/* Initializes |trav| for |tree|
and selects and returns a pointer to its least-valued item.
Returns |NULL| if |tree| contains no nodes. */
void *
bst_t_first (struct bst_traverser *trav, struct bst_table *tree)
{
struct bst_node *x;
assert (tree != NULL && trav != NULL);
trav->bst_table = tree;
trav->bst_height = 0;
trav->bst_generation = tree->bst_generation;
x = tree->bst_root;
if (x != NULL)
while (x->bst_link[0] != NULL)
{
if (trav->bst_height >= BST_MAX_HEIGHT)
{
bst_balance (tree);
return bst_t_first (trav, tree);
}
trav->bst_stack[trav->bst_height++] = x;
x = x->bst_link[0];
}
trav->bst_node = x;
return x != NULL ? x->bst_data : NULL;
}
/* Returns the next data item in inorder
within the tree being traversed with |trav|,
or if there are no more data items returns |NULL|. */
void *
bst_t_next (struct bst_traverser *trav)
{
struct bst_node *x;
assert (trav != NULL);
if (trav->bst_generation != trav->bst_table->bst_generation)
trav_refresh (trav);
x = trav->bst_node;
if (x == NULL)
{
return bst_t_first (trav, trav->bst_table);
}
else if (x->bst_link[1] != NULL)
{
if (trav->bst_height >= BST_MAX_HEIGHT)
{
bst_balance (trav->bst_table);
return bst_t_next (trav);
}
trav->bst_stack[trav->bst_height++] = x;
x = x->bst_link[1];
while (x->bst_link[0] != NULL)
{
if (trav->bst_height >= BST_MAX_HEIGHT)
{
bst_balance (trav->bst_table);
return bst_t_next (trav);
}
trav->bst_stack[trav->bst_height++] = x;
x = x->bst_link[0];
}
}
else
{
struct bst_node *y;
do
{
if (trav->bst_height == 0)
{
trav->bst_node = NULL;
return NULL;
}
y = x;
x = trav->bst_stack[--trav->bst_height];
}
while (y == x->bst_link[1]);
}
trav->bst_node = x;
return x->bst_data;
}
const struct ccl_pair_t *ccl_iterate (struct ccl_t *data)
{
struct ccl_pair_t *pair;
if (data == 0)
return 0;
if (data->iterating)
{
pair = bst_t_next (&data->traverser);
}
else
{
data->iterating = 1;
pair = bst_t_first (&data->traverser, data->table);
}
return pair;
}
