public CachedSequence <T> Reverse()
{
CachedSequence <T> newHead = new CachedSequence <T>(Head);
CachedSequence <T> t = Tail;
while (t != null)
{
newHead = new CachedSequence <T>(t.Head, newHead);
t = t.Tail;
}
return(newHead);
}
public T ElementAt(int index)
{
if (index < 0)
{
throw new ArgumentOutOfRangeException("index");
}
CachedSequence <T> c = this;
while (--index >= 0)
{
c = c.Tail;
if (c == null)
{
throw new ArgumentOutOfRangeException("index", "`index` is larger than the collection size.");
}
}
return(c.Head);
}
public CachedSequence <T> Append(T value)
{
CachedSequence <T> start, c;
start = c = new CachedSequence <T>(Head);
CachedSequence <T> end = Tail;
while (end != null)
{
var n = new CachedSequence <T>(end.Head);
c.rest = Either(n);
c = n;
end = end.Tail;
}
c.rest = Either(new CachedSequence <T>(value));
return(start);
}
private Either <CachedSequence <T>, IEnumerator <T> > Either(CachedSequence <T> tail)
{
return(Either <CachedSequence <T>, IEnumerator <T> > .A(tail));
}
public CachedSequence(T head, CachedSequence <T> tail)
{
this.head = head;
this.rest = tail == null ? null : Either(tail);
}