/*
  * 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 */