/**
* Locates the last entry.
*
* @return the last entry of this subset, or <code>null</code> if the subset is empty.
*/
public LongAVLTreeSet.Entry lastEntry() {
if (tree == null) return null;
// If this subset goes to infinity, we return the main set last entry; otherwise, we locate
// the end of the set.
LongAVLTreeSet.Entry e;
if (top) e = lastEntry;
else {
e = locateKey(to);
// If we find something smaller than the end we're OK.
if (compare(e.key, to) >= 0) e = e.prev();
}
// Finally, if this subset doesn't go to -infinity, we check that the resulting key isn't
// smaller than the start.
if (e == null || !bottom && compare(e.key, from) < 0) return null;
return e;
}
/**
* Locates the first entry.
*
* @return the first entry of this subset, or <code>null</code> if the subset is empty.
*/
public LongAVLTreeSet.Entry firstEntry() {
if (tree == null) return null;
// If this subset goes to -infinity, we return the main set first entry; otherwise, we locate
// the start of the set.
LongAVLTreeSet.Entry e;
if (bottom) e = firstEntry;
else {
e = locateKey(from);
// If we find either the start or something greater we're OK.
if (compare(e.key, from) < 0) e = e.next();
}
// Finally, if this subset doesn't go to infinity, we check that the resulting key isn't
// greater than the end.
if (e == null || !top && compare(e.key, to) >= 0) return null;
return e;
}