1/* 2 * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at> 3 * 4 * This file is part of Libav. 5 * 6 * Libav 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 * Libav 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 Libav; 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/** 31 * @addtogroup lavu_tree AVTree 32 * @ingroup lavu_data 33 * 34 * Low complexity tree container 35 * 36 * Insertion, removal, finding equal, largest which is smaller than and 37 * smallest which is larger than, all have O(log n) worst case complexity. 38 * @{ 39 */ 40 41 42struct AVTreeNode; 43extern const int av_tree_node_size; 44 45/** 46 * Find an element. 47 * @param root a pointer to the root node of the tree 48 * @param next If next is not NULL, then next[0] will contain the previous 49 * element and next[1] the next element. If either does not exist, 50 * then the corresponding entry in next is unchanged. 51 * @return An element with cmp(key, elem)==0 or NULL if no such element exists in 52 * the tree. 53 */ 54void *av_tree_find(const struct AVTreeNode *root, void *key, int (*cmp)(void *key, const void *b), void *next[2]); 55 56/** 57 * Insert or remove an element. 58 * If *next is NULL, then the supplied element will be removed if it exists. 59 * If *next is not NULL, then the supplied element will be inserted, unless 60 * it already exists in the tree. 61 * @param rootp A pointer to a pointer to the root node of the tree; note that 62 * the root node can change during insertions, this is required 63 * to keep the tree balanced. 64 * @param next Used to allocate and free AVTreeNodes. For insertion the user 65 * must set it to an allocated and zeroed object of at least 66 * av_tree_node_size bytes size. av_tree_insert() will set it to 67 * NULL if it has been consumed. 68 * For deleting elements *next is set to NULL by the user and 69 * av_tree_node_size() will set it to the AVTreeNode which was 70 * used for the removed element. 71 * This allows the use of flat arrays, which have 72 * lower overhead compared to many malloced elements. 73 * You might want to define a function like: 74 * @code 75 * void *tree_insert(struct AVTreeNode **rootp, void *key, int (*cmp)(void *key, const void *b), AVTreeNode **next){ 76 * if(!*next) *next= av_mallocz(av_tree_node_size); 77 * return av_tree_insert(rootp, key, cmp, next); 78 * } 79 * void *tree_remove(struct AVTreeNode **rootp, void *key, int (*cmp)(void *key, const void *b, AVTreeNode **next)){ 80 * av_freep(next); 81 * return av_tree_insert(rootp, key, cmp, next); 82 * } 83 * @endcode 84 * @return If no insertion happened, the found element; if an insertion or 85 * removal happened, then either key or NULL will be returned. 86 * Which one it is depends on the tree state and the implementation. You 87 * should make no assumptions that it's one or the other in the code. 88 */ 89void *av_tree_insert(struct AVTreeNode **rootp, void *key, int (*cmp)(void *key, const void *b), struct AVTreeNode **next); 90void av_tree_destroy(struct AVTreeNode *t); 91 92/** 93 * Apply enu(opaque, &elem) to all the elements in the tree in a given range. 94 * 95 * @param cmp a comparison function that returns < 0 for a element below the 96 * range, > 0 for a element above the range and == 0 for a 97 * element inside the range 98 * 99 * @note The cmp function should use the same ordering used to construct the 100 * tree. 101 */ 102void av_tree_enumerate(struct AVTreeNode *t, void *opaque, int (*cmp)(void *opaque, void *elem), int (*enu)(void *opaque, void *elem)); 103 104/** 105 * @} 106 */ 107 108#endif /* AVUTIL_TREE_H */ 109