Tizen Native API  5.5

Hash table management. Maps keys to values.

The hash table associates keys (e.g. strings) to data, with relatively fast access time. The performance is proportional to the load factor of the table (number of elements / number of buckets). See Algorithm for implementation details.

There are optimized implementations for some common key types, such as strings, integers, pointers, and stringshared; custom optimizations are also permitted.

The hash table keys can be either copied or non-copied, using eina_hash_add() or eina_hash_direct_add(), respectively.

Algorithm

The Eina_Hash is implemented using an array of N "buckets", where each bucket is a pointer to a structure that is the head of a red-black tree. The array can then be indexed by the [hash_of_element mod N]. The hash_of_element is calculated using the hashing function, passed as a parameter to the eina_hash_new function. N is the number of buckets (array positions), and is calculated based on the buckets_power_size (argument of eina_hash_new too). The following picture illustrates the basic idea:

01_hash-table.png

Adding an element to the hash table involves the following steps:

  • calculate the hash for that key (using the specified hash function);
  • calculate the array position [hash mod N];
  • add the element to the rbtree on that position.

The first two steps have constant time, proportional to the hash function being used. Adding the key to the rbtree will be proportional to the number of keys in that bucket.

The average lookup cost depends on the number of keys per bucket (load factor) of the table, assuming the distribution of keys is sufficiently uniform.

Performance

Keeping the load factor small will improve the hash table performance. But increasing the buckets_power_size will also increase the memory consumption. The default hash table creation functions provides enough buckets for most cases. If just a few string keys (less than 30) will be added to the hash table, eina_hash_string_small_new should be used, since it reduces the memory consumption for the buckets without causing too many collisions. However, eina_hash_string_small_new still uses the same hash calculation function that eina_hash_string_superfast_new, which is more complex than eina_hash_string_djb2_new. The latter has a faster hash computation function, but that will imply a not so good distribution. But if just a few keys are being added, this is not a problem, it will still have not many collisions and be faster to calculate the hash than in a hash created with eina_hash_string_small_new and eina_hash_string_superfast_new.

A simple comparison between them would be:

  • djb2 - faster hash function - 256 buckets (higher memory consumption)
  • string_small - slower hash function but less collisions - 32 buckets (lower memory consumption)
  • string_superfast - slower hash function but less collisions - 256 buckets (higher memory consumption) - not randomized, avoid it on public remote interface.

Basically for a very small number of keys (10 or less), djb2 should be used, or string_small if you have a restriction on memory usage. And for a higher number of keys, string_superfast should be preferred if not used on a public remote interface.

If just stringshared keys are being added, use eina_hash_stringshared_new. If a lot of keys will be added to the hash table (e.g. more than 1000), then it's better to increase the buckets_power_size. See eina_hash_new for more details.

When adding a new key to a hash table, use eina_hash_add or eina_hash_direct_add (the latter if this key is already stored elsewhere). If the key may be already inside the hash table, rather than checking with eina_hash_find followed by eina_hash_add, one can use just eina_hash_set (this will change the data pointed by this key if it was already present in the table).

Tutorial

These examples show many Eina_Hash functions in action:

