Main Page | Modules | Data Structures | File List | Data Fields | Globals | Related Pages

apr_hash.h

Go to the documentation of this file.
00001 /* Copyright 2000-2005 The Apache Software Foundation or its licensors, as 00002 * applicable. 00003 * 00004 * Licensed under the Apache License, Version 2.0 (the "License"); 00005 * you may not use this file except in compliance with the License. 00006 * You may obtain a copy of the License at 00007 * 00008 * http://www.apache.org/licenses/LICENSE-2.0 00009 * 00010 * Unless required by applicable law or agreed to in writing, software 00011 * distributed under the License is distributed on an "AS IS" BASIS, 00012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 00013 * See the License for the specific language governing permissions and 00014 * limitations under the License. 00015 */ 00016 00017 #ifndef APR_HASH_H 00018 #define APR_HASH_H 00019 00020 /** 00021 * @file apr_hash.h 00022 * @brief APR Hash Tables 00023 */ 00024 00025 #include "apr_pools.h" 00026 00027 #ifdef __cplusplus 00028 extern "C" { 00029 #endif 00030 00031 /** 00032 * @defgroup apr_hash Hash Tables 00033 * @ingroup APR 00034 * @{ 00035 */ 00036 00037 /** 00038 * When passing a key to apr_hash_set or apr_hash_get, this value can be 00039 * passed to indicate a string-valued key, and have apr_hash compute the 00040 * length automatically. 00041 * 00042 * @remark apr_hash will use strlen(key) for the length. The NUL terminator 00043 * is not included in the hash value (why throw a constant in?). 00044 * Since the hash table merely references the provided key (rather 00045 * than copying it), apr_hash_this() will return the NUL-term'd key. 00046 */ 00047 #define APR_HASH_KEY_STRING (-1) 00048 00049 /** 00050 * Abstract type for hash tables. 00051 */ 00052 typedef struct apr_hash_t apr_hash_t; 00053 00054 /** 00055 * Abstract type for scanning hash tables. 00056 */ 00057 typedef struct apr_hash_index_t apr_hash_index_t; 00058 00059 /** 00060 * Callback functions for calculating hash values. 00061 * @param key The key. 00062 * @param klen The length of the key, or APR_HASH_KEY_STRING to use the string 00063 * length. If APR_HASH_KEY_STRING then returns the actual key length. 00064 */ 00065 typedef unsigned int (*apr_hashfunc_t)(const char *key, apr_ssize_t *klen); 00066 00067 /** 00068 * The default hash function. 00069 */ 00070 unsigned int apr_hashfunc_default(const char *key, apr_ssize_t *klen); 00071 00072 /** 00073 * Create a hash table. 00074 * @param pool The pool to allocate the hash table out of 00075 * @return The hash table just created 00076 */ 00077 APR_DECLARE(apr_hash_t *) apr_hash_make(apr_pool_t *pool); 00078 00079 /** 00080 * Create a hash table with a custom hash function 00081 * @param pool The pool to allocate the hash table out of 00082 * @param hash_func A custom hash function. 00083 * @return The hash table just created 00084 */ 00085 APR_DECLARE(apr_hash_t *) apr_hash_make_custom(apr_pool_t *pool, 00086 apr_hashfunc_t hash_func); 00087 00088 /** 00089 * Make a copy of a hash table 00090 * @param pool The pool from which to allocate the new hash table 00091 * @param h The hash table to clone 00092 * @return The hash table just created 00093 * @remark Makes a shallow copy 00094 */ 00095 APR_DECLARE(apr_hash_t *) apr_hash_copy(apr_pool_t *pool, 00096 const apr_hash_t *h); 00097 00098 /** 00099 * Associate a value with a key in a hash table. 00100 * @param ht The hash table 00101 * @param key Pointer to the key 00102 * @param klen Length of the key. Can be APR_HASH_KEY_STRING to use the string length. 00103 * @param val Value to associate with the key 00104 * @remark If the value is NULL the hash entry is deleted. 00105 */ 00106 APR_DECLARE(void) apr_hash_set(apr_hash_t *ht, const void *key, 00107 apr_ssize_t klen, const void *val); 00108 00109 /** 00110 * Look up the value associated with a key in a hash table. 00111 * @param ht The hash table 00112 * @param key Pointer to the key 00113 * @param klen Length of the key. Can be APR_HASH_KEY_STRING to use the string length. 00114 * @return Returns NULL if the key is not present. 