- * Finds a element for which cmp(key, elem)==0, if no such element is found key
- * is inserted into the tree.
- * @param rootp a pointer to a pointer to the root node of the tree note the
- * root node can change during insertions, this is required to
- * keep the tree balanced
+ * Inserts or removes an element.
+ * If *next is NULL, then the supplied element will be removed if it exists.
+ * If *next is not NULL, then the supplied element will be inserted, unless
+ * it already exists in the tree.
+ * @param rootp A pointer to a pointer to the root node of the tree; note that
+ * the root node can change during insertions, this is required
+ * to keep the tree balanced.
+ * @param next Used to allocate and free AVTreeNodes. For insertion the user
+ * must set it to an allocated and zeroed object of at least
+ * av_tree_node_size bytes size. av_tree_insert() will set it to
+ * NULL if it has been consumed.
+ * For deleting elements *next is set to NULL by the user and
+ * av_tree_node_size() will set it to the AVTreeNode which was
+ * used for the removed element.
+ * This allows the use of flat arrays, which have
+ * lower overhead compared to many malloced elements.
+ * You might want to define a function like:
+ * void *tree_insert(struct AVTreeNode **rootp, void *key, int (*cmp)(void *key, const void *b), AVTreeNode **next){
+ * if(!*next) *next= av_mallocz(av_tree_node_size);
+ * return av_tree_insert(rootp, key, cmp, next);
+ * }
+ * void *tree_remove(struct AVTreeNode **rootp, void *key, int (*cmp)(void *key, const void *b, AVTreeNode **next)){
+ * if(*next) av_freep(next);
+ * return av_tree_insert(rootp, key, cmp, next);
+ * }