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1 /*
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2 * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
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3 *
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4 * This file is part of FFmpeg.
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5 *
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6 * FFmpeg is free software; you can redistribute it and/or
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7 * modify it under the terms of the GNU Lesser General Public
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8 * License as published by the Free Software Foundation; either
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9 * version 2.1 of the License, or (at your option) any later version.
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10 *
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11 * FFmpeg is distributed in the hope that it will be useful,
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12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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14 * Lesser General Public License for more details.
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15 *
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16 * You should have received a copy of the GNU Lesser General Public
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17 * License along with FFmpeg; if not, write to the Free Software
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18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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19 */
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20
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21 /**
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22 * @file
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23 * A tree container.
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24 * @author Michael Niedermayer <michaelni@gmx.at>
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25 */
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26
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27 #ifndef AVUTIL_TREE_H
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28 #define AVUTIL_TREE_H
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29
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30 #include "attributes.h"
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31 #include "version.h"
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32
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33 /**
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34 * @addtogroup lavu_tree AVTree
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35 * @ingroup lavu_data
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36 *
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37 * Low-complexity tree container
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38 *
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39 * Insertion, removal, finding equal, largest which is smaller than and
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40 * smallest which is larger than, all have O(log n) worst-case complexity.
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41 * @{
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42 */
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43
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44
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45 struct AVTreeNode;
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46 extern const int av_tree_node_size;
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47
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48 /**
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49 * Allocate an AVTreeNode.
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50 */
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51 struct AVTreeNode *av_tree_node_alloc(void);
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52
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53 /**
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54 * Find an element.
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55 * @param root a pointer to the root node of the tree
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56 * @param next If next is not NULL, then next[0] will contain the previous
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57 * element and next[1] the next element. If either does not exist,
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58 * then the corresponding entry in next is unchanged.
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59 * @return An element with cmp(key, elem) == 0 or NULL if no such element
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60 * exists in the tree.
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61 */
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62 void *av_tree_find(const struct AVTreeNode *root, void *key,
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63 int (*cmp)(void *key, const void *b), void *next[2]);
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64
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65 /**
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66 * Insert or remove an element.
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67 *
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68 * If *next is NULL, then the supplied element will be removed if it exists.
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69 * If *next is non-NULL, then the supplied element will be inserted, unless
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70 * it already exists in the tree.
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71 *
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72 * @param rootp A pointer to a pointer to the root node of the tree; note that
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73 * the root node can change during insertions, this is required
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74 * to keep the tree balanced.
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75 * @param key pointer to the element key to insert in the tree
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76 * @param next Used to allocate and free AVTreeNodes. For insertion the user
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77 * must set it to an allocated and zeroed object of at least
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78 * av_tree_node_size bytes size. av_tree_insert() will set it to
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79 * NULL if it has been consumed.
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80 * For deleting elements *next is set to NULL by the user and
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81 * av_tree_insert() will set it to the AVTreeNode which was
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82 * used for the removed element.
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83 * This allows the use of flat arrays, which have
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84 * lower overhead compared to many malloced elements.
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85 * You might want to define a function like:
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86 * @code
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87 * void *tree_insert(struct AVTreeNode **rootp, void *key,
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88 * int (*cmp)(void *key, const void *b),
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89 * AVTreeNode **next)
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90 * {
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91 * if (!*next)
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92 * *next = av_mallocz(av_tree_node_size);
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93 * return av_tree_insert(rootp, key, cmp, next);
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94 * }
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95 * void *tree_remove(struct AVTreeNode **rootp, void *key,
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96 * int (*cmp)(void *key, const void *b, AVTreeNode **next))
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97 * {
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98 * av_freep(next);
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99 * return av_tree_insert(rootp, key, cmp, next);
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100 * }
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101 * @endcode
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102 * @param cmp compare function used to compare elements in the tree
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103 * @return If no insertion happened, the found element; if an insertion or
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104 * removal happened, then either key or NULL will be returned.
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105 * Which one it is depends on the tree state and the implementation. You
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106 * should make no assumptions that it's one or the other in the code.
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107 */
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108 void *av_tree_insert(struct AVTreeNode **rootp, void *key,
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109 int (*cmp)(void *key, const void *b),
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110 struct AVTreeNode **next);
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111
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112 void av_tree_destroy(struct AVTreeNode *t);
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113
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114 /**
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115 * Apply enu(opaque, &elem) to all the elements in the tree in a given range.
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116 *
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117 * @param cmp a comparison function that returns < 0 for a element below the
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118 * range, > 0 for a element above the range and == 0 for a
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119 * element inside the range
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120 *
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121 * @note The cmp function should use the same ordering used to construct the
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122 * tree.
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123 */
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124 void av_tree_enumerate(struct AVTreeNode *t, void *opaque,
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125 int (*cmp)(void *opaque, void *elem),
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126 int (*enu)(void *opaque, void *elem));
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127
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128 /**
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129 * @}
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130 */
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131
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132 #endif /* AVUTIL_TREE_H */
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