/// <summary>
/// Returns an automaton that accepts the concatenation of the languages of the
/// given automata.
/// <para/>
/// Complexity: linear in number of states.
/// </summary>
public static Automaton Concatenate(Automaton a1, Automaton a2)
{
if (a1.IsSingleton && a2.IsSingleton)
{
return(BasicAutomata.MakeString(a1.singleton + a2.singleton));
}
if (IsEmpty(a1) || IsEmpty(a2))
{
return(BasicAutomata.MakeEmpty());
}
// adding epsilon transitions with the NFA concatenation algorithm
// in this case always produces a resulting DFA, preventing expensive
// redundant determinize() calls for this common case.
bool deterministic = a1.IsSingleton && a2.IsDeterministic;
if (a1 == a2)
{
a1 = a1.CloneExpanded();
a2 = a2.CloneExpanded();
}
else
{
a1 = a1.CloneExpandedIfRequired();
a2 = a2.CloneExpandedIfRequired();
}
foreach (State s in a1.GetAcceptStates())
{
s.accept = false;
s.AddEpsilon(a2.initial);
}
a1.deterministic = deterministic;
//a1.clearHashCode();
a1.ClearNumberedStates();
a1.CheckMinimizeAlways();
return(a1);
}
/// <summary>
/// Returns an automaton that accepts the concatenation of the languages of the
/// given automata.
/// <para/>
/// Complexity: linear in total number of states.
/// </summary>
public static Automaton Concatenate(IList <Automaton> l)
{
if (l.Count == 0)
{
return(BasicAutomata.MakeEmptyString());
}
bool all_singleton = true;
foreach (Automaton a in l)
{
if (!a.IsSingleton)
{
all_singleton = false;
break;
}
}
if (all_singleton)
{
StringBuilder b = new StringBuilder();
foreach (Automaton a in l)
{
b.Append(a.singleton);
}
return(BasicAutomata.MakeString(b.ToString()));
}
else
{
foreach (Automaton a in l)
{
if (BasicOperations.IsEmpty(a))
{
return(BasicAutomata.MakeEmpty());
}
}
JCG.HashSet <int> ids = new JCG.HashSet <int>();
foreach (Automaton a in l)
{
ids.Add(a.GetHashCode());
}
bool has_aliases = ids.Count != l.Count;
Automaton b = l[0];
if (has_aliases)
{
b = b.CloneExpanded();
}
else
{
b = b.CloneExpandedIfRequired();
}
ISet <State> ac = b.GetAcceptStates();
bool first = true;
foreach (Automaton a in l)
{
if (first)
{
first = false;
}
else
{
if (a.IsEmptyString)
{
continue;
}
Automaton aa = a;
if (has_aliases)
{
aa = aa.CloneExpanded();
}
else
{
aa = aa.CloneExpandedIfRequired();
}
ISet <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.deterministic = false;
//b.clearHashCode();
b.ClearNumberedStates();
b.CheckMinimizeAlways();
return(b);
}
}
/// <summary>
/// Returns an automaton that accepts the intersection of the languages of the
/// given automata. Never modifies the input automata languages.
/// <para/>
/// Complexity: quadratic in number of states.
