Globally rename the header inclusion guard names.
[libav.git] / libavutil / tree.h
1 /*
2 * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
3 *
4 * This file is part of FFmpeg.
5 *
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21 /**
22 * @file tree.h
23 * A tree container.
24 * Insertion, Removial, Finding equal, largest which is smaller than and
25 * smallest which is larger than all have O(log n) worst case time.
26 * @author Michael Niedermayer <michaelni@gmx.at>
27 */
28
29 #ifndef AVUTIL_TREE_H
30 #define AVUTIL_TREE_H
31
32 struct AVTreeNode;
33 extern const int av_tree_node_size;
34
35 /**
36 * Finds an element.
37 * @param root a pointer to the root node of the tree
38 * @param next If next is not NULL then next[0] will contain the previous
39 * element and next[1] the next element if either does not exist
40 * then the corresponding entry in next is unchanged.
41 * @return An element with cmp(key, elem)==0 or NULL if no such element exists in
42 * the tree.
43 */
44 void *av_tree_find(const struct AVTreeNode *root, void *key, int (*cmp)(void *key, const void *b), void *next[2]);
45
46 /**
47 * Inserts or removes an element.
48 * If *next is NULL then the element supplied will be removed, if no such
49 * element exists behavior is undefined.
50 * If *next is not NULL then the element supplied will be inserted, unless
51 * it already exists in the tree.
52 * @param rootp A pointer to a pointer to the root node of the tree. Note that
53 * the root node can change during insertions, this is required
54 * to keep the tree balanced.
55 * @param next Used to allocate and free AVTreeNodes. For insertion the user
56 * must set it to an allocated and zeroed object of at least
57 * av_tree_node_size bytes size. av_tree_insert() will set it to
58 * NULL if it has been consumed.
59 * For deleting elements *next is set to NULL by the user and
60 * av_tree_node_size() will set it to the AVTreeNode which was
61 * used for the removed element.
62 * This allows the use of flat arrays, which have
63 * lower overhead compared to many malloced elements.
64 * You might want to define a function like:
65 * void *tree_insert(struct AVTreeNode **rootp, void *key, int (*cmp)(void *key, const void *b), AVTreeNode **next){
66 * if(!*next) *next= av_mallocz(av_tree_node_size);
67 * return av_tree_insert(rootp, key, cmp, next);
68 * }
69 * void *tree_remove(struct AVTreeNode **rootp, void *key, int (*cmp)(void *key, const void *b, AVTreeNode **next)){
70 * if(*next) av_freep(next);
71 * return av_tree_insert(rootp, key, cmp, next);
72 * }
73 *
74 * @return If no insertion happened, the found element.
75 * If an insertion or removial happened, then either key or NULL will be returned.
76 * Which one it is depends on the tree state and the implementation. You
77 * should make no assumptions that it's one or the other in the code.
78 */
79 void *av_tree_insert(struct AVTreeNode **rootp, void *key, int (*cmp)(void *key, const void *b), struct AVTreeNode **next);
80 void av_tree_destroy(struct AVTreeNode *t);
81
82 #endif /* AVUTIL_TREE_H */