internal ReKleeneStar(ReElement element)
{
if (element == null)
{
throw new ArgumentNullException(nameof(element));
}
_element = element;
}
public static ReElement NewRepetition(ReElement element, int min, int?max)
{
if (element == null)
{
throw new ArgumentNullException(nameof(element));
}
if (max.HasValue && min > max.Value)
{
throw new ArgumentException("min cannot be greater than max", nameof(min));
}
switch (element.Kind)
{
case ReElementKind.EmptyString:
case ReElementKind.EmptyLanguage:
case ReElementKind.KleenStar:
return(element);
}
if (element.MatchesEmptyString)
{
min = 0;
}
var builder = ImmutableArray.CreateBuilder <ReElement>();
for (var i = 0; i < min; i++)
{
builder.Add(element);
}
if (max.HasValue)
{
var optionalElement = new ReUnion(
ImmutableArray.Create(
element,
ReEmptyString.Instance));
for (var i = min; i < max; i++)
{
builder.Add(optionalElement);
}
}
else
{
builder.Add(new ReKleeneStar(element));
}
switch (builder.Count)
{
case 0: return(ReEmptyString.Instance);
case 1: return(builder[0]);
default: return(new ReConcatenation(builder.ToImmutable()));
}
}
static ReElement ParseRepitition(ReElement element, ReParseContext context)
{
var min = ParseInt(context) ?? 0;
if (context.Current == ',')
{
if (!context.MoveNext())
{
ThrowUnexpectedEnd();
}
var max = ParseInt(context);
return(ReFactory.NewRepetition(element, min, max));
}
else
{
return(ReFactory.NewRepetition(element, min, min));
}
}
public static ReElement NewKleeneStar(ReElement element)
{
if (element == null)
{
throw new ArgumentNullException(nameof(element));
}
switch (element.Kind)
{
case ReElementKind.KleenStar:
case ReElementKind.EmptyLanguage:
case ReElementKind.EmptyString:
return(element);
default:
return(new ReKleeneStar(element));
}
}
