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/*
* Copyright © 2008 Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*/
/**
* \file hash_table.h
* \brief Implementation of a generic, opaque hash table data type.
*
* \author Ian Romanick <ian.d.romanick@intel.com>
*/
#ifndef HASH_TABLE_H
#define HASH_TABLE_H
#include <string.h>
struct hash_table;
typedef unsigned (*hash_func_t)(const void *key);
typedef int (*hash_compare_func_t)(const void *key1, const void *key2);
#ifdef __cplusplus
extern "C" {
#endif
/**
* Hash table constructor
*
* Creates a hash table with the specified number of buckets. The supplied
* \c hash and \c compare routines are used when adding elements to the table
* and when searching for elements in the table.
*
* \param num_buckets Number of buckets (bins) in the hash table.
* \param hash Function used to compute hash value of input keys.
* \param compare Function used to compare keys.
*/
extern struct hash_table *hash_table_ctor(unsigned num_buckets,
hash_func_t hash, hash_compare_func_t compare);
/**
* Release all memory associated with a hash table
*
* \warning
* This function cannot release memory occupied either by keys or data.
*/
extern void hash_table_dtor(struct hash_table *ht);
/**
* Flush all entries from a hash table
*
* \param ht Table to be cleared of its entries.
*/
extern void hash_table_clear(struct hash_table *ht);
/**
* Search a hash table for a specific element
*
* \param ht Table to be searched
* \param key Key of the desired element
*
* \return
* The \c data value supplied to \c hash_table_insert when the element with
* the matching key was added. If no matching key exists in the table,
* \c NULL is returned.
*/
extern void *hash_table_find(struct hash_table *ht, const void *key);
/**
* Add an element to a hash table
*/
extern void hash_table_insert(struct hash_table *ht, void *data,
const void *key);
/**
* Compute hash value of a string
*
* Computes the hash value of a string using the DJB2 algorithm developed by
* Professor Daniel J. Bernstein. It was published on comp.lang.c once upon
* a time. I was unable to find the original posting in the archives.
*
* \param key Pointer to a NUL terminated string to be hashed.
*
* \sa hash_table_string_compare
*/
extern unsigned hash_table_string_hash(const void *key);
/**
* Compare two strings used as keys
*
* This is just a macro wrapper around \c strcmp.
*
* \sa hash_table_string_hash
*/
#define hash_table_string_compare ((hash_compare_func_t) strcmp)
/**
* Compute hash value of a pointer
*
* \param key Pointer to be used as a hash key
*
* \note
* The memory pointed to by \c key is \b never accessed. The value of \c key
* itself is used as the hash key
*
* \sa hash_table_pointer_compare
*/
unsigned
hash_table_pointer_hash(const void *key);
/**
* Compare two pointers used as keys
*
* \sa hash_table_pointer_hash
*/
int
hash_table_pointer_compare(const void *key1, const void *key2);
#ifdef __cplusplus
};
#endif
#endif /* HASH_TABLE_H */
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