hashtable.h File Reference

a simple hash table implementation More...

#include <sys/types.h>
#include <stdint.h>

Go to the source code of this file.

Data Structures
struct	hash_table_element
	stores an hash table element for use in the hash table More...
struct	hash_table
	identifies the hashtable for which operations are to be performed More...

Macros
#define	HASH_LEN   table->key_num
#define	HASH(x, y)   hash_table_do_hash(x,y,HASH_LEN)
#define	hash_table_element_s   sizeof(hash_table_element_t)
#define	hash_table_s   sizeof(hash_table_t)
#define	HT_ADD(table, key, value)   hash_table_add(table, (void *) key, sizeof(*key), (void *) value, sizeof(*value))
#define	HT_REMOVE(table, key)   hash_table_remove(table, key, sizeof(*key))
#define	HT_LOOKUP(table, key)   hash_table_lookup(table, key, sizeof(*key))
#define	HT_HAS_KEY(table, key)   hash_table_has_key(table, key, sizeof(*key))

Typedefs
typedef struct hash_table_element	hash_table_element_t
typedef enum hash_table_mode	hash_table_mode_t
typedef struct hash_table	hash_table_t

Enumerations
enum	hash_table_mode { MODE_COPY, MODE_VALUEREF, MODE_ALLREF }

Functions
hash_table_element_t *	hash_table_element_new ()
void	hash_table_element_delete (hash_table_t *, hash_table_element_t *)
uint16_t	hash_table_do_hash (void *key, size_t key_len, uint16_t max_key)
hash_table_t *	hash_table_new (hash_table_mode_t)
void	hash_table_delete (hash_table_t *)
int	hash_table_add (hash_table_t *, void *, size_t, void *, size_t)
int	hash_table_remove (hash_table_t *, void *, size_t)
void *	hash_table_lookup (hash_table_t *, void *, size_t)
int	hash_table_has_key (hash_table_t *, void *, size_t)
size_t	hash_table_get_keys (hash_table_t *, void ***)
size_t	hash_table_get_elements (hash_table_t *, hash_table_element_t ***)
int	hash_table_resize (hash_table_t *, size_t)
int	hash_table_iterate (hash_table_t *table, int(*fct)(void *user, void *value, void *key, size_t key_len), void *user)

Detailed Description

a simple hash table implementation

License GPLv3+

Author

Ankur Shrivastava

Macro Definition Documentation

#define HASH	(		x,
			y
	)		hash_table_do_hash(x,y,HASH_LEN)

#define HASH_LEN   table->key_num

#define hash_table_element_s   sizeof(hash_table_element_t)

#define hash_table_s   sizeof(hash_table_t)

#define HT_ADD	(		table,
			key,
			value
	)		hash_table_add(table, (void *) key, sizeof(*key), (void *) value, sizeof(*value))

macro to add a key - value pair to the hash table

Note

use this macro when size of key and/or value can be given by sizeof

Parameters

table	hash table to add element to
key	pointer to the key for the hash table
value	pointer to the value to be added against the key

Returns

0 on sucess

-1 when no memory

#define HT_HAS_KEY	(		table,
			key
	)		hash_table_has_key(table, key, sizeof(*key))

macro to look if the exists in the hash table

Note

use this macro when size of key and/or value can be given by sizeof

Parameters

key	pointer to key to be looked for

Returns

0 when key is not found

1 when key is found

#define HT_LOOKUP	(		table,
			key
	)		hash_table_lookup(table, key, sizeof(*key))

macro to lookup a key in a particular table

Parameters

table	table to look key in
key	pointer to key to be looked for

Returns

NULL when key is not found in the hash table

void* pointer to the value in the table

#define HT_REMOVE	(		table,
			key
	)		hash_table_remove(table, key, sizeof(*key))

macro to remove an hash table element (for a given key) from a given hash table

Note

use this macro when size of key and/or value can be given by sizeof

Parameters

table	hash table from which element has to be removed
key	pointer to the key which has to be removed

