blob: d5e0aebfbdb7c1f7e4fc36b437f5c6147c82b94a
| 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 */ |
| 139 |