avl_node *
avl_new_avl_node (void * key,
avl_node * parent)
{
avl_node * node = (avl_node *) malloc (sizeof (avl_node));
if (!node) {
return NULL;
} else {
node->parent = parent;
node->key = key;
node->left = NULL;
node->right = NULL;
node->rank_and_balance = 0;
AVL_SET_BALANCE (node, 0);
AVL_SET_RANK (node, 1);
return node;
}
}
avl_node *
avl_node_new (void * key,
avl_node * parent)
{
avl_node * node = (avl_node *) malloc (sizeof (avl_node));
if (!node)
abort();
node->parent = parent;
node->key = key;
node->left = NULL;
node->right = NULL;
node->rank_and_balance = 0;
AVL_SET_BALANCE (node, 0);
AVL_SET_RANK (node, 1);
#ifdef HAVE_AVL_NODE_LOCK
thread_rwlock_create(&node->rwlock);
#endif
return node;
}
int avl_delete(avl_tree *tree, void *key, avl_free_key_fun_type free_key_fun)
{
avl_node *x, *y, *p, *q, *r, *top, *x_child;
int shortened_side, shorter;
x = tree->root->right;
if (!x) {
return -1;
}
while (1) {
int compare_result = tree->compare_fun (tree->compare_arg, key, x->key);
if (compare_result < 0) {
/* move left
* We will be deleting from the left, adjust this node's
* rank accordingly
*/
AVL_SET_RANK (x, (AVL_GET_RANK(x) - 1));
if (x->left) {
x = x->left;
} else {
/* Oops! now we have to undo the rank changes
* all the way up the tree
*/
AVL_SET_RANK(x, (AVL_GET_RANK (x) + 1));
while (x != tree->root->right) {
if (x->parent->left == x) {
AVL_SET_RANK(x->parent, (AVL_GET_RANK (x->parent) + 1));
}
x = x->parent;
}
return -1; /* key not in tree */
}
} else if (compare_result > 0) {
/* move right */
if (x->right) {
x = x->right;
} else {
AVL_SET_RANK(x, (AVL_GET_RANK (x) + 1));
while (x != tree->root->right) {
if (x->parent->left == x) {
AVL_SET_RANK(x->parent, (AVL_GET_RANK (x->parent) + 1));
}
x = x->parent;
}
return -1; /* key not in tree */
}
} else {
break;
}
}
if (x->left && x->right) {
void * temp_key;
/* The complicated case.
* reduce this to the simple case where we are deleting
* a node with at most one child.
*/
/* find the immediate predecessor <y> */
y = x->left;
while (y->right) {
y = y->right;
}
/* swap <x> with <y> */
temp_key = x->key;
x->key = y->key;
y->key = temp_key;
/* we know <x>'s left subtree lost a node because that's
* where we took it from
*/
AVL_SET_RANK (x, (AVL_GET_RANK (x) - 1));
x = y;
}
/* now <x> has at most one child
* scoot this child into the place of <x>
*/
if (x->left) {
x_child = x->left;
x_child->parent = x->parent;
} else if (x->right) {
x_child = x->right;
x_child->parent = x->parent;
} else {
x_child = NULL;
}
/* now tell <x>'s parent that a grandchild became a child */
if (x == x->parent->left) {
x->parent->left = x_child;
shortened_side = -1;
} else {
x->parent->right = x_child;
shortened_side = +1;
}
/*
* the height of the subtree <x>
* has now been shortened. climb back up
* the tree, rotating when necessary to adjust
* for the change.