Functions

Eina_Hasheina_hash_new (Eina_Key_Length key_length_cb, Eina_Key_Cmp key_cmp_cb, Eina_Key_Hash key_hash_cb, Eina_Free_Cb data_free_cb, int buckets_power_size)
 Creates a new hash table.
void eina_hash_free_cb_set (Eina_Hash *hash, Eina_Free_Cb data_free_cb)
 Sets the data cleanup callback for a hash.
Eina_Hasheina_hash_string_djb2_new (Eina_Free_Cb data_free_cb)
 Creates a new hash table using the djb2 algorithm.
Eina_Hasheina_hash_string_superfast_new (Eina_Free_Cb data_free_cb)
 Creates a new hash table for use with strings.
Eina_Hasheina_hash_string_small_new (Eina_Free_Cb data_free_cb)
 Creates a new hash table for use with strings with small bucket size.
Eina_Hasheina_hash_int32_new (Eina_Free_Cb data_free_cb)
 Creates a new hash table for use with 32bit integers.
Eina_Hasheina_hash_int64_new (Eina_Free_Cb data_free_cb)
 Creates a new hash table for use with 64bit integers.
Eina_Hasheina_hash_pointer_new (Eina_Free_Cb data_free_cb)
 Creates a new hash table for use with pointers.
Eina_Hasheina_hash_stringshared_new (Eina_Free_Cb data_free_cb)
 Creates a new hash table optimized for stringshared values.
Eina_Bool eina_hash_add (Eina_Hash *hash, const void *key, const void *data)
 Adds an entry to the given hash table.
Eina_Bool eina_hash_direct_add (Eina_Hash *hash, const void *key, const void *data)
 Adds an entry to the given hash table without duplicating the string.
Eina_Bool eina_hash_del (Eina_Hash *hash, const void *key, const void *data)
 Removes the entry identified by a key or a data from the given hash table.
void * eina_hash_find (const Eina_Hash *hash, const void *key)
 Retrieves a specific entry in the given hash table.
void * eina_hash_modify (Eina_Hash *hash, const void *key, const void *data)
 Modifies the entry pointer at the specified key and returns the previous entry.
void * eina_hash_set (Eina_Hash *hash, const void *key, const void *data)
 Modifies the entry pointer at the specified key and returns the previous entry or adds the entry if not found.
Eina_Bool eina_hash_move (Eina_Hash *hash, const void *old_key, const void *new_key)
 Changes the key of an entry in a hash without triggering the free callback.
void eina_hash_free (Eina_Hash *hash)
 Frees the given hash table's resources.
void eina_hash_free_buckets (Eina_Hash *hash)
 Frees the given hash table buckets resources.
int eina_hash_population (const Eina_Hash *hash)
 Returns the number of entries in the given hash table.
Eina_Bool eina_hash_add_by_hash (Eina_Hash *hash, const void *key, int key_length, int key_hash, const void *data)
 Adds an entry to the given hash table by its key hash.
Eina_Bool eina_hash_direct_add_by_hash (Eina_Hash *hash, const void *key, int key_length, int key_hash, const void *data)
 Adds an entry to a hash table by its key hash without duplicating the string key.
Eina_Bool eina_hash_del_by_key_hash (Eina_Hash *hash, const void *key, int key_length, int key_hash)
 Removes the entry identified by a key and a key hash from the given hash table.
Eina_Bool eina_hash_del_by_key (Eina_Hash *hash, const void *key)
 Removes the entry identified by a key from the given hash table.
Eina_Bool eina_hash_del_by_data (Eina_Hash *hash, const void *data)
 Removes an entry from a hash table identified by its data value.
Eina_Bool eina_hash_del_by_hash (Eina_Hash *hash, const void *key, int key_length, int key_hash, const void *data)
 Removes the entry identified by a key and a key hash, or a data value from the given hash table.
void * eina_hash_find_by_hash (const Eina_Hash *hash, const void *key, int key_length, int key_hash)
 Retrieves a specific entry from the given hash table.
void * eina_hash_modify_by_hash (Eina_Hash *hash, const void *key, int key_length, int key_hash, const void *data)
 Modifies the entry pointer at the specified key and returns the previous entry.
Eina_Iteratoreina_hash_iterator_key_new (const Eina_Hash *hash)
 Returns a new iterator associated with hash keys.
Eina_Iteratoreina_hash_iterator_data_new (const Eina_Hash *hash)
 Returns a new iterator associated with a hash.
Eina_Iteratoreina_hash_iterator_tuple_new (const Eina_Hash *hash)
 Returned a new iterator associated with hash keys and data.
void eina_hash_foreach (const Eina_Hash *hash, Eina_Hash_Foreach func, const void *fdata)
 Calls a function on every member stored in the hash table.
void eina_hash_list_append (Eina_Hash *hash, const void *key, const void *data)
 Appends data to an Eina_List inside a hash.
void eina_hash_list_prepend (Eina_Hash *hash, const void *key, const void *data)
 Appends data to an Eina_List inside a hash using eina_hash_direct_add().
void eina_hash_list_remove (Eina_Hash *hash, const void *key, const void *data)
 Prepends data to an Eina_List inside a hash using eina_hash_direct_add().
int eina_hash_superfast (const char *key, int len)
 Paul Hsieh (http://www.azillionmonkeys.com/qed/hash.html) hash function used by WebCore (http://webkit.org/blog/8/hashtables-part-2/)
static int eina_hash_djb2 (const char *key, int len)
 Hash function first reported by Dan Bernstein many years ago in comp.lang.c.
static int eina_hash_djb2_len (const char *key, int *plen)
 Hash function first reported by Dan Bernstein many years ago in comp.lang.c.
static int eina_hash_int32 (const unsigned int *pkey, int len)
 Hash function from http://web.archive.org/web/20071223173210/http://www.concentric.net/~Ttwang/tech/inthash.htm.
static int eina_hash_int64 (const unsigned long long int *pkey, int len)
 Hash function from http://web.archive.org/web/20071223173210/http://www.concentric.net/~Ttwang/tech/inthash.htm.
static int eina_hash_murmur3 (const char *key, int len)
 Hash function from http://sites.google.com/site/murmurhash/.
static int eina_hash_crc (const char *key, int len)
 Hash function using crc-32 algorithm and and 0xEDB88320 polynomial.

