Hash table management. More...
Data Structures | |
struct | _Eina_Hash_Tuple |
Macros | |
#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) |
Typedefs | |
typedef struct _Eina_Hash | Eina_Hash |
Type for a generic hash table. | |
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) |
Functions | |
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) |
Create a new hash table. More... | |
void | eina_hash_free_cb_set (Eina_Hash *hash, Eina_Free_Cb data_free_cb) |
Redefine the callback that clean the data of a hash. More... | |
Eina_Hash * | eina_hash_string_djb2_new (Eina_Free_Cb data_free_cb) |
Create a new hash table using the djb2 algorithm. More... | |
Eina_Hash * | eina_hash_string_superfast_new (Eina_Free_Cb data_free_cb) |
Create a new hash table for use with strings. More... | |
Eina_Hash * | eina_hash_string_small_new (Eina_Free_Cb data_free_cb) |
Create a new hash table for use with strings with small bucket size. More... | |
Eina_Hash * | eina_hash_int32_new (Eina_Free_Cb data_free_cb) |
Create a new hash table for use with 32bit integers. More... | |
Eina_Hash * | eina_hash_int64_new (Eina_Free_Cb data_free_cb) |
Create a new hash table for use with 64bit integers. More... | |
Eina_Hash * | eina_hash_pointer_new (Eina_Free_Cb data_free_cb) |
Create a new hash table for use with pointers. More... | |
Eina_Hash * | eina_hash_stringshared_new (Eina_Free_Cb data_free_cb) |
Create a new hash table optimized for stringshared values. More... | |
Eina_Bool | eina_hash_add (Eina_Hash *hash, const void *key, const void *data) |
Add an entry to the given hash table. More... | |
Eina_Bool | eina_hash_direct_add (Eina_Hash *hash, const void *key, const void *data) |
Add an entry to the given hash table without duplicating the string key. More... | |
Eina_Bool | eina_hash_del (Eina_Hash *hash, const void *key, const void *data) |
Remove the entry identified by a key or a data from the given hash table. More... | |
void * | eina_hash_find (const Eina_Hash *hash, const void *key) |
Retrieve a specific entry in the given hash table. More... | |
void * | eina_hash_modify (Eina_Hash *hash, const void *key, const void *data) |
Modify the entry pointer at the specified key and return the old entry. More... | |
void * | eina_hash_set (Eina_Hash *hash, const void *key, const void *data) |
Modify the entry pointer at the specified key and return the old entry or add the entry if not found. More... | |
Eina_Bool | eina_hash_move (Eina_Hash *hash, const void *old_key, const void *new_key) |
Change the key associated with a data without triggering the free callback. More... | |
void | eina_hash_free (Eina_Hash *hash) |
Free the given hash table resources. More... | |
void | eina_hash_free_buckets (Eina_Hash *hash) |
Free the given hash table buckets resources. More... | |
int | eina_hash_population (const Eina_Hash *hash) |
Returns the number of entries in the given hash table. More... | |
Eina_Bool | eina_hash_add_by_hash (Eina_Hash *hash, const void *key, int key_length, int key_hash, const void *data) |
Add an entry to the given hash table. More... | |
Eina_Bool | eina_hash_direct_add_by_hash (Eina_Hash *hash, const void *key, int key_length, int key_hash, const void *data) |
Add an entry to the given hash table and do not duplicate the string key. More... | |
Eina_Bool | eina_hash_del_by_key_hash (Eina_Hash *hash, const void *key, int key_length, int key_hash) |
Remove the entry identified by a key and a key hash from the given hash table. More... | |
Eina_Bool | eina_hash_del_by_key (Eina_Hash *hash, const void *key) |
Remove the entry identified by a key from the given hash table. More... | |
Eina_Bool | eina_hash_del_by_data (Eina_Hash *hash, const void *data) |
Remove the entry identified by a data from the given hash table. More... | |
Eina_Bool | eina_hash_del_by_hash (Eina_Hash *hash, const void *key, int key_length, int key_hash, const void *data) |
Remove the entry identified by a key and a key hash or a data from the given hash table. More... | |
void * | eina_hash_find_by_hash (const Eina_Hash *hash, const void *key, int key_length, int key_hash) |
Retrieve a specific entry in the given hash table. More... | |
void * | eina_hash_modify_by_hash (Eina_Hash *hash, const void *key, int key_length, int key_hash, const void *data) |
Modify the entry pointer at the specified key and returns the old entry. More... | |
