Tizen Native API
7.0
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This group discusses the functions to manage an accessor on containers.
These functions allow to access elements of a container in a generic way, without knowing which container is used (a bit like iterators in the C++ STL). Accessors allows random access (that is, any element in the container). For sequential access, see Iterator Functions.
Getting an accessor to access elements of a given container is done through the functions of that particular container. There is no function to create a generic accessor as accessors absolutely depend on the container. This means you won't find an accessor creation function here, those can be found on the documentation of the container type you're using. Though created with container specific functions, accessors are always deleted by the same function: eina_accessor_free().
To get the data of an element at a given position, use eina_accessor_data_get(). To call a function on chosen elements of a container, use eina_accessor_over().
See an example here.
Functions | |
void | eina_accessor_free (Eina_Accessor *accessor) |
Frees an accessor. | |
Eina_Bool | eina_accessor_data_get (Eina_Accessor *accessor, unsigned int position, void **data) |
Gets the data of an accessor at the given position. | |
void * | eina_accessor_container_get (Eina_Accessor *accessor) |
Gets the container of an accessor. | |
void | eina_accessor_over (Eina_Accessor *accessor, Eina_Each_Cb cb, unsigned int start, unsigned int end, const void *fdata) |
Iterates over the container and executes a callback on the chosen elements. | |
Eina_Bool | eina_accessor_lock (Eina_Accessor *accessor) |
Locks the container of the accessor. | |
Eina_Accessor * | eina_accessor_clone (Eina_Accessor *accessor) |
Clones the container of the accessor. | |
Eina_Bool | eina_accessor_unlock (Eina_Accessor *accessor) |
Unlocks the container of the accessor. | |
Eina_Accessor * | eina_carray_length_ptr_accessor_new (void **array, unsigned int step, unsigned int length) |
Creates an Eina_Accessor that wraps a plain fixed size C array. | |
Typedefs | |
typedef struct _Eina_Accessor | Eina_Accessor |
Type for a accessor structure. | |
typedef Eina_Bool(* | Eina_Accessor_Get_At_Callback )(Eina_Accessor *it, unsigned int idx, void **data) |
Type for a callback that returns the data of a container as the given index. | |
typedef void *(* | Eina_Accessor_Get_Container_Callback )(Eina_Accessor *it) |
Type for a callback to return the container of the accessor. | |
typedef void(* | Eina_Accessor_Free_Callback )(Eina_Accessor *it) |
Type for a callback to free the accessor. | |
typedef Eina_Bool(* | Eina_Accessor_Lock_Callback )(Eina_Accessor *it) |
Type for a callback to lock the accessor. | |
typedef Eina_Accessor *(* | Eina_Accessor_Clone_Callback )(Eina_Accessor *it) |
Type for a callback to return a clone for the accessor. | |
Defines | |
#define | FUNC_ACCESSOR_GET_AT(Function) ((Eina_Accessor_Get_At_Callback)Function) |
Definition for helper macro to cast Function to a Eina_Accessor_Get_At_Callback. | |
#define | FUNC_ACCESSOR_GET_CONTAINER(Function) ((Eina_Accessor_Get_Container_Callback)Function) |
Definition for helper macro to cast Function to a Eina_Accessor_Get_Container_Callback. | |
#define | FUNC_ACCESSOR_FREE(Function) ((Eina_Accessor_Free_Callback)Function) |
Definition for helper macro to cast Function to a Eina_Accessor_Free_Callback. | |
#define | FUNC_ACCESSOR_LOCK(Function) ((Eina_Accessor_Lock_Callback)Function) |
Definition for helper macro to cast Function to a Eina_Iterator_Lock_Callback. | |
#define | FUNC_ACCESSOR_CLONE(Function) ((Eina_Accessor_Clone_Callback)Function) |
Definition for helper macro to cast Function to a Eina_Iterator_Clone_Callback. | |
#define | EINA_ACCESSOR_FOREACH(accessor, counter, data) |
Definition for helper macro to iterate over all the elements easily. | |
#define | EINA_C_ARRAY_ACCESSOR_NEW(Array) eina_carray_length_accessor_new((void**) Array, sizeof (Array[0]), EINA_C_ARRAY_LENGTH(Array)) |
Creates an Eina_Accessor that wraps a plain fixed size C array. |
Define Documentation
#define EINA_ACCESSOR_FOREACH | ( | accessor, | |
counter, | |||
data | |||
) |
for ((counter) = 0; \ eina_accessor_data_get((accessor), (counter), (void **)(void *)&(data)); \ (counter)++)
Definition for helper macro to iterate over all the elements easily.
This macro allows a convenient way to loop over all elements in an accessor, very similar to EINA_LIST_FOREACH().
- Parameters:
-
[in] accessor The accessor to use [out] counter A counter used by eina_accessor_data_get() when iterating over the container. [out] data A pointer to store the data
It must be a pointer to support getting its address since eina_accessor_data_get() requires a pointer.
This macro can be used for freeing the data of a list, like in the following example. It has the same goal as the one documented in EINA_LIST_FOREACH(), but using accessors:
Eina_List *list; Eina_Accessor *accessor; unsigned int i; char *data; // list is already filled, // its elements are just duplicated strings accessor = eina_list_accessor_new(list); EINA_ACCESSOR_FOREACH(accessor, i, data) free(data); eina_accessor_free(accessor); eina_list_free(list);
- Note:
- If the data type provides both iterators and accessors, prefer to use iterators to iterate over, as they're likely to be more optimized for such a task.
- This example is not an optimal algorithm to release a list as it walks through the list twice, but it serves as an example. For an optimized version use EINA_LIST_FREE().
