Data Structures | Macros | Typedefs | Functions
Accessor Functions

This group discusses the functions to manage an accessor on containers. More...

Data Structures

struct  _Eina_Accessor
 Structure to provide random access to data structures. More...
 

Macros

#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. More...
 
#define EINA_ACCESSOR_FOREACH(accessor, counter, data)
 Definition for helper macro to iterate over all the elements easily. More...
 
#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. More...
 
#define EINA_C_ARRAY_ACCESSOR_PTR_NEW(Array)   eina_carray_length_ptr_accessor_new((void**) Array, sizeof (Array[0]), EINA_C_ARRAY_LENGTH(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. More...
 

Functions

EINA_API void eina_accessor_free (Eina_Accessor *accessor)
 Frees an accessor. More...
 
EINA_API Eina_Bool eina_accessor_data_get (Eina_Accessor *accessor, unsigned int position, void **data)
 Gets the data of an accessor at the given position. More...
 
EINA_API void * eina_accessor_container_get (Eina_Accessor *accessor)
 Gets the container of an accessor. More...
 
EINA_API 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. More...
 
EINA_API Eina_Bool eina_accessor_lock (Eina_Accessor *accessor)
 Locks the container of the accessor. More...
 
EINA_API Eina_Accessoreina_accessor_clone (Eina_Accessor *accessor)
 Clones the container of the accessor. More...
 
EINA_API Eina_Bool eina_accessor_unlock (Eina_Accessor *accessor)
 Unlocks the container of the accessor. More...
 
EINA_API Eina_Accessoreina_carray_length_accessor_new (void **array, unsigned int step, unsigned int length)
 Creates an Eina_Accessor that wraps a plain fixed size C array. More...
 
EINA_API Eina_Accessoreina_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. More...
 

Detailed Description

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.

Macro Definition Documentation

◆ FUNC_ACCESSOR_CLONE

#define FUNC_ACCESSOR_CLONE (   Function)    ((Eina_Accessor_Clone_Callback)Function)

Definition for helper macro to cast Function to a Eina_Iterator_Clone_Callback.

Since
1.10

◆ EINA_ACCESSOR_FOREACH

#define EINA_ACCESSOR_FOREACH (   accessor,
  counter,
  data 
)
Value:
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]accessorThe accessor to use
[out]counterA counter used by eina_accessor_data_get() when iterating over the container.
[out]dataA 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_API void eina_accessor_free(Eina_Accessor *accessor)
Frees an accessor.
Definition: eina_accessor.c:96
#define EINA_ACCESSOR_FOREACH(accessor, counter, data)
Definition for helper macro to iterate over all the elements easily.
Definition: eina_accessor.h:346
EINA_API Eina_Accessor * eina_list_accessor_new(const Eina_List *list)
Returns a new accessor associated with a list.
Definition: eina_list.c:1620
EINA_API Eina_List * eina_list_free(Eina_List *list)
Frees an entire list and all the nodes, ignoring the data contained.
Definition: eina_list.c:823
Structure to provide random access to data structures.
Definition: eina_accessor.h:153
Type for a generic double linked list.
Definition: eina_list.h:318
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.

◆ EINA_C_ARRAY_ACCESSOR_NEW

#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]ArrayThe 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
1.23

Typedef Documentation

◆ Eina_Accessor_Clone_Callback

Eina_Accessor_Clone_Callback

Type for a callback to return a clone for the accessor.

Since
1.10

Function Documentation

◆ eina_accessor_free()

EINA_API void eina_accessor_free ( Eina_Accessor accessor)

Frees an accessor.

This function frees accessor if it is not NULL.

Parameters
[in]accessorThe accessor to free

References EINA_SAFETY_ON_NULL_RETURN, and _Eina_Accessor::free.

Referenced by elm_gengrid_nth_item_get(), and elm_genlist_nth_item_get().

◆ eina_accessor_data_get()

EINA_API 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]accessorThe accessor
[in]positionThe position of the element
[in]dataThe pointer that stores the data to retrieve
Returns
EINA_TRUE on success, otherwise EINA_FALSE

References EINA_FALSE, EINA_SAFETY_ON_NULL_RETURN_VAL, and _Eina_Accessor::get_at.

Referenced by elm_gengrid_nth_item_get(), and elm_genlist_nth_item_get().

◆ eina_accessor_container_get()

EINA_API 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]accessorThe accessor
Returns
The container that created the accessor

References EINA_SAFETY_ON_NULL_RETURN_VAL, and _Eina_Accessor::get_container.

◆ eina_accessor_over()

EINA_API 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]accessorThe accessor
[in]cbThe callback called on the chosen elements
[in]startThe position of the first element
[in]endThe position of the last element
[in]fdataThe data passed to the callback

References eina_accessor_lock(), eina_accessor_unlock(), EINA_SAFETY_ON_FALSE_RETURN, EINA_SAFETY_ON_NULL_RETURN, EINA_TRUE, _Eina_Accessor::get_at, and _Eina_Accessor::get_container.

◆ eina_accessor_lock()

EINA_API Eina_Bool eina_accessor_lock ( Eina_Accessor accessor)

Locks the container of the accessor.

Parameters
[in]accessorThe 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. If accessor is NULL 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.

References EINA_FALSE, EINA_SAFETY_ON_NULL_RETURN_VAL, EINA_TRUE, and _Eina_Accessor::lock.

Referenced by eina_accessor_over().

◆ eina_accessor_clone()

EINA_API Eina_Accessor * eina_accessor_clone ( Eina_Accessor accessor)

Clones the container of the accessor.

Parameters
[in]accessorThe accessor.
Returns
Another accessor
Since
1.10

References _Eina_Accessor::clone, and EINA_SAFETY_ON_NULL_RETURN_VAL.

◆ eina_accessor_unlock()

EINA_API Eina_Bool eina_accessor_unlock ( Eina_Accessor accessor)

Unlocