--- /dev/null
+/*
+ * 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 guranteed 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 a element below the
+ * range, > 0 for a element above the range and == 0 for a
+ * 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 */
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