/// </summary>
public static Automaton Intersection(Automaton a1, Automaton a2)
{
if (a1.IsSingleton)
{
if (BasicOperations.Run(a2, a1.singleton))
{
return(a1.CloneIfRequired());
}
else
{
return(BasicAutomata.MakeEmpty());
}
}
if (a2.IsSingleton)
{
if (BasicOperations.Run(a1, a2.singleton))
{
return(a2.CloneIfRequired());
}
else
{
return(BasicAutomata.MakeEmpty());
}
}
if (a1 == a2)
{
return(a1.CloneIfRequired());
}
Transition[][] transitions1 = a1.GetSortedTransitions();
Transition[][] transitions2 = a2.GetSortedTransitions();
Automaton c = new Automaton();
Queue <StatePair> worklist = new Queue <StatePair>(); // LUCENENET specific - Queue is much more performant than LinkedList
Dictionary <StatePair, StatePair> newstates = new Dictionary <StatePair, StatePair>();
StatePair p = new StatePair(c.initial, a1.initial, a2.initial);
worklist.Enqueue(p);
newstates[p] = p;
while (worklist.Count > 0)
{
p = worklist.Dequeue();
p.s.accept = p.s1.accept && p.s2.accept;
Transition[] t1 = transitions1[p.s1.number];
Transition[] t2 = transitions2[p.s2.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)
{
StatePair q = new StatePair(t1[n1].to, t2[n2].to);
if (!newstates.TryGetValue(q, out StatePair r) || r is null)
{
q.s = new State();
worklist.Enqueue(q);
newstates[q] = q;
r = q;
}
int min = t1[n1].min > t2[n2].min ? t1[n1].min : t2[n2].min;
int max = t1[n1].max < t2[n2].max ? t1[n1].max : t2[n2].max;
p.s.AddTransition(new Transition(min, max, r.s));
}
}
}
}
c.deterministic = a1.deterministic && a2.deterministic;
c.RemoveDeadTransitions();
c.CheckMinimizeAlways();
return(c);
}
private Automaton ToAutomaton(IDictionary <string, Automaton> automata, IAutomatonProvider automaton_provider)
{
IList <Automaton> list;
Automaton a = null;
switch (kind)
{
case Kind.REGEXP_UNION:
list = new List <Automaton>();
FindLeaves(exp1, Kind.REGEXP_UNION, list, automata, automaton_provider);
FindLeaves(exp2, Kind.REGEXP_UNION, list, automata, automaton_provider);
a = BasicOperations.Union(list);
MinimizationOperations.Minimize(a);
break;
case Kind.REGEXP_CONCATENATION:
list = new List <Automaton>();
FindLeaves(exp1, Kind.REGEXP_CONCATENATION, list, automata, automaton_provider);
FindLeaves(exp2, Kind.REGEXP_CONCATENATION, list, automata, automaton_provider);
a = BasicOperations.Concatenate(list);
MinimizationOperations.Minimize(a);
break;
case Kind.REGEXP_INTERSECTION:
a = exp1.ToAutomaton(automata, automaton_provider).Intersection(exp2.ToAutomaton(automata, automaton_provider));
MinimizationOperations.Minimize(a);
break;
case Kind.REGEXP_OPTIONAL:
a = exp1.ToAutomaton(automata, automaton_provider).Optional();
MinimizationOperations.Minimize(a);
break;
case Kind.REGEXP_REPEAT:
a = exp1.ToAutomaton(automata, automaton_provider).Repeat();
MinimizationOperations.Minimize(a);
break;
case Kind.REGEXP_REPEAT_MIN:
a = exp1.ToAutomaton(automata, automaton_provider).Repeat(min);
MinimizationOperations.Minimize(a);
break;
case Kind.REGEXP_REPEAT_MINMAX:
a = exp1.ToAutomaton(automata, automaton_provider).Repeat(min, max);
MinimizationOperations.Minimize(a);
break;
case Kind.REGEXP_COMPLEMENT:
a = exp1.ToAutomaton(automata, automaton_provider).Complement();
MinimizationOperations.Minimize(a);
break;
case Kind.REGEXP_CHAR:
a = BasicAutomata.MakeChar(c);
break;
case Kind.REGEXP_CHAR_RANGE:
a = BasicAutomata.MakeCharRange(from, to);
break;
case Kind.REGEXP_ANYCHAR:
a = BasicAutomata.MakeAnyChar();
break;
case Kind.REGEXP_EMPTY:
a = BasicAutomata.MakeEmpty();
break;
case Kind.REGEXP_STRING:
a = BasicAutomata.MakeString(s);
break;
case Kind.REGEXP_ANYSTRING:
a = BasicAutomata.MakeAnyString();
break;
case Kind.REGEXP_AUTOMATON:
Automaton aa = null;
if (automata != null)
{
aa = automata[s];
}
if (aa == null && automaton_provider != null)
{
try
{
aa = automaton_provider.GetAutomaton(s);
}
catch (System.IO.IOException e)
{
throw new System.ArgumentException(e.ToString(), e);
}
}
if (aa == null)
{
throw new System.ArgumentException("'" + s + "' not found");
}
a = (Automaton)aa.Clone(); // always clone here (ignore allow_mutate)
break;
case Kind.REGEXP_INTERVAL:
a = BasicAutomata.MakeInterval(min, max, digits);
break;
}
return(a);
}