Eina_Iterator * | eina_hash_iterator_key_new (const Eina_Hash *hash) |
Returned a new iterator associated to hash keys. More... | |
Eina_Iterator * | eina_hash_iterator_data_new (const Eina_Hash *hash) |
Returned a new iterator associated to hash data. More... | |
Eina_Iterator * | eina_hash_iterator_tuple_new (const Eina_Hash *hash) |
Returned a new iterator associated to hash keys and data. More... | |
void | eina_hash_foreach (const Eina_Hash *hash, Eina_Hash_Foreach func, const void *fdata) |
Call a function on every member stored in the hash table. More... | |
int | eina_hash_superfast (const char *key, int len) |
static int | eina_hash_djb2 (const char *key, int len) |
static int | eina_hash_djb2_len (const char *key, int *plen) |
static int | eina_hash_int32 (const unsigned int *pkey, int len) |
static int | eina_hash_int64 (const unsigned long int *pkey, int len) |
static int | eina_hash_murmur3 (const char *key, int len) |
Detailed Description
Hash table management.
Useful for mapping keys to values.
The hash table is useful for when one wants to implement a table that maps keys (usually strings) to data, and have 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.
Different implementations exists depending on what kind of key will be used to access the data: strings, integers, pointers, stringshared or your own.
Eina hash tables can copy the keys when using eina_hash_add() or not when using eina_hash_direct_add().
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 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 ilustrates the basic idea:
Adding an element to the hash table is made of:
- calculating 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 two first steps have constant time, proportional to the hash function being used. Adding the key to the rbtree will be proportional on the number of keys on that bucket.
The average cost of lookup depends on the number of keys per bucket (load factor) of the table, if the distribution of keys is sufficiently uniform.
Performance
As said before, the performance depends on the load factor. So trying to keep the load factor as small as possible will improve the hash table performance. But increasing the buckets_power_size will also increase the memory consumption. The default hash table creation functions already have a good number of buckets, enough for most cases. Particularly for strings, if just a few keys (less than 30) will be added to the hash table, eina_hash_string_small_new should be used, since it will reduce the memory consumption for the buckets, and you still won't have 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 on 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)
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 always preferred.
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, instead of checking with eina_hash_find and then doing 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:
- Eina_Hash in action
- Different types of tables
- Different types of hash in use:
- Different add and delete functions
Macro Definition Documentation
#define EINA_KEY_LENGTH | ( | Function | ) | ((Eina_Key_Length)Function) |
- Parameters
-
Function The function used to hash calculation.
- Examples:
- eina_hash_02.c.
Referenced by eina_file_open(), eina_hash_int32_new(), eina_hash_int64_new(), eina_hash_pointer_new(), eina_hash_string_djb2_new(), eina_hash_string_small_new(), and eina_hash_string_superfast_new().
#define EINA_KEY_CMP | ( | Function | ) | ((Eina_Key_Cmp)Function) |
- Parameters
-
Function The function used to hash calculation.
- Examples:
- eina_hash_02.c.
Referenced by eina_file_open(), eina_hash_int32_new(), eina_hash_int64_new(), eina_hash_pointer_new(), eina_hash_string_djb2_new(), eina_hash_string_small_new(), eina_hash_string_superfast_new(), and eina_hash_stringshared_new().
#define EINA_KEY_HASH | ( | Function | ) | ((Eina_Key_Hash)Function) |
- Parameters
-
Function The function used to hash calculation.
- Examples:
- eina_hash_02.c.
Referenced by eina_file_open(), eina_hash_int32_new(), eina_hash_int64_new(), eina_hash_pointer_new(), eina_hash_string_djb2_new(), eina_hash_string_small_new(), eina_hash_string_superfast_new(), and eina_hash_stringshared_new().
Function Documentation
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 | ||
) |
Create a new hash table.
