1 /* Licensed to the Apache Software Foundation (ASF) under one or more 2 * contributor license agreements. See the NOTICE file distributed with 3 * this work for additional information regarding copyright ownership. 4 * The ASF licenses this file to You under the Apache License, Version 2.0 5 * (the "License"); you may not use this file except in compliance with 6 * the License. You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef APR_HASH_H 18 #define APR_HASH_H 19 20 /** 21 * @file apr_hash.h 22 * @brief APR Hash Tables 23 */ 24 25 #include "apr_pools.h" 26 27 #ifdef __cplusplus 28 extern "C" { 29 #endif 30 31 /** 32 * @defgroup apr_hash Hash Tables 33 * @ingroup APR 34 * @{ 35 */ 36 37 /** 38 * When passing a key to apr_hash_set or apr_hash_get, this value can be 39 * passed to indicate a string-valued key, and have apr_hash compute the 40 * length automatically. 41 * 42 * @remark apr_hash will use strlen(key) for the length. The NUL terminator 43 * is not included in the hash value (why throw a constant in?). 44 * Since the hash table merely references the provided key (rather 45 * than copying it), apr_hash_this() will return the NUL-term'd key. 46 */ 47 #define APR_HASH_KEY_STRING (-1) 48 49 /** 50 * Abstract type for hash tables. 51 */ 52 typedef struct apr_hash_t apr_hash_t; 53 54 /** 55 * Abstract type for scanning hash tables. 56 */ 57 typedef struct apr_hash_index_t apr_hash_index_t; 58 59 /** 60 * Callback functions for calculating hash values. 61 * @param key The key. 62 * @param klen The length of the key, or APR_HASH_KEY_STRING to use the string 63 * length. If APR_HASH_KEY_STRING then returns the actual key length. 64 */ 65 typedef unsigned int (*apr_hashfunc_t)(const char *key, apr_ssize_t *klen); 66 67 /** 68 * The default hash function. 69 */ 70 APR_DECLARE_NONSTD(unsigned int) apr_hashfunc_default(const char *key, 71 apr_ssize_t *klen); 72 73 /** 74 * Create a hash table. 75 * @param pool The pool to allocate the hash table out of 76 * @return The hash table just created 77 */ 78 APR_DECLARE(apr_hash_t *) apr_hash_make(apr_pool_t *pool); 79 80 /** 81 * Create a hash table with a custom hash function 82 * @param pool The pool to allocate the hash table out of 83 * @param hash_func A custom hash function. 84 * @return The hash table just created 85 */ 86 APR_DECLARE(apr_hash_t *) apr_hash_make_custom(apr_pool_t *pool, 87 apr_hashfunc_t hash_func); 88 89 /** 90 * Make a copy of a hash table 91 * @param pool The pool from which to allocate the new hash table 92 * @param h The hash table to clone 93 * @return The hash table just created 94 * @remark Makes a shallow copy 95 */ 96 APR_DECLARE(apr_hash_t *) apr_hash_copy(apr_pool_t *pool, 97 const apr_hash_t *h); 98 99 /** 100 * Associate a value with a key in a hash table. 101 * @param ht The hash table 102 * @param key Pointer to the key 103 * @param klen Length of the key. Can be APR_HASH_KEY_STRING to use the string length. 104 * @param val Value to associate with the key 105 * @remark If the value is NULL the hash entry is deleted. 106 */ 107 APR_DECLARE(void) apr_hash_set(apr_hash_t *ht, const void *key, 108 apr_ssize_t klen, const void *val); 109 110 /** 111 * Look up the value associated with a key in a hash table. 112 * @param ht The hash table 113 * @param key Pointer to the key 114 * @param klen Length of the key. Can be APR_HASH_KEY_STRING to use the string length. 115 * @return Returns NULL if the key is not present. 116 */ 117 APR_DECLARE(void *) apr_hash_get(apr_hash_t *ht, const void *key, 118 apr_ssize_t klen); 119 120 /** 121 * Start iterating over the entries in a hash table. 122 * @param p The pool to allocate the apr_hash_index_t iterator. If this 123 * pool is NULL, then an internal, non-thread-safe iterator is used. 124 * @param ht The hash table 125 * @return The iteration state 126 * @remark There is no restriction on adding or deleting hash entries during 127 * an iteration (although the results may be unpredictable unless all you do 128 * is delete the current entry) and multiple iterations can be in 129 * progress at the same time. 130 * 131 * @par Example: 132 * 133 * @code 134 * int sum_values(apr_pool_t *p, apr_hash_t *ht) 135 * { 136 * apr_hash_index_t *hi; 137 * void *val; 138 * int sum = 0; 139 * for (hi = apr_hash_first(p, ht); hi; hi = apr_hash_next(hi)) { 140 * apr_hash_this(hi, NULL, NULL, &val); 141 * sum += *(int *)val; 142 * } 143 * return sum; 144 * } 145 * @endcode 146 */ 147 APR_DECLARE(apr_hash_index_t *) apr_hash_first(apr_pool_t *p, apr_hash_t *ht); 148 149 /** 150 * Continue iterating over the entries in a hash table. 151 * @param hi The iteration state 152 * @return a pointer to the updated iteration state. NULL if there are no more 153 * entries. 