int fwAvlInsert(uint32_t key, void* data, struct FwAvlTree* tree)
{
int is_left;
struct FwAvlNode* parent;
struct FwAvlNode* right;
struct FwAvlNode* left;
struct FwAvlNode* unbalanced;
struct FwAvlNode* node;
if(do_lookup(key, tree, &parent, &unbalanced, &is_left) != NULL)
return 1;
if(!(node = new_node(key, data)))
return -1;
tree->count++;
if(parent == NULL)
{
tree->root = node;
tree->first = node;
tree->last = node;
return 0;
}
if(is_left != 0)
{
if(parent == tree->first)
tree->first = node;
}
else
{
if(parent == tree->last)
tree->last = node;
}
set_parent(parent, node);
set_child(node, parent, is_left);
while(1)
{
if(parent->left == node)
dec_balance(parent);
else
inc_balance(parent);
if(parent == unbalanced)
break;
node = parent;
parent = get_parent(node);
}
switch(get_balance(unbalanced))
{
case 1:
case -1:
tree->height++;
break;
case 0:
break;
case 2:
right = unbalanced->right;
if(get_balance(right) == 1)
{
set_balance(0, unbalanced);
set_balance(0, right);
}
else
{
switch(get_balance(right->left))
{
case 1:
set_balance(-1, unbalanced);
set_balance(0, right);
break;
case 0:
set_balance(0, unbalanced);
set_balance(0, right);
break;
case -1:
set_balance(0, unbalanced);
set_balance(1, right);
break;
}
set_balance(0, right->left);
rotate_right(right, tree);
}
rotate_left(unbalanced, tree);
break;
case -2:
left = unbalanced->left;
if(get_balance(left) == -1)
{
set_balance(0, unbalanced);
set_balance(0, left);
}
else
{
switch(get_balance(left->right))
{
case 1:
set_balance(0, unbalanced);
set_balance(-1, left);
break;
case 0:
set_balance(0, unbalanced);
set_balance(0, left);
break;
case -1:
set_balance(1, unbalanced);
set_balance(0, left);
break;
}
set_balance(0, left->right);
rotate_left(left, tree);
}
rotate_right(unbalanced, tree);
break;
}
return 0;
}
/* Insertion never needs more than 2 rotations */
struct avltree_node *avltree_insert(struct avltree_node *node, struct avltree *tree)
{
struct avltree_node *key, *parent, *unbalanced;
int is_left;
key = do_lookup(node, tree, &parent, &unbalanced, &is_left);
if (key)
return key;
INIT_NODE(node);
if (!parent) {
tree->root = node;
tree->first = tree->last = node;
tree->height++;
return NULL;
}
if (is_left) {
if (parent == tree->first)
tree->first = node;
} else {
if (parent == tree->last)
tree->last = node;
}
set_parent(parent, node);
set_child(node, parent, is_left);
for (;;) {
if (parent->left == node)
dec_balance(parent);
else
inc_balance(parent);
if (parent == unbalanced)
break;
node = parent;
parent = get_parent(parent);
}
switch (get_balance(unbalanced)) {
case 1: case -1:
tree->height++;
/* fall through */
case 0:
break;
case 2: {
struct avltree_node *right = unbalanced->right;
if (get_balance(right) == 1) {
set_balance(0, unbalanced);
set_balance(0, right);
} else {
switch (get_balance(right->left)) {
case 1:
set_balance(-1, unbalanced);
set_balance( 0, right);
break;
case 0:
set_balance(0, unbalanced);
set_balance(0, right);
break;
case -1:
set_balance(0, unbalanced);
set_balance(1, right);
break;
}
set_balance(0, right->left);
rotate_right(right, tree);
}
rotate_left(unbalanced, tree);
break;
}
case -2: {
struct avltree_node *left = unbalanced->left;
if (get_balance(left) == -1) {
set_balance(0, unbalanced);
set_balance(0, left);
} else {
switch (get_balance(left->right)) {
case 1:
set_balance( 0, unbalanced);
set_balance(-1, left);
break;
case 0:
set_balance(0, unbalanced);
set_balance(0, left);
break;
case -1:
set_balance(1, unbalanced);
set_balance(0, left);
break;
}
set_balance(0, left->right);
rotate_left(left, tree);
}
rotate_right(unbalanced, tree);
break;
}
}
return NULL;
}
/* Deletion might require up to log(n) rotations */
void avltree_remove(struct avltree_node *node, struct avltree *tree)
{
struct avltree_node *parent = get_parent(node);
struct avltree_node *left = node->left;
struct avltree_node *right = node->right;
struct avltree_node *next;
int is_left = is_left;
if (node == tree->first)
tree->first = avltree_next(node);
if (node == tree->last)
tree->last = avltree_prev(node);
if (!left)
next = right;
else if (!right)
next = left;
else
next = get_first(right);
if (parent) {
is_left = parent->left == node;
set_child(next, parent, is_left);
} else
tree->root = next;
if (left && right) {
set_balance(get_balance(node), next);
next->left = left;
set_parent(next, left);
if (next != right) {
parent = get_parent(next);
set_parent(get_parent(node), next);
node = next->right;
parent->left = node;
is_left = 1;
next->right = right;
set_parent(next, right);
} else {
set_parent(parent, next);
parent = next;
node = parent->right;
is_left = 0;
}
assert(parent != NULL);
} else
node = next;
if (node)
set_parent(parent, node);
/*
* At this point, 'parent' can only be null, if 'node' is the
* tree's root and has at most one child.
