hash_table.h File Reference

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Detailed Description

Implementation of a generic, opaque hash table data type.

Author:

Ian Romanick <ian.d.romanick@intel.com>

#include <string.h>

Defines
#define	hash_table_string_compare   ((hash_compare_func_t) strcmp)
	Compare two strings used as keys.
Typedefs
typedef unsigned(*	hash_func_t )(const void *key)
typedef int(*	hash_compare_func_t )(const void *key1, const void *key2)
Functions
struct hash_table *	hash_table_ctor (unsigned num_buckets, hash_func_t hash, hash_compare_func_t compare)
	Hash table constructor.
void	hash_table_dtor (struct hash_table *ht)
	Release all memory associated with a hash table.
void	hash_table_clear (struct hash_table *ht)
	Flush all entries from a hash table.
void *	hash_table_find (struct hash_table *ht, const void *key)
	Search a hash table for a specific element.
void	hash_table_insert (struct hash_table *ht, void *data, const void *key)
	Add an element to a hash table.
unsigned	hash_table_string_hash (const void *key)
	Compute hash value of a string.

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Define Documentation

#define hash_table_string_compare   ((hash_compare_func_t) strcmp)

Compare two strings used as keys.

This is just a macro wrapper around strcmp.

See also:

hash_table_string_hash

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Typedef Documentation

typedef int(* hash_compare_func_t)(const void *key1, const void *key2)

typedef unsigned(* hash_func_t)(const void *key)

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Function Documentation

void hash_table_clear

(

struct hash_table *

ht

)

Flush all entries from a hash table.

Parameters:

ht

Table to be cleared of its entries.

struct hash_table* hash_table_ctor	(	unsigned	num_buckets,
		hash_func_t	hash,
		hash_compare_func_t	compare
	)			[read]

Hash table constructor.

Creates a hash table with the specified number of buckets. The supplied hash and compare routines are used when adding elements to the table and when searching for elements in the table.

Parameters:

	num_buckets	Number of buckets (bins) in the hash table.
	hash	Function used to compute hash value of input keys.
	compare	Function used to compare keys.

void hash_table_dtor

(

struct hash_table *

ht

)

Release all memory associated with a hash table.

Warning:

This function cannot release memory occupied either by keys or data.

void* hash_table_find	(	struct hash_table *	ht,
		const void *	key
	)

Search a hash table for a specific element.

Parameters:

	ht	Table to be searched
	key	Key of the desired element

Returns:

The data value supplied to hash_table_insert when the element with the matching key was added. If no matching key exists in the table, NULL is returned.

void hash_table_insert	(	struct hash_table *	ht,
		void *	data,
		const void *	key
	)

Add an element to a hash table.

unsigned hash_table_string_hash

(

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.

Parameters:

key

Pointer to a NUL terminated string to be hashed.

See also:

hash_table_string_compare

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