- Warning:
- Unless explicitly stated in the function's returning accessors, do not modify the accessed object while you walk through it. In this example using lists, do not remove list nodes or the program might crash. This is not a limitation of the accessors themselves, but a limitation in the accessors implementations to keep them as simple and fast as possible.
#define EINA_C_ARRAY_ACCESSOR_NEW | ( | Array | ) | eina_carray_length_accessor_new((void**) Array, sizeof (Array[0]), EINA_C_ARRAY_LENGTH(Array)) |
Creates an Eina_Accessor that wraps a plain fixed size C array.
- Parameters:
-
[in] Array The array
- Returns:
- The accessor that will give access to the passed array
You can create it like this: int array[] = {1, 2, 3, 4, 1337, 42};
Eina_Accessor* accessor = EINA_C_ARRAY_ACCESSOR_NEW(array)
- Since (EFL) :
- 1.23
- Examples:
- spinner_cxx_example.cc.
#define FUNC_ACCESSOR_CLONE | ( | Function | ) | ((Eina_Accessor_Clone_Callback)Function) |
Definition for helper macro to cast Function
to a Eina_Iterator_Clone_Callback.
- Since (EFL) :
- 1.10
Typedef Documentation
Type for a callback to return a clone for the accessor.
- Since (EFL) :
- 1.10
Function Documentation
Eina_Accessor* eina_accessor_clone | ( | Eina_Accessor * | accessor | ) |
Clones the container of the accessor.
- Parameters:
-
[in] accessor The accessor.
- Returns:
- Another accessor
- Since (EFL) :
- 1.10
- Since :
- 3.0
void* eina_accessor_container_get | ( | Eina_Accessor * | accessor | ) |
Gets the container of an accessor.
This function returns the container that created accessor
. If accessor
is NULL
, this function returns NULL
.
- Parameters:
-
[in] accessor The accessor
- Returns:
- The container that created the accessor
- Since :
- 2.3
- Examples:
- eina_accessor_01.c.
Eina_Bool eina_accessor_data_get | ( | Eina_Accessor * | accessor, |
unsigned int | position, | ||
void ** | data | ||
) |
Gets the data of an accessor at the given position.
This function retrieves the data of the element pointed by accessor
at the position position
, and stores it in data
. If accessor
is NULL
or if an error occurs, EINA_FALSE
is returned, otherwise EINA_TRUE
is returned.
- Parameters:
-
[in] accessor The accessor [in] position The position of the element [in] data The pointer that stores the data to retrieve
- Returns:
- EINA_TRUE on success, otherwise EINA_FALSE
- Since :
- 2.3
- Examples:
- eina_accessor_01.c.
void eina_accessor_free | ( | Eina_Accessor * | accessor | ) |
Frees an accessor.
This function frees accessor if it is not NULL
.
- Parameters:
-
[in] accessor The accessor to free
- Since :
- 2.3
- Examples:
- eina_accessor_01.c.
Eina_Bool eina_accessor_lock | ( | Eina_Accessor * | accessor | ) |
Locks the container of the accessor.
- Parameters:
-
[in] accessor The accessor
- Returns:
- EINA_TRUE on success, otherwise EINA_FALSE
- Note:
- If the container of the
accessor
permits it, it is locked. When a container is locked by calling eina_accessor_over() on it, it returns immediately. Ifaccessor
isNULL
or if a problem occurs, EINA_FALSE is returned, otherwise EINA_TRUE is returned. If the container is not lockable, it returns EINA_TRUE.
- Warning:
- None of the existing eina data structures are lockable.
- Since :
- 2.3
void eina_accessor_over | ( | Eina_Accessor * | accessor, |
Eina_Each_Cb | cb, | ||
unsigned int | start, | ||
unsigned int | end, | ||
const void * | fdata | ||
) |
Iterates over the container and executes a callback on the chosen elements.
This function iterates over the elements pointed by accessor
, starting from the element at position start
and ending at the element at position end
. For each element, the callback cb
is called with the data fdata
. If accessor
is NULL
or if start
is greater than or equal to end
, the function returns immediately.
- Parameters:
-
[in] accessor The accessor [in] cb The callback called on the chosen elements [in] start The position of the first element [in] end The position of the last element [in] fdata The data passed to the callback
- Since :
- 2.3
Eina_Bool eina_accessor_unlock | ( | Eina_Accessor * | accessor | ) |
Unlocks the container of the accessor.
- Parameters:
-
[in] accessor The accessor
- Returns:
- EINA_TRUE on success, otherwise EINA_FALSE
- Note:
- If the container of the
accessor
permits it and is previously locked, it is unlocked. Ifaccessor
isNULL
or if a problem occurs, EINA_FALSE is returned, otherwise EINA_TRUE is returned. If the container is not lockable, it returns EINA_TRUE.
- Warning:
- None of the existing eina data structures are lockable.
- Since :
- 2.3
Eina_Accessor* eina_carray_length_ptr_accessor_new | ( | void ** | array, |
unsigned int | step, | ||
unsigned int | length | ||
) |
Creates an Eina_Accessor that wraps a plain fixed size C array.
- Parameters:
-
[in] array The array [in] step The size of one element in the array [in] length The number of elements in the array
- Returns:
- The accessor that will give access to the passed array
You can create it like this: int array[] = {1, 2, 3, 4, 1337, 42};
Eina_Accessor* accessor = eina_carray_length_accessor_new(array, sizeof(int), sizeof(array)/sizeof(int));
Note: The difference to eina_carray_length_accessor_new is that this will fill the pointer to the value into the data pointer. *
- Since (EFL) :
- 1.24