00115 */ 00116 APR_DECLARE(void *) apr_hash_get(apr_hash_t *ht, const void *key, 00117 apr_ssize_t klen); 00118 00119 /** 00120 * Start iterating over the entries in a hash table. 00121 * @param p The pool to allocate the apr_hash_index_t iterator. If this 00122 * pool is NULL, then an internal, non-thread-safe iterator is used. 00123 * @param ht The hash table 00124 * @remark There is no restriction on adding or deleting hash entries during 00125 * an iteration (although the results may be unpredictable unless all you do 00126 * is delete the current entry) and multiple iterations can be in 00127 * progress at the same time. 00128 00129 * @example 00130 */ 00131 /** 00132 * <PRE> 00133 * 00134 * int sum_values(apr_pool_t *p, apr_hash_t *ht) 00135 * { 00136 * apr_hash_index_t *hi; 00137 * void *val; 00138 * int sum = 0; 00139 * for (hi = apr_hash_first(p, ht); hi; hi = apr_hash_next(hi)) { 00140 * apr_hash_this(hi, NULL, NULL, &val); 00141 * sum += *(int *)val; 00142 * } 00143 * return sum; 00144 * } 00145 * </PRE> 00146 */ 00147 APR_DECLARE(apr_hash_index_t *) apr_hash_first(apr_pool_t *p, apr_hash_t *ht); 00148 00149 /** 00150 * Continue iterating over the entries in a hash table. 00151 * @param hi The iteration state 00152 * @return a pointer to the updated iteration state. NULL if there are no more 00153 * entries. 00154 */ 00155 APR_DECLARE(apr_hash_index_t *) apr_hash_next(apr_hash_index_t *hi); 00156 00157 /** 00158 * Get the current entry's details from the iteration state. 00159 * @param hi The iteration state 00160 * @param key Return pointer for the pointer to the key. 00161 * @param klen Return pointer for the key length. 00162 * @param val Return pointer for the associated value. 00163 * @remark The return pointers should point to a variable that will be set to the 00164 * corresponding data, or they may be NULL if the data isn't interesting. 00165 */ 00166 APR_DECLARE(void) apr_hash_this(apr_hash_index_t *hi, const void **key, 00167 apr_ssize_t *klen, void **val); 00168 00169 /** 00170 * Get the number of key/value pairs in the hash table. 00171 * @param ht The hash table 00172 * @return The number of key/value pairs in the hash table. 00173 */ 00174 APR_DECLARE(unsigned int) apr_hash_count(apr_hash_t *ht); 00175 00176 /** 00177 * Merge two hash tables into one new hash table. The values of the overlay 00178 * hash override the values of the base if both have the same key. Both 00179 * hash tables must use the same hash function. 00180 * @param p The pool to use for the new hash table 00181 * @param overlay The table to add to the initial table 00182 * @param base The table that represents the initial values of the new table 00183 * @return A new hash table containing all of the data from the two passed in 00184 */ 00185 APR_DECLARE(apr_hash_t *) apr_hash_overlay(apr_pool_t *p, 00186 const apr_hash_t *overlay, 00187 const apr_hash_t *base); 00188 00189 /** 00190 * Merge two hash tables into one new hash table. If the same key 00191 * is present in both tables, call the supplied merge function to 00192 * produce a merged value for the key in the new table. Both 00193 * hash tables must use the same hash function. 00194 * @param p The pool to use for the new hash table 00195 * @param h1 The first of the tables to merge 00196 * @param h2 The second of the tables to merge 00197 * @param merger A callback function to merge values, or NULL to 00198 * make values from h1 override values from h2 (same semantics as 00199 * apr_hash_overlay()) 00200 * @param data Client data to pass to the merger function 00201 * @return A new hash table containing all of the data from the two passed in 00202 */ 00203 APR_DECLARE(apr_hash_t *) apr_hash_merge(apr_pool_t *p, 00204 const apr_hash_t *h1, 00205 const apr_hash_t *h2, 00206 void * (*merger)(apr_pool_t *p, 00207 const void *key, 00208 apr_ssize_t klen, 00209 const void *h1_val, 00210 const void *h2_val, 00211 const void *data), 00212 const void *data); 00213 00214 /** 00215 * Get a pointer to the pool which the hash table was created in 00216 */ 00217 APR_POOL_DECLARE_ACCESSOR(hash); 00218 00219 /** @} */ 00220 00221 #ifdef __cplusplus 00222 } 00223 #endif 00224 00225 #endif /* !APR_HASH_H */

Generated on Sun Nov 20 18:49:39 2005 for Apache Portable Runtime by doxygen 1.3.8