Returns

0 on sucess

-1 when key is not found

Typedef Documentation

typedef struct hash_table_element hash_table_element_t

typedef enum hash_table_mode hash_table_mode_t

typedef struct hash_table hash_table_t

Enumeration Type Documentation

enum hash_table_mode

defines the mode of operation of hash table

Enumerator
MODE_COPY	copy mode here values as well as key is copied
MODE_VALUEREF	value reference mode, here ONLY key is copies and value is always referred
MODE_ALLREF	in this mode all keys and values are referred

Function Documentation

int hash_table_add	(	hash_table_t *	table,
		void *	key,
		size_t	key_len,
		void *	value,
		size_t	value_len
	)

Function to add a key - value pair to the hash table, use HT_ADD macro

Parameters

table	hash table to add element to
key	pointer to the key for the hash table
key_len	length of the key in bytes
value	pointer to the value to be added against the key
value_len	length of the value in bytes

Returns

0 on sucess

-1 when no memory

void hash_table_delete

(

hash_table_t *

table

)

Function to delete the hash table

Parameters

table

hash table to be deleted

uint16_t hash_table_do_hash	(	void *	key,
		size_t	key_len,
		uint16_t	max_key
	)

Function that returns a hash value for a given key and key_len

Parameters

key	pointer to the key
key_len	length of the key
max_key	max value of the hash to be returned by the function

Returns

hash value belonging to [0, max_key)

void hash_table_element_delete	(	hash_table_t *	table,
		hash_table_element_t *	element
	)

Function to delete an hash table element

Parameters

table	table from which element has to be deleted
element	hash table element to be deleted

hash_table_element_t* hash_table_element_new

(

)

Function to create a now hash_table element

Returns

hash_table_element_t object when success

NULL when no memory

size_t hash_table_get_elements	(	hash_table_t *	table,
		hash_table_element_t ***	elements
	)

Function to get all elements (key - value pairs) from the given hash table

Parameters

table	hash table from which elements have to be retrieved
elements	a pointer to an array of hash_table_element_t pointer (malloced by function)

Returns

1 when no memory

count of elements

size_t hash_table_get_keys	(	hash_table_t *	table,
		void ***	keys_ptr
	)

Function to return all the keys in a given hash table

Parameters

table	hash table from which key are to be reterived
keys	a void** pointer where keys are filled in (memory allocated internally and must be freed)

Returns

total number of keys filled in keys

int hash_table_has_key	(	hash_table_t *	table,
		void *	key,
		size_t	key_len
	)

Function to look if the exists in the hash table

Parameters

key	pointer to key to be looked for
key_len	size of the key to be searched

Returns

0 when key is not found

1 when key is found

int hash_table_iterate	(	hash_table_t *	table,
		int(*)(void *user, void *value, void *key, size_t key_len)	fct,
		void *	user
	)

Function to iterate through all elements of the hashtable

Parameters

table	hash table to be iterated
fct	pointer to a function returning 1 if the element has to be removed
user	arbitrary user pointer passed to the fct callback

Returns

0 when success

void* hash_table_lookup	(	hash_table_t *	table,
		void *	key,
		size_t	key_len
	)

Function to lookup a key in a particular table

Note

use this macro when size of key and/or value can be given by sizeof

Parameters

table	table to look key in
key	pointer to key to be looked for
key_len	size of the key to be searched

Returns

NULL when key is not found in the hash table

void* pointer to the value in the table

Function to lookup a key in a particular table

Parameters

table	table to look key in
key	pointer to key to be looked for
key_len	size of the key to be searched

Returns

NULL when key is not found in the hash table

void* pointer to the value in the table

hash_table_t* hash_table_new

(

hash_table_mode_t

mode

)

Fuction to create a new hash table

Parameters

mode	hash_table_mode which the hash table should follow

Returns

hash_table_t object which references the hash table

NULL when no memory

int hash_table_remove	(	hash_table_t *	table,
		void *	key,
		size_t	key_len
	)

Function to remove an hash table element (for a given key) from a given hash table

Parameters

table	hash table from which element has to be removed
key	pointer to the key which has to be removed
key_len	size of the key in bytes

Returns

0 on sucess

-1 when key is not found

int hash_table_resize	(	hash_table_t *	table,
		size_t	len
	)

Function to resize the hash table store house

Parameters

table	hash table to be resized
len	new length of the hash table

Returns

-1 when no elements in hash table

-2 when no emmory for new store house

0 when sucess