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 28extern "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 */ 52typedef struct apr_hash_t apr_hash_t; 53 54/** 55 * Abstract type for scanning hash tables. 56 */ 57typedef 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 */ 65typedef unsigned int (*apr_hashfunc_t)(const char *key, apr_ssize_t *klen); 66 67/** 68 * The default hash function. 69 */ 70APR_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 */ 78APR_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 */ 86APR_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 */ 96APR_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. The key is stored as is, 106 * and so must have a lifetime at least as long as the hash table's pool. 107 */ 108APR_DECLARE(void) apr_hash_set(apr_hash_t *ht, const void *key, 109 apr_ssize_t klen, const void *val); 110 111/** 112 * Look up the value associated with a key in a hash table. 113 * @param ht The hash table 114 * @param key Pointer to the key 115 * @param klen Length of the key. Can be APR_HASH_KEY_STRING to use the string length. 116 * @return Returns NULL if the key is not present. 117 */ 118APR_DECLARE(void *) apr_hash_get(apr_hash_t *ht, const void *key, 119 apr_ssize_t klen); 120 121/** 122 * Start iterating over the entries in a hash table. 123 * @param p The pool to allocate the apr_hash_index_t iterator. If this 124 * pool is NULL, then an internal, non-thread-safe iterator is used. 125 * @param ht The hash table 126 * @return The iteration state 127 * @remark There is no restriction on adding or deleting hash entries during 128 * an iteration (although the results may be unpredictable unless all you do 129 * is delete the current entry) and multiple iterations can be in 130 * progress at the same time. 131 * 132 * @par Example: 133 * 134 * @code 135 * int sum_values(apr_pool_t *p, apr_hash_t *ht) 136 * { 137 * apr_hash_index_t *hi; 138 * void *val; 139 * int sum = 0; 140 * for (hi = apr_hash_first(p, ht); hi; hi = apr_hash_next(hi)) { 141 * apr_hash_this(hi, NULL, NULL, &val); 142 * sum += *(int *)val; 143 * } 144 * return sum; 145 * } 146 * @endcode 147 */ 148APR_DECLARE(apr_hash_index_t *) apr_hash_first(apr_pool_t *p, apr_hash_t *ht); 149 150/** 151 * Continue iterating over the entries in a hash table. 152 * @param hi The iteration state 153 * @return a pointer to the updated iteration state. NULL if there are no more 154 * entries. 155 */ 156APR_DECLARE(apr_hash_index_t *) apr_hash_next(apr_hash_index_t *hi); 157 158/** 159 * Get the current entry's details from the iteration state. 160 * @param hi The iteration state 161 * @param key Return pointer for the pointer to the key. 162 * @param klen Return pointer for the key length. 163 * @param val Return pointer for the associated value. 164 * @remark The return pointers should point to a variable that will be set to the 165 * corresponding data, or they may be NULL if the data isn't interesting. 166 */ 167APR_DECLARE(void) apr_hash_this(apr_hash_index_t *hi, const void **key, 168 apr_ssize_t *klen, void **val); 169 170/** 171 * Get the current entry's key from the iteration state. 172 * @param hi The iteration state 173 * @return The pointer to the key 174 */ 175APR_DECLARE(const void*) apr_hash_this_key(apr_hash_index_t *hi); 176 177/** 178 * Get the current entry's key length from the iteration state. 179 * @param hi The iteration state 180 * @return The key length 181 */ 182APR_DECLARE(apr_ssize_t) apr_hash_this_key_len(apr_hash_index_t *hi); 183 184/** 185 * Get the current entry's value from the iteration state. 186 * @param hi The iteration state 187 * @return The pointer to the value 188 */ 189APR_DECLARE(void*) apr_hash_this_val(apr_hash_index_t *hi); 190 191/** 192 * Get the number of key/value pairs in the hash table. 193 * @param ht The hash table 194 * @return The number of key/value pairs in the hash table. 195 */ 196APR_DECLARE(unsigned int) apr_hash_count(apr_hash_t *ht); 197 198/** 199 * Clear any key/value pairs in the hash table. 200 * @param ht The hash table 201 */ 202APR_DECLARE(void) apr_hash_clear(apr_hash_t *ht); 203 204/** 205 * Merge two hash tables into one new hash table. The values of the overlay 206 * hash override the values of the base if both have the same key. Both 207 * hash tables must use the same hash function. 208 * @param p The pool to use for the new hash table 209 * @param overlay The table to add to the initial table 210 * @param base The table that represents the initial values of the new table 211 * @return A new hash table containing all of the data from the two passed in 212 */ 213APR_DECLARE(apr_hash_t *) apr_hash_overlay(apr_pool_t *p, 214 const apr_hash_t *overlay, 215 const apr_hash_t *base); 216 217/** 218 * Merge two hash tables into one new hash table. If the same key 219 * is present in both tables, call the supplied merge function to 220 * produce a merged value for the key in the new table. Both 221 * hash tables must use the same hash function. 222 * @param p The pool to use for the new hash table 223 * @param h1 The first of the tables to merge 224 * @param h2 The second of the tables to merge 225 * @param merger A callback function to merge values, or NULL to 226 * make values from h1 override values from h2 (same semantics as 227 * apr_hash_overlay()) 228 * @param data Client data to pass to the merger function 229 * @return A new hash table containing all of the data from the two passed in 230 */ 231APR_DECLARE(apr_hash_t *) apr_hash_merge(apr_pool_t *p, 232 const apr_hash_t *h1, 233 const apr_hash_t *h2, 234 void * (*merger)(apr_pool_t *p, 235 const void *key, 236 apr_ssize_t klen, 237 const void *h1_val, 238 const void *h2_val, 239 const void *data), 240 const void *data); 241 242/** 243 * Declaration prototype for the iterator callback function of apr_hash_do(). 244 * 245 * @param rec The data passed as the first argument to apr_hash_[v]do() 246 * @param key The key from this iteration of the hash table 247 * @param klen The key length from this iteration of the hash table 248 * @param value The value from this iteration of the hash table 249 * @remark Iteration continues while this callback function returns non-zero. 250 * To export the callback function for apr_hash_do() it must be declared 251 * in the _NONSTD convention. 252 */ 253typedef int (apr_hash_do_callback_fn_t)(void *rec, const void *key, 254 apr_ssize_t klen, 255 const void *value); 256 257/** 258 * Iterate over a hash table running the provided function once for every 259 * element in the hash table. The @param comp function will be invoked for 260 * every element in the hash table. 261 * 262 * @param comp The function to run 263 * @param rec The data to pass as the first argument to the function 264 * @param ht The hash table to iterate over 265 * @return FALSE if one of the comp() iterations returned zero; TRUE if all 266 * iterations returned non-zero 267 * @see apr_hash_do_callback_fn_t 268 */ 269APR_DECLARE(int) apr_hash_do(apr_hash_do_callback_fn_t *comp, 270 void *rec, const apr_hash_t *ht); 271 272/** 273 * Get a pointer to the pool which the hash table was created in 274 */ 275APR_POOL_DECLARE_ACCESSOR(hash); 276 277/** @} */ 278 279#ifdef __cplusplus 280} 281#endif 282 283#endif /* !APR_HASH_H */ 284