comparison: ucx/cx/hash_map.h
ucx/cx/hash_map.h
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| 1 /* | |
| 2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER. | |
| 3 * | |
| 4 * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved. | |
| 5 * | |
| 6 * Redistribution and use in source and binary forms, with or without | |
| 7 * modification, are permitted provided that the following conditions are met: | |
| 8 * | |
| 9 * 1. Redistributions of source code must retain the above copyright | |
| 10 * notice, this list of conditions and the following disclaimer. | |
| 11 * | |
| 12 * 2. Redistributions in binary form must reproduce the above copyright | |
| 13 * notice, this list of conditions and the following disclaimer in the | |
| 14 * documentation and/or other materials provided with the distribution. | |
| 15 * | |
| 16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" | |
| 17 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
| 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
| 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE | |
| 20 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR | |
| 21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF | |
| 22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS | |
| 23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN | |
| 24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
| 25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE | |
| 26 * POSSIBILITY OF SUCH DAMAGE. | |
| 27 */ | |
| 28 /** | |
| 29 * \file hash_map.h | |
| 30 * \brief Hash map implementation. | |
| 31 * \author Mike Becker | |
| 32 * \author Olaf Wintermann | |
| 33 * \copyright 2-Clause BSD License | |
| 34 */ | |
| 35 | |
| 36 #ifndef UCX_HASH_MAP_H | |
| 37 #define UCX_HASH_MAP_H | |
| 38 | |
| 39 #include "map.h" | |
| 40 | |
| 41 #ifdef __cplusplus | |
| 42 extern "C" { | |
| 43 #endif | |
| 44 | |
| 45 /** Internal structure for an element of a hash map. */ | |
| 46 struct cx_hash_map_element_s; | |
| 47 | |
| 48 /** | |
| 49 * Internal structure for a hash map. | |
| 50 */ | |
| 51 struct cx_hash_map_s { | |
| 52 /** | |
| 53 * Base structure for maps. | |
| 54 */ | |
| 55 struct cx_map_s base; | |
| 56 /** | |
| 57 * The buckets of this map, each containing a linked list of elements. | |
| 58 */ | |
| 59 struct cx_hash_map_element_s **buckets; | |
| 60 /** | |
| 61 * The number of buckets. | |
| 62 */ | |
| 63 size_t bucket_count; | |
| 64 }; | |
| 65 | |
| 66 | |
| 67 /** | |
| 68 * Creates a new hash map with the specified number of buckets. | |
| 69 * | |
| 70 * If \p buckets is zero, an implementation defined default will be used. | |
| 71 * | |
| 72 * If \p elem_size is CX_STORE_POINTERS, the created map will be created as if | |
| 73 * cxMapStorePointers() was called immediately after creation. | |
| 74 * | |
| 75 * @note Iterators provided by this hash map implementation provide the remove operation. | |
| 76 * The index value of an iterator is incremented when the iterator advanced without removal. | |
| 77 * In other words, when the iterator is finished, \c index==size . | |
| 78 * | |
| 79 * @param allocator the allocator to use | |
| 80 * @param itemsize the size of one element | |
| 81 * @param buckets the initial number of buckets in this hash map | |
| 82 * @return a pointer to the new hash map | |
| 83 */ | |
| 84 __attribute__((__nonnull__, __warn_unused_result__)) | |
| 85 CxMap *cxHashMapCreate( | |
| 86 const CxAllocator *allocator, | |
| 87 size_t itemsize, | |
| 88 size_t buckets | |
| 89 ); | |
| 90 | |
| 91 /** | |
| 92 * Creates a new hash map with a default number of buckets. | |
| 93 * | |
| 94 * If \p elem_size is CX_STORE_POINTERS, the created map will be created as if | |
| 95 * cxMapStorePointers() was called immediately after creation. | |
| 96 * | |
| 97 * @note Iterators provided by this hash map implementation provide the remove operation. | |
| 98 * The index value of an iterator is incremented when the iterator advanced without removal. | |
| 99 * In other words, when the iterator is finished, \c index==size . | |
| 100 * | |
| 101 * @param itemsize the size of one element | |
| 102 * @return a pointer to the new hash map | |
| 103 */ | |
| 104 #define cxHashMapCreateSimple(itemsize) \ | |
| 105 cxHashMapCreate(cxDefaultAllocator, itemsize, 0) | |
| 106 | |
| 107 /** | |
| 108 * Increases the number of buckets, if necessary. | |
| 109 * | |
| 110 * The load threshold is \c 0.75*buckets. If the element count exceeds the load | |
| 111 * threshold, the map will be rehashed. Otherwise, no action is performed and | |
| 112 * this function simply returns 0. | |
| 113 * | |
| 114 * The rehashing process ensures, that the number of buckets is at least | |
| 115 * 2.5 times the element count. So there is enough room for additional | |
| 116 * elements without the need of another soon rehashing. | |
| 117 * | |
| 118 * You can use this function after filling a map to increase access performance. | |
| 119 * | |
| 120 * @note If the specified map is not a hash map, the behavior is undefined. | |
| 121 * | |
| 122 * @param map the map to rehash | |
| 123 * @return zero on success, non-zero if a memory allocation error occurred | |
| 124 */ | |
| 125 __attribute__((__nonnull__)) | |
| 126 int cxMapRehash(CxMap *map); | |
| 127 | |
| 128 | |
| 129 #ifdef __cplusplus | |
| 130 } // extern "C" | |
| 131 #endif | |
| 132 | |
| 133 #endif // UCX_HASH_MAP_H |