- Parameters
-
key_length_cb The function called when getting the size of the key. key_cmp_cb The function called when comparing the keys. key_hash_cb The function called when getting the values. data_free_cb The 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.buckets_power_size The size of the buckets.
- Returns
- The new hash table.
This function creates a new hash table using user-defined callbacks to manage the hash table. On failure, NULL
is returned and EINA_ERROR_OUT_OF_MEMORY is set. 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. 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().
- Examples:
- eina_hash_02.c.
References EINA_ERROR_OUT_OF_MEMORY, eina_error_set(), and EINA_MAGIC_SET.
Referenced by eina_file_open(), eina_hash_int32_new(), eina_hash_int64_new(), eina_hash_pointer_new(), eina_hash_string_djb2_new(), eina_hash_string_small_new(), eina_hash_string_superfast_new(), and eina_hash_stringshared_new().
void eina_hash_free_cb_set | ( | Eina_Hash * | hash, |
Eina_Free_Cb | data_free_cb | ||
) |
Redefine the callback that clean the data of a hash.
- Parameters
-
hash The given hash table data_free_cb The 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.
- Since
- 1.1 See eina_hash_new.
Eina_Hash* eina_hash_string_djb2_new | ( | Eina_Free_Cb | data_free_cb | ) |
Create a new hash table using the djb2 algorithm.
- Parameters
-
data_free_cb The 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.
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. On failure, this function returns NULL
.
- Examples:
- eina_hash_04.c.
References eina_hash_new(), EINA_KEY_CMP, EINA_KEY_HASH, and EINA_KEY_LENGTH.
Eina_Hash* eina_hash_string_superfast_new | ( | Eina_Free_Cb | data_free_cb | ) |
Create a new hash table for use with strings.
- Parameters
-
data_free_cb The 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.
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. On failure, this function returns NULL
.
- Examples:
- eina_hash_01.c, and eina_hash_08.c.
References eina_hash_new(), EINA_KEY_CMP, EINA_KEY_HASH, and EINA_KEY_LENGTH.
Eina_Hash* eina_hash_string_small_new | ( | Eina_Free_Cb | data_free_cb | ) |
Create a new hash table for use with strings with small bucket size.
- Parameters
-
data_free_cb The 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.
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. On failure, this function returns NULL
.
- Examples:
- eina_hash_03.c.
References eina_hash_new(), EINA_KEY_CMP, EINA_KEY_HASH, and EINA_KEY_LENGTH.
Eina_Hash* eina_hash_int32_new | ( | Eina_Free_Cb | data_free_cb | ) |
Create a new hash table for use with 32bit integers.
- Parameters
-
data_free_cb The 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.
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. On failure, this function returns NULL
.
- Examples:
- eina_hash_05.c.
References eina_hash_new(), EINA_KEY_CMP, EINA_KEY_HASH, and EINA_KEY_LENGTH.
Eina_Hash* eina_hash_int64_new | ( | Eina_Free_Cb | data_free_cb | ) |
Create a new hash table for use with 64bit integers.
- Parameters
-
data_free_cb The 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.
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. On failure, this function returns NULL
.
- Examples:
- eina_hash_06.c.
References eina_hash_new(), EINA_KEY_CMP, EINA_KEY_HASH, and EINA_KEY_LENGTH.
Eina_Hash* eina_hash_pointer_new | ( | Eina_Free_Cb | data_free_cb | ) |
Create a new hash table for use with pointers.
- Parameters
-
data_free_cb The 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.
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, actually it only matches the first character. On failure, this function returns NULL
.
- Examples:
- eina_hash_07.c.
References eina_hash_new(), EINA_KEY_CMP, EINA_KEY_HASH, and EINA_KEY_LENGTH.
Referenced by eina_file_open().
Eina_Hash* eina_hash_stringshared_new | ( | Eina_Free_Cb | data_free_cb | ) |
Create a new hash table optimized for stringshared values.
- Parameters
-
data_free_cb The 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.
This function creates a new hash table optimized for stringshared values. Values CAN NOT be looked up with pointers not equal to the original key pointer that was used to add a value. On failure, this function returns NULL
.
