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312 lines
8.8 KiB
C
312 lines
8.8 KiB
C
/*
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* CDDL HEADER START
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*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License (the "License").
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* You may not use this file except in compliance with the License.
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*
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* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
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* or http://www.opensolaris.org/os/licensing.
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* See the License for the specific language governing permissions
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* and limitations under the License.
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*
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
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* If applicable, add the following below this CDDL HEADER, with the
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* fields enclosed by brackets "[]" replaced with your own identifying
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* information: Portions Copyright [yyyy] [name of copyright owner]
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*
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* CDDL HEADER END
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*/
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/*
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* Copyright 2008 Sun Microsystems, Inc. All rights reserved.
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* Use is subject to license terms.
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*/
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#ifndef _AVL_H
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#define _AVL_H
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#pragma ident "%Z%%M% %I% %E% SMI"
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/*
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* This is a private header file. Applications should not directly include
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* this file.
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*/
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include <sys/types.h>
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#include <sys/avl_impl.h>
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/*
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* This is a generic implemenatation of AVL trees for use in the Solaris kernel.
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* The interfaces provide an efficient way of implementing an ordered set of
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* data structures.
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*
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* AVL trees provide an alternative to using an ordered linked list. Using AVL
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* trees will usually be faster, however they requires more storage. An ordered
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* linked list in general requires 2 pointers in each data structure. The
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* AVL tree implementation uses 3 pointers. The following chart gives the
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* approximate performance of operations with the different approaches:
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*
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* Operation Link List AVL tree
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* --------- -------- --------
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* lookup O(n) O(log(n))
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*
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* insert 1 node constant constant
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*
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* delete 1 node constant between constant and O(log(n))
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*
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* delete all nodes O(n) O(n)
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*
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* visit the next
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* or prev node constant between constant and O(log(n))
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*
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*
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* The data structure nodes are anchored at an "avl_tree_t" (the equivalent
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* of a list header) and the individual nodes will have a field of
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* type "avl_node_t" (corresponding to list pointers).
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*
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* The type "avl_index_t" is used to indicate a position in the list for
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* certain calls.
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*
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* The usage scenario is generally:
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*
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* 1. Create the list/tree with: avl_create()
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*
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* followed by any mixture of:
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*
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* 2a. Insert nodes with: avl_add(), or avl_find() and avl_insert()
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*
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* 2b. Visited elements with:
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* avl_first() - returns the lowest valued node
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* avl_last() - returns the highest valued node
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* AVL_NEXT() - given a node go to next higher one
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* AVL_PREV() - given a node go to previous lower one
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*
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* 2c. Find the node with the closest value either less than or greater
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* than a given value with avl_nearest().
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*
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* 2d. Remove individual nodes from the list/tree with avl_remove().
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*
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* and finally when the list is being destroyed
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*
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* 3. Use avl_destroy_nodes() to quickly process/free up any remaining nodes.
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* Note that once you use avl_destroy_nodes(), you can no longer
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* use any routine except avl_destroy_nodes() and avl_destoy().
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*
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* 4. Use avl_destroy() to destroy the AVL tree itself.
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*
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* Any locking for multiple thread access is up to the user to provide, just
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* as is needed for any linked list implementation.
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*/
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/*
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* Type used for the root of the AVL tree.
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*/
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typedef struct avl_tree avl_tree_t;
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/*
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* The data nodes in the AVL tree must have a field of this type.
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*/
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typedef struct avl_node avl_node_t;
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/*
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* An opaque type used to locate a position in the tree where a node
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* would be inserted.
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*/
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typedef uintptr_t avl_index_t;
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/*
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* Direction constants used for avl_nearest().
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*/
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#define AVL_BEFORE (0)
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#define AVL_AFTER (1)
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/*
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* Prototypes
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*
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* Where not otherwise mentioned, "void *" arguments are a pointer to the
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* user data structure which must contain a field of type avl_node_t.
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*
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* Also assume the user data structures looks like:
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* stuct my_type {
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* ...
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* avl_node_t my_link;
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* ...
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* };
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*/
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/*
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* Initialize an AVL tree. Arguments are:
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*
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* tree - the tree to be initialized
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* compar - function to compare two nodes, it must return exactly: -1, 0, or +1
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* -1 for <, 0 for ==, and +1 for >
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* size - the value of sizeof(struct my_type)
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* offset - the value of OFFSETOF(struct my_type, my_link)
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*/
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extern void avl_create(avl_tree_t *tree,
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int (*compar) (const void *, const void *), size_t size, size_t offset);
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/*
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* Find a node with a matching value in the tree. Returns the matching node
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* found. If not found, it returns NULL and then if "where" is not NULL it sets
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* "where" for use with avl_insert() or avl_nearest().