*
* case 1: the subtree is now balanced but its height has
* decreased.
*
* case 2: the subtree is mostly balanced and its height is
* unchanged.
*
* case 3: the subtree is unbalanced and its height may have
* been changed during the rebalancing process, see below.
*
* case 3.1: after a left rotation, the subtree becomes mostly
* balanced and its height is unchanged.
*
* case 3.2: after a left rotation, the subtree becomes
* balanced but its height has decreased.
*
* case 3.3: after a left and a right rotation, the subtree
* becomes balanced or mostly balanced but its height has
* decreased for all cases.
*/
while (parent) {
int balance;
node = parent;
parent = get_parent(parent);
if (is_left) {
is_left = parent && parent->left == node;
balance = inc_balance(node);
if (balance == 0) /* case 1 */
continue;
if (balance == 1) /* case 2 */
return;
right = node->right; /* case 3 */
switch (get_balance(right)) {
case 0: /* case 3.1 */
set_balance( 1, node);
set_balance(-1, right);
rotate_left(node, tree);
return;
case 1: /* case 3.2 */
set_balance(0, node);
set_balance(0, right);
break;
case -1: /* case 3.3 */
switch (get_balance(right->left)) {
case 1:
set_balance(-1, node);
set_balance( 0, right);
break;
case 0:
set_balance(0, node);
set_balance(0, right);
break;
case -1:
set_balance(0, node);
set_balance(1, right);
break;
}
set_balance(0, right->left);
rotate_right(right, tree);
}
rotate_left(node, tree);
} else {
is_left = parent && parent->left == node;
balance = dec_balance(node);
if (balance == 0)
continue;
if (balance == -1)
return;
left = node->left;
switch (get_balance(left)) {
case 0:
set_balance(-1, node);
set_balance(1, left);
rotate_right(node, tree);
return;
case -1:
set_balance(0, node);
set_balance(0, left);
break;
case 1:
switch (get_balance(left->right)) {
case 1:
set_balance(0, node);
set_balance(-1, left);
break;
case 0:
set_balance(0, node);
set_balance(0, left);
break;
case -1:
set_balance(1, node);
set_balance(0, left);
break;
}
set_balance(0, left->right);
rotate_left(left, tree);
}
rotate_right(node, tree);
}
}
tree->height--;
}
/* Insertion never needs more than 2 rotations */
struct avltree_node *avltree_insert(struct avltree_node *node, struct avltree *tree) {
struct avltree_node *parent = 0, *unbalanced = tree->root;
bool is_left;
// Find a suitable parent.
for (struct avltree_node *next_parent = tree->root; next_parent != 0;) {
parent = next_parent;
if (get_balance(parent) != 0)
unbalanced = parent;
int cmp_r = tree->cmp_fn(parent, node);
if (cmp_r == 0) {
if (tree->unique_index)
return parent;
// For non unique indexes any insert direction is acceptable.
if (parent->left == 0) {
is_left = true;
break;
} else if (parent->right == 0) {
is_left = false;
break;
} else {
// Be smart and travel to the least balanced subtree to minimize balancing overhead.
next_parent = (get_balance(parent) <= 0)? parent->left: parent->right;
}
} else {
is_left = (cmp_r > 0);
next_parent = is_left? parent->left: parent->right;
}
}
INIT_NODE(node);
if (!parent) {
tree->root = node;
tree->first = tree->last = node;
tree->height++;
return 0;
}
if (is_left) {
if (parent == tree->first)
tree->first = node;
} else {
if (parent == tree->last)
tree->last = node;
}
set_parent(parent, node);
set_child(node, parent, is_left);
for (;;) {
if (parent->left == node)
dec_balance(parent);
else
inc_balance(parent);
if (parent == unbalanced) {
for (;;) {
node = parent;
node->count++;
if (is_root(node))
break;
parent = get_parent(parent);
}
break;
}
node = parent;
node->count++;
parent = get_parent(parent);
}
switch (get_balance(unbalanced)) {
case 1: case -1:
tree->height++;
/* fall through */
case 0:
break;
case 2:
{
struct avltree_node *right = unbalanced->right;
if (get_balance(right) == 1) {
set_balance(0, unbalanced);
set_balance(0, right);
} else {
switch (get_balance(right->left)) {
case 1:
set_balance(-1, unbalanced);
set_balance(0, right);
break;
case 0:
set_balance(0, unbalanced);
set_balance(0, right);
break;
case -1:
set_balance(0, unbalanced);
set_balance(1, right);
break;
}
set_balance(0, right->left);
rotate_right(right, tree);
}
rotate_left(unbalanced, tree);
break;
}
case -2:
{
struct avltree_node *left = unbalanced->left;
if (get_balance(left) == -1) {
set_balance(0, unbalanced);
set_balance(0, left);
} else {
switch (get_balance(left->right)) {
case 1:
set_balance(0, unbalanced);
set_balance(-1, left);
break;
case 0:
set_balance(0, unbalanced);
set_balance(0, left);
break;
case -1:
set_balance(1, unbalanced);
set_balance(0, left);
break;
}
set_balance(0, left->right);
rotate_left(left, tree);
}
rotate_right(unbalanced, tree);
break;
}
}
return 0;
}
