4 * The contents of this file are subject to the terms of the
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6 * (the "License"). You may not use this file except in compliance
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11 * See the License for the specific language governing permissions
12 * and limitations under the License.
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16 * If applicable, add the following below this CDDL HEADER, with the
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23 * Copyright 2005 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
30 #pragma ident "%Z%%M% %I% %E% SMI"
33 * This is a private header file. Applications should not directly include
41 #include <sys/avl_impl.h>
44 * This is a generic implemenatation of AVL trees for use in the Solaris kernel.
45 * The interfaces provide an efficient way of implementing an ordered set of
48 * AVL trees provide an alternative to using an ordered linked list. Using AVL
49 * trees will usually be faster, however they requires more storage. An ordered
50 * linked list in general requires 2 pointers in each data structure. The
51 * AVL tree implementation uses 3 pointers. The following chart gives the
52 * approximate performance of operations with the different approaches:
54 * Operation Link List AVL tree
55 * --------- -------- --------
56 * lookup O(n) O(log(n))
58 * insert 1 node constant constant
60 * delete 1 node constant between constant and O(log(n))
62 * delete all nodes O(n) O(n)
65 * or prev node constant between constant and O(log(n))
68 * The data structure nodes are anchored at an "avl_tree_t" (the equivalent
69 * of a list header) and the individual nodes will have a field of
70 * type "avl_node_t" (corresponding to list pointers).
72 * The type "avl_index_t" is used to indicate a position in the list for
75 * The usage scenario is generally:
77 * 1. Create the list/tree with: avl_create()
79 * followed by any mixture of:
81 * 2a. Insert nodes with: avl_add(), or avl_find() and avl_insert()
83 * 2b. Visited elements with:
84 * avl_first() - returns the lowest valued node
85 * avl_last() - returns the highest valued node
86 * AVL_NEXT() - given a node go to next higher one
87 * AVL_PREV() - given a node go to previous lower one
89 * 2c. Find the node with the closest value either less than or greater
90 * than a given value with avl_nearest().
92 * 2d. Remove individual nodes from the list/tree with avl_remove().
94 * and finally when the list is being destroyed
96 * 3. Use avl_destroy_nodes() to quickly process/free up any remaining nodes.
97 * Note that once you use avl_destroy_nodes(), you can no longer
98 * use any routine except avl_destroy_nodes() and avl_destoy().
100 * 4. Use avl_destroy() to destroy the AVL tree itself.
102 * Any locking for multiple thread access is up to the user to provide, just
103 * as is needed for any linked list implementation.
108 * Type used for the root of the AVL tree.
110 typedef struct avl_tree avl_tree_t;
113 * The data nodes in the AVL tree must have a field of this type.
115 typedef struct avl_node avl_node_t;
118 * An opaque type used to locate a position in the tree where a node
121 typedef uintptr_t avl_index_t;
125 * Direction constants used for avl_nearest().
127 #define AVL_BEFORE (0)
128 #define AVL_AFTER (1)
135 * Where not otherwise mentioned, "void *" arguments are a pointer to the
136 * user data structure which must contain a field of type avl_node_t.
138 * Also assume the user data structures looks like:
141 * avl_node_t my_link;
147 * Initialize an AVL tree. Arguments are:
149 * tree - the tree to be initialized
150 * compar - function to compare two nodes, it must return exactly: -1, 0, or +1
151 * -1 for <, 0 for ==, and +1 for >
152 * size - the value of sizeof(struct my_type)
153 * offset - the value of OFFSETOF(struct my_type, my_link)
155 extern void avl_create(avl_tree_t *tree,
156 int (*compar) (const void *, const void *), size_t size, size_t offset);
160 * Find a node with a matching value in the tree. Returns the matching node
161 * found. If not found, it returns NULL and then if "where" is not NULL it sets
162 * "where" for use with avl_insert() or avl_nearest().
164 * node - node that has the value being looked for
165 * where - position for use with avl_nearest() or avl_insert(), may be NULL
167 extern void *avl_find(avl_tree_t *tree, void *node, avl_index_t *where);
170 * Insert a node into the tree.
172 * node - the node to insert
173 * where - position as returned from avl_find()
175 extern void avl_insert(avl_tree_t *tree, void *node, avl_index_t where);
178 * Insert "new_data" in "tree" in the given "direction" either after
179 * or before the data "here".
181 * This might be usefull for avl clients caching recently accessed
182 * data to avoid doing avl_find() again for insertion.
184 * new_data - new data to insert
185 * here - existing node in "tree"
186 * direction - either AVL_AFTER or AVL_BEFORE the data "here".
188 extern void avl_insert_here(avl_tree_t *tree, void *new_data, void *here,
193 * Return the first or last valued node in the tree. Will return NULL
194 * if the tree is empty.
197 extern void *avl_first(avl_tree_t *tree);
198 extern void *avl_last(avl_tree_t *tree);
202 * Return the next or previous valued node in the tree.
203 * AVL_NEXT() will return NULL if at the last node.
204 * AVL_PREV() will return NULL if at the first node.
206 * node - the node from which the next or previous node is found
208 #define AVL_NEXT(tree, node) avl_walk(tree, node, AVL_AFTER)
209 #define AVL_PREV(tree, node) avl_walk(tree, node, AVL_BEFORE)
213 * Find the node with the nearest value either greater or less than
214 * the value from a previous avl_find(). Returns the node or NULL if
215 * there isn't a matching one.
217 * where - position as returned from avl_find()
218 * direction - either AVL_BEFORE or AVL_AFTER
220 * EXAMPLE get the greatest node that is less than a given value:
223 * struct my_data look_for_value = {....};
224 * struct my_data *node;
225 * struct my_data *less;
228 * node = avl_find(tree, &look_for_value, &where);
230 * less = AVL_PREV(tree, node);
232 * less = avl_nearest(tree, where, AVL_BEFORE);
234 extern void *avl_nearest(avl_tree_t *tree, avl_index_t where, int direction);
238 * Add a single node to the tree.
239 * The node must not be in the tree, and it must not
240 * compare equal to any other node already in the tree.
242 * node - the node to add
244 extern void avl_add(avl_tree_t *tree, void *node);
248 * Remove a single node from the tree. The node must be in the tree.
250 * node - the node to remove
252 extern void avl_remove(avl_tree_t *tree, void *node);
256 * Return the number of nodes in the tree
258 extern ulong_t avl_numnodes(avl_tree_t *tree);
262 * Used to destroy any remaining nodes in a tree. The cookie argument should
263 * be initialized to NULL before the first call. Returns a node that has been
264 * removed from the tree and may be free()'d. Returns NULL when the tree is
267 * Once you call avl_destroy_nodes(), you can only continuing calling it and
268 * finally avl_destroy(). No other AVL routines will be valid.
270 * cookie - a "void *" used to save state between calls to avl_destroy_nodes()
274 * struct my_data *node;
278 * while ((node = avl_destroy_nodes(tree, &cookie)) != NULL)
282 extern void *avl_destroy_nodes(avl_tree_t *tree, void **cookie);
286 * Final destroy of an AVL tree. Arguments are:
288 * tree - the empty tree to destroy
290 extern void avl_destroy(avl_tree_t *tree);