Excerpt of code that will NOT work with this type of hash:
- Examples:
- eina_hash_02.c.
References eina_hash_new(), EINA_KEY_CMP, and EINA_KEY_HASH.
Add an entry to the given hash table.
- Parameters
-
hash The given hash table. Cannot be NULL
.key A unique key. Cannot be NULL
.data Data to associate with the string given by key
. Cannot beNULL
.
- Returns
- EINA_FALSE if an error occurred, EINA_TRUE otherwise.
This function adds key
to hash
. key
is expected to be unique within the hash table. Key uniqueness varies depending on the type of hash:
a stringshared Eina_Hash need to have unique pointers (which implies unique strings). All other string hash types require the strings themselves to be unique. Pointer, int32 and int64 hashes need to have these values as unique. 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. If an error occurs, eina_error_get() should be used to determine if an allocation error occurred during this function. This function returns EINA_FALSE if an error occurred, EINA_TRUE otherwise.
- 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.
References EINA_FALSE.
Referenced by eina_file_map_new(), and eina_hash_move().
Add an entry to the given hash table without duplicating the string key.
- Parameters
-
hash The given hash table. Cannot be NULL
.key A unique key. Cannot be NULL
.data Data to associate with the string given by key
. Cannot beNULL
- Returns
- EINA_FALSE if an error occurred, EINA_TRUE otherwise.
This function adds key
to hash
. key
is expected to be unique within the hash table. Key uniqueness varies depending on the type of hash:
a stringshared Eina_Hash need have unique pointers (which implies unique strings). All other string hash types require the strings themselves to be unique. Pointer, int32 and int64 hashes need to have these values as unique. 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(). This function does not make a copy of key
, so it must be a string constant or stored elsewhere ( in the object being added). Key strings are case sensitive. If an error occurs, eina_error_get() should be used to determine if an allocation error occurred during this function. This function returns EINA_FALSE if an error occurred, EINA_TRUE otherwise.
- Examples:
- eina_hash_02.c.
References EINA_FALSE.
Referenced by eina_file_map_new(), and eina_file_open().
Remove the entry identified by a key or a data from the given hash table.
- Parameters
-
hash The given hash table. key The key. data The 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 functions 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
. This function returns EINA_FALSE if an error occurred, EINA_TRUE otherwise.
- Note
- if you know you already have the key, use eina_hash_del_by_key() or eina_hash_del_by_key_hash(). If you know you don't have the key, use eina_hash_del_by_data() directly.
- 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.
References EINA_FALSE, and eina_hash_del_by_data().
Referenced by eina_file_close(), eina_file_map_free(), eina_file_open(), and eina_hash_move().
void* eina_hash_find | ( | const Eina_Hash * | hash, |
const void * | key | ||
) |
Retrieve a specific entry in the given hash table.
- Parameters
-
hash The given hash table. key The key of the entry to find.
- Returns
- The data pointer for the stored entry on success,
NULL
otherwise.
This function retrieves the entry associated to key
in hash
. If hash
is NULL
, this function returns immediately NULL
. This function returns the data pointer on success, NULL
otherwise.
- 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.
References eina_hash_find_by_hash().
Referenced by eina_file_map_faulted(), eina_file_map_free(), eina_file_map_new(), eina_file_open(), and eina_hash_move().
void* eina_hash_modify | ( | Eina_Hash * | hash, |
const void * | key, | ||
const void * | data | ||
) |
Modify the entry pointer at the specified key and return the old entry.
- Parameters
-
hash The given hash table. key The key of the entry to modify. data The data to replace the old entry.
- Returns
- The data pointer for the old 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
. On success this function returns the old entry, otherwise it returns NULL
.
- 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.
References eina_hash_modify_by_hash().
void* eina_hash_set | ( | Eina_Hash * | hash, |
const void * | key, | ||
const void * | data | ||
) |
Modify the entry pointer at the specified key and return the old entry or add the entry if not found.
- Parameters
-
hash The given hash table. key The key of the entry to modify. data The data to replace the old entry
- Returns
- The data pointer for the old stored entry, or
NULL
otherwise.
