/** @brief Validate and fix-up tree properties for a new insert/colored node
*
* This routine checks and fixes the Red-Black Tree properties based on
* @a the_node being just added to the tree.
*
* @note It does NOT disable interrupts to ensure the atomicity of the
* append operation.
*/
static void _RBTree_Validate_insert( RBTree_Node *the_node )
{
RBTree_Node *parent = _RBTree_Parent( the_node );
RBTree_Color parentcolor;
RBTree_Node *grandparent = _RBTree_Parent_and_color( parent, &parentcolor );
/* note: the insert root case is handled already */
/* if the parent is black, nothing needs to be done
* otherwise may need to loop a few times */
while ( parentcolor == RBT_RED ) {
/* The root is black, so the grandparent must exist */
RBTree_Node *uncle = _RBTree_Sibling( parent, grandparent );
RBTree_Node *grandgrandparent = _RBTree_Parent( grandparent );
/*
* If uncle exists and is red, repaint uncle/parent black and grandparent
* red.
*/
if ( uncle != NULL && _RBTree_Color( uncle ) == RBT_RED ) {
_RBTree_Set_parent_and_color( parent, grandparent, RBT_BLACK );
_RBTree_Set_parent_and_color( uncle, grandparent, RBT_BLACK );
_RBTree_Set_parent_and_color( grandparent, grandgrandparent, RBT_RED );
the_node = grandparent;
parent = grandgrandparent;
grandparent = _RBTree_Parent_and_color( parent, &parentcolor );
if ( grandparent == NULL )
break;
} else { /* If uncle does not exist or is black */
RBTree_Direction dir = _RBTree_Direction( the_node, parent );
RBTree_Direction parentdir = _RBTree_Direction( parent, grandparent );
/* ensure node is on the same branch direction as parent */
if ( dir != parentdir ) {
RBTree_Node *oldparent = parent;
parent = the_node;
the_node = oldparent;
_RBTree_Rotate( oldparent, parentdir );
}
_RBTree_Set_color( parent, RBT_BLACK );
_RBTree_Set_parent_and_color( grandparent, grandgrandparent, RBT_RED );
/* now rotate grandparent in the other branch direction (toward uncle) */
_RBTree_Rotate( grandparent, _RBTree_Opposite_direction( parentdir ) );
grandparent = _RBTree_Parent( parent );
break;
}
}
if ( grandparent == NULL )
_RBTree_Set_parent_and_color( the_node, parent, RBT_BLACK );
}
/** @brief Validate and fix-up tree properties for a new insert/colored node
*
* This routine checks and fixes the Red-Black Tree properties based on
* @a the_node being just added to the tree.
*
* @note It does NOT disable interrupts to ensure the atomicity of the
* append operation.
*/
void _RBTree_Validate_insert_unprotected(
RBTree_Node *the_node
)
{
RBTree_Node *u,*g;
/* note: the insert root case is handled already */
/* if the parent is black, nothing needs to be done
* otherwise may need to loop a few times */
while (_RBTree_Is_red(_RBTree_Parent(the_node))) {
u = _RBTree_Parent_sibling(the_node);
g = the_node->parent->parent;
/* if uncle is red, repaint uncle/parent black and grandparent red */
if(_RBTree_Is_red(u)) {
the_node->parent->color = RBT_BLACK;
u->color = RBT_BLACK;
g->color = RBT_RED;
the_node = g;
} else { /* if uncle is black */
RBTree_Direction dir = the_node != the_node->parent->child[0];
RBTree_Direction pdir = the_node->parent != g->child[0];
/* ensure node is on the same branch direction as parent */
if (dir != pdir) {
_RBTree_Rotate(the_node->parent, pdir);
the_node = the_node->child[pdir];
}
the_node->parent->color = RBT_BLACK;
g->color = RBT_RED;
/* now rotate grandparent in the other branch direction (toward uncle) */
_RBTree_Rotate(g, (1-pdir));
}
}
if(!the_node->parent->parent) the_node->color = RBT_BLACK;
}
