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Red-Black Trees
(C) 1999 Andrea Arcangeli <>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
To use rbtrees you'll have to implement your own insert and search cores.
This will avoid us to use callbacks and to drop drammatically performances.
I know it's not the cleaner way, but in C (not in C++) to get
performances and genericity...
Some example of insert and search follows here. The search is a plain
normal search over an ordered tree. The insert instead must be implemented
int two steps: as first thing the code must insert the element in
order as a leaf in the tree, then the support library function
rb_rebalance() must be called. Such function will do the
not trivial work to rebalance the rbtree if necessary.
static inline struct page *rb_search_page_cache(struct inode *inode,
unsigned long offset)
rb_node_t *n = inode->i_rb_page_cache;
struct page *page;
while (n)
page = (struct page *) n;
if (offset < page->offset)
n = n->rb_left;
else if (offset > page->offset)
n = n->rb_right;
return page;
return NULL;
static inline struct page *rb_insert_page_cache(struct inode *inode,
unsigned long offset,
rb_node_t *node)
rb_node_t **p = &inode->i_rb_page_cache;
rb_node_t *parent = NULL;
struct page *page;
while (*p)
parent = *p;
page = (struct page *) parent;
if (offset < page->offset)
p = &(*p)->rb_left;
else if (offset > page->offset)
p = &(*p)->rb_right;
return page;
node->rb_parent = parent;
node->rb_left = node->rb_right = NULL;
*p = node;
rb_rebalance(node, &inode->i_rb_page_cache);
return NULL;
#ifndef RBTREES_H
#define RBTREES_H
#define RB_RED 0
#define RB_BLACK 1
typedef struct rb_node_t
struct rb_node_t *rb_parent;
struct rb_node_t *rb_right;
struct rb_node_t *rb_left;
int rb_color;
typedef struct rb_traverse_t
struct rb_node_t *node;
extern void rb_rebalance(rb_node_t *, rb_node_t **);
extern void rb_erase(rb_node_t *, rb_node_t **);
extern void rb_destroy(rb_node_t *);
extern rb_node_t *rb_first(rb_node_t *, rb_traverse_t *);
extern rb_node_t *rb_next(rb_traverse_t *);
#endif /* RBTREES_H */