*/
shorter = 1;
p = x->parent;
/* return the key and node to storage */
if (free_key_fun)
free_key_fun (x->key);
#ifdef HAVE_AVL_NODE_LOCK
thread_rwlock_destroy (&x->rwlock);
#endif
free (x);
while (shorter && p->parent) {
/* case 1: height unchanged */
if (AVL_GET_BALANCE(p) == 0) {
if (shortened_side == -1) {
/* we removed a left child, the tree is now heavier
* on the right
*/
AVL_SET_BALANCE (p, +1);
} else {
/* we removed a right child, the tree is now heavier
* on the left
*/
AVL_SET_BALANCE (p, -1);
}
shorter = 0;
} else if (AVL_GET_BALANCE (p) == shortened_side) {
/* case 2: taller subtree shortened, height reduced */
AVL_SET_BALANCE (p, 0);
} else {
/* case 3: shorter subtree shortened */
top = p->parent;
/* set <q> to the taller of the two subtrees of <p> */
if (shortened_side == 1) {
q = p->left;
} else {
q = p->right;
}
if (AVL_GET_BALANCE (q) == 0) {
/* case 3a: height unchanged */
if (shortened_side == -1) {
/* single rotate left */
q->parent = p->parent;
p->right = q->left;
if (q->left) {
q->left->parent = p;
}
q->left = p;
p->parent = q;
AVL_SET_RANK (q, (AVL_GET_RANK (q) + AVL_GET_RANK (p)));
} else {
/* single rotate right */
q->parent = p->parent;
p->left = q->right;
if (q->right) {
q->right->parent = p;
}
q->right = p;
p->parent = q;
AVL_SET_RANK (p, (AVL_GET_RANK (p) - AVL_GET_RANK (q)));
}
shorter = 0;
AVL_SET_BALANCE (q, shortened_side);
AVL_SET_BALANCE (p, (- shortened_side));
} else if (AVL_GET_BALANCE (q) == AVL_GET_BALANCE (p)) {
/* case 3b: height reduced */
if (shortened_side == -1) {
/* single rotate left */
q->parent = p->parent;
p->right = q->left;
if (q->left) {
q->left->parent = p;
}
q->left = p;
p->parent = q;
AVL_SET_RANK (q, (AVL_GET_RANK (q) + AVL_GET_RANK (p)));
} else {
/* single rotate right */
q->parent = p->parent;
p->left = q->right;
if (q->right) {
q->right->parent = p;
}
q->right = p;
p->parent = q;
AVL_SET_RANK (p, (AVL_GET_RANK (p) - AVL_GET_RANK (q)));
}
shorter = 1;
AVL_SET_BALANCE (q, 0);
AVL_SET_BALANCE (p, 0);
} else {
/* case 3c: height reduced, balance factors opposite */
if (shortened_side == 1) {
/* double rotate right */
/* first, a left rotation around q */
r = q->right;
r->parent = p->parent;
q->right = r->left;
if (r->left) {
r->left->parent = q;
}
r->left = q;
q->parent = r;
/* now, a right rotation around p */
p->left = r->right;
if (r->right) {
r->right->parent = p;
}
r->right = p;
p->parent = r;
AVL_SET_RANK (r, (AVL_GET_RANK (r) + AVL_GET_RANK (q)));
AVL_SET_RANK (p, (AVL_GET_RANK (p) - AVL_GET_RANK (r)));
} else {
/* double rotate left */
/* first, a right rotation around q */
r = q->left;
r->parent = p->parent;
q->left = r->right;
if (r->right) {
r->right->parent = q;
}
r->right = q;
q->parent = r;
/* now a left rotation around p */
p->right = r->left;
if (r->left) {
r->left->parent = p;
}
r->left = p;
p->parent = r;
AVL_SET_RANK (q, (AVL_GET_RANK (q) - AVL_GET_RANK (r)));
AVL_SET_RANK (r, (AVL_GET_RANK (r) + AVL_GET_RANK (p)));
}
if (AVL_GET_BALANCE (r) == shortened_side) {
AVL_SET_BALANCE (q, (- shortened_side));
AVL_SET_BALANCE (p, 0);
} else if (AVL_GET_BALANCE (r) == (- shortened_side)) {
AVL_SET_BALANCE (q, 0);
AVL_SET_BALANCE (p, shortened_side);
} else {
AVL_SET_BALANCE (q, 0);
AVL_SET_BALANCE (p, 0);
}
AVL_SET_BALANCE (r, 0);
q = r;
}
/* a rotation has caused <q> (or <r> in case 3c) to become
* the root. let <p>'s former parent know this.