Typedefs

typedef struct _Eina_Hash Eina_Hash
typedef struct _Eina_Hash_Tuple Eina_Hash_Tuple
typedef unsigned int(* Eina_Key_Length )(const void *key)
typedef int(* Eina_Key_Cmp )(const void *key1, int key1_length, const void *key2, int key2_length)
typedef int(* Eina_Key_Hash )(const void *key, int key_length)
typedef Eina_Bool(* Eina_Hash_Foreach )(const Eina_Hash *hash, const void *key, void *data, void *fdata)

Defines

#define EINA_KEY_LENGTH(Function)   ((Eina_Key_Length)Function)
#define EINA_KEY_CMP(Function)   ((Eina_Key_Cmp)Function)
#define EINA_KEY_HASH(Function)   ((Eina_Key_Hash)Function)

Define Documentation

#define EINA_KEY_CMP (   Function)    ((Eina_Key_Cmp)Function)
Parameters:
[in]The function used to compare hash key.
Examples:
eina_hash_02.c.
#define EINA_KEY_HASH (   Function)    ((Eina_Key_Hash)Function)
Parameters:
[in]FunctionThe function used to hash key.
Examples:
eina_hash_02.c.
#define EINA_KEY_LENGTH (   Function)    ((Eina_Key_Length)Function)
Parameters:
[in]FunctionThe function used to calculate length of hash key.
Examples:
eina_hash_02.c.

Typedef Documentation

Type for a generic hash table.

Type for a function to iterate over a hash table.

Type for a hash table of key/value pairs.

Type for a function to compare two hash keys.

Type for a function to create a hash key.

Type for a function to determine the length of a hash key.


Function Documentation

Eina_Bool eina_hash_add ( Eina_Hash hash,
const void *  key,
const void *  data 
)

Adds an entry to the given hash table.

Parameters:
[in,out]hashThe given hash table. Cannot be NULL.
[in]keyA unique key. Cannot be NULL.
[in]dataThe data to associate with the string given by key. Cannot be NULL.
Returns:
EINA_FALSE if an error occurred, EINA_TRUE otherwise.

This function adds key to hash. key must be unique within the hash table so that eina_hash_find() and eina_hash_del() operate on the correct data item.

Key uniqueness varies depending on the type of hash: a stringshared Eina_Hash needs unique pointers (which implies unique strings). All other string hash types require that the strings themselves are unique. Pointer, int32 and int64 hashes need to have unique values. Failure to use sufficient uniqueness will result in unexpected results when inserting data pointers accessed with eina_hash_find(), and removed with eina_hash_del().

Key strings are case sensitive.

Since :
2.3
Examples:
eina_hash_01.c, eina_hash_02.c, eina_hash_03.c, eina_hash_04.c, eina_hash_05.c, eina_hash_06.c, eina_hash_07.c, and eina_hash_08.c.
Eina_Bool eina_hash_add_by_hash ( Eina_Hash hash,
const void *  key,
int  key_length,
int  key_hash,
const void *  data 
)

Adds an entry to the given hash table by its key hash.

Parameters:
[in,out]hashThe given hash table. Cannot be NULL.
[in]keyA unique key. Cannot be NULL.
[in]key_lengthThe length of key (including terminating '\0').
[in]key_hashThe hash of key.
[in]dataThe data to associate with the string given by the key. Cannot be NULL.
Returns:
EINA_FALSE if an error occurred, EINA_TRUE otherwise.

This function adds key to hash.

key must be unique within the hash table so that eina_hash_find() and eina_hash_del() operate on the correct data item. key_hash must match key so that the correct item can be found by eina_hash_find_by_hash(). Key strings are case sensitive.

See also:
eina_hash_add()
Since :
2.3
Examples:
eina_hash_08.c.
static int eina_hash_crc ( const char *  key,
int  len 
) [static]

Hash function using crc-32 algorithm and and 0xEDB88320 polynomial.

Parameters:
[in]keyThe key to hash.
[in]lenThe length of the key.
Returns:
The hash value.
Eina_Bool eina_hash_del ( Eina_Hash hash,
const void *  key,
const void *  data 
)

Removes the entry identified by a key or a data from the given hash table.

Parameters:
[in,out]hashThe given hash table.
[in]keyThe key.
[in]dataThe data pointer to remove if the key is NULL.
Returns:
EINA_FALSE if an error occurred, EINA_TRUE otherwise.

This function removes the entry identified by key or data from hash. If a free function was given to the callback on creation, it will be called for the data being deleted. If hash is NULL, the function returns immediately EINA_FALSE. If key is NULL, then data is used to find the a match to remove, otherwise key is used and data is not required and can be NULL.

Note:
If you already have the key, use eina_hash_del_by_key() or eina_hash_del_by_key_hash(). If you don't have the key, use eina_hash_del_by_data() directly.
Since :
2.3
Examples:
eina_hash_01.c, eina_hash_03.c, eina_hash_04.c, eina_hash_05.c, eina_hash_06.c, eina_hash_07.c, and eina_hash_08.c.
Eina_Bool eina_hash_del_by_data ( Eina_Hash hash,
const void *  data 
)

Removes an entry from a hash table identified by its data value.

Parameters:
[in,out]hashThe given hash table. Cannot be NULL.
[in]dataThe data value to search and remove. Cannot be NULL.
Returns:
EINA_FALSE if an error occurred or if hash or data are NULL, EINA_TRUE otherwise. thing goes fine.

