/* Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #ifndef APR_HASH_H #define APR_HASH_H /** * @file apr_hash.h * @brief APR Hash Tables */ #include "apr_pools.h" #ifdef __cplusplus extern "C" { #endif /** * @defgroup apr_hash Hash Tables * @ingroup APR * @{ */ /** * When passing a key to apr_hash_set or apr_hash_get, this value can be * passed to indicate a string-valued key, and have apr_hash compute the * length automatically. * * @remark apr_hash will use strlen(key) for the length. The NUL terminator * is not included in the hash value (why throw a constant in?). * Since the hash table merely references the provided key (rather * than copying it), apr_hash_this() will return the NUL-term'd key. */ #define APR_HASH_KEY_STRING (-1) /** * Abstract type for hash tables. */ typedef struct apr_hash_t apr_hash_t; /** * Abstract type for scanning hash tables. */ typedef struct apr_hash_index_t apr_hash_index_t; /** * Callback functions for calculating hash values. * @param key The key. * @param klen The length of the key, or APR_HASH_KEY_STRING to use the string * length. If APR_HASH_KEY_STRING then returns the actual key length. */ typedef unsigned int (*apr_hashfunc_t)(const char *key, apr_ssize_t *klen); /** * The default hash function. */ APR_DECLARE_NONSTD(unsigned int) apr_hashfunc_default(const char *key, apr_ssize_t *klen); /** * Create a hash table. * @param pool The pool to allocate the hash table out of * @return The hash table just created */ APR_DECLARE(apr_hash_t *) apr_hash_make(apr_pool_t *pool); /** * Create a hash table with a custom hash function * @param pool The pool to allocate the hash table out of * @param hash_func A custom hash function. * @return The hash table just created */ APR_DECLARE(apr_hash_t *) apr_hash_make_custom(apr_pool_t *pool, apr_hashfunc_t hash_func); /** * Make a copy of a hash table * @param pool The pool from which to allocate the new hash table * @param h The hash table to clone * @return The hash table just created * @remark Makes a shallow copy */ APR_DECLARE(apr_hash_t *) apr_hash_copy(apr_pool_t *pool, const apr_hash_t *h); /** * Associate a value with a key in a hash table. * @param ht The hash table * @param key Pointer to the key * @param klen Length of the key. Can be APR_HASH_KEY_STRING to use the string length. * @param val Value to associate with the key * @remark If the value is NULL the hash entry is deleted. */ APR_DECLARE(void) apr_hash_set(apr_hash_t *ht, const void *key, apr_ssize_t klen, const void *val); /** * Look up the value associated with a key in a hash table. * @param ht The hash table * @param key Pointer to the key * @param klen Length of the key. Can be APR_HASH_KEY_STRING to use the string length. * @return Returns NULL if the key is not present. */ APR_DECLARE(void *) apr_hash_get(apr_hash_t *ht, const void *key, apr_ssize_t klen); /** * Start iterating over the entries in a hash table. * @param p The pool to allocate the apr_hash_index_t iterator. If this * pool is NULL, then an internal, non-thread-safe iterator is used. * @param ht The hash table * @return The iteration state * @remark There is no restriction on adding or deleting hash entries during * an iteration (although the results may be unpredictable unless all you do * is delete the current entry) and multiple iterations can be in * progress at the same time. * * @par Example: * * @code * int sum_values(apr_pool_t *p, apr_hash_t *ht) * { * apr_hash_index_t *hi; * void *val; * int sum = 0; * for (hi = apr_hash_first(p, ht); hi; hi = apr_hash_next(hi)) { * apr_hash_this(hi, NULL, NULL, &val); * sum += *(int *)val; * } * return sum; * } * @endcode */ APR_DECLARE(apr_hash_index_t *) apr_hash_first(apr_pool_t *p, apr_hash_t *ht); /** * Continue iterating over the entries in a hash table. * @param hi The iteration state * @return a pointer to the updated iteration state. NULL if there are no more * entries. */ APR_DECLARE(apr_hash_index_t *) apr_hash_next(apr_hash_index_t *hi); /** * Get the current entry's details from the iteration state. * @param hi The iteration state * @param key Return pointer for the pointer to the key. * @param klen Return pointer for the key length. * @param val Return pointer for the associated value. * @remark The return pointers should point to a variable that will be set to the * corresponding data, or they may be NULL if the data isn't interesting. */ APR_DECLARE(void) apr_hash_this(apr_hash_index_t *hi, const void **key, apr_ssize_t *klen, void **val); /** * Get the number of key/value pairs in the hash table. * @param ht The hash table * @return The number of key/value pairs in the hash table. */ APR_DECLARE(unsigned int) apr_hash_count(apr_hash_t *ht); /** * Clear any key/value pairs in the hash table. * @param ht The hash table */ APR_DECLARE(void) apr_hash_clear(apr_hash_t *ht); /** * Merge two hash tables into one new hash table. The values of the overlay * hash override the values of the base if both have the same key. Both * hash tables must use the same hash function. * @param p The pool to use for the new hash table * @param overlay The table to add to the initial table * @param base The table that represents the initial values of the new table * @return A new hash table containing all of the data from the two passed in */ APR_DECLARE(apr_hash_t *) apr_hash_overlay(apr_pool_t *p, const apr_hash_t *overlay, const apr_hash_t *base); /** * Merge two hash tables into one new hash table. If the same key * is present in both tables, call the supplied merge function to * produce a merged value for the key in the new table. Both * hash tables must use the same hash function. * @param p The pool to use for the new hash table * @param h1 The first of the tables to merge * @param h2 The second of the tables to merge * @param merger A callback function to merge values, or NULL to * make values from h1 override values from h2 (same semantics as * apr_hash_overlay()) * @param data Client data to pass to the merger function * @return A new hash table containing all of the data from the two passed in */ APR_DECLARE(apr_hash_t *) apr_hash_merge(apr_pool_t *p, const apr_hash_t *h1, const apr_hash_t *h2, void * (*merger)(apr_pool_t *p, const void *key, apr_ssize_t klen, const void *h1_val, const void *h2_val, const void *data), const void *data); /** * Declaration prototype for the iterator callback function of apr_hash_do(). * * @param rec The data passed as the first argument to apr_hash_[v]do() * @param key The key from this iteration of the hash table * @param klen The key length from this iteration of the hash table * @param value The value from this iteration of the hash table * @remark Iteration continues while this callback function returns non-zero. * To export the callback function for apr_hash_do() it must be declared * in the _NONSTD convention. */ typedef int (apr_hash_do_callback_fn_t)(void *rec, const void *key, apr_ssize_t klen, const void *value); /** * Iterate over a hash table running the provided function once for every * element in the hash table. The @param comp function will be invoked for * every element in the hash table. * * @param comp The function to run * @param rec The data to pass as the first argument to the function * @param ht The hash table to iterate over * @return FALSE if one of the comp() iterations returned zero; TRUE if all * iterations returned non-zero * @see apr_hash_do_callback_fn_t */ APR_DECLARE(int) apr_hash_do(apr_hash_do_callback_fn_t *comp, void *rec, const apr_hash_t *ht); /** * Get a pointer to the pool which the hash table was created in */ APR_POOL_DECLARE_ACCESSOR(hash); /** @} */ #ifdef __cplusplus } #endif #endif /* !APR_HASH_H */