/* TreeTraverseAndDelete -- traverse a tree while deleting nodes
*
* The visitor function must return TRUE to delete the current node,
* or FALSE to keep it.
*
* See <design/arena/#chunk.delete.tricky>.
*/
void TreeTraverseAndDelete(Tree *treeIO, TreeVisitor visitor,
void *closureP, Size closureS)
{
Tree *treeref = treeIO;
AVER(treeIO != NULL);
AVERT(Tree, *treeIO);
AVER(FUNCHECK(visitor));
/* closureP and closureS are arbitrary */
TreeToVine(treeIO);
while (*treeref != TreeEMPTY) {
Tree tree = *treeref; /* Current node. */
Tree *nextref = &tree->right; /* Location of pointer to next node. */
Tree next = *nextref; /* Next node. */
if ((*visitor)(tree, closureP, closureS)) {
/* Delete current node. */
*treeref = next;
} else {
/* Keep current node. */
treeref = nextref;
}
}
TreeBalance(treeIO);
}
void TreeBalance(Tree *treeIO)
{
Count depth;
AVER(treeIO != NULL);
AVERT(Tree, *treeIO);
depth = TreeToVine(treeIO);
if (depth > 2) {
Count n = depth - 1;
do {
Count m = n / 2, i;
Tree *link = treeIO;
for (i = 0; i < m; ++i) {
TreeRotateLeft(link);
link = &((*link)->right);
}
n = n - m - 1;
} while (n > 1);
}
}