This function removes the entry identified by data from hash. If a free function was given to the callback on creation, it will be called for the data being deleted.

Note:
This version is slow since there is no quick access to nodes based on data.
If you already have the key, use eina_hash_del_by_key() or eina_hash_del_by_key_hash() instead.
Since :
2.3
Examples:
eina_hash_08.c.
Eina_Bool eina_hash_del_by_hash ( Eina_Hash hash,
const void *  key,
int  key_length,
int  key_hash,
const void *  data 
)

Removes the entry identified by a key and a key hash, or a data value from the given hash table.

If key is NULL, then data is used to find a match to remove.

Parameters:
[in,out]hashThe given hash table. Cannot be NULL.
[in]keyThe key.
[in]key_lengthThe length of the key.
[in]key_hashThe hash that always match the key.
[in]dataThe data pointer to remove if the key is NULL.
Returns:
EINA_FALSE if an error occurred, EINA_TRUE otherwise.

This function removes the entry identified by key and key_hash, or data, from hash. If a free function was given to the callback on creation, it will be called for the data being deleted. If hash is NULL, the function returns EINA_FALSE immediately. If key is NULL, then key_length and key_hash are ignored and data is used to find a match to remove, otherwise key and key_hash are used and data is not required and can be NULL. Do not forget to count '\0' for string when setting the value of key_length.

Note:
If you already have the key, use eina_hash_del_by_key_hash(). If you don't have the key, use eina_hash_del_by_data() directly.
Since :
2.3
Eina_Bool eina_hash_del_by_key ( Eina_Hash hash,
const void *  key 
)

Removes the entry identified by a key from the given hash table.

This version will calculate key length and hash by using functions provided to the hash creation function.

Parameters:
[in,out]hashThe given hash table. Cannot be NULL.
[in]keyThe key. Cannot be NULL.
Returns:
EINA_FALSE if an error occurred, EINA_TRUE otherwise.

This function removes the entry identified by key from hash. The key length and hash will be calculated automatically via a function provided to the hash creation function. If a free function was given to the callback on creation, it will be called for the data being deleted. If hash or key are NULL, the function returns EINA_FALSE immediately.

Note:
If you already have the key_hash, use eina_hash_del_by_key_hash() instead.
If you don't have the key, use eina_hash_del_by_data() instead.
Since :
2.3
Examples:
eina_hash_08.c.
Eina_Bool eina_hash_del_by_key_hash ( Eina_Hash hash,
const void *  key,
int  key_length,
int  key_hash 
)

Removes the entry identified by a key and a key hash from the given hash table.

Parameters:
[in,out]hashThe given hash table. Cannot be NULL.
[in]keyThe key. Cannot be NULL.
[in]key_lengthThe length of the key (including terminating '\0').
[in]key_hashThe hash that always matches the key.
Returns:
EINA_FALSE if an error occurred, EINA_TRUE otherwise.

This function removes the entry identified by key and key_hash from hash. If a free function was given to the callback on creation, it will be called for the data being deleted. If hash or key are NULL, the function returns EINA_FALSE immediately.

Note:
If you don't have the key_hash, use eina_hash_del_by_key() instead.
If you don't have the key, use eina_hash_del_by_data() instead.
Since :
2.3
Examples:
eina_hash_08.c.
Eina_Bool eina_hash_direct_add ( Eina_Hash hash,
const void *  key,
const void *  data 
)

Adds an entry to the given hash table without duplicating the string.

Parameters:
[in,out]hashThe given hash table. Cannot be NULL.
[in]keyA unique key. Cannot be NULL.
[in]dataThe data to associate with the string given by key. Cannot be NULL
Returns:
EINA_FALSE if an error occurred, EINA_TRUE otherwise.

This function adds key to hash. key must be unique within the hash table so that eina_hash_find() and eina_hash_del() operate on the correct data item.

Key uniqueness varies depending on the type of hash: a stringshared Eina_Hash needs unique pointers (which implies unique strings). All other string hash types require that the strings themselves are unique. Pointer, int32 and int64 hashes need to have unique values. Failure to use sufficient uniqueness will result in unexpected results when inserting data pointers accessed with eina_hash_find(), and removed with eina_hash_del().

Unlike eina_hash_add(), this function does not make a copy of key, so it must be a string constant or stored elsewhere (such as in the object being added). Key strings are case sensitive.

Since :
2.3
Examples:
eina_hash_02.c.
Eina_Bool eina_hash_direct_add_by_hash ( Eina_Hash hash,
const void *  key,
int  key_length,
int  key_hash,
const void *  data 
)

Adds an entry to a hash table by its key hash without duplicating the string key.