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*
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* node - node that has the value being looked for
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* where - position for use with avl_nearest() or avl_insert(), may be NULL
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*/
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extern void *avl_find(avl_tree_t *tree, void *node, avl_index_t *where);
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/*
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* Insert a node into the tree.
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*
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* node - the node to insert
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* where - position as returned from avl_find()
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*/
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extern void avl_insert(avl_tree_t *tree, void *node, avl_index_t where);
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/*
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* Insert "new_data" in "tree" in the given "direction" either after
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* or before the data "here".
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*
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* This might be usefull for avl clients caching recently accessed
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* data to avoid doing avl_find() again for insertion.
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*
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* new_data - new data to insert
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* here - existing node in "tree"
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* direction - either AVL_AFTER or AVL_BEFORE the data "here".
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*/
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extern void avl_insert_here(avl_tree_t *tree, void *new_data, void *here,
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int direction);
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/*
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* Return the first or last valued node in the tree. Will return NULL
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* if the tree is empty.
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*
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*/
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extern void *avl_first(avl_tree_t *tree);
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extern void *avl_last(avl_tree_t *tree);
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/*
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* Return the next or previous valued node in the tree.
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* AVL_NEXT() will return NULL if at the last node.
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* AVL_PREV() will return NULL if at the first node.
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*
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* node - the node from which the next or previous node is found
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*/
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#define AVL_NEXT(tree, node) avl_walk(tree, node, AVL_AFTER)
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#define AVL_PREV(tree, node) avl_walk(tree, node, AVL_BEFORE)
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/*
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* Find the node with the nearest value either greater or less than
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* the value from a previous avl_find(). Returns the node or NULL if
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* there isn't a matching one.
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*
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* where - position as returned from avl_find()
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* direction - either AVL_BEFORE or AVL_AFTER
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*
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* EXAMPLE get the greatest node that is less than a given value:
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*
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* avl_tree_t *tree;
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* struct my_data look_for_value = {....};
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* struct my_data *node;
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* struct my_data *less;
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* avl_index_t where;
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*
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* node = avl_find(tree, &look_for_value, &where);
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* if (node != NULL)
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* less = AVL_PREV(tree, node);
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* else
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* less = avl_nearest(tree, where, AVL_BEFORE);
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*/
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extern void *avl_nearest(avl_tree_t *tree, avl_index_t where, int direction);
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/*
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* Add a single node to the tree.
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* The node must not be in the tree, and it must not
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* compare equal to any other node already in the tree.
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*
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* node - the node to add
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*/
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extern void avl_add(avl_tree_t *tree, void *node);
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/*
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* Remove a single node from the tree. The node must be in the tree.
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*
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* node - the node to remove
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*/
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extern void avl_remove(avl_tree_t *tree, void *node);
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/*
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* Reinsert a node only if its order has changed relative to its nearest
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* neighbors. To optimize performance avl_update_lt() checks only the previous
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* node and avl_update_gt() checks only the next node. Use avl_update_lt() and
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* avl_update_gt() only if you know the direction in which the order of the
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* node may change.
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*/
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extern boolean_t avl_update(avl_tree_t *, void *);
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extern boolean_t avl_update_lt(avl_tree_t *, void *);
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extern boolean_t avl_update_gt(avl_tree_t *, void *);
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/*
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* Return the number of nodes in the tree
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*/
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extern ulong_t avl_numnodes(avl_tree_t *tree);
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/*
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* Return B_TRUE if there are zero nodes in the tree, B_FALSE otherwise.
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*/
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extern boolean_t avl_is_empty(avl_tree_t *tree);
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/*
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* Used to destroy any remaining nodes in a tree. The cookie argument should
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* be initialized to NULL before the first call. Returns a node that has been
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* removed from the tree and may be free()'d. Returns NULL when the tree is
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* empty.
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*
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* Once you call avl_destroy_nodes(), you can only continuing calling it and
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* finally avl_destroy(). No other AVL routines will be valid.
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*
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* cookie - a "void *" used to save state between calls to avl_destroy_nodes()
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*
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* EXAMPLE:
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* avl_tree_t *tree;
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* struct my_data *node;
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* void *cookie;
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*
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* cookie = NULL;
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* while ((node = avl_destroy_nodes(tree, &cookie)) != NULL)
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* free(node);
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* avl_destroy(tree);
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*/
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extern void *avl_destroy_nodes(avl_tree_t *tree, void **cookie);
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/*
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* Final destroy of an AVL tree. Arguments are:
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*
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* tree - the empty tree to destroy
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*/
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extern void avl_destroy(avl_tree_t *tree);
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#ifdef __cplusplus
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}
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#endif
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#endif /* _AVL_H */
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