255 lines
8 KiB
C
255 lines
8 KiB
C
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/* $Id$ */
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/*
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* Copyright (C) 2008-2011 Teluu Inc. (http://www.teluu.com)
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* Copyright (C) 2003-2008 Benny Prijono <benny@prijono.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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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 indicates the size of of each hash entry.
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*/
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#define PJ_HASH_ENTRY_BUF_SIZE (3*sizeof(void*) + 2*sizeof(pj_uint32_t))
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/**
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* Type declaration for entry buffer, used by #pj_hash_set_np()
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*/
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typedef void *pj_hash_entry_buf[(PJ_HASH_ENTRY_BUF_SIZE+sizeof(void*)-1)/(sizeof(void*))];
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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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* Convert the key to lowercase and calculate the hash value. The resulting
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* string is stored in \c result.
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*
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* @param hval The initial hash value, normally zero.
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* @param result Optional. Buffer to store the result, which must be enough
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* to hold the string.
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* @param key The input key to be converted and calculated.
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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_tolower(pj_uint32_t hval,
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char *result,
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const pj_str_t *key);
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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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* @param hval if this argument is not NULL and the value is not zero,
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* the value will be used as the computed hash value. If
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* the argument is not NULL and the value is zero, it will
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* be filled with the computed hash upon return.
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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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pj_uint32_t *hval );
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/**
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* Variant of #pj_hash_get() with the key being converted to lowercase when
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* calculating the hash value.
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*
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* @see pj_hash_get()
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*/
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PJ_DECL(void *) pj_hash_get_lower( pj_hash_table_t *ht,
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const void *key, unsigned keylen,
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pj_uint32_t *hval );
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/**
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* Associate/disassociate a value with the specified key. If value is not
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* NULL and entry already exists, the entry's value will be overwritten.
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* If value is not NULL and entry does not exist, a new one will be created
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* with the specified pool. Otherwise if value is NULL, entry will be
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* deleted if it exists.
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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. If pool is not specified, the key MUST point to
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* buffer that remains valid for the duration of the entry.
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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 hval if the value is not zero, then the hash table will use
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* this value to search the entry's index, otherwise it will
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* compute the key. This value can be obtained when calling
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* #pj_hash_get().
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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, pj_uint32_t hval,
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void *value );
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/**
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* Variant of #pj_hash_set() with the key being converted to lowercase when
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* calculating the hash value.
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*
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* @see pj_hash_set()
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*/
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PJ_DECL(void) pj_hash_set_lower( pj_pool_t *pool, pj_hash_table_t *ht,
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const void *key, unsigned keylen,
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pj_uint32_t hval, void *value );
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/**
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* Associate/disassociate a value with the specified key. This function works
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* like #pj_hash_set(), except that it doesn't use pool (hence the np -- no
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* pool suffix). If new entry needs to be allocated, it will use the entry_buf.
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*
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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 hval if the value is not zero, then the hash table will use
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* this value to search the entry's index, otherwise it will
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* compute the key. This value can be obtained when calling
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* #pj_hash_get().
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* @param entry_buf Buffer which will be used for the new entry, when one needs
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* to be created.
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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_np(pj_hash_table_t *ht,
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const void *key, unsigned keylen,
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pj_uint32_t hval, pj_hash_entry_buf entry_buf,
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void *value);
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/**
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* Variant of #pj_hash_set_np() with the key being converted to lowercase
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* when calculating the hash value.
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*
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* @see pj_hash_set_np()
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*/
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PJ_DECL(void) pj_hash_set_np_lower(pj_hash_table_t *ht,
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const void *key, unsigned keylen,
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pj_uint32_t hval,
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pj_hash_entry_buf entry_buf,
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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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