/// <summary>
/// Returns an automaton that accepts the intersection of the languages of the given automata.
/// Never modifies the input automata languages.
/// </summary>
/// <param name="a1">The a1.</param>
/// <param name="a2">The a2.</param>
/// <returns></returns>
internal static Automaton Intersection(Automaton a1, Automaton a2)
{
if (a1.IsSingleton)
{
if (a2.Run(a1.Singleton))
{
return(a1.CloneIfRequired());
}
return(BasicAutomata.MakeEmpty());
}
if (a2.IsSingleton)
{
if (a1.Run(a2.Singleton))
{
return(a2.CloneIfRequired());
}
return(BasicAutomata.MakeEmpty());
}
if (a1 == a2)
{
return(a1.CloneIfRequired());
}
Transition[][] transitions1 = Automaton.GetSortedTransitions(a1.GetStates());
Transition[][] transitions2 = Automaton.GetSortedTransitions(a2.GetStates());
var c = new Automaton();
var worklist = new LinkedList <StatePair>();
var newstates = new Dictionary <StatePair, StatePair>();
var p = new StatePair(c.Initial, a1.Initial, a2.Initial);
worklist.AddLast(p);
newstates.Add(p, p);
while (worklist.Count > 0)
{
p = worklist.RemoveAndReturnFirst();
p.S.Accept = p.FirstState.Accept && p.SecondState.Accept;
Transition[] t1 = transitions1[p.FirstState.Number];
Transition[] t2 = transitions2[p.SecondState.Number];
for (int n1 = 0, b2 = 0; n1 < t1.Length; n1++)
{
while (b2 < t2.Length && t2[b2].Max < t1[n1].Min)
{
b2++;
}
for (int n2 = b2; n2 < t2.Length && t1[n1].Max >= t2[n2].Min; n2++)
{
if (t2[n2].Max >= t1[n1].Min)
{
var q = new StatePair(t1[n1].To, t2[n2].To);
StatePair r;
newstates.TryGetValue(q, out r);
if (r == null)
{
q.S = new State();
worklist.AddLast(q);
newstates.Add(q, q);
r = q;
}
char min = t1[n1].Min > t2[n2].Min ? t1[n1].Min : t2[n2].Min;
char max = t1[n1].Max < t2[n2].Max ? t1[n1].Max : t2[n2].Max;
p.S.Transitions.Add(new Transition(min, max, r.S));
}
}
}
}
c.IsDeterministic = a1.IsDeterministic && a2.IsDeterministic;
c.RemoveDeadTransitions();
c.CheckMinimizeAlways();
return(c);
}
private Automaton ToAutomaton(
IDictionary <string, Automaton> automata,
IAutomatonProvider automatonProvider,
bool minimize)
{
IList <Automaton> list;
Automaton a = null;
switch (this.kind)
{
case Kind.RegexpUnion:
list = new List <Automaton>();
this.FindLeaves(this.exp1, Kind.RegexpUnion, list, automata, automatonProvider, minimize);
this.FindLeaves(this.exp2, Kind.RegexpUnion, list, automata, automatonProvider, minimize);
a = BasicOperations.Union(list);
a.Minimize();
break;
case Kind.RegexpConcatenation:
list = new List <Automaton>();
this.FindLeaves(this.exp1, Kind.RegexpConcatenation, list, automata, automatonProvider, minimize);
this.FindLeaves(this.exp2, Kind.RegexpConcatenation, list, automata, automatonProvider, minimize);
a = BasicOperations.Concatenate(list);
a.Minimize();
break;
case Kind.RegexpIntersection:
a = this.exp1.ToAutomaton(automata, automatonProvider, minimize)
.Intersection(this.exp2.ToAutomaton(automata, automatonProvider, minimize));
a.Minimize();
break;
case Kind.RegexpOptional:
a = this.exp1.ToAutomaton(automata, automatonProvider, minimize).Optional();
a.Minimize();
break;
case Kind.RegexpRepeat:
a = this.exp1.ToAutomaton(automata, automatonProvider, minimize).Repeat();
a.Minimize();
break;
case Kind.RegexpRepeatMin:
a = this.exp1.ToAutomaton(automata, automatonProvider, minimize).Repeat(this.min);
a.Minimize();
break;
case Kind.RegexpRepeatMinMax:
a = this.exp1.ToAutomaton(automata, automatonProvider, minimize).Repeat(this.min, this.max);
a.Minimize();
break;
case Kind.RegexpComplement:
a = this.exp1.ToAutomaton(automata, automatonProvider, minimize).Complement();
a.Minimize();
break;
case Kind.RegexpChar:
a = BasicAutomata.MakeChar(this.c);
break;
case Kind.RegexpCharRange:
a = BasicAutomata.MakeCharRange(this.@from, this.to);
break;
case Kind.RegexpAnyChar:
a = BasicAutomata.MakeAnyChar();
break;
case Kind.RegexpEmpty:
a = BasicAutomata.MakeEmpty();
break;
case Kind.RegexpString:
a = BasicAutomata.MakeString(this.s);
break;
case Kind.RegexpAnyString:
a = BasicAutomata.MakeAnyString();
break;
case Kind.RegexpAutomaton:
Automaton aa = null;
if (automata != null)
{
automata.TryGetValue(this.s, out aa);
}
if (aa == null && automatonProvider != null)
{
try
{
aa = automatonProvider.GetAutomaton(this.s);
}
catch (IOException e)
{
throw new ArgumentException(string.Empty, e);
}
}
if (aa == null)
{
throw new ArgumentException("'" + this.s + "' not found");
}
a = aa.Clone(); // Always clone here (ignore allowMutate).
break;
case Kind.RegexpInterval:
a = BasicAutomata.MakeInterval(this.min, this.max, this.digits);
break;
}
return(a);
}
internal static Automaton Concatenate(IList <Automaton> l)
{
if (l.Count == 0)
{
return(BasicAutomata.MakeEmptyString());
}
bool allSingleton = l.All(a => a.IsSingleton);
if (allSingleton)
{
var b = new StringBuilder();
foreach (Automaton a in l)
{
b.Append(a.Singleton);
}
return(BasicAutomata.MakeString(b.ToString()));
}
else
{
if (l.Any(a => a.IsEmpty))
{
return(BasicAutomata.MakeEmpty());
}
var ids = new HashSet <int>();
foreach (Automaton a in l)
{
ids.Add(RuntimeHelpers.GetHashCode(a));
}
bool hasAliases = ids.Count != l.Count;
Automaton b = l[0];
b = hasAliases ? b.CloneExpanded() : b.CloneExpandedIfRequired();
var ac = b.GetAcceptStates();
bool first = true;
foreach (Automaton a in l)
{
if (first)
{
first = false;
}
else
{
if (a.IsEmptyString())
{
continue;
}
Automaton aa = a;
aa = hasAliases ? aa.CloneExpanded() : aa.CloneExpandedIfRequired();
HashSet <State> ns = aa.GetAcceptStates();
foreach (State s in ac)
{
s.Accept = false;
s.AddEpsilon(aa.Initial);
if (s.Accept)
{
ns.Add(s);
}
}
ac = ns;
}
}
b.IsDeterministic = false;
b.ClearHashCode();
b.CheckMinimizeAlways();
return(b);
}
}