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