/* * 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"#include "version.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 */