enum COLOR {
	RED,
	BLACK
};

/**
 * The Red-Black node struct definition
 */
typedef struct rb_node_t rb_node_t;
struct rb_node_t {
	/* parent - RB_NODE_NULL for root */
	rb_node_t   *parent;
	/* left child - smaller key */
	rb_node_t   *left;
	/* right child - bigger key */
	rb_node_t   *right;

	/* the sorting is based on key */
	void		*key;
	/* data contained by the node */
	void		*data;

	/* color of the node */
	enum COLOR	color;
};

/**
 * The Red-Black tree struct definition
 */
typedef struct rb_tree_t rb_tree_t;
struct rb_tree_t {
	/* root of the tree */
	rb_node_t	*root;

	/* key size */
	size_t 		key_size;

    /* data size */
    size_t 		data_size;

	/* function used for sorting the keys */
	int	(*cmp)(const void *key1, const void *key2);
};