public static FA Build(FA dfa1, FA dfa2, Func <State, State, bool> isFinal)
{
EnsureDfa(dfa1);
EnsureDfa(dfa2);
dfa1 = Complete(dfa1);
dfa2 = Complete(dfa2);
EnsureComplete(dfa1);
EnsureComplete(dfa2);
var cross = new State[dfa1.States.Count, dfa2.States.Count];
var t1 = dfa1.States.Select(s => GetTransitions(s)).ToList();
var t2 = dfa2.States.Select(s => GetTransitions(s)).ToList();
for (var n1 = 0; n1 < dfa1.States.Count; n1 += 1)
{
for (var n2 = 0; n2 < dfa2.States.Count; n2 += 1)
{
cross[n1, n2] = new State(isFinal(dfa1.States[n1], dfa2.States[n2]));
}
}
for (var n1 = 0; n1 < dfa1.States.Count; n1 += 1)
{
for (var n2 = 0; n2 < dfa2.States.Count; n2 += 1)
{
var state = cross[n1, n2];
var ctranses = GetMerge(t1[n1], t2[n2]);
foreach (var ctrans in ctranses)
{
state.Add(Codepoints.From(ctrans.Range.Min, ctrans.Range.Max), cross[ctrans.Target1, ctrans.Target2]);
}
}
}
var dfa = From(cross[0, 0]);
EnsureComplete(dfa);
return(dfa.RemoveDead().Minimize());
}
private static void EnsureComplete(FA dfa)
{
EnsureDfa(dfa);
foreach (var state in dfa.States)
{
var all = new Codepoints();
var sum = 0;
foreach (var transition in state.Transitions)
{
sum += transition.Terminal.Cardinality;
all.Add(transition.Terminal);
}
if (!UnicodeSets.IsAny(all))
{
throw new Exception("DFA: incomplete transition set (DFA is not `complete´)");
}
if (sum != all.Cardinality)
{
throw new Exception("DFA: overlapping transitions (DFA is not `sane´)");
}
}
}
public static FA Complete(FA dfa)
{
EnsureDfa(dfa);
State sink = null;
foreach (var state in dfa.States)
{
var rest = UnicodeSets.Any();
foreach (var transition in state.Transitions)
{
rest = rest.ExceptWith(transition.Terminal);
}
if (!rest.IsEmpty)
{
if (sink == null)
{
sink = new State();
sink.Add(Codepoints.Any, sink);
}
state.Add(Codepoints.From(rest), sink);
}
}
if (sink != null)
{
sink.Id = dfa.States.Count;
dfa.States.Add(sink);
}
EnsureComplete(dfa);
return(dfa);
}
public static FA ToDfa(FA nfa)
{
if (nfa.Final == null)
{
EnsureDfa(nfa);
return(nfa);
}
var once = new UniqueQueue <Closure>();
var start = new Closure(nfa.Start, nfa.Final);
once.Enqueue(start);
while (once.Count > 0)
{
var closure = once.Dequeue();
var transitions = closure.UnambiguateTransitions();
foreach (var transition in transitions)
{
var terminal = transition.Key;
var targets = transition.Value;
var targetClosure = new Closure(targets, nfa.Final);
once.Enqueue(targetClosure, out targetClosure);
var target = targetClosure.DfaState;
closure.DfaState.Add(Codepoints.From(terminal), target);
}
}
var dfa = From(start.DfaState);
EnsureDfa(dfa);
return(dfa);
}
private Codepoints(Codepoints other)
: this(other.ranges)
{
}
public void Add(Codepoints terminal, State target)
{
Transitions.Add(new Transition(terminal, target));
}