Parameters:
[in,out]hashThe given hash table. Cannot be NULL.
[in]keyA unique key. Cannot be NULL.
[in]key_lengthThe length of key (including terminating '\0').
[in]key_hashThe hash of key.
[in]dataThe data to associate with the string given by key. Cannot be NULL.
Returns:
EINA_FALSE if an error occurred, EINA_TRUE otherwise.

This function adds key to hash.

key must be unique within the hash table so that eina_hash_find() and eina_hash_del() operate on the correct data item. key_hash must match key so that the correct item can be found by eina_hash_find_by_hash(). Key strings are case sensitive.

Unlike eina_hash_add_by_hash(), this function does not make a copy of key, so it must be a string constant or stored elsewhere (such as inside the object being added).

See also:
eina_hash_direct_add()
Since :
2.3
Examples:
eina_hash_08.c.
static int eina_hash_djb2 ( const char *  key,
int  len 
) [static]

Hash function first reported by Dan Bernstein many years ago in comp.lang.c.

Parameters:
[in]keyThe key to hash.
[in]lenThe length of the key.
Returns:
The hash value.
static int eina_hash_djb2_len ( const char *  key,
int *  plen 
) [static]

Hash function first reported by Dan Bernstein many years ago in comp.lang.c.

Parameters:
[in]keyThe key to hash.
[in]plenThe length of the key.
Returns:
The hash value.
void* eina_hash_find ( const Eina_Hash hash,
const void *  key 
)

Retrieves a specific entry in the given hash table.

Parameters:
[in]hashThe given hash table.
[in]keyThe key of the entry to find.
Returns:
The data pointer for the stored entry on success, or NULL otherwise.

This function retrieves the entry associated with key in hash. If hash is NULL, this function returns NULL.

Since :
2.3
Examples:
eina_hash_01.c, eina_hash_02.c, eina_hash_03.c, eina_hash_04.c, eina_hash_05.c, eina_hash_06.c, and eina_hash_07.c.
void* eina_hash_find_by_hash ( const Eina_Hash hash,
const void *  key,
int  key_length,
int  key_hash 
)

Retrieves a specific entry from the given hash table.

Parameters:
[in]hashThe given hash table. Cannot be NULL.
[in]keyThe key of the entry to find.
[in]key_lengthThe length of the key.
[in]key_hashThe hash that always matches the key
Returns:
The data pointer for the stored entry on success, or NULL if hash is NULL or if the data pointer could not be retrieved.

This function retrieves the entry associated with key of length key_length in hash. key_hash is the hash that always matches key. It is ignored if key is NULL. Do not forget to count '\0' for string when setting the value of key_length.

Since :
2.3
Examples:
eina_hash_08.c.
void eina_hash_foreach ( const Eina_Hash hash,
Eina_Hash_Foreach  func,
const void *  fdata 
)

Calls a function on every member stored in the hash table.

Parameters:
[in]hashThe hash table whose members will be walked.
[in]funcThe function to call on each parameter.
[in]fdataThe data pointer to pass to the function being called.

This function iterates over the hash table hash, calling the function func on each member. If func modifies the contents of the hash table, or wishes to stop processing it should return EINA_FALSE. If func returns EINA_TRUE the foreach loop will keep processing.

Example:

 extern Eina_Hash *hash;

 Eina_Bool hash_fn(const Eina_Hash *hash, const void *key,
                   void *data, void *fdata)
 {
   printf("Func data: %s, Hash entry: %s / %p\n",
          fdata, (const char *)key, data);
   return EINA_TRUE;
 }

 int main(int argc, char **argv)
 {
   char *hash_fn_data;

   hash_fn_data = strdup("Hello World");
   eina_hash_foreach(hash, hash_fn, hash_fn_data);
   free(hash_fn_data);
 }
Since :
2.3
Examples:
eina_hash_01.c, eina_hash_02.c, eina_hash_03.c, eina_hash_04.c, eina_hash_05.c, eina_hash_06.c, and eina_hash_07.c.
void eina_hash_free ( Eina_Hash hash)

Frees the given hash table's resources.

Parameters:
[in]hashThe hash table to be freed.

This function frees memory allocated for the hash and to its internal buckets.

If data_free_cb was specified at creation time in eina_hash_new, it will be called for each element as it gets freed. If the callback was not specified, then any data in these elements may now be lost, if not stored or freed elsewhere.

If hash is NULL, the function returns immediately.

Example:

 extern Eina_Hash *hash;

 eina_hash_free(hash);
 hash = NULL;
Since :
2.3
Examples:
eina_hash_01.c, eina_hash_02.c, eina_hash_03.c, eina_hash_04.c, eina_hash_05.c, eina_hash_06.c, eina_hash_07.c, and eina_hash_08.c.

Frees the given hash table buckets resources.

Parameters:
[in]hashThe hash table whose buckets have to be freed.

This function frees memory allocated to internal buckets for hash.

If data_free_cb was specified at creation time in eina_hash_new(), it will be called for each element as it gets freed. If the callback was not specified, then any data in these elements may now be lost, if not stored or freed elsewhere.

