2 * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
4 * This file is part of Libav.
6 * Libav 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.
11 * Libav 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.
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with Libav; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 * @author Michael Niedermayer <michaelni@gmx.at>
31 * @addtogroup lavu_tree AVTree
34 * Low complexity tree container
36 * Insertion, removal, finding equal, largest which is smaller than and
37 * smallest which is larger than, all have O(log n) worst case complexity.
43 extern const int av_tree_node_size;
47 * @param root a pointer to the root node of the tree
48 * @param next If next is not NULL, then next[0] will contain the previous
49 * element and next[1] the next element. If either does not exist,
50 * then the corresponding entry in next is unchanged.
51 * @return An element with cmp(key, elem)==0 or NULL if no such element exists in
54 void *av_tree_find(const struct AVTreeNode *root, void *key, int (*cmp)(void *key, const void *b), void *next[2]);
57 * Insert or remove an element.
58 * If *next is NULL, then the supplied element will be removed if it exists.
59 * If *next is not NULL, then the supplied element will be inserted, unless
60 * it already exists in the tree.
61 * @param rootp A pointer to a pointer to the root node of the tree; note that
62 * the root node can change during insertions, this is required
63 * to keep the tree balanced.
64 * @param next Used to allocate and free AVTreeNodes. For insertion the user
65 * must set it to an allocated and zeroed object of at least
66 * av_tree_node_size bytes size. av_tree_insert() will set it to
67 * NULL if it has been consumed.
68 * For deleting elements *next is set to NULL by the user and
69 * av_tree_node_size() will set it to the AVTreeNode which was
70 * used for the removed element.
71 * This allows the use of flat arrays, which have
72 * lower overhead compared to many malloced elements.
73 * You might want to define a function like:
75 * void *tree_insert(struct AVTreeNode **rootp, void *key, int (*cmp)(void *key, const void *b), AVTreeNode **next){
76 * if(!*next) *next= av_mallocz(av_tree_node_size);
77 * return av_tree_insert(rootp, key, cmp, next);
79 * void *tree_remove(struct AVTreeNode **rootp, void *key, int (*cmp)(void *key, const void *b, AVTreeNode **next)){
81 * return av_tree_insert(rootp, key, cmp, next);
84 * @return If no insertion happened, the found element; if an insertion or
85 * removal happened, then either key or NULL will be returned.
86 * Which one it is depends on the tree state and the implementation. You
87 * should make no assumptions that it's one or the other in the code.
89 void *av_tree_insert(struct AVTreeNode **rootp, void *key, int (*cmp)(void *key, const void *b), struct AVTreeNode **next);
90 void av_tree_destroy(struct AVTreeNode *t);
93 * Apply enu(opaque, &elem) to all the elements in the tree in a given range.
95 * @param cmp a comparison function that returns < 0 for a element below the
96 * range, > 0 for a element above the range and == 0 for a
97 * element inside the range
99 * @note The cmp function should use the same ordering used to construct the
102 void av_tree_enumerate(struct AVTreeNode *t, void *opaque, int (*cmp)(void *opaque, void *elem), int (*enu)(void *opaque, void *elem));
108 #endif /* AVUTIL_TREE_H */