This function modifies the data of key
with data
in hash
. If no entry is found, data
is added to hash
with the key key
. On success this function returns the old entry, otherwise it returns NULL
. To check for errors, use eina_error_get().
- 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.
References _Eina_Hash_Tuple::data, _Eina_Hash_Tuple::key, and _Eina_Hash_Tuple::key_length.
Change the key associated with a data without triggering the free callback.
- Parameters
-
hash The given hash table. old_key The current key associated with the data new_key The new key to associate data with
- Returns
- EINA_FALSE in any case but success, EINA_TRUE on success.
This function allows for the move of data from one key to another, but does not call the Eina_Free_Cb associated with the hash table when destroying the old key.
- 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.
References EINA_FALSE, eina_hash_add(), eina_hash_del(), and eina_hash_find().
void eina_hash_free | ( | Eina_Hash * | hash | ) |
Free the given hash table resources.
- Parameters
-
hash The hash table to be freed.
This function frees up all the memory allocated to storing hash
, and call the free callback if it has been passed to the hash table at creation time. If no free callback has been passed, any entries in the table that the program has no more pointers for elsewhere may now be lost, so this should only be called if the program has already freed any allocated data in the hash table or has the pointers for data in the table stored elsewhere as well. If hash
is NULL
, the function returns immediately.
Example:
- 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.
References eina_rbtree_delete(), and EINA_RBTREE_FREE_CB.
void eina_hash_free_buckets | ( | Eina_Hash * | hash | ) |
Free the given hash table buckets resources.
- Parameters
-
hash The hash table whose buckets have to be freed.
This function frees up all the memory allocated to storing the buckets of hash
, and calls the free callback on all hash table buckets if it has been passed to the hash table at creation time, then frees the buckets. If no free callback has been passed, no buckets value will be freed. If hash
is NULL
, the function returns immediately.
- 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.
References eina_rbtree_delete(), and EINA_RBTREE_FREE_CB.
int eina_hash_population | ( | const Eina_Hash * | hash | ) |
Returns the number of entries in the given hash table.
- Parameters
-
hash The given hash table.
- Returns
- The number of entries in the hash table.
This function returns the number of entries in hash
, or 0 on error. If hash
is NULL
, 0 is returned.
- 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.
Eina_Bool eina_hash_add_by_hash | ( | Eina_Hash * | hash, |
const void * | key, | ||
int | key_length, | ||
int | key_hash, | ||
const void * | data | ||
) |
Add an entry to the given hash table.
- Parameters
-
hash The given hash table. Cannot be NULL
.key A unique key. Cannot be NULL
.key_length The length of the key. key_hash The hash that will always match key. data The 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
. hash
, key
and data
cannot be NULL
, in that case EINA_FALSE is returned. key
is expected to be a unique within the hash table. Otherwise, one cannot be sure which inserted data pointer will be accessed with eina_hash_find, and removed with eina_hash_del. Do not forget to count '\0' for string when setting the value of key_length
. key_hash
is expected to always match key
. Otherwise, one cannot be sure to find it again with eina_hash_find_by_hash. Key strings are case sensitive. If an error occurs, eina_error_get() should be used to determine if an allocation error occurred during this function. This function returns EINA_FALSE if an error occurred, EINA_TRUE otherwise.
- See also
- eina_hash_add()
- Examples:
- eina_hash_08.c.
Eina_Bool eina_hash_direct_add_by_hash | ( | Eina_Hash * | hash, |
const void * | key, | ||
int | key_length, | ||
int | key_hash, | ||
const void * | data | ||
) |
Add an entry to the given hash table and do not duplicate the string key.
- Parameters
-
hash The given hash table. Cannot be NULL
.key A unique key. Cannot be NULL
.key_length Should be the length of key
(don't forget to count '\0' for string).key_hash The hash that will always match key. data Data to associate with the string given by key
. Cannot beNULL
.
- Returns
- EINA_FALSE if an error occurred, EINA_TRUE otherwise.
