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/*
* copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file tree.h
* A tree container.
* Insertion, Removial, Finding equal, largest which is smaller than and
* smallest which is larger than all have O(log n) worst case time.
* @author Michael Niedermayer <michaelni@gmx.at>
*/
#ifndef AVUTIL_TREE_H
#define AVUTIL_TREE_H
struct AVTreeNode;
extern const int av_tree_node_size;
/**
* Finds an element.
* @param root a pointer to the root node of the tree
* @param next If next is not NULL then next[0] will contain the previous
* element and next[1] the next element if either does not exist
* then the corresponding entry in next is unchanged.
* @return An element with cmp(key, elem)==0 or NULL if no such element exists in
* the tree.
*/
void *av_tree_find(const struct AVTreeNode *root, void *key, int (*cmp)(void *key, const void *b), void *next[2]);
/**
* Inserts or removes an element.
* If *next is NULL then the element supplied will be removed, if no such
* element exists behavior is undefined.
* If *next is not NULL then the element supplied will be inserted, unless
* it already exists in the tree.
* @param rootp A pointer to a pointer to the root node of the tree. Note that
* the root node can change during insertions, this is required
* to keep the tree balanced.
* @param next Used to allocate and free AVTreeNodes. For insertion the user
* must set it to an allocated and zeroed object of at least
* av_tree_node_size bytes size. av_tree_insert() will set it to
* NULL if it has been consumed.
* For deleting elements *next is set to NULL by the user and
* av_tree_node_size() will set it to the AVTreeNode which was
* used for the removed element.
* This allows the use of flat arrays, which have
* lower overhead compared to many malloced elements.
* You might want to define a function like:
* void *tree_insert(struct AVTreeNode **rootp, void *key, int (*cmp)(void *key, const void *b), AVTreeNode **next){
* if(!*next) *next= av_mallocz(av_tree_node_size);
* return av_tree_insert(rootp, key, cmp, next);
* }
* void *tree_remove(struct AVTreeNode **rootp, void *key, int (*cmp)(void *key, const void *b, AVTreeNode **next)){
* if(*next) av_freep(next);
* return av_tree_insert(rootp, key, cmp, next);
* }
*
* @return If no insertion happened, the found element.
* If an insertion or removial happened, then either key or NULL will be returned.
* Which one it is depends on the tree state and the implementation. You
* should make no assumptions that it's one or the other in the code.
*/
void *av_tree_insert(struct AVTreeNode **rootp, void *key, int (*cmp)(void *key, const void *b), struct AVTreeNode **next);
void av_tree_destroy(struct AVTreeNode *t);
#endif /* AVUTIL_TREE_H */
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