If hash is NULL, the function returns immediately.

Since :
2.3
Examples:
eina_hash_01.c, eina_hash_03.c, eina_hash_04.c, eina_hash_05.c, eina_hash_06.c, and eina_hash_07.c.
void eina_hash_free_cb_set ( Eina_Hash hash,
Eina_Free_Cb  data_free_cb 
)

Sets the data cleanup callback for a hash.

Parameters:
[in,out]hashThe given hash table.
[in]data_free_cbThe function called on each value when the hash table is freed, or when an item is deleted from it. NULL can be passed as callback to remove an existing callback.

The argument received by data_free_cb will be the data of the item being removed.

Since (EFL) :
1.1
See also:
eina_hash_new.
Since :
2.3
static int eina_hash_int32 ( const unsigned int *  pkey,
int  len 
) [static]

Hash function from http://web.archive.org/web/20071223173210/http://www.concentric.net/~Ttwang/tech/inthash.htm.

Parameters:
[in]pkeyThe key to hash.
[in]lenThe length of the key.
Returns:
The hash value.

Creates a new hash table for use with 32bit integers.

Parameters:
[in]data_free_cbThe function called on each value when the hash table is freed, or when an item is deleted from it. NULL can be passed as callback.
Returns:
The new hash table, or NULL on failure.

This function creates a new hash table where keys are 32bit integers. When adding or looking up in the hash table, pointers to 32bit integers must be passed. They can be addresses on the stack if you let the eina_hash copy the key. Values can then be looked up with pointers other than the original key pointer that was used to add values. This method is not suitable to match string keys as it would only match the first character.

Since :
2.3
Examples:
eina_hash_05.c.
static int eina_hash_int64 ( const unsigned long long int *  pkey,
int  len 
) [static]

Hash function from http://web.archive.org/web/20071223173210/http://www.concentric.net/~Ttwang/tech/inthash.htm.

Parameters:
[in]pkeyThe key to hash.
[in]lenThe length of the key.
Returns:
The hash value.

Creates a new hash table for use with 64bit integers.

Parameters:
[in]data_free_cbThe function called on each value when the hash table is freed, or when an item is deleted from it. NULL can be passed as callback.
Returns:
The new hash table, or NULL on failure.

This function creates a new hash table where keys are 64bit integers. When adding or looking up in the hash table, pointers to 64bit integers must be passed. They can be addresses on the stack. Values can then be looked up with pointers other than the original key pointer that was used to add values. This method is not suitable to match string keys as it would only match the first character.

Since :
2.3
Examples:
eina_hash_06.c.

Returns a new iterator associated with a hash.

Parameters:
[in]hashThe hash.
Returns:
A new iterator, or NULL if memory could not be allocated.

This function returns a newly allocated iterator associated with hash. If hash is not populated, this function still returns a valid iterator that will always return false on eina_iterator_next().

Warning:
If the hash structure changes then the iterator becomes invalid; adding or removing items may lead to program crash.
Since :
2.3
Examples:
eina_hash_01.c, eina_hash_03.c, eina_hash_04.c, eina_hash_05.c, eina_hash_06.c, and eina_hash_07.c.

Returns a new iterator associated with hash keys.

Parameters:
[in]hashThe hash.
Returns:
A new iterator, or NULL if memory could not be allocated.

This function returns a newly allocated iterator associated with hash. If hash is not populated, this function still returns a valid iterator that will always return false on eina_iterator_next().

Warning:
If the hash structure changes then the iterator becomes invalid; adding or removing items may lead to program crash.
Since :
2.3
Examples:
eina_hash_01.c, eina_hash_03.c, eina_hash_04.c, eina_hash_05.c, eina_hash_06.c, and eina_hash_07.c.

Returned a new iterator associated with hash keys and data.

Parameters:
[in]hashThe hash.
Returns:
A new iterator, or NULL if memory could not be allocated.

This function returns a newly allocated iterator associated with hash. If hash is not populated, this function still returns a valid iterator that will always return false on eina_iterator_next().

Note:
Iterator data will provide values as Eina_Hash_Tuple that should not be modified!
Warning:
If the hash structure changes then the iterator becomes invalid; adding or removing items may lead to program crash.
Since :
2.3
Examples:
eina_hash_01.c, eina_hash_03.c, eina_hash_04.c, eina_hash_05.c, eina_hash_06.c, and eina_hash_07.c.
void eina_hash_list_append ( Eina_Hash hash,
const void *  key,
const void *  data 
)

Appends data to an Eina_List inside a hash.

This function is identical to the sequence of calling eina_hash_find(), eina_list_append(), eina_hash_set(), but with one fewer required hash lookup.

Parameters:
[in,out]hashThe hash table.
[in]keyThe key associated with the data.
[in]dataThe data to append to the list.
Since (EFL) :
1.10
Since :
3.0f(2.3.1)
void eina_hash_list_prepend ( Eina_Hash hash,
const void *  key,
const void *  data 
)

Appends data to an Eina_List inside a hash using eina_hash_direct_add().

