struct tree_node* _insert_rebalance(struct tree_node* node, struct tree_node* root)
{
struct tree_node *parent, *gparent, *uncle, *tmp;
while ((parent = node->parent_node) && parent->color == Red)
{
gparent = parent->parent_node;
if (parent == gparent->left_node)
{
uncle = gparent->right_node;
if (uncle && uncle->color == Red)
{
uncle->color = Black;
parent->color = Black;
gparent->color = Red;
node = gparent;
}
else
{
if (parent->right_node == node)
{
root = _rotate_left(parent, root);
tmp = parent;
parent = node;
node = tmp;
}
parent->color = Black;
gparent->color = Red;
root = _rotate_right(gparent, root);
}
}
else
{
uncle = gparent->left_node;
if (uncle && uncle->color == Red)
{
uncle->color = Black;
parent->color = Black;
gparent->color = Red;
node = gparent;
}
else
{
if (parent->left_node == node)
{
root = _rotate_right(parent, root);
tmp = parent;
parent = node;
node = tmp;
}
parent->color = Black;
gparent->color = Red;
root = _rotate_left(gparent, root);
}
}
}
root->color = Black;
return root;
}
/*! Rebalance the tree after insertion of a node. */
void GsTreeBase::_rebalance ( GsTreeNode *x )
{
GS_TRACE1("Rebalance");
GsTreeNode *y;
while ( x!=_root && RED(x->parent) )
{ // if ( !x->parent->parent ) REPORT_ERROR
if ( x->parent==x->parent->parent->left )
{ y = x->parent->parent->right;
if ( RED(y) )
{ // handle case 1 (see CLR book, pp. 269)
x->parent->color = GsTreeNode::Black;
y->color = GsTreeNode::Black;
x->parent->parent->color = GsTreeNode::Red;
x = x->parent->parent;
}
else
{ if ( x==x->parent->right )
{ // transform case 2 into case 3 (see CLR book, pp. 269)
x = x->parent;
_rotate_left ( x );
}
// handle case 3 (see CLR book, pp. 269)
x->parent->color = GsTreeNode::Black;
x->parent->parent->color = GsTreeNode::Red;
_rotate_right ( x->parent->parent );
}
}
else
{ y = x->parent->parent->left;
if ( RED(y) )
{ // handle case 1 (see CLR book, pp. 269)
x->parent->color = GsTreeNode::Black;
y->color = GsTreeNode::Black;
x->parent->parent->color = GsTreeNode::Red;
x = x->parent->parent;
}
else
{ if ( x==x->parent->left )
{ // transform case 2 into case 3 (see CLR book, pp. 269)
x = x->parent;
_rotate_right ( x );
}
// handle case 3 (see CLR book, pp. 269)
x->parent->color = GsTreeNode::Black;
x->parent->parent->color = GsTreeNode::Red;
_rotate_left ( x->parent->parent );
}
}
}
}
/*! Method for restoring red-black properties after deletion. */
void GsTreeBase::_fix_remove ( GsTreeNode *x )
{
GS_TRACE1("Fix Remove");
while ( x!=_root && BLACK(x) )
{
if ( x==x->parent->left )
{ GsTreeNode *w = x->parent->right;
if ( RED(w) )
{ w->color = GsTreeNode::Black;
x->parent->color = GsTreeNode::Red;
_rotate_left ( x->parent );
w = x->parent->right;
}
if ( BLACK(w->left) && BLACK(w->right) )
{ w->color = GsTreeNode::Red;
x = x->parent;
}
else
{ if ( BLACK(w->right) )
{ w->left->color = GsTreeNode::Black;
w->color = GsTreeNode::Red;
_rotate_right ( w );
w = x->parent->right;
}
w->color = x->parent->color;
x->parent->color = GsTreeNode::Black;
w->right->color = GsTreeNode::Black;
_rotate_left ( x->parent );
x = _root;
}
}
else
{ GsTreeNode *w = x->parent->left;
if ( RED(w) )
{ w->color = GsTreeNode::Black;
x->parent->color = GsTreeNode::Red;
_rotate_right ( x->parent );
w = x->parent->left;
}
if ( BLACK(w->left) && BLACK(w->right) )
{ w->color = GsTreeNode::Red;
x = x->parent;
}
else
{ if ( BLACK(w->left) )
{ w->right->color = GsTreeNode::Black;
w->color = GsTreeNode::Red;
_rotate_left ( w );
w = x->parent->left;
}
w->color = x->parent->color;
x->parent->color = GsTreeNode::Black;
w->left->color = GsTreeNode::Black;
_rotate_right ( x->parent );
x = _root;
}
}
}
x->color = GsTreeNode::Black;
}
struct tree_node* _remove_rebalance(struct tree_node *node, struct tree_node *parent, struct tree_node *root)
{
struct tree_node *other, *o_left, *o_right;
while ((!node || node->color == Black) && node != root)
{
if (parent->left_node == node)
{
other = parent->right_node;
if (other->color == Red)
{
other->color = Black;
parent->color = Red;
root = _rotate_left(parent, root);
other = parent->right_node;
}
if ((!other->left_node || other->left_node->color == Black) &&
(!other->right_node || other->right_node->color == Black))
{
other->color = Red;
node = parent;
parent = node->parent_node;
}
else
{
if (!other->right_node || other->right_node->color == Black)
{
if ((o_left = other->left_node))
{
o_left->color = Black;
}
other->color = Red;
root = _rotate_right(other, root);
other = parent->right_node;
}
other->color = parent->color;
parent->color = Black;
if (other->right_node)
{
other->right_node->color = Black;
}
root = _rotate_left(parent, root);
node = root;
break;
}
}
else
{
other = parent->left_node;
if (other->color == Red)
{
other->color = Black;
parent->color = Red;
root = _rotate_right(parent, root);
other = parent->left_node;
}
if ((!other->left_node || other->left_node->color == Black) &&
(!other->right_node || other->right_node->color == Black))
{
other->color = Red;
node = parent;
parent = node->parent_node;
}
else
{
if (!other->left_node || other->left_node->color == Black)
{
if ((o_right = other->right_node))
{
o_right->color = Black;
}
other->color = Red;
root = _rotate_left(other, root);
other = parent->left_node;
}
other->color = parent->color;
parent->color = Black;
if (other->left_node)
{
other->left_node->color = Black;
}
root = _rotate_right(parent, root);
node = root;
break;
}
}
}
if (node)
{
node->color = Black;
}
return root;
}