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Diffstat (limited to 'contrib/ffmpeg/libavutil/tree.h')
| -rw-r--r-- | contrib/ffmpeg/libavutil/tree.h | 82 |
1 files changed, 82 insertions, 0 deletions
diff --git a/contrib/ffmpeg/libavutil/tree.h b/contrib/ffmpeg/libavutil/tree.h new file mode 100644 index 000000000..111ea81a0 --- /dev/null +++ b/contrib/ffmpeg/libavutil/tree.h @@ -0,0 +1,82 @@ +/* + * 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 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 */ |