This function is identical to the sequence of calling eina_hash_find(), eina_list_append(), eina_hash_set(), but with one fewer required hash lookup.

Parameters:
[in,out]hashThe hash table.
[in]keyThe key associated with the data.
[in]dataThe data to append to the list.
Since (EFL) :
1.23 Prepends data to an Eina_List inside a hash.

This function is identical to the sequence of calling eina_hash_find(), eina_list_prepend(), eina_hash_set(), but with one fewer required hash lookup.

Parameters:
[in,out]hashThe hash table.
[in]keyThe key associated with the data.
[in]dataThe data to prepend to the list.
Since (EFL) :
1.10
Since :
3.0f(2.3.1)
void eina_hash_list_remove ( Eina_Hash hash,
const void *  key,
const void *  data 
)

Prepends data to an Eina_List inside a hash using eina_hash_direct_add().

This function is identical to the sequence of calling eina_hash_find(), eina_list_prepend(), eina_hash_set(), but with one fewer required hash lookup.

Parameters:
[in,out]hashThe hash table.
[in]keyThe key associated with the data.
[in]dataThe data to prepend to the list.
Since (EFL) :
1.23 Removes data from an Eina_List inside a hash.

This function is identical to the sequence of calling eina_hash_find(), eina_list_remove(), eina_hash_set(), but with one fewer required hash lookup.

Parameters:
[in,out]hashThe hash table.
[in]keyThe key associated with the data.
[in]dataThe data to remove from the list.
Since (EFL) :
1.10
Since :
3.0f(2.3.1)
void* eina_hash_modify ( Eina_Hash hash,
const void *  key,
const void *  data 
)

Modifies the entry pointer at the specified key and returns the previous entry.

Parameters:
[in,out]hashThe given hash table.
[in]keyThe key of the entry to modify.
[in]dataThe new data.
Returns:
The data pointer for the previously stored entry on success, or NULL otherwise.

This function modifies the data of key with data in hash. If no entry is found, nothing is added to hash.

Since :
2.3
Examples:
eina_hash_01.c, eina_hash_03.c, eina_hash_04.c, eina_hash_05.c, eina_hash_06.c, and eina_hash_07.c.
void* eina_hash_modify_by_hash ( Eina_Hash hash,
const void *  key,
int  key_length,
int  key_hash,
const void *  data 
)

Modifies the entry pointer at the specified key and returns the previous entry.

Parameters:
[in,out]hashThe given hash table.
[in]keyThe key of the entry to modify.
[in]key_lengthShould be the length of key (don't forget to count '\0' for string).
[in]key_hashThe hash that always matches the key. Ignored if key is NULL.
[in]dataThe data to replace the current entry, if it exists.
Returns:
The data pointer for the previously stored entry, or NULL if not found. If an existing entry is not found, nothing is added to the hash.
Since :
2.3
Examples:
eina_hash_08.c.
Eina_Bool eina_hash_move ( Eina_Hash hash,
const void *  old_key,
const void *  new_key 
)

Changes the key of an entry in a hash without triggering the free callback.

Parameters:
[in,out]hashThe given hash table.
[in]old_keyThe current key associated with the data.
[in]new_keyThe new key to associate data with.
Returns:
EINA_FALSE in any case but success, EINA_TRUE on success.

This function moves data from one key to another, but does not call the Eina_Free_Cb associated with the hash table when destroying the old key.

Since :
2.3
Examples:
eina_hash_01.c, eina_hash_03.c, eina_hash_04.c, eina_hash_05.c, eina_hash_06.c, and eina_hash_07.c.
static int eina_hash_murmur3 ( const char *  key,
int  len 
) [static]

Hash function from http://sites.google.com/site/murmurhash/.

Parameters:
[in]keyThe key to hash.
[in]lenThe length of the key.
Returns:
The hash value.
Eina_Hash* eina_hash_new ( Eina_Key_Length  key_length_cb,
Eina_Key_Cmp  key_cmp_cb,
Eina_Key_Hash  key_hash_cb,
Eina_Free_Cb  data_free_cb,
int  buckets_power_size 
)

Creates a new hash table.

Parameters:
[in]key_length_cbThe function called when getting the size of the key.
[in]key_cmp_cbThe function called when comparing the keys.
[in]key_hash_cbThe function called when getting the values.
[in]data_free_cbThe function called on each value when the hash table is freed, or when an item is deleted from it. NULL can be passed as a callback.
[in]buckets_power_sizeThe size of the buckets.
Returns:
The new hash table, or NULL on failure.

This function creates a new hash table using user-defined callbacks to manage the hash table. If key_cmp_cb or key_hash_cb are NULL, NULL is returned. If buckets_power_size is smaller or equal than 2, or if it is greater or equal than 17, NULL is returned.

The number of buckets created will be 2 ^ buckets_power_size. This means that if buckets_power_size is 5, there will be created 32 buckets, whereas for a buckets_power_size of 8, there will be 256 buckets.

