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| Rev | Author | Line No. | Line |
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| 6147 | serge | 1 | /* |
| 2 | * copyright (c) 2006 Michael Niedermayer |
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| 3 | * |
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| 4 | * This file is part of FFmpeg. |
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| 5 | * |
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| 6 | * FFmpeg is free software; you can redistribute it and/or |
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| 7 | * modify it under the terms of the GNU Lesser General Public |
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| 8 | * License as published by the Free Software Foundation; either |
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| 9 | * version 2.1 of the License, or (at your option) any later version. |
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| 10 | * |
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| 11 | * FFmpeg is distributed in the hope that it will be useful, |
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| 12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 14 | * Lesser General Public License for more details. |
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| 15 | * |
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| 16 | * You should have received a copy of the GNU Lesser General Public |
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| 17 | * License along with FFmpeg; if not, write to the Free Software |
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| 18 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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| 19 | */ |
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| 20 | |||
| 21 | /** |
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| 22 | * @file |
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| 23 | * A tree container. |
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| 24 | * @author Michael Niedermayer |
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| 25 | */ |
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| 26 | |||
| 27 | #ifndef AVUTIL_TREE_H |
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| 28 | #define AVUTIL_TREE_H |
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| 29 | |||
| 30 | #include "attributes.h" |
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| 31 | #include "version.h" |
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| 32 | |||
| 33 | /** |
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| 34 | * @addtogroup lavu_tree AVTree |
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| 35 | * @ingroup lavu_data |
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| 36 | * |
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| 37 | * Low-complexity tree container |
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| 38 | * |
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| 39 | * Insertion, removal, finding equal, largest which is smaller than and |
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| 40 | * smallest which is larger than, all have O(log n) worst-case complexity. |
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| 41 | * @{ |
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| 42 | */ |
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| 43 | |||
| 44 | |||
| 45 | struct AVTreeNode; |
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| 46 | extern const int av_tree_node_size; |
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| 47 | |||
| 48 | /** |
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| 49 | * Allocate an AVTreeNode. |
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| 50 | */ |
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| 51 | struct AVTreeNode *av_tree_node_alloc(void); |
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| 52 | |||
| 53 | /** |
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| 54 | * Find an element. |
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| 55 | * @param root a pointer to the root node of the tree |
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| 56 | * @param next If next is not NULL, then next[0] will contain the previous |
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| 57 | * element and next[1] the next element. If either does not exist, |
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| 58 | * then the corresponding entry in next is unchanged. |
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| 59 | * @return An element with cmp(key, elem) == 0 or NULL if no such element |
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| 60 | * exists in the tree. |
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| 61 | */ |
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| 62 | void *av_tree_find(const struct AVTreeNode *root, void *key, |
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| 63 | int (*cmp)(void *key, const void *b), void *next[2]); |
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| 64 | |||
| 65 | /** |
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| 66 | * Insert or remove an element. |
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| 67 | * |
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| 68 | * If *next is NULL, then the supplied element will be removed if it exists. |
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| 69 | * If *next is non-NULL, then the supplied element will be inserted, unless |
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| 70 | * it already exists in the tree. |
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| 71 | * |
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| 72 | * @param rootp A pointer to a pointer to the root node of the tree; note that |
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| 73 | * the root node can change during insertions, this is required |
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| 74 | * to keep the tree balanced. |
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| 75 | * @param key pointer to the element key to insert in the tree |
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| 76 | * @param next Used to allocate and free AVTreeNodes. For insertion the user |
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| 77 | * must set it to an allocated and zeroed object of at least |
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| 78 | * av_tree_node_size bytes size. av_tree_insert() will set it to |
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| 79 | * NULL if it has been consumed. |
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| 80 | * For deleting elements *next is set to NULL by the user and |
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| 81 | * av_tree_insert() will set it to the AVTreeNode which was |
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| 82 | * used for the removed element. |
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| 83 | * This allows the use of flat arrays, which have |
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| 84 | * lower overhead compared to many malloced elements. |
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| 85 | * You might want to define a function like: |
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| 86 | * @code |
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| 87 | * void *tree_insert(struct AVTreeNode **rootp, void *key, |
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| 88 | * int (*cmp)(void *key, const void *b), |
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| 89 | * AVTreeNode **next) |
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| 90 | * { |
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| 91 | * if (!*next) |
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| 92 | * *next = av_mallocz(av_tree_node_size); |
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| 93 | * return av_tree_insert(rootp, key, cmp, next); |
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| 94 | * } |
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| 95 | * void *tree_remove(struct AVTreeNode **rootp, void *key, |
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| 96 | * int (*cmp)(void *key, const void *b, AVTreeNode **next)) |
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| 97 | * { |
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| 98 | * av_freep(next); |
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| 99 | * return av_tree_insert(rootp, key, cmp, next); |
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| 100 | * } |
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| 101 | * @endcode |
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| 102 | * @param cmp compare function used to compare elements in the tree |
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| 103 | * @return If no insertion happened, the found element; if an insertion or |
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| 104 | * removal happened, then either key or NULL will be returned. |
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| 105 | * Which one it is depends on the tree state and the implementation. You |
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| 106 | * should make no assumptions that it's one or the other in the code. |
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| 107 | */ |
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| 108 | void *av_tree_insert(struct AVTreeNode **rootp, void *key, |
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| 109 | int (*cmp)(void *key, const void *b), |
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| 110 | struct AVTreeNode **next); |
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| 111 | |||
| 112 | void av_tree_destroy(struct AVTreeNode *t); |
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| 113 | |||
| 114 | /** |
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| 115 | * Apply enu(opaque, &elem) to all the elements in the tree in a given range. |
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| 116 | * |
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| 117 | * @param cmp a comparison function that returns < 0 for a element below the |
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| 118 | * range, > 0 for a element above the range and == 0 for a |
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| 119 | * element inside the range |
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| 120 | * |
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| 121 | * @note The cmp function should use the same ordering used to construct the |
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| 122 | * tree. |
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| 123 | */ |
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| 124 | void av_tree_enumerate(struct AVTreeNode *t, void *opaque, |
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| 125 | int (*cmp)(void *opaque, void *elem), |
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| 126 | int (*enu)(void *opaque, void *elem)); |
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| 127 | |||
| 128 | /** |
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| 129 | * @} |
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| 130 | */ |
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| 131 | |||
| 132 | #endif /* AVUTIL_TREE_H */ |