PeerStreamer

/*

 * 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.

 * @author Michael Niedermayer <michaelni@gmx.at>

 */

#ifndef FFMPEG_TREE_H

#define FFMPEG_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 /* FFMPEG_TREE_H */