectionPerState[i]);
}
HashSet <char> interestingChars = new HashSet <char>();
foreach (Connection c in allConnections)
{
if (c is AnythingConnection)
{
anyReachable.Add(c.end);
}
if (c is AnythingConnection || c is ConnectionAnythingBut)
{
uninterestingConnections.Add(c);
}
interestingChars.UnionWith(c.interestingCharacters());
}
foreach (char ch in interestingChars)
{
HashSet <int> reachable = new HashSet <int>();
foreach (Connection c in allConnections)
{
if (c.accepts(ch))
{
reachable.Add(c.end);
}
}
int newAddIndex = newStates.FindIndex(h => reachable.SetEquals(h));
if (newAddIndex == -1)
{
bool endState = false;
foreach (int i in reachable)
{
if (temp.endStates.Contains(i))
{
endState = true;
break;
}
}
newAddIndex = ret.addState(endState);
newStates.Add(reachable);
statesThatNeedProcessing.Enqueue(reachable);
}
ret.connect(hasState, newAddIndex, new ConnectionExactCharacter(hasState, newAddIndex, ch));
}
if (uninterestingConnections.Count > 0)
{
HashSet <int> reachable = new HashSet <int>();
foreach (Connection c in uninterestingConnections)
{
reachable.Add(c.end);
}
int newAddIndex = newStates.FindIndex(h => reachable.SetEquals(h));
if (newAddIndex == -1)
{
bool endState = false;
foreach (int i in reachable)
{
if (temp.endStates.Contains(i))
{
endState = true;
break;
}
}
newAddIndex = ret.addState(endState);
newStates.Add(reachable);
statesThatNeedProcessing.Enqueue(reachable);
}
if (interestingChars.Count > 0)
{
ret.connect(hasState, newAddIndex, new ConnectionAnythingBut(hasState, newAddIndex, interestingChars));
}
else
{
ret.connect(hasState, newAddIndex, new AnythingConnection(hasState, newAddIndex));
}
}
}
int garbageState = ret.addState(false);
ret.calculateConnectionPerState();
for (int i = 1; i < ret.numStates; i++)
{
HashSet <char> unUsableConnections = new HashSet <char>();
foreach (Connection c in ret.connectionPerState[i])
{
unUsableConnections.UnionWith(c.acceptSet());
}
bool canUseAll = true;
bool canUseAny = true;
HashSet <char> usableConnections = new HashSet <char>();
foreach (Connection c in ret.connectionPerState[i])
{
if (c is AnythingConnection)
{
canUseAny = false;
break;
}
if (c is ConnectionAnythingBut)
{
if (canUseAll)
{
usableConnections = new HashSet <char>(((ConnectionAnythingBut)c).forbidden);
canUseAll = false;
}
else
{
usableConnections.IntersectWith(((ConnectionAnythingBut)c).forbidden);
}
}
}
if (canUseAny)
{
if (!canUseAll)
{
usableConnections.ExceptWith(unUsableConnections);
if (usableConnections.Count > 0)
{
ret.connect(i, garbageState, new ConnectionAnyOf(i, garbageState, usableConnections));
}
}
else
{
if (unUsableConnections.Count > 0)
{
ret.connect(i, garbageState, new ConnectionAnythingBut(i, garbageState, unUsableConnections));
}
else
{
ret.connect(i, garbageState, new AnythingConnection(i, garbageState));
}
}
}
}
ret.connect(garbageState, garbageState, new AnythingConnection(garbageState, garbageState));
ret.calculateConnectionPerState();
return(ret);
}