This function adds key
to hash
. hash
, key
and data
can be NULL
, in that case EINA_FALSE is returned. key
is expected to be unique within the hash table. Otherwise, one cannot be sure which inserted data pointer will be accessed with eina_hash_find, and removed with eina_hash_del. This function does not make a copy of key
so it must be a string constant or stored elsewhere (in the object being added). Do not forget to count '\0' for string when setting the value of key_length
. key_hash
is expected to always match key
. Otherwise, one cannot be sure to find it again with eina_hash_find_by_hash. Key strings are case sensitive. If an error occurs, eina_error_get() should be used to determine if an allocation error occurred during this function. This function returns EINA_FALSE if an error occurred, EINA_TRUE otherwise.
- See also
- eina_hash_direct_add()
- 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 | ||
) |
Remove the entry identified by a key and a key hash from the given hash table.
- Parameters
-
hash The given hash table. Cannot be NULL
.key The key. Cannot be NULL
.key_length The length of the key. key_hash The hash that always match 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. Do not forget to count '\0' for string when setting the value of key_length
. If hash
or key
are NULL
, the functions returns immediately EINA_FALSE. This function returns EINA_FALSE if an error occurred, EINA_TRUE otherwise.
- 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.
- Examples:
- eina_hash_08.c.
References EINA_FALSE.
Remove the entry identified by a key from the given hash table.
This version will calculate key length and hash by using functions provided to hash creation function.
- Parameters
-
hash The given hash table. Cannot be NULL
.key The 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 by using functiond provided to has 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 functions returns immediately EINA_FALSE. This function returns EINA_FALSE if an error occurred, EINA_TRUE otherwise.
- 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.
- Examples:
- eina_hash_08.c.
References EINA_FALSE.
Remove the entry identified by a data from the given hash table.
This version is slow since there is no quick access to nodes based on data.
- Parameters
-
hash The given hash table. Cannot be NULL
.data The data value to search and remove. Cannot be NULL
.
- Returns
- EINA_FALSE if an error occurred, 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. If hash
or data
are NULL
, the functions returns immediately EINA_FALSE. This function returns EINA_FALSE if an error occurred, EINA_TRUE otherwise.
- Note
- if you already have the key, use eina_hash_del_by_key() or eina_hash_del_by_key_hash() instead.
- Examples:
- eina_hash_08.c.
References EINA_FALSE.
Referenced by eina_hash_del(), and eina_hash_del_by_hash().
Eina_Bool eina_hash_del_by_hash | ( | Eina_Hash * | hash, |
const void * | key, | ||
int | key_length, | ||
int | key_hash, | ||
const void * | data | ||
) |
Remove the entry identified by a key and a key hash or a data from the given hash table.
If key
is NULL
, then data
is used to find a match to remove.
- Parameters
-
hash The given hash table. Cannot be NULL
.key The key. key_length The length of the key. key_hash The hash that always match the key. data The 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 functions returns immediately EINA_FALSE. 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
. This function returns EINA_FALSE if an error occurred, EINA_TRUE otherwise.
- Note
- if you know you already have the key, use eina_hash_del_by_key_hash(), if you know you don't have the key, use eina_hash_del_by_data() directly.
References EINA_FALSE, and eina_hash_del_by_data().
void* eina_hash_find_by_hash | ( | const Eina_Hash * | hash, |
const void * | key, | ||
int | key_length, | ||
int | key_hash | ||
) |
Retrieve a specific entry in the given hash table.
- Parameters
-
hash The given hash table. Cannot be NULL
.key The key of the entry to find. key_length The length of the key. key_hash The hash that always match the key
- Returns
- The data pointer for the stored entry on success,
NULL
otherwise.
This function retrieves the entry associated to key
of length key_length
in hash
. key_hash
is the hash that always match key
. It is ignored if key
is NULL
. Do not forget to count '\0' for string when setting the value of key_length
. If hash
is NULL
, this function returns immediately NULL
. This function returns the data pointer on success, NULL
otherwise.
- Examples:
- eina_hash_08.c.
References _Eina_Hash_Tuple::data, _Eina_Hash_Tuple::key, and _Eina_Hash_Tuple::key_length.
Referenced by eina_hash_find().
void* eina_hash_modify_by_hash | ( | Eina_Hash * | hash, |
const void * | key, | ||
int | key_length, | ||
int | key_hash, | ||
const void * | data | ||
) |
Modify the entry pointer at the specified key and returns the old entry.
