Benny Prijono | 9033e31 | 2005-11-21 02:08:39 +0000 | [diff] [blame] | 1 | /* $Id$ */ |
| 2 | /* |
| 3 | * Copyright (C)2003-2006 Benny Prijono <benny@prijono.org> |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or modify |
| 6 | * it under the terms of the GNU General Public License as published by |
| 7 | * the Free Software Foundation; either version 2 of the License, or |
| 8 | * (at your option) any later version. |
| 9 | * |
| 10 | * This program is distributed in the hope that it will be useful, |
| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | * GNU General Public License for more details. |
| 14 | * |
| 15 | * You should have received a copy of the GNU General Public License |
| 16 | * along with this program; if not, write to the Free Software |
| 17 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| 18 | */ |
| 19 | #ifndef __PJ_HASH_H__ |
| 20 | #define __PJ_HASH_H__ |
| 21 | |
| 22 | /** |
| 23 | * @file hash.h |
| 24 | * @brief Hash Table. |
| 25 | */ |
| 26 | |
| 27 | #include <pj/types.h> |
| 28 | |
| 29 | PJ_BEGIN_DECL |
| 30 | |
| 31 | /** |
| 32 | * @defgroup PJ_HASH Hash Table |
| 33 | * @ingroup PJ_DS |
| 34 | * @{ |
| 35 | * A hash table is a dictionary in which keys are mapped to array positions by |
| 36 | * hash functions. Having the keys of more than one item map to the same |
| 37 | * position is called a collision. In this library, we will chain the nodes |
| 38 | * that have the same key in a list. |
| 39 | */ |
| 40 | |
| 41 | /** |
| 42 | * If this constant is used as keylen, then the key is interpreted as |
| 43 | * NULL terminated string. |
| 44 | */ |
| 45 | #define PJ_HASH_KEY_STRING ((unsigned)-1) |
| 46 | |
| 47 | /** |
| 48 | * This is the function that is used by the hash table to calculate hash value |
| 49 | * of the specified key. |
| 50 | * |
| 51 | * @param hval the initial hash value, or zero. |
| 52 | * @param key the key to calculate. |
| 53 | * @param keylen the length of the key, or PJ_HASH_KEY_STRING to treat |
| 54 | * the key as null terminated string. |
| 55 | * |
| 56 | * @return the hash value. |
| 57 | */ |
| 58 | PJ_DECL(pj_uint32_t) pj_hash_calc(pj_uint32_t hval, |
| 59 | const void *key, unsigned keylen); |
| 60 | |
| 61 | |
| 62 | /** |
| 63 | * Convert the key to lowercase and calculate the hash value. The resulting |
| 64 | * string is stored in \c result. |
| 65 | * |
| 66 | * @param hval The initial hash value, normally zero. |
| 67 | * @param result Buffer to store the result, which must be enough to hold |
| 68 | * the string. |
| 69 | * @param key The input key to be converted and calculated. |
| 70 | * |
| 71 | * @return The hash value. |
| 72 | */ |
| 73 | PJ_DECL(pj_uint32_t) pj_hash_calc_tolower(pj_uint32_t hval, |
| 74 | char *result, |
| 75 | const pj_str_t *key); |
| 76 | |
| 77 | /** |
| 78 | * Create a hash table with the specified 'bucket' size. |
| 79 | * |
| 80 | * @param pool the pool from which the hash table will be allocated from. |
| 81 | * @param size the bucket size, which will be round-up to the nearest 2^n+1 |
| 82 | * |
| 83 | * @return the hash table. |
| 84 | */ |
| 85 | PJ_DECL(pj_hash_table_t*) pj_hash_create(pj_pool_t *pool, unsigned size); |
| 86 | |
| 87 | |
| 88 | /** |
| 89 | * Get the value associated with the specified key. |
| 90 | * |
| 91 | * @param ht the hash table. |
| 92 | * @param key the key to look for. |
| 93 | * @param keylen the length of the key, or PJ_HASH_KEY_STRING to use the |
| 94 | * string length of the key. |
| 95 | * |
| 96 | * @return the value associated with the key, or NULL if the key is not found. |
| 97 | */ |
| 98 | PJ_DECL(void *) pj_hash_get( pj_hash_table_t *ht, |
| 99 | const void *key, unsigned keylen ); |
| 100 | |
| 101 | |
| 102 | /** |
| 103 | * Associate/disassociate a value with the specified key. |
| 104 | * |
| 105 | * @param pool the pool to allocate the new entry if a new entry has to be |
| 106 | * created. |
| 107 | * @param ht the hash table. |
| 108 | * @param key the key. |
| 109 | * @param keylen the length of the key, or PJ_HASH_KEY_STRING to use the |
| 110 | * string length of the key. |
| 111 | * @param value value to be associated, or NULL to delete the entry with |
| 112 | * the specified key. |
| 113 | */ |
| 114 | PJ_DECL(void) pj_hash_set( pj_pool_t *pool, pj_hash_table_t *ht, |
| 115 | const void *key, unsigned keylen, |
| 116 | void *value ); |
| 117 | |
| 118 | /** |
| 119 | * Get the total number of entries in the hash table. |
| 120 | * |
| 121 | * @param ht the hash table. |
| 122 | * |
| 123 | * @return the number of entries in the hash table. |
| 124 | */ |
| 125 | PJ_DECL(unsigned) pj_hash_count( pj_hash_table_t *ht ); |
| 126 | |
| 127 | |
| 128 | /** |
| 129 | * Get the iterator to the first element in the hash table. |
| 130 | * |
| 131 | * @param ht the hash table. |
| 132 | * @param it the iterator for iterating hash elements. |
| 133 | * |
| 134 | * @return the iterator to the hash element, or NULL if no element presents. |
| 135 | */ |
| 136 | PJ_DECL(pj_hash_iterator_t*) pj_hash_first( pj_hash_table_t *ht, |
| 137 | pj_hash_iterator_t *it ); |
| 138 | |
| 139 | |
| 140 | /** |
| 141 | * Get the next element from the iterator. |
| 142 | * |
| 143 | * @param ht the hash table. |
| 144 | * @param it the hash iterator. |
| 145 | * |
| 146 | * @return the next iterator, or NULL if there's no more element. |
| 147 | */ |
| 148 | PJ_DECL(pj_hash_iterator_t*) pj_hash_next( pj_hash_table_t *ht, |
| 149 | pj_hash_iterator_t *it ); |
| 150 | |
| 151 | /** |
| 152 | * Get the value associated with a hash iterator. |
| 153 | * |
| 154 | * @param ht the hash table. |
| 155 | * @param it the hash iterator. |
| 156 | * |
| 157 | * @return the value associated with the current element in iterator. |
| 158 | */ |
| 159 | PJ_DECL(void*) pj_hash_this( pj_hash_table_t *ht, |
| 160 | pj_hash_iterator_t *it ); |
| 161 | |
| 162 | |
| 163 | /** |
| 164 | * @} |
| 165 | */ |
| 166 | |
| 167 | PJ_END_DECL |
| 168 | |
| 169 | #endif |
| 170 | |
| 171 | |