public static Automaton Repeat(Automaton a, int min, int max)
{
if (min > max)
{
return(BasicAutomata.MakeEmpty());
}
max -= min;
a.ExpandSingleton();
Automaton b;
if (min == 0)
{
b = BasicAutomata.MakeEmptyString();
}
else if (min == 1)
{
b = a.Clone();
}
else
{
var @as = new List <Automaton>();
while (min-- > 0)
{
@as.Add(a);
}
b = Concatenate(@as);
}
if (max > 0)
{
var d = a.Clone();
while (--max > 0)
{
var c = a.Clone();
foreach (var p in c.GetAcceptStates())
{
p.AddEpsilon(d.Initial);
}
d = c;
}
foreach (var p in b.GetAcceptStates())
{
p.AddEpsilon(d.Initial);
}
b.IsDeterministic = false;
b.ClearHashCode();
b.CheckMinimizeAlways();
}
return(b);
}
public static void AddEpsilons(Automaton a, ICollection <StatePair> pairs)
{
a.ExpandSingleton();
var forward = new Dictionary <State, HashSet <State> >();
var back = new Dictionary <State, HashSet <State> >();
foreach (var p in pairs)
{
var to = forward[p.FirstState];
if (to == null)
{
to = new HashSet <State>();
forward.Add(p.FirstState, to);
}
_ = to.Add(p.SecondState);
var from = back[p.SecondState];
if (from == null)
{
from = new HashSet <State>();
back.Add(p.SecondState, from);
}
_ = from.Add(p.FirstState);
}
var worklist = new LinkedList <StatePair>(pairs);
var workset = new HashSet <StatePair>(pairs);
while (worklist.Count != 0)
{
var p = worklist.RemoveAndReturnFirst();
_ = workset.Remove(p);
var to = forward[p.SecondState];
var from = back[p.FirstState];
if (to != null)
{
foreach (var s in to)
{
var pp = new StatePair(p.FirstState, s);
if (!pairs.Contains(pp))
{
pairs.Add(pp);
_ = forward[p.FirstState].Add(s);
_ = back[s].Add(p.FirstState);
_ = worklist.AddLast(pp);
_ = workset.Add(pp);
if (from != null)
{
foreach (var q in from)
{
var qq = new StatePair(q, p.FirstState);
if (!workset.Contains(qq))
{
_ = worklist.AddLast(qq);
_ = workset.Add(qq);
}
}
}
}
}
}
}
foreach (var p in pairs)
{
p.FirstState.AddEpsilon(p.SecondState);
}
a.IsDeterministic = false;
a.ClearHashCode();
a.CheckMinimizeAlways();
}