FFmpeg 5.1.5
tree.h
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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
32/**
33 * @addtogroup lavu_tree AVTree
34 * @ingroup lavu_data
35 *
36 * Low-complexity tree container
37 *
38 * Insertion, removal, finding equal, largest which is smaller than and
39 * smallest which is larger than, all have O(log n) worst-case complexity.
40 * @{
41 */
42
43
44struct AVTreeNode;
45extern const int av_tree_node_size;
46
47/**
48 * Allocate an AVTreeNode.
49 */
50struct AVTreeNode *av_tree_node_alloc(void);
51
52/**
53 * Find an element.
54 * @param root a pointer to the root node of the tree
55 * @param next If next is not NULL, then next[0] will contain the previous
56 * element and next[1] the next element. If either does not exist,
57 * then the corresponding entry in next is unchanged.
58 * @param cmp compare function used to compare elements in the tree,
59 * API identical to that of Standard C's qsort
60 * It is guaranteed that the first and only the first argument to cmp()
61 * will be the key parameter to av_tree_find(), thus it could if the
62 * user wants, be a different type (like an opaque context).
63 * @return An element with cmp(key, elem) == 0 or NULL if no such element
64 * exists in the tree.
65 */
66void *av_tree_find(const struct AVTreeNode *root, void *key,
67 int (*cmp)(const void *key, const void *b), void *next[2]);
68
69/**
70 * Insert or remove an element.
71 *
72 * If *next is NULL, then the supplied element will be removed if it exists.
73 * If *next is non-NULL, then the supplied element will be inserted, unless
74 * it already exists in the tree.
75 *
76 * @param rootp A pointer to a pointer to the root node of the tree; note that
77 * the root node can change during insertions, this is required
78 * to keep the tree balanced.
79 * @param key pointer to the element key to insert in the tree
80 * @param next Used to allocate and free AVTreeNodes. For insertion the user
81 * must set it to an allocated and zeroed object of at least
82 * av_tree_node_size bytes size. av_tree_insert() will set it to
83 * NULL if it has been consumed.
84 * For deleting elements *next is set to NULL by the user and
85 * av_tree_insert() will set it to the AVTreeNode which was
86 * used for the removed element.
87 * This allows the use of flat arrays, which have
88 * lower overhead compared to many malloced elements.
89 * You might want to define a function like:
90 * @code
91 * void *tree_insert(struct AVTreeNode **rootp, void *key,
92 * int (*cmp)(void *key, const void *b),
93 * AVTreeNode **next)
94 * {
95 * if (!*next)
96 * *next = av_mallocz(av_tree_node_size);
97 * return av_tree_insert(rootp, key, cmp, next);
98 * }
99 * void *tree_remove(struct AVTreeNode **rootp, void *key,
100 * int (*cmp)(void *key, const void *b, AVTreeNode **next))
101 * {
102 * av_freep(next);
103 * return av_tree_insert(rootp, key, cmp, next);
104 * }
105 * @endcode
106 * @param cmp compare function used to compare elements in the tree, API identical
107 * to that of Standard C's qsort
108 * @return If no insertion happened, the found element; if an insertion or
109 * removal happened, then either key or NULL will be returned.
110 * Which one it is depends on the tree state and the implementation. You
111 * should make no assumptions that it's one or the other in the code.
112 */
113void *av_tree_insert(struct AVTreeNode **rootp, void *key,
114 int (*cmp)(const void *key, const void *b),
115 struct AVTreeNode **next);
116
117void av_tree_destroy(struct AVTreeNode *t);
118
119/**
120 * Apply enu(opaque, &elem) to all the elements in the tree in a given range.
121 *
122 * @param cmp a comparison function that returns < 0 for an element below the
123 * range, > 0 for an element above the range and == 0 for an
124 * element inside the range
125 *
126 * @note The cmp function should use the same ordering used to construct the
127 * tree.
128 */
129void av_tree_enumerate(struct AVTreeNode *t, void *opaque,
130 int (*cmp)(void *opaque, void *elem),
131 int (*enu)(void *opaque, void *elem));
132
133/**
134 * @}
135 */
136
137#endif /* AVUTIL_TREE_H */
attributes.h
Macro definitions for various function/variable attributes.
av_tree_enumerate
void av_tree_enumerate(struct AVTreeNode *t, void *opaque, int(*cmp)(void *opaque, void *elem), int(*enu)(void *opaque, void *elem))
Apply enu(opaque, &elem) to all the elements in the tree in a given range.
av_tree_find
void * av_tree_find(const struct AVTreeNode *root, void *key, int(*cmp)(const void *key, const void *b), void *next[2])
Find an element.
av_tree_insert
void * av_tree_insert(struct AVTreeNode **rootp, void *key, int(*cmp)(const void *key, const void *b), struct AVTreeNode **next)
Insert or remove an element.
av_tree_node_size
const int av_tree_node_size
av_tree_destroy
void av_tree_destroy(struct AVTreeNode *t)
av_tree_node_alloc
struct AVTreeNode * av_tree_node_alloc(void)
Allocate an AVTreeNode.
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