void insert(struct node **root, int key)
{
struct node *z;
z = bst_insert(root, key);
z->color = RED;
fix_rb_tree(root, z);
}
void insert(
const char *name
) {
debug("Insert node: %s", name);
// Is name exceeding MAX_NAME_LENGTH chars?
unsigned int len = strlen(name);
// MAX_NAME_LENGTH is 59 bytes+'\0'
check(len<MAX_NAME_LENGTH, "Insert: Name exceeds maximal length.");
// Allocate and initialize a new node
Node *n = malloc(sizeof(Node));
check_mem(n);
n->parent = NULL; n->left = NIL; n->right = NIL; n->color = RED;
strncpy(n->name, name, len);
n->name[len] = '\0';
if(root == NULL) {
ins_count = 0;
dbl_count = 0;
del_count = 0;
root = n;
} else {
// if already exsits skip
if(find_by_name(n->name)) {
debug("Insert node: %salready exists", n->name);
dbl_count++;
free(n);
return;
}
// search for the proper place to include the node
Node *current = root;
while (1) {
// debug("Cmp %s with %s", n->name, current->name);
int res = strcmp(n->name, current->name);
if(res < 0) {
if(current->left == NIL) {
current->left = n;
n->parent = current;
break;
} else {
current = current->left;
}
} else if(res > 0) {
if(current->right == NIL) {
current->right = n;
n->parent = current;
break;
} else {
current = current->right;
}
}
}
}
// ensure red black tree properties
fix_rb_tree(n);
ins_count++;
debug("Insert Counter: %d\n", ins_count);
// check for properties
check_requirements(root);
error:
return;
}
/*
* An inserted node is always red. This violates maybe req. 2.) --> repairing necessary
* Given a Node N to be inserted, it's Uncle (U), it's parent (P) and grandparent (GP),
* five cases have to be considered:
* 1.) root == NULL, (obvious)
* 2.) The parent of N is black -> nothing to do
* 3.) U and P of N is red -> color U,P black and GP red. -> req. 2.) maybe violated
* then recursivley insert GP to the tree
* 4.) N has non or a black U while N is the right child of his red P and P is left of GP
* -> left rotation around P and apply case 5.)
* 5.) N has non or a black U and is the left child of his red P and P is left of GP.
* -> right rotation around GP. Then swap colors of former GP and P.
*/
void fix_rb_tree(
Node *n
) {
check(n, "Insert node: new_node == NULL");
Node *parent = n->parent;
// case 1.)
if(parent == NULL) {
// debug("Insert node: case 1.)");
n->color = BLACK;
return;
}
// case 2.) The parent is black. There is no need to fix the tree.
if(parent->color == BLACK) {
// debug("Insert node: case 2.)");
return;
}
// case 3.) U and P of N is red -> color U,P black and GP red.
if(uncle(n)->color == RED) {
// debug("Insert node: case 3.)");
n->parent->color = BLACK;
uncle(n)->color = BLACK;
grandparent(n)->color = RED;
fix_rb_tree(grandparent(n));
return;
}
// case 4.) N has non or a black U while N is the right child of his red P and P is left of GP
if(
n == n->parent->right &&
n->parent == grandparent(n)->left
) {
// debug("Fixing: case 4.) rotate left.");
rotate_left(n->parent);
n = n->left;
} else if(
n == n->parent->left &&
n->parent == grandparent(n)->right) {
// debug("Fixing: case 4.) rotate right.");
rotate_right(n->parent);
n = n->right;
}
// 5.) N has non or a black U and is the left child of his red P and P is left of GP.
n->parent->color = BLACK;
grandparent(n)->color = RED;
if(
n == n->parent->left &&
n->parent == grandparent(n)->left
) {
// debug("Fixing: case 5.) rotate right.");
rotate_right(grandparent(n));
} else {
// debug("Fixing: case 5.) rotate left.");
rotate_left(grandparent(n));
}
error:
return;
}