/* * 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 */