/** Balances part of the tree after an alteration to the index. */
private void balance(Session session, Node x, boolean isleft) throws HsqlException {
while (true) {
int sign = isleft ? 1 : -1;
switch (x.getBalance() * sign) {
case 1:
x.setBalance(0);
return;
case 0:
x.setBalance(-sign);
break;
case -1:
Node l = child(x, isleft);
if (l.getBalance() == -sign) {
replace(session, x, l);
set(x, isleft, child(l, !isleft));
set(l, !isleft, x);
x.setBalance(0);
l.setBalance(0);
} else {
Node r = child(l, !isleft);
replace(session, x, r);
set(l, !isleft, child(r, isleft));
set(r, isleft, l);
set(x, isleft, child(r, !isleft));
set(r, !isleft, x);
int rb = r.getBalance();
x.setBalance((rb == -sign) ? sign : 0);
l.setBalance((rb == sign) ? -sign : 0);
r.setBalance(0);
}
return;
}
if (x.equals(getRoot(session))) {
return;
}
isleft = x.isFromLeft();
x = x.getParent();
}
}
public void insert_restore_AVL_prop(Node curr) {
curr.setHeight(-1);
curr.setBalance(0);
while (curr != null && curr.getBalance() == 0) {
curr.setHeight(curr.getHeight() + 1);
computeBalance(curr);
curr = curr.getParent();
}
if (curr != null) {
computeBalance(curr);
if (curr.getBalance() == -2) {
if (curr.getLeftChild().getBalance() == 1) {
left_rotate(curr.getLeftChild());
height_of_node(curr.getLeftChild());
computeBalance(curr.getLeftChild());
computeBalance(curr.getLeftChild().getLeftChild());
}
right_rotate(curr);
height_of_node(curr.getParent());
computeBalance(curr);
computeBalance(curr.getParent());
} else if (curr.getBalance() == 2) {
if (curr.getRightChild().getBalance() == -1) {
right_rotate(curr.getRightChild());
height_of_node(curr.getRightChild());
computeBalance(curr.getRightChild());
computeBalance(curr.getRightChild().getRightChild());
}
left_rotate(curr);
height_of_node(curr.getParent());
computeBalance(curr);
computeBalance(curr.getParent());
}
}
}
public void delete_restore_AVL_prop(Node curr) {
height_of_node(curr);
while (curr != null) {
computeBalance(curr);
if (curr.getBalance() == -2) {
if (curr.getLeftChild().getBalance() == 1) {
left_rotate(curr.getLeftChild());
height_of_node(curr.getLeftChild());
computeBalance(curr.getLeftChild());
computeBalance(curr.getLeftChild().getLeftChild());
}
right_rotate(curr);
height_of_node(curr.getParent());
computeBalance(curr);
computeBalance(curr.getParent());
curr = curr.getParent();
} else if (curr.getBalance() == 2) {
if (curr.getRightChild().getBalance() == -1) {
right_rotate(curr.getRightChild());
height_of_node(curr.getRightChild());
computeBalance(curr.getRightChild());
computeBalance(curr.getRightChild().getRightChild());
}
left_rotate(curr);
height_of_node(curr.getParent());
computeBalance(curr);
computeBalance(curr.getParent());
curr = curr.getParent();
}
curr = curr.getParent();
}
}
/** Delete a node from the index */
void delete(Session session, Node x) throws HsqlException {
if (x == null) {
return;
}
for (IndexRowIterator it = updatableIterators.next; it != updatableIterators; it = it.next) {
it.updateForDelete(x);
}
Node n;
if (x.getLeft() == null) {
n = x.getRight();
} else if (x.getRight() == null) {
n = x.getLeft();
} else {
Node d = x;
x = x.getLeft();
/*
// todo: this can be improved
while (x.getRight() != null) {
if (Trace.STOP) {
Trace.stop();
}
x = x.getRight();
}
*/
for (Node temp = x; (temp = temp.getRight()) != null; ) {
x = temp;
}
// x will be replaced with n later
n = x.getLeft();
// swap d and x
int b = x.getBalance();
x.setBalance(d.getBalance());
d.setBalance(b);
// set x.parent
Node xp = x.getParent();
Node dp = d.getParent();
if (d == getRoot(session)) {
setRoot(session, x);
}
x.setParent(dp);
if (dp != null) {
if (dp.getRight().equals(d)) {
dp.setRight(x);
} else {
dp.setLeft(x);
}
}
// for in-memory tables we could use: d.rData=x.rData;
// but not for cached tables
// relink d.parent, x.left, x.right
if (xp == d) {
d.setParent(x);
if (d.getLeft().equals(x)) {
x.setLeft(d);
x.setRight(d.getRight());
} else {
x.setRight(d);
x.setLeft(d.getLeft());
}
} else {
d.setParent(xp);
xp.setRight(d);
x.setRight(d.getRight());
x.setLeft(d.getLeft());
}
x.getRight().setParent(x);
x.getLeft().setParent(x);
// set d.left, d.right
d.setLeft(n);
if (n != null) {
n.setParent(d);
}
d.setRight(null);
x = d;
}
boolean isleft = x.isFromLeft();
replace(session, x, n);
n = x.getParent();
x.delete();
while (n != null) {
x = n;
int sign = isleft ? 1 : -1;
switch (x.getBalance() * sign) {
case -1:
x.setBalance(0);
break;
case 0:
x.setBalance(sign);
return;
case 1:
Node r = child(x, !isleft);
int b = r.getBalance();
if (b * sign >= 0) {
replace(session, x, r);
set(x, !isleft, child(r, isleft));
set(r, isleft, x);
if (b == 0) {
x.setBalance(sign);
r.setBalance(-sign);
return;
}
x.setBalance(0);
r.setBalance(0);
x = r;
} else {
Node l = child(r, isleft);
replace(session, x, l);
b = l.getBalance();
set(r, isleft, child(l, !isleft));
set(l, !isleft, r);
set(x, !isleft, child(l, isleft));
set(l, isleft, x);
x.setBalance((b == sign) ? -sign : 0);
r.setBalance((b == -sign) ? sign : 0);
l.setBalance(0);
x = l;
}
}
isleft = x.isFromLeft();
n = x.getParent();
}
}