public RegexElem(object atom, Repetition repetition)
{
this.atom = atom;
RegexAtomTraits.AtomType(atom); // validation
this.repetition = repetition;
if (this.atom == null)
{
throw new ArgumentNullException();
}
}
internal RegexElem ToCaseComparison(StringCaseComparison caseComp)
{
return(new RegexElem(RegexAtomTraits.ToCaseComparison(atom, caseComp), repetition));
}
public override string ToString()
{
return(RegexAtomTraits.ToString(atom) + repetition.ToString());
}
internal Nfa.Nfa BuildNfa()
{
// build a chain (not connected here) of the minimal repetitions
Nfa.Nfa[] min_coll = Enumerable.Range(0, Math.Max(1, repetition.Min)).Select(it => RegexAtomTraits.BuildNfa(atom)).ToArray();
var nfa = Nfa.Nfa.Concat(min_coll).ClearAccepting(min_coll.Last().Accepting());
if (!repetition.Max.HasValue)
{
min_coll.Last().StartNode.ConnectFrom(min_coll.Last().Accepting(), NfaEdge.CreateEmpty());
}
else
{
IEnumerable <Nfa.Nfa> max_coll = Enumerable.Range(0, repetition.Max.Value - min_coll.Length).Select(it => RegexAtomTraits.BuildNfa(atom)).ToList();
if (max_coll.Any())
{
var max_nfa = Nfa.Nfa.Concat(max_coll);
max_nfa.StartNode.ConnectFrom(min_coll.Last().Accepting(), NfaEdge.CreateEmpty());
}
}
// put it as last step, otherwise we could get connection right from the start node
if (repetition.Min == 0)
{
nfa.Accepting().ForEach(it => nfa.StartNode.ConnectTo(it, NfaEdge.CreateEmpty()));
}
return(nfa);
}