*/
if (top->left == p) {
top->left = q;
} else {
top->right = q;
}
/* end case 3 */
p = q;
}
x = p;
p = x->parent;
/* shortened_side tells us which side we came up from */
if (x == p->left) {
shortened_side = -1;
} else {
shortened_side = +1;
}
} /* end while(shorter) */
/* when we're all done, we're one shorter */
tree->length = tree->length - 1;
return (0);
}
int
avl_insert (avl_tree * ob,
void * key)
{
if (!(ob->root->right)) {
avl_node * node = avl_node_new (key, ob->root);
if (!node) {
return -1;
} else {
ob->root->right = node;
ob->length = ob->length + 1;
return 0;
}
} else { /* not self.right == None */
avl_node *t, *p, *s, *q, *r;
int a;
t = ob->root;
s = p = t->right;
while (1) {
if (ob->compare_fun (ob->compare_arg, key, p->key) < 1) {
/* move left */
AVL_SET_RANK (p, (AVL_GET_RANK (p) + 1));
q = p->left;
if (!q) {
/* insert */
avl_node * q_node = avl_node_new (key, p);
if (!q_node) {
return (-1);
} else {
q = q_node;
p->left = q;
break;
}
} else if (AVL_GET_BALANCE(q)) {
t = p;
s = q;
}
p = q;
} else {
/* move right */
q = p->right;
if (!q) {
/* insert */
avl_node * q_node = avl_node_new (key, p);
if (!q_node) {
return -1;
} else {
q = q_node;
p->right = q;
break;
}
} else if (AVL_GET_BALANCE(q)) {
t = p;
s = q;
}
p = q;
}
}
ob->length = ob->length + 1;
/* adjust balance factors */
if (ob->compare_fun (ob->compare_arg, key, s->key) < 1) {
r = p = s->left;
} else {
r = p = s->right;
}
while (p != q) {
if (ob->compare_fun (ob->compare_arg, key, p->key) < 1) {
AVL_SET_BALANCE (p, -1);
p = p->left;
} else {
AVL_SET_BALANCE (p, +1);
p = p->right;
}
}
/* balancing act */
if (ob->compare_fun (ob->compare_arg, key, s->key) < 1) {
a = -1;
} else {
a = +1;
}
if (AVL_GET_BALANCE (s) == 0) {
AVL_SET_BALANCE (s, a);
ob->height = ob->height + 1;
return 0;
} else if (AVL_GET_BALANCE (s) == -a) {
AVL_SET_BALANCE (s, 0);
return 0;
} else if (AVL_GET_BALANCE(s) == a) {
if (AVL_GET_BALANCE (r) == a) {
/* single rotation */
p = r;
if (a == -1) {
s->left = r->right;
if (r->right) {
r->right->parent = s;
}
r->right = s;
s->parent = r;
AVL_SET_RANK (s, (AVL_GET_RANK (s) - AVL_GET_RANK (r)));
} else {
s->right = r->left;
if (r->left) {
r->left->parent = s;
}
r->left = s;
s->parent = r;
AVL_SET_RANK (r, (AVL_GET_RANK (r) + AVL_GET_RANK (s)));
}
AVL_SET_BALANCE (s, 0);
AVL_SET_BALANCE (r, 0);
} else if (AVL_GET_BALANCE (r) == -a) {
/* double rotation */
if (a == -1) {
p = r->right;
r->right = p->left;
if (p->left) {
p->left->parent = r;
}
p->left = r;
r->parent = p;
s->left = p->right;
if (p->right) {
p->right->parent = s;
}
p->right = s;
s->parent = p;
AVL_SET_RANK (p, (AVL_GET_RANK (p) + AVL_GET_RANK (r)));
AVL_SET_RANK (s, (AVL_GET_RANK (s) - AVL_GET_RANK (p)));
} else {
p = r->left;
r->left = p->right;
if (p->right) {
p->right->parent = r;
}
p->right = r;
r->parent = p;
s->right = p->left;
if (p->left) {
p->left->parent = s;
}
p->left = s;
s->parent = p;
AVL_SET_RANK (r, (AVL_GET_RANK (r) - AVL_GET_RANK (p)));
AVL_SET_RANK (p, (AVL_GET_RANK (p) + AVL_GET_RANK (s)));
}
if (AVL_GET_BALANCE (p) == a) {
AVL_SET_BALANCE (s, -a);
AVL_SET_BALANCE (r, 0);
} else if (AVL_GET_BALANCE (p) == -a) {
AVL_SET_BALANCE (s, 0);
AVL_SET_BALANCE (r, a);
} else {
AVL_SET_BALANCE (s, 0);
AVL_SET_BALANCE (r, 0);
}
AVL_SET_BALANCE (p, 0);
}
/* finishing touch */
if (s == t->right) {
t->right = p;
} else {
t->left = p;
}
p->parent = t;
}
}
return 0;
}