154 */ 155 APR_DECLARE(apr_hash_index_t *) apr_hash_next(apr_hash_index_t *hi); 156 157 /** 158 * Get the current entry's details from the iteration state. 159 * @param hi The iteration state 160 * @param key Return pointer for the pointer to the key. 161 * @param klen Return pointer for the key length. 162 * @param val Return pointer for the associated value. 163 * @remark The return pointers should point to a variable that will be set to the 164 * corresponding data, or they may be NULL if the data isn't interesting. 165 */ 166 APR_DECLARE(void) apr_hash_this(apr_hash_index_t *hi, const void **key, 167 apr_ssize_t *klen, void **val); 168 169 /** 170 * Get the current entry's key from the iteration state. 171 * @param hi The iteration state 172 * @return The pointer to the key 173 */ 174 APR_DECLARE(const void*) apr_hash_this_key(apr_hash_index_t *hi); 175 176 /** 177 * Get the current entry's key length from the iteration state. 178 * @param hi The iteration state 179 * @return The key length 180 */ 181 APR_DECLARE(apr_ssize_t) apr_hash_this_key_len(apr_hash_index_t *hi); 182 183 /** 184 * Get the current entry's value from the iteration state. 185 * @param hi The iteration state 186 * @return The pointer to the value 187 */ 188 APR_DECLARE(void*) apr_hash_this_val(apr_hash_index_t *hi); 189 190 /** 191 * Get the number of key/value pairs in the hash table. 192 * @param ht The hash table 193 * @return The number of key/value pairs in the hash table. 194 */ 195 APR_DECLARE(unsigned int) apr_hash_count(apr_hash_t *ht); 196 197 /** 198 * Clear any key/value pairs in the hash table. 199 * @param ht The hash table 200 */ 201 APR_DECLARE(void) apr_hash_clear(apr_hash_t *ht); 202 203 /** 204 * Merge two hash tables into one new hash table. The values of the overlay 205 * hash override the values of the base if both have the same key. Both 206 * hash tables must use the same hash function. 207 * @param p The pool to use for the new hash table 208 * @param overlay The table to add to the initial table 209 * @param base The table that represents the initial values of the new table 210 * @return A new hash table containing all of the data from the two passed in 211 */ 212 APR_DECLARE(apr_hash_t *) apr_hash_overlay(apr_pool_t *p, 213 const apr_hash_t *overlay, 214 const apr_hash_t *base); 215 216 /** 217 * Merge two hash tables into one new hash table. If the same key 218 * is present in both tables, call the supplied merge function to 219 * produce a merged value for the key in the new table. Both 220 * hash tables must use the same hash function. 221 * @param p The pool to use for the new hash table 222 * @param h1 The first of the tables to merge 223 * @param h2 The second of the tables to merge 224 * @param merger A callback function to merge values, or NULL to 225 * make values from h1 override values from h2 (same semantics as 226 * apr_hash_overlay()) 227 * @param data Client data to pass to the merger function 228 * @return A new hash table containing all of the data from the two passed in 229 */ 230 APR_DECLARE(apr_hash_t *) apr_hash_merge(apr_pool_t *p, 231 const apr_hash_t *h1, 232 const apr_hash_t *h2, 233 void * (*merger)(apr_pool_t *p, 234 const void *key, 235 apr_ssize_t klen, 236 const void *h1_val, 237 const void *h2_val, 238 const void *data), 239 const void *data); 240 241 /** 242 * Declaration prototype for the iterator callback function of apr_hash_do(). 243 * 244 * @param rec The data passed as the first argument to apr_hash_[v]do() 245 * @param key The key from this iteration of the hash table 246 * @param klen The key length from this iteration of the hash table 247 * @param value The value from this iteration of the hash table 248 * @remark Iteration continues while this callback function returns non-zero. 249 * To export the callback function for apr_hash_do() it must be declared 250 * in the _NONSTD convention. 251 */ 252 typedef int (apr_hash_do_callback_fn_t)(void *rec, const void *key, 253 apr_ssize_t klen, 254 const void *value); 255 256 /** 257 * Iterate over a hash table running the provided function once for every 258 * element in the hash table. The @param comp function will be invoked for 259 * every element in the hash table. 260 * 261 * @param comp The function to run 262 * @param rec The data to pass as the first argument to the function 263 * @param ht The hash table to iterate over 264 * @return FALSE if one of the comp() iterations returned zero; TRUE if all 265 * iterations returned non-zero 266 * @see apr_hash_do_callback_fn_t 267 */ 268 APR_DECLARE(int) apr_hash_do(apr_hash_do_callback_fn_t *comp, 269 void *rec, const apr_hash_t *ht); 270 271 /** 272 * Get a pointer to the pool which the hash table was created in 273 */ 274 APR_POOL_DECLARE_ACCESSOR(hash); 275 276 /** @} */ 277 278 #ifdef __cplusplus 279 } 280 #endif 281 282 #endif /* !APR_HASH_H */ 283