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/* 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
* @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.
* @example
*/
/**
* <PRE>
*
* 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;
* }
* </PRE>
*/
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);
/**
* 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);
/**
* 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 */
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