FFmpeg
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 #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  * @param cmp compare function used to compare elements in the tree,
60  * API identical to that of Standard C's qsort
61  * It is guaranteed that the first and only the first argument to cmp()
62  * will be the key parameter to av_tree_find(), thus it could if the
63  * user wants, be a different type (like an opaque context).
64  * @return An element with cmp(key, elem) == 0 or NULL if no such element
65  * exists in the tree.
66  */
67 void *av_tree_find(const struct AVTreeNode *root, void *key,
68  int (*cmp)(const void *key, const void *b), void *next[2]);
69 
70 /**
71  * Insert or remove an element.
72  *
73  * If *next is NULL, then the supplied element will be removed if it exists.
74  * If *next is non-NULL, then the supplied element will be inserted, unless
75  * it already exists in the tree.
76  *
77  * @param rootp A pointer to a pointer to the root node of the tree; note that
78  * the root node can change during insertions, this is required
79  * to keep the tree balanced.
80  * @param key pointer to the element key to insert in the tree
81  * @param next Used to allocate and free AVTreeNodes. For insertion the user
82  * must set it to an allocated and zeroed object of at least
83  * av_tree_node_size bytes size. av_tree_insert() will set it to
84  * NULL if it has been consumed.
85  * For deleting elements *next is set to NULL by the user and
86  * av_tree_insert() will set it to the AVTreeNode which was
87  * used for the removed element.
88  * This allows the use of flat arrays, which have
89  * lower overhead compared to many malloced elements.
90  * You might want to define a function like:
91  * @code
92  * void *tree_insert(struct AVTreeNode **rootp, void *key,
93  * int (*cmp)(void *key, const void *b),
94  * AVTreeNode **next)
95  * {
96  * if (!*next)
97  * *next = av_mallocz(av_tree_node_size);
98  * return av_tree_insert(rootp, key, cmp, next);
99  * }
100  * void *tree_remove(struct AVTreeNode **rootp, void *key,
101  * int (*cmp)(void *key, const void *b, AVTreeNode **next))
102  * {
103  * av_freep(next);
104  * return av_tree_insert(rootp, key, cmp, next);
105  * }
106  * @endcode
107  * @param cmp compare function used to compare elements in the tree, API identical
108  * to that of Standard C's qsort
109  * @return If no insertion happened, the found element; if an insertion or
110  * removal happened, then either key or NULL will be returned.
111  * Which one it is depends on the tree state and the implementation. You
112  * should make no assumptions that it's one or the other in the code.
113  */
114 void *av_tree_insert(struct AVTreeNode **rootp, void *key,
115  int (*cmp)(const void *key, const void *b),
116  struct AVTreeNode **next);
117 
118 void av_tree_destroy(struct AVTreeNode *t);
119 
120 /**
121  * Apply enu(opaque, &elem) to all the elements in the tree in a given range.
122  *
123  * @param cmp a comparison function that returns < 0 for an element below the
124  * range, > 0 for an element above the range and == 0 for an
125  * element inside the range
126  *
127  * @note The cmp function should use the same ordering used to construct the
128  * tree.
129  */
130 void av_tree_enumerate(struct AVTreeNode *t, void *opaque,
131  int (*cmp)(void *opaque, void *elem),
132  int (*enu)(void *opaque, void *elem));
133 
134 /**
135  * @}
136  */
137 
138 #endif /* AVUTIL_TREE_H */
void * av_tree_find(const struct AVTreeNode *root, void *key, int(*cmp)(const void *key, const void *b), void *next[2])
Find an element.
const char * key
Macro definitions for various function/variable attributes.
struct AVTreeNode * av_tree_node_alloc(void)
Allocate an AVTreeNode.
Definition: tree.c:34
void av_tree_destroy(struct AVTreeNode *t)
Definition: tree.c:146
Libavutil version macros.
#define b
Definition: input.c:41
static av_always_inline int cmp(MpegEncContext *s, const int x, const int y, const int subx, const int suby, const int size, const int h, int ref_index, int src_index, me_cmp_func cmp_func, me_cmp_func chroma_cmp_func, const int flags)
compares a block (either a full macroblock or a partition thereof) against a proposed motion-compensa...
Definition: motion_est.c:260
const int av_tree_node_size
Definition: tree.c:32
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.
Definition: tree.c:59
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.
Definition: tree.c:155
void * elem
Definition: tree.c:28