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996 | cejka | 1 | /* |
2 | * Copyright (C) 2006 Jakub Jermar |
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3 | * All rights reserved. |
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4 | * |
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5 | * Redistribution and use in source and binary forms, with or without |
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6 | * modification, are permitted provided that the following conditions |
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7 | * are met: |
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8 | * |
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9 | * - 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 | * - Redistributions in binary form must reproduce the above copyright |
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12 | * notice, this list of conditions and the following disclaimer in the |
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13 | * documentation and/or other materials provided with the distribution. |
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14 | * - The name of the author may not be used to endorse or promote products |
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15 | * derived from this software without specific prior written permission. |
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16 | * |
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17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
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21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
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26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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27 | */ |
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28 | |||
29 | /* |
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30 | * This is an implementation of generic chained hash table. |
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31 | */ |
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32 | |||
33 | #include <hash_table.h> |
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34 | #include <list.h> |
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35 | #include <unistd.h> |
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36 | #include <malloc.h> |
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37 | #include <assert.h> |
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997 | cejka | 38 | #include <stdio.h> |
39 | #include <string.h> |
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996 | cejka | 40 | |
41 | /** Create chained hash table. |
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42 | * |
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43 | * @param h Hash table structure. Will be initialized by this call. |
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44 | * @param m Number of slots in the hash table. |
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45 | * @param max_keys Maximal number of keys needed to identify an item. |
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46 | * @param op Hash table operations structure. |
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997 | cejka | 47 | * @return true on success |
996 | cejka | 48 | */ |
997 | cejka | 49 | int hash_table_create(hash_table_t *h, hash_count_t m, hash_count_t max_keys, hash_table_operations_t *op) |
996 | cejka | 50 | { |
997 | cejka | 51 | hash_count_t i; |
996 | cejka | 52 | |
997 | cejka | 53 | assert(h); |
54 | assert(op && op->hash && op->compare); |
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55 | assert(max_keys > 0); |
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996 | cejka | 56 | |
1202 | jermar | 57 | h->entry = malloc(m * sizeof(link_t)); |
996 | cejka | 58 | if (!h->entry) { |
997 | cejka | 59 | printf("cannot allocate memory for hash table\n"); |
60 | return false; |
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996 | cejka | 61 | } |
1202 | jermar | 62 | memset((void *) h->entry, 0, m * sizeof(link_t)); |
996 | cejka | 63 | |
64 | for (i = 0; i < m; i++) |
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65 | list_initialize(&h->entry[i]); |
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66 | |||
67 | h->entries = m; |
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68 | h->max_keys = max_keys; |
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69 | h->op = op; |
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997 | cejka | 70 | return true; |
996 | cejka | 71 | } |
72 | |||
73 | /** Insert item into hash table. |
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74 | * |
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75 | * @param h Hash table. |
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76 | * @param hey Array of all keys necessary to compute hash index. |
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77 | * @param item Item to be inserted into the hash table. |
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78 | */ |
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997 | cejka | 79 | void hash_table_insert(hash_table_t *h, unsigned long key[], link_t *item) |
996 | cejka | 80 | { |
81 | hash_index_t chain; |
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82 | |||
997 | cejka | 83 | assert(item); |
84 | assert(h && h->op && h->op->hash && h->op->compare); |
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996 | cejka | 85 | |
86 | chain = h->op->hash(key); |
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997 | cejka | 87 | assert(chain < h->entries); |
996 | cejka | 88 | |
89 | list_append(item, &h->entry[chain]); |
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90 | } |
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91 | |||
92 | /** Search hash table for an item matching keys. |
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93 | * |
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94 | * @param h Hash table. |
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95 | * @param key Array of all keys needed to compute hash index. |
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96 | * |
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97 | * @return Matching item on success, NULL if there is no such item. |
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98 | */ |
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997 | cejka | 99 | link_t *hash_table_find(hash_table_t *h, unsigned long key[]) |
996 | cejka | 100 | { |
101 | link_t *cur; |
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102 | hash_index_t chain; |
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103 | |||
997 | cejka | 104 | assert(h && h->op && h->op->hash && h->op->compare); |
996 | cejka | 105 | |
106 | chain = h->op->hash(key); |
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997 | cejka | 107 | assert(chain < h->entries); |
996 | cejka | 108 | |
109 | for (cur = h->entry[chain].next; cur != &h->entry[chain]; cur = cur->next) { |
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110 | if (h->op->compare(key, h->max_keys, cur)) { |
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111 | /* |
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112 | * The entry is there. |
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113 | */ |
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114 | return cur; |
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115 | } |
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116 | } |
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117 | |||
118 | return NULL; |
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119 | } |
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120 | |||
121 | /** Remove all matching items from hash table. |
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122 | * |
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123 | * For each removed item, h->remove_callback() is called. |
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124 | * |
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125 | * @param h Hash table. |
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126 | * @param key Array of keys that will be compared against items of the hash table. |
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127 | * @param keys Number of keys in the 'key' array. |
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128 | */ |
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997 | cejka | 129 | void hash_table_remove(hash_table_t *h, unsigned long key[], hash_count_t keys) |
996 | cejka | 130 | { |
131 | hash_index_t chain; |
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132 | link_t *cur; |
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133 | |||
997 | cejka | 134 | assert(h && h->op && h->op->hash && h->op->compare && h->op->remove_callback); |
135 | assert(keys <= h->max_keys); |
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996 | cejka | 136 | |
137 | if (keys == h->max_keys) { |
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138 | |||
139 | /* |
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140 | * All keys are known, hash_table_find() can be used to find the entry. |
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141 | */ |
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142 | |||
143 | cur = hash_table_find(h, key); |
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144 | if (cur) { |
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145 | list_remove(cur); |
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146 | h->op->remove_callback(cur); |
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147 | } |
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148 | return; |
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149 | } |
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150 | |||
151 | /* |
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152 | * Fewer keys were passed. |
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153 | * Any partially matching entries are to be removed. |
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154 | */ |
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155 | for (chain = 0; chain < h->entries; chain++) { |
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156 | for (cur = h->entry[chain].next; cur != &h->entry[chain]; cur = cur->next) { |
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157 | if (h->op->compare(key, keys, cur)) { |
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158 | link_t *hlp; |
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159 | |||
160 | hlp = cur; |
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161 | cur = cur->prev; |
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162 | |||
163 | list_remove(hlp); |
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164 | h->op->remove_callback(hlp); |
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165 | |||
166 | continue; |
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167 | } |
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168 | } |
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169 | } |
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170 | } |