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1 /* |
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2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER. |
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3 * |
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4 * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved. |
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5 * |
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6 * Redistribution and use in source and binary forms, with or without |
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7 * modification, are permitted provided that the following conditions are met: |
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8 * |
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9 * 1. Redistributions of source code must retain the above copyright |
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10 * notice, this list of conditions and the following disclaimer. |
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11 * |
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12 * 2. Redistributions in binary form must reproduce the above copyright |
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13 * notice, this list of conditions and the following disclaimer in the |
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14 * documentation and/or other materials provided with the distribution. |
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15 * |
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16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
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17 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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19 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE |
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20 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
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21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
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22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
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23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
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24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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26 * POSSIBILITY OF SUCH DAMAGE. |
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27 */ |
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28 /** |
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29 * \file map.h |
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30 * \brief Interface for map implementations. |
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31 * \author Mike Becker |
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32 * \author Olaf Wintermann |
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33 * \version 3.0 |
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34 * \copyright 2-Clause BSD License |
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35 */ |
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36 |
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37 #ifndef UCX_HASH_MAP_H |
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38 #define UCX_HASH_MAP_H |
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39 |
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40 #include "map.h" |
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41 |
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42 #ifdef __cplusplus |
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43 extern "C" { |
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44 #endif |
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45 |
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46 /** Internal structure for a key within a hash map. */ |
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47 struct cx_hash_map_key_s { |
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48 /** The key data. */ |
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49 CxDataPtr data; |
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50 /** The hash value of the key data. */ |
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51 unsigned hash; |
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52 }; |
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53 |
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54 /** Internal structure for an element of a hash map. */ |
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55 struct cx_hash_map_element_s { |
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56 /** The value data. */ |
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57 void *data; |
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58 |
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59 /** A pointer to the next element in the current bucket. */ |
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60 struct cx_hash_map_element_s *next; |
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61 |
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62 /** The corresponding key. */ |
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63 struct cx_hash_map_key_s key; |
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64 }; |
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65 |
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66 |
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67 /** |
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68 * Creates a new hash map with the specified size using a UcxAllocator. |
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69 * |
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70 * @param allocator the allocator to use |
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71 * @param buckets the initial number of buckets in this hash map |
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72 * @return a pointer to the new hash map |
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73 */ |
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74 CxMap *cxHashMapCreate( |
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75 CxAllocator *allocator, |
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76 size_t buckets |
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77 ); |
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78 |
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79 /** |
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80 * Increases the number of buckets, if necessary. |
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81 * |
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82 * The load value is \c loadFactor*buckets. If the element count exceeds the load |
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83 * value, the map needs to be rehashed. Otherwise, no action is performed and |
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84 * this function simply returns 0. |
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85 * |
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86 * The rehashing process ensures, that the number of buckets is at least |
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87 * \p bucketFactor times the number of stored items. So there is enough room for additional |
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88 * elements without the need of another soon rehashing. |
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89 * |
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90 * You can use this function after filling a map to dramatically increase access performance. |
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91 * |
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92 * @note If the specified map is not a hash map, the behavior is undefined. |
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93 * |
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94 * @param map the map to rehash |
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95 * @param loadFactor a percentage threshold for the load of the map |
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96 * @param bucketFactor a factor for the number of buckets that shall be available after rehashing |
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97 * @return zero on success, non-zero if a memory allocation error occurred |
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98 */ |
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99 __attribute__((__nonnull__)) |
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100 int cxMapRehash2( |
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101 CxMap *map, |
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102 float loadFactor, |
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103 float bucketFactor |
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104 ); |
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105 |
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106 /** |
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107 * Rehashes the map with load factor 0.75 and bucket factor 2.5. |
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108 * |
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109 * @param map the map to rehash |
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110 * @return zero on success, non-zero if a memory allocation error occurred |
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111 * @see cxMapRehash2() |
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112 */ |
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113 __attribute__((__nonnull__)) |
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114 static inline int cxMapRehash(CxMap *map) { |
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115 return cxMapRehash2(map, 0.75f, 2.5f); |
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116 } |
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117 |
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118 |
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119 #ifdef __cplusplus |
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120 } // extern "C" |
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121 #endif |
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122 |
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123 #endif // UCX_HASH_MAP_H |