RB(3) Library Functions Manual RB(3)
NAME
rbred-black tree
SYNOPSIS
#include <sys/rb.h>
void
rb_tree_init(struct rb_tree *, const struct rb_tree_ops *);
bool
rb_tree_insert_node(struct rb_tree *, struct rb_node *);
struct rb_node *
rb_tree_find_node(struct rb_tree *, const void *);
struct rb_node *
rb_tree_find_node_geq(struct rb_tree *, const void *);
struct rb_node *
rb_tree_find_node_leq(struct rb_tree *, const void *);
struct rb_node *
rb_tree_iterate(struct rb_tree *, struct rb_node *, const unsigned int);
DESCRIPTION
rb provides red-black trees. A red-black tree is a binary search tree with the node color as an extra attribute. It fulfills a set of conditions:
1.
Every search path from the root to a leaf consists of the same number of black nodes.
2.
Each red node (except for the root) has a black parent.
3.
Each leaf node is black.
 
Every operation on a red-black tree is bounded as O(lg n). The maximum height of a red-black tree is 2lg (n+1).
TYPES
struct rb_tree
A red-black tree.
typedef signed int (*const rbto_compare_nodes_fn)(const struct rb_node *, const struct rb_node *);
The node-comparison operator. Defines an ordering on nodes. Returns a positive value if the first node precedes the second node. Returns a negative value if the first node follows the second node. Returns 0 if the first node and the second are identical according to the ordering.
typedef signed int (*const rbto_compare_key_fn)(const struct rb_node *, const void *);
The node-key comparison operator. Defines the order of nodes and keys. Returns a positive value if the node precedes the key. Returns a negative value if the node follows the key. Returns 0 if the node is identical to the key according to the ordering.
struct rb_tree_ops
Defines the operators for comparing two nodes in the same tree, and for comparing a node in the tree with a key. Members of rb_tree_ops are
rbto_compare_nodes_fn rbto_compare_nodes; rbto_compare_key_fn rbto_compare_key;
struct rb_node
A node in a red-black tree.
FUNCTIONS
rb_tree_init(rbt, ops)
Initialize the red-black tree rbt. Let the comparison operators given by ops define the order of nodes in the tree for the purposes of insertion, search, and iteration. rb_tree_init() always succeeds.
rb_tree_insert_node(rbt, rb)
Insert the node rb into the tree rbt. Return true on success, false on failure.
rb_tree_find_node(rbt, key)
Search the tree rbt for a node exactly matching key. If no such node is in the tree, return NULL. Otherwise, return the matching node.
rb_tree_find_node_geq(rbt, key)
Search the tree rbt for a node that exactly matches key and return it. If no such node is present, return the first node following key or, if no such node is in the tree, return NULL.
rb_tree_find_node_leq(rbt, key)
Search the tree rbt for a node that exactly matches key and return it. If no such node is present, return the first node preceding key or, if no such node is in the tree, return NULL.
rb_tree_iterate(rbt, rb, direction)
If direction is RB_DIR_LEFT, return the node in the tree rbt immediately preceding the node rb or, if rb is NULL, return the last node in rbt or, if the tree is empty, return NULL.
 
If direction is RB_DIR_RIGHT, return the node in the tree rbt immediately following the node rb or, if rb is NULL, return the first node in rbt or, if the tree is empty, return NULL.
CODE REFERENCES
This section describes places within the NetBSD source tree where actual code implementing rb can be found. All pathnames are relative to /usr/src.
 
rb is implemented within the file common/lib/libc/gen/rb.c.
SEE ALSO
HISTORY
The rb interface first appeared in NetBSD 6.0.
AUTHORS
Matt Thomas <matt@NetBSD.org> wrote rb.
 
Niels Provos <provos@citi.umich.edu> wrote the tree(3) manual page. Portions of this page derive from that page.