Imported Debian version 2.5.0~trusty1.1
[deb_ffmpeg.git] / ffmpeg / 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
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 #include "attributes.h"
31 #include "version.h"
32
33 /**
34 * @addtogroup lavu_tree AVTree
35 * @ingroup lavu_data
36 *
37 * Low-complexity tree container
38 *
39 * Insertion, removal, finding equal, largest which is smaller than and
40 * smallest which is larger than, all have O(log n) worst-case complexity.
41 * @{
42 */
43
44
45 struct AVTreeNode;
46 extern const int av_tree_node_size;
47
48 /**
49 * Allocate an AVTreeNode.
50 */
51 struct AVTreeNode *av_tree_node_alloc(void);
52
53 /**
54 * Find an element.
55 * @param root a pointer to the root node of the tree
56 * @param next If next is not NULL, then next[0] will contain the previous
57 * element and next[1] the next element. If either does not exist,
58 * then the corresponding entry in next is unchanged.
59 * @return An element with cmp(key, elem) == 0 or NULL if no such element
60 * exists in the tree.
61 */
62 void *av_tree_find(const struct AVTreeNode *root, void *key,
63 int (*cmp)(void *key, const void *b), void *next[2]);
64
65 /**
66 * Insert or remove an element.
67 *
68 * If *next is NULL, then the supplied element will be removed if it exists.
69 * If *next is non-NULL, then the supplied element will be inserted, unless
70 * it already exists in the tree.
71 *
72 * @param rootp A pointer to a pointer to the root node of the tree; note that
73 * the root node can change during insertions, this is required
74 * to keep the tree balanced.
75 * @param key pointer to the element key to insert in the tree
76 * @param next Used to allocate and free AVTreeNodes. For insertion the user
77 * must set it to an allocated and zeroed object of at least
78 * av_tree_node_size bytes size. av_tree_insert() will set it to
79 * NULL if it has been consumed.
80 * For deleting elements *next is set to NULL by the user and
81 * av_tree_insert() will set it to the AVTreeNode which was
82 * used for the removed element.
83 * This allows the use of flat arrays, which have
84 * lower overhead compared to many malloced elements.
85 * You might want to define a function like:
86 * @code
87 * void *tree_insert(struct AVTreeNode **rootp, void *key,
88 * int (*cmp)(void *key, const void *b),
89 * AVTreeNode **next)
90 * {
91 * if (!*next)
92 * *next = av_mallocz(av_tree_node_size);
93 * return av_tree_insert(rootp, key, cmp, next);
94 * }
95 * void *tree_remove(struct AVTreeNode **rootp, void *key,
96 * int (*cmp)(void *key, const void *b, AVTreeNode **next))
97 * {
98 * av_freep(next);
99 * return av_tree_insert(rootp, key, cmp, next);
100 * }
101 * @endcode
102 * @param cmp compare function used to compare elements in the tree
103 * @return If no insertion happened, the found element; if an insertion or
104 * removal happened, then either key or NULL will be returned.
105 * Which one it is depends on the tree state and the implementation. You
106 * should make no assumptions that it's one or the other in the code.
107 */
108 void *av_tree_insert(struct AVTreeNode **rootp, void *key,
109 int (*cmp)(void *key, const void *b),
110 struct AVTreeNode **next);
111
112 void av_tree_destroy(struct AVTreeNode *t);
113
114 /**
115 * Apply enu(opaque, &elem) to all the elements in the tree in a given range.
116 *
117 * @param cmp a comparison function that returns < 0 for a element below the
118 * range, > 0 for a element above the range and == 0 for a
119 * element inside the range
120 *
121 * @note The cmp function should use the same ordering used to construct the
122 * tree.
123 */
124 void av_tree_enumerate(struct AVTreeNode *t, void *opaque,
125 int (*cmp)(void *opaque, void *elem),
126 int (*enu)(void *opaque, void *elem));
127
128 /**
129 * @}
130 */
131
132 #endif /* AVUTIL_TREE_H */