/**
* Remove an element from the right digit.
*
* @param pos position inside the right digit
* @return resulting tree
*/
private FingerTree<N, E> removeRight(final long pos) {
if (right.length > 1) {
// right digit cannot underflow, just delete the element
return new DeepTree<>(left, leftSize, middle, remove(right, pos), size - 1);
}
// singleton digit might underflow
final Node<N, E> node = right[0];
if (!middle.isEmpty()) {
// potentially balance with middle tree
final InnerNode<N, E> last = (InnerNode<N, E>) middle.last();
final Node<N, E> lastSub = last.getSub(last.arity() - 1);
final NodeLike<N, E>[] rem = node.remove(lastSub, null, pos);
final Node<N, E> newLastSub = (Node<N, E>) rem[0], newNode = (Node<N, E>) rem[1];
if (newNode == null) {
// nodes were merged
final Node<N, E>[] newRight = last.children.clone();
newRight[newRight.length - 1] = newLastSub;
return new DeepTree<>(left, leftSize, middle.init(), newRight, size - 1);
}
@SuppressWarnings("unchecked")
final Node<N, E>[] newRight = new Node[] {newNode};
// replace last node in middle tree
final Node<Node<N, E>, E> newLast = last.replaceLast(newLastSub);
return new DeepTree<>(left, leftSize, middle.replaceLast(newLast), newRight, size - 1);
}
// balance with left digit
final Node<N, E> lastLeft = left[left.length - 1];
final NodeLike<N, E>[] rem = node.remove(lastLeft, null, pos);
final Node<N, E> newLastLeft = (Node<N, E>) rem[0], newNode = (Node<N, E>) rem[1];
if (newNode == null) {
// nodes were merged
if (left.length == 1) {
// only one node left
return new SingletonTree<>(newLastLeft);
}
@SuppressWarnings("unchecked")
final Node<N, E>[] newRight = new Node[] {newLastLeft};
return get(slice(left, 0, left.length - 1), newRight, size - 1);
}
@SuppressWarnings("unchecked")
final Node<N, E>[] newRight = new Node[] {newNode};
if (newLastLeft == lastLeft) {
// deletion could be absorbed
return get(left, leftSize, newRight, size - 1);
}
// adapt the left digit
final Node<N, E>[] newLeft = left.clone();
newLeft[newLeft.length - 1] = newLastLeft;
return get(newLeft, newRight, size - 1);
}
