Hash Tables
[Apache Portability Runtime library]

Defines
#define	APR_HASH_KEY_STRING   (-1)
Typedefs
typedef apr_hash_t	apr_hash_t
typedef apr_hash_index_t	apr_hash_index_t
Functions
apr_hash_t *	apr_hash_make (apr_pool_t *pool)
apr_hash_t *	apr_hash_copy (apr_pool_t *pool, const apr_hash_t *h)
void	apr_hash_set (apr_hash_t *ht, const void *key, apr_ssize_t klen, const void *val)
void *	apr_hash_get (apr_hash_t *ht, const void *key, apr_ssize_t klen)
apr_hash_index_t *	apr_hash_first (apr_pool_t *p, apr_hash_t *ht)
apr_hash_index_t *	apr_hash_next (apr_hash_index_t *hi)
void	apr_hash_this (apr_hash_index_t *hi, const void **key, apr_ssize_t *klen, void **val)
unsigned int	apr_hash_count (apr_hash_t *ht)
apr_hash_t *	apr_hash_overlay (apr_pool_t *p, const apr_hash_t *overlay, const apr_hash_t *base)
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)
apr_pool_t *	apr_hash_pool_get (const apr_hash_t *thehash)

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Define Documentation

#define APR_HASH_KEY_STRING   (-1)

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. Remarks: apr_hash will use strlen(key) for the length. The null-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 null-term'd key.

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Typedef Documentation

typedef struct apr_hash_index_t apr_hash_index_t

Abstract type for scanning hash tables.

typedef struct apr_hash_t apr_hash_t

Abstract type for hash tables.

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Function Documentation

apr_hash_t* apr_hash_copy (  apr_pool_t *  pool, const apr_hash_t *  h )

Make a copy of a hash table Parameters: pool  The pool from which to allocate the new hash table h  The hash table to clone Returns: The hash table just created Remarks: Makes a shallow copy

unsigned int apr_hash_count (  apr_hash_t *  ht  )

Get the number of key/value pairs in the hash table. Parameters: ht  The hash table Returns: The number of key/value pairs in the hash table.

apr_hash_index_t* apr_hash_first (  apr_pool_t *  p, apr_hash_t *  ht )

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; }

void* apr_hash_get (  apr_hash_t *  ht, const void *  key, apr_ssize_t  klen )

Look up the value associated with a key in a hash table. Parameters: ht  The hash table key  Pointer to the key klen  Length of the key. Can be APR_HASH_KEY_STRING to use the string length. Returns: Returns NULL if the key is not present.

apr_hash_t* apr_hash_make (  apr_pool_t *  pool  )

Create a hash table. Parameters: pool  The pool to allocate the hash table out of Returns: The hash table just created

apr_hash_t* apr_hash_merge (  apr_pool_t *  p, const apr_hash_t *  h1, const apr_hash_t *  h2, void *(*)(apr_pool_t *p, const void *key, apr_ssize_t klen, const void *h1_val, const void *h2_val, const void *data)  merger, const void *  data )

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. Parameters: p  The pool to use for the new hash table h1  The first of the tables to merge h2  The second of the tables to merge merger  A callback function to merge values, or NULL to make values from h1 override values from h2 (same semantics as apr_hash_overlay()) data  Client data to pass to the merger function Returns: A new hash table containing all of the data from the two passed in

apr_hash_index_t* apr_hash_next (  apr_hash_index_t *  hi  )

Continue iterating over the entries in a hash table. Parameters: hi  The iteration state Returns: a pointer to the updated iteration state. NULL if there are no more entries.

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. The values of the overlay hash override the values of the base if both have the same key. Parameters: p  The pool to use for the new hash table overlay  The table to add to the initial table base  The table that represents the initial values of the new table Returns: A new hash table containing all of the data from the two passed in

apr_pool_t* apr_hash_pool_get (  const apr_hash_t *  thehash  )

Get a pointer to the pool which the hash table was created in

void apr_hash_set (  apr_hash_t *  ht, const void *  key, apr_ssize_t  klen, const void *  val )

Associate a value with a key in a hash table. Parameters: ht  The hash table key  Pointer to the key klen  Length of the key. Can be APR_HASH_KEY_STRING to use the string length. val  Value to associate with the key Remarks: If the value is NULL the hash entry is deleted.

void apr_hash_this (  apr_hash_index_t *  hi, const void **  key, apr_ssize_t *  klen, void **  val )

Get the current entry's details from the iteration state. Parameters: hi  The iteration state key  Return pointer for the pointer to the key. klen  Return pointer for the key length. val  Return pointer for the associated value. Remarks: 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.

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