143 lines
3.5 KiB
C
143 lines
3.5 KiB
C
/* $Id$
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*
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*/
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#ifndef __PJ_HASH_H__
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#define __PJ_HASH_H__
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/**
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* @file hash.h
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* @brief Hash Table.
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*/
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#include <pj/types.h>
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PJ_BEGIN_DECL
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/**
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* @defgroup PJ_HASH Hash Table
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* @ingroup PJ_DS
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* @{
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* A hash table is a dictionary in which keys are mapped to array positions by
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* hash functions. Having the keys of more than one item map to the same
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* position is called a collision. In this library, we will chain the nodes
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* that have the same key in a list.
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*/
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/**
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* If this constant is used as keylen, then the key is interpreted as
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* NULL terminated string.
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*/
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#define PJ_HASH_KEY_STRING ((unsigned)-1)
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/**
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* This is the function that is used by the hash table to calculate hash value
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* of the specified key.
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*
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* @param hval the initial hash value, or zero.
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* @param key the key to calculate.
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* @param keylen the length of the key, or PJ_HASH_KEY_STRING to treat
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* the key as null terminated string.
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*
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* @return the hash value.
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*/
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PJ_DECL(pj_uint32_t) pj_hash_calc(pj_uint32_t hval,
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const void *key, unsigned keylen);
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/**
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* Create a hash table with the specified 'bucket' size.
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*
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* @param pool the pool from which the hash table will be allocated from.
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* @param size the bucket size, which will be round-up to the nearest 2^n+1
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*
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* @return the hash table.
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*/
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PJ_DECL(pj_hash_table_t*) pj_hash_create(pj_pool_t *pool, unsigned size);
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/**
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* Get the value associated with the specified key.
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*
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* @param ht the hash table.
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* @param key the key to look for.
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* @param keylen the length of the key, or PJ_HASH_KEY_STRING to use the
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* string length of the key.
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*
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* @return the value associated with the key, or NULL if the key is not found.
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*/
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PJ_DECL(void *) pj_hash_get( pj_hash_table_t *ht,
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const void *key, unsigned keylen );
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/**
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* Associate/disassociate a value with the specified key.
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*
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* @param pool the pool to allocate the new entry if a new entry has to be
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* created.
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* @param ht the hash table.
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* @param key the key.
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* @param keylen the length of the key, or PJ_HASH_KEY_STRING to use the
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* string length of the key.
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* @param value value to be associated, or NULL to delete the entry with
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* the specified key.
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*/
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PJ_DECL(void) pj_hash_set( pj_pool_t *pool, pj_hash_table_t *ht,
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const void *key, unsigned keylen,
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void *value );
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/**
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* Get the total number of entries in the hash table.
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*
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* @param ht the hash table.
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*
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* @return the number of entries in the hash table.
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*/
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PJ_DECL(unsigned) pj_hash_count( pj_hash_table_t *ht );
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/**
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* Get the iterator to the first element in the hash table.
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*
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* @param ht the hash table.
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* @param it the iterator for iterating hash elements.
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*
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* @return the iterator to the hash element, or NULL if no element presents.
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*/
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PJ_DECL(pj_hash_iterator_t*) pj_hash_first( pj_hash_table_t *ht,
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pj_hash_iterator_t *it );
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/**
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* Get the next element from the iterator.
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*
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* @param ht the hash table.
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* @param it the hash iterator.
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*
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* @return the next iterator, or NULL if there's no more element.
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*/
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PJ_DECL(pj_hash_iterator_t*) pj_hash_next( pj_hash_table_t *ht,
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pj_hash_iterator_t *it );
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/**
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* Get the value associated with a hash iterator.
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*
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* @param ht the hash table.
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* @param it the hash iterator.
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*
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* @return the value associated with the current element in iterator.
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*/
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PJ_DECL(void*) pj_hash_this( pj_hash_table_t *ht,
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pj_hash_iterator_t *it );
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/**
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* @}
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*/
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PJ_END_DECL
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#endif
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