- Parameters
-
hash The given hash table. key The key of the entry to modify. key_length Should be the length of key
(don't forget to count '\0' for string).key_hash The hash that always match the key. Ignored if key
isNULL
.data The data to replace the old entry, if it exists.
- Returns
- The data pointer for the old stored entry, or
NULL
if not found. If an existing entry is not found, nothing is added to the hash.
- Examples:
- eina_hash_08.c.
References _Eina_Hash_Tuple::data, _Eina_Hash_Tuple::key, and _Eina_Hash_Tuple::key_length.
Referenced by eina_hash_modify().
Eina_Iterator* eina_hash_iterator_key_new | ( | const Eina_Hash * | hash | ) |
Returned a new iterator associated to hash keys.
- Parameters
-
hash The hash.
- Returns
- A new iterator.
This function returns a newly allocated iterator associated to hash
. If hash
is not populated, this function still returns a valid iterator that will always return false on eina_iterator_next(), thus keeping API sane.
If the memory can not be allocated, NULL is returned and EINA_ERROR_OUT_OF_MEMORY is set. Otherwise, a valid iterator is returned.
- Warning
- if the hash structure changes then the iterator becomes invalid! That is, if you add or remove items this iterator behavior is undefined and your program may crash!
- 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.
References EINA_ERROR_OUT_OF_MEMORY, eina_error_set(), EINA_MAGIC_SET, FUNC_ITERATOR_FREE, FUNC_ITERATOR_GET_CONTAINER, and FUNC_ITERATOR_NEXT.
Eina_Iterator* eina_hash_iterator_data_new | ( | const Eina_Hash * | hash | ) |
Returned a new iterator associated to hash data.
- Parameters
-
hash The hash.
- Returns
- A new iterator.
This function returns a newly allocated iterator associated to hash
. If hash
is not populated, this function still returns a valid iterator that will always return false on eina_iterator_next(), thus keeping API sane.
If the memory can not be allocated, NULL
is returned and EINA_ERROR_OUT_OF_MEMORY is set. Otherwise, a valid iterator is returned.
- Warning
- if the hash structure changes then the iterator becomes invalid. That is, if you add or remove items this iterator behavior is undefined and your program may crash.
- 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.
References EINA_ERROR_OUT_OF_MEMORY, eina_error_set(), EINA_MAGIC_SET, FUNC_ITERATOR_FREE, FUNC_ITERATOR_GET_CONTAINER, and FUNC_ITERATOR_NEXT.
Eina_Iterator* eina_hash_iterator_tuple_new | ( | const Eina_Hash * | hash | ) |
Returned a new iterator associated to hash keys and data.
- Parameters
-
hash The hash.
- Returns
- A new iterator.
This function returns a newly allocated iterator associated to hash
. If hash
is not populated, this function still returns a valid iterator that will always return false on eina_iterator_next(), thus keeping API sane.
If the memory can not be allocated, NULL is returned and EINA_ERROR_OUT_OF_MEMORY is set. Otherwise, a valid iterator is returned.
- 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! That is, if you add or remove items this iterator behavior is undefined and your program may crash!
- 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.
References EINA_ERROR_OUT_OF_MEMORY, eina_error_set(), EINA_MAGIC_SET, FUNC_ITERATOR_FREE, FUNC_ITERATOR_GET_CONTAINER, and FUNC_ITERATOR_NEXT.
Referenced by eina_hash_foreach().
void eina_hash_foreach | ( | const Eina_Hash * | hash, |
Eina_Hash_Foreach | func, | ||
const void * | fdata | ||
) |
Call a function on every member stored in the hash table.
- Parameters
-
hash The hash table whose members will be walked func The function to call on each parameter fdata The data pointer to pass to the function being called
This function goes through every entry in the hash table hash
and calls the function func
on each member. The function should not modify the hash table contents if it returns 1. If the hash table contents are modified by this function or the function wishes to stop processing it must return 0, otherwise return 1 to keep processing.
Example:
- 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.
References EINA_EACH_CB, eina_hash_iterator_tuple_new(), eina_iterator_foreach(), and eina_iterator_free().