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30 * \brief Hash map implementation.
32 * \author Olaf Wintermann
34 * \copyright 2-Clause BSD License
37 #ifndef UCX_HASH_MAP_H
38 #define UCX_HASH_MAP_H
46 /** Internal structure for an element of a hash map. */
47 struct cx_hash_map_element_s;
50 * Internal structure for a hash map.
52 struct cx_hash_map_s {
54 * Base structure for maps.
58 * The buckets of this map, each containing a linked list of elements.
60 struct cx_hash_map_element_s **buckets;
62 * The number of buckets.
69 * Creates a new hash map with the specified number of buckets.
71 * If \p buckets is zero, an implementation defined default will be used.
73 * If \p item_size is CX_STORE_POINTERS, the created map will be created as if
74 * cxMapStorePointers() was called immediately after creation.
76 * @note Iterators provided by this hash map implementation provide the remove operation.
77 * The index value of an iterator is incremented when the iterator advanced without removal.
78 * In other words, when the iterator is finished, \c index==size .
80 * @param allocator the allocator to use
81 * @param itemsize the size of one element
82 * @param buckets the initial number of buckets in this hash map
83 * @return a pointer to the new hash map
85 __attribute__((__nonnull__, __warn_unused_result__))
86 CxMap *cxHashMapCreate(
87 CxAllocator const *allocator,
93 * Creates a new hash map with a default number of buckets.
95 * If \p item_size is CX_STORE_POINTERS, the created map will be created as if
96 * cxMapStorePointers() was called immediately after creation.
98 * @note Iterators provided by this hash map implementation provide the remove operation.
99 * The index value of an iterator is incremented when the iterator advanced without removal.
100 * In other words, when the iterator is finished, \c index==size .
102 * @param itemsize the size of one element
103 * @return a pointer to the new hash map
105 #define cxHashMapCreateSimple(itemsize) \
106 cxHashMapCreate(cxDefaultAllocator, itemsize, 0)
109 * Increases the number of buckets, if necessary.
111 * The load threshold is \c 0.75*buckets. If the element count exceeds the load
112 * threshold, the map will be rehashed. Otherwise, no action is performed and
113 * this function simply returns 0.
115 * The rehashing process ensures, that the number of buckets is at least
116 * 2.5 times the element count. So there is enough room for additional
117 * elements without the need of another soon rehashing.
119 * You can use this function after filling a map to increase access performance.
121 * @note If the specified map is not a hash map, the behavior is undefined.
123 * @param map the map to rehash
124 * @return zero on success, non-zero if a memory allocation error occurred
126 __attribute__((__nonnull__))
127 int cxMapRehash(CxMap *map);
134 #endif // UCX_HASH_MAP_H