tree.h 4.24 KB
Newer Older
Michael Niedermayer's avatar
Michael Niedermayer committed
1 2 3
/*
 * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
 *
4
 * This file is part of Libav.
Michael Niedermayer's avatar
Michael Niedermayer committed
5
 *
6
 * Libav is free software; you can redistribute it and/or
Michael Niedermayer's avatar
Michael Niedermayer committed
7 8 9 10
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * 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,
Michael Niedermayer's avatar
Michael Niedermayer committed
12 13 14 15 16
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
17
 * License along with Libav; if not, write to the Free Software
Michael Niedermayer's avatar
Michael Niedermayer committed
18 19 20
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

21
/**
22
 * @file
23
 * A tree container.
24 25
 * Insertion, removal, finding equal, largest which is smaller than and
 * smallest which is larger than, all have O(log n) worst case complexity.
26 27 28
 * @author Michael Niedermayer <michaelni@gmx.at>
 */

29 30
#ifndef AVUTIL_TREE_H
#define AVUTIL_TREE_H
Michael Niedermayer's avatar
Michael Niedermayer committed
31 32

struct AVTreeNode;
33
extern const int av_tree_node_size;
Michael Niedermayer's avatar
doxy  
Michael Niedermayer committed
34 35

/**
36
 * Find an element.
Michael Niedermayer's avatar
doxy  
Michael Niedermayer committed
37
 * @param root a pointer to the root node of the tree
38 39
 * @param next If next is not NULL, then next[0] will contain the previous
 *             element and next[1] the next element. If either does not exist,
40 41 42
 *             then the corresponding entry in next is unchanged.
 * @return An element with cmp(key, elem)==0 or NULL if no such element exists in
 *         the tree.
Michael Niedermayer's avatar
doxy  
Michael Niedermayer committed
43 44 45 46
 */
void *av_tree_find(const struct AVTreeNode *root, void *key, int (*cmp)(void *key, const void *b), void *next[2]);

/**
47
 * Insert or remove an element.
48 49
 * If *next is NULL, then the supplied element will be removed if it exists.
 * If *next is not NULL, then the supplied element will be inserted, unless
50
 * it already exists in the tree.
51
 * @param rootp A pointer to a pointer to the root node of the tree; note that
52 53
 *              the root node can change during insertions, this is required
 *              to keep the tree balanced.
54 55 56 57 58 59 60 61
 * @param next Used to allocate and free AVTreeNodes. For insertion the user
 *             must set it to an allocated and zeroed object of at least
 *             av_tree_node_size bytes size. av_tree_insert() will set it to
 *             NULL if it has been consumed.
 *             For deleting elements *next is set to NULL by the user and
 *             av_tree_node_size() will set it to the AVTreeNode which was
 *             used for the removed element.
 *             This allows the use of flat arrays, which have
62 63
 *             lower overhead compared to many malloced elements.
 *             You might want to define a function like:
64
 *             @code
65 66 67 68
 *             void *tree_insert(struct AVTreeNode **rootp, void *key, int (*cmp)(void *key, const void *b), AVTreeNode **next){
 *                 if(!*next) *next= av_mallocz(av_tree_node_size);
 *                 return av_tree_insert(rootp, key, cmp, next);
 *             }
69
 *             void *tree_remove(struct AVTreeNode **rootp, void *key, int (*cmp)(void *key, const void *b, AVTreeNode **next)){
70
 *                 av_freep(next);
71 72
 *                 return av_tree_insert(rootp, key, cmp, next);
 *             }
73
 *             @endcode
74
 * @return If no insertion happened, the found element; if an insertion or
75
 *         removal happened, then either key or NULL will be returned.
76 77
 *         Which one it is depends on the tree state and the implementation. You
 *         should make no assumptions that it's one or the other in the code.
Michael Niedermayer's avatar
doxy  
Michael Niedermayer committed
78
 */
79
void *av_tree_insert(struct AVTreeNode **rootp, void *key, int (*cmp)(void *key, const void *b), struct AVTreeNode **next);
Michael Niedermayer's avatar
Michael Niedermayer committed
80 81
void av_tree_destroy(struct AVTreeNode *t);

82
/**
83
 * Apply enu(opaque, &elem) to all the elements in the tree in a given range.
84 85 86 87 88 89 90 91 92 93 94
 *
 * @param cmp a comparison function that returns < 0 for a element below the
 *            range, > 0 for a element above the range and == 0 for a
 *            element inside the range
 *
 * @note The cmp function should use the same ordering used to construct the
 *       tree.
 */
void av_tree_enumerate(struct AVTreeNode *t, void *opaque, int (*cmp)(void *opaque, void *elem), int (*enu)(void *opaque, void *elem));


95
#endif /* AVUTIL_TREE_H */