1/*
2 * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
3 *
4 * This file is part of Libav.
5 *
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.
10 *
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.
15 *
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
19 */
20
21/**
22 * @file
23 * A tree container.
24 * @author Michael Niedermayer <michaelni@gmx.at>
25 */
26
27#ifndef AVUTIL_TREE_H
28#define AVUTIL_TREE_H
29
30/**
31 * @addtogroup lavu_tree AVTree
32 * @ingroup lavu_data
33 *
34 * Low complexity tree container
35 *
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.
38 * @{
39 */
40
41
42struct AVTreeNode;
43extern const int av_tree_node_size;
44
45/**
46 * Find an element.
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
52 *         the tree.
53 */
54void *av_tree_find(const struct AVTreeNode *root, void *key, int (*cmp)(void *key, const void *b), void *next[2]);
55
56/**
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:
74 *             @code
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);
78 *             }
79 *             void *tree_remove(struct AVTreeNode **rootp, void *key, int (*cmp)(void *key, const void *b, AVTreeNode **next)){
80 *                 av_freep(next);
81 *                 return av_tree_insert(rootp, key, cmp, next);
82 *             }
83 *             @endcode
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.
88 */
89void *av_tree_insert(struct AVTreeNode **rootp, void *key, int (*cmp)(void *key, const void *b), struct AVTreeNode **next);
90void av_tree_destroy(struct AVTreeNode *t);
91
92/**
93 * Apply enu(opaque, &elem) to all the elements in the tree in a given range.
94 *
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
98 *
99 * @note The cmp function should use the same ordering used to construct the
100 *       tree.
101 */
102void av_tree_enumerate(struct AVTreeNode *t, void *opaque, int (*cmp)(void *opaque, void *elem), int (*enu)(void *opaque, void *elem));
103
104/**
105 * @}
106 */
107
108#endif /* AVUTIL_TREE_H */
109