| /* |
| * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at> |
| * |
| * This file is part of FFmpeg. |
| * |
| * FFmpeg is free software; you can redistribute it and/or |
| * 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. |
| * |
| * FFmpeg is distributed in the hope that it will be useful, |
| * 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 |
| * License along with FFmpeg; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| |
| /** |
| * @file |
| * A tree container. |
| * @author Michael Niedermayer <michaelni@gmx.at> |
| */ |
| |
| #ifndef AVUTIL_TREE_H |
| #define AVUTIL_TREE_H |
| |
| #include "attributes.h" |
| |
| /** |
| * @addtogroup lavu_tree AVTree |
| * @ingroup lavu_data |
| * |
| * Low-complexity tree container |
| * |
| * Insertion, removal, finding equal, largest which is smaller than and |
| * smallest which is larger than, all have O(log n) worst-case complexity. |
| * @{ |
| */ |
| |
| |
| struct AVTreeNode; |
| extern const int av_tree_node_size; |
| |
| /** |
| * Allocate an AVTreeNode. |
| */ |
| struct AVTreeNode *av_tree_node_alloc(void); |
| |
| /** |
| * Find an element. |
| * @param root a pointer to the root node of the tree |
| * @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, |
| * then the corresponding entry in next is unchanged. |
| * @param cmp compare function used to compare elements in the tree, |
| * API identical to that of Standard C's qsort |
| * It is guaranteed that the first and only the first argument to cmp() |
| * will be the key parameter to av_tree_find(), thus it could if the |
| * user wants, be a different type (like an opaque context). |
| * @return An element with cmp(key, elem) == 0 or NULL if no such element |
| * exists in the tree. |
| */ |
| void *av_tree_find(const struct AVTreeNode *root, void *key, |
| int (*cmp)(const void *key, const void *b), void *next[2]); |
| |
| /** |
| * Insert or remove an element. |
| * |
| * If *next is NULL, then the supplied element will be removed if it exists. |
| * If *next is non-NULL, then the supplied element will be inserted, unless |
| * it already exists in the tree. |
| * |
| * @param rootp A pointer to a pointer to the root node of the tree; note that |
| * the root node can change during insertions, this is required |
| * to keep the tree balanced. |
| * @param key pointer to the element key to insert in the tree |
| * @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_insert() will set it to the AVTreeNode which was |
| * used for the removed element. |
| * This allows the use of flat arrays, which have |
| * lower overhead compared to many malloced elements. |
| * You might want to define a function like: |
| * @code |
| * 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); |
| * } |
| * void *tree_remove(struct AVTreeNode **rootp, void *key, |
| * int (*cmp)(void *key, const void *b, AVTreeNode **next)) |
| * { |
| * av_freep(next); |
| * return av_tree_insert(rootp, key, cmp, next); |
| * } |
| * @endcode |
| * @param cmp compare function used to compare elements in the tree, API identical |
| * to that of Standard C's qsort |
| * @return If no insertion happened, the found element; if an insertion or |
| * removal happened, then either key or NULL will be returned. |
| * 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. |
| */ |
| void *av_tree_insert(struct AVTreeNode **rootp, void *key, |
| int (*cmp)(const void *key, const void *b), |
| struct AVTreeNode **next); |
| |
| void av_tree_destroy(struct AVTreeNode *t); |
| |
| /** |
| * Apply enu(opaque, &elem) to all the elements in the tree in a given range. |
| * |
| * @param cmp a comparison function that returns < 0 for an element below the |
| * range, > 0 for an element above the range and == 0 for an |
| * 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)); |
| |
| /** |
| * @} |
| */ |
| |
| #endif /* AVUTIL_TREE_H */ |