Pre-defined functions are available to create a hash table. See eina_hash_string_djb2_new(), eina_hash_string_superfast_new(), eina_hash_string_small_new(), eina_hash_int32_new(), eina_hash_int64_new(), eina_hash_pointer_new() and eina_hash_stringshared_new().

Since :
2.3
Examples:
eina_hash_02.c.

Creates a new hash table for use with pointers.

Parameters:
[in]data_free_cbThe function called on each value when the hash table is freed, or when an item is deleted from it. NULL can be passed as callback.
Returns:
The new hash table, or NULL on failure.

This function creates a new hash table using the int64/int32 algorithm for table management and dereferenced pointers to compare the keys. Values can then be looked up with pointers other than the original key pointer that was used to add values. This method may appear to be able to match string keys, but actually it only matches the first character.

 // For a hash that will have only one pointer to each structure
 extern Eina_Hash *hash;
 extern void *data;

 if (!eina_hash_find(hash, &data))
    eina_hash_add(hash, &data, data);
Since :
2.3
Examples:
eina_hash_07.c.
int eina_hash_population ( const Eina_Hash hash)

Returns the number of entries in the given hash table.

Parameters:
[in]hashThe given hash table.
Returns:
The number of entries in the hash table, or 0 on error or if hash is NULL.
Since :
2.3
Examples:
eina_hash_01.c, eina_hash_03.c, eina_hash_04.c, eina_hash_05.c, eina_hash_06.c, and eina_hash_07.c.
void* eina_hash_set ( Eina_Hash hash,
const void *  key,
const void *  data 
)

Modifies the entry pointer at the specified key and returns the previous entry or adds the entry if not found.

Parameters:
[in,out]hashThe given hash table.
[in]keyThe key of the entry to modify.
[in]dataThe data to replace the previous entry.
Returns:
The data pointer for the previous stored entry, or NULL otherwise.

This function modifies the value of key to data in hash. If no entry is found, data is added to hash with the key key.

Since :
2.3
Examples:
eina_hash_01.c, eina_hash_03.c, eina_hash_04.c, eina_hash_05.c, eina_hash_06.c, and eina_hash_07.c.

Creates a new hash table using the djb2 algorithm.

Parameters:
[in]data_free_cbThe function called on each value when the hash table is freed, or when an item is deleted from it. NULL can be passed as callback.
Returns:
The new hash table, or NULL on failure.

This function creates a new hash table using the djb2 algorithm for table management and strcmp() to compare the keys. Values can then be looked up with pointers other than the original key pointer that was used to add values.

Since :
2.3
Examples:
eina_hash_04.c.

Creates a new hash table for use with strings with small bucket size.

Parameters:
[in]data_free_cbThe function called on each value when the hash table is freed, or when an item is deleted from it. NULL can be passed as callback.
Returns:
The new hash table, or NULL on failure.

This function creates a new hash table using the superfast algorithm for table management and strcmp() to compare the keys, but with a smaller bucket size (compared to eina_hash_string_superfast_new()) which will minimize the memory used by the returned hash table. Values can then be looked up with pointers other than the original key pointer that was used to add values.

Since :
2.3
Examples:
eina_hash_03.c.

Creates a new hash table for use with strings.

Parameters:
[in]data_free_cbThe function called on each value when the hash table is freed, or when an item is deleted from it. NULL can be passed as callback.
Returns:
The new hash table, or NULL on failure.

This function creates a new hash table using the superfast algorithm for table management and strcmp() to compare the keys. Values can then be looked up with pointers other than the original key pointer that was used to add values.

Warning:
Don't use this kind of hash when there is a possibility to remotely request and push data in it. This hash is subject to denial of service.
Since :
2.3
Examples:
eina_hash_01.c, and eina_hash_08.c.

Creates a new hash table optimized for stringshared values.

Parameters:
[in]data_free_cbThe function called on each value when the hash table is freed, or when an item is deleted from it. NULL can be passed as callback.
Returns:
The new hash table, or NULL on failure.

This function creates a new hash table optimized for stringshared values. Values CANNOT be looked up with pointers not equal to the original key pointer that was used to add a value.

Excerpt of code that will NOT work with this type of hash:

 extern Eina_Hash *hash;
 extern const char *value;
 const char *a = eina_stringshare_add("key");

 eina_hash_add(hash, a, value);
 eina_hash_find(hash, "key");
Since :
2.3
Examples:
eina_hash_02.c.
int eina_hash_superfast ( const char *  key,
int  len 
)

Paul Hsieh (http://www.azillionmonkeys.com/qed/hash.html) hash function used by WebCore (http://webkit.org/blog/8/hashtables-part-2/)

Parameters:
[in]keyThe key to hash.
[in]lenThe length of the key.
Returns:
The hash value.
Since :
2.3
Examples:
eina_hash_02.c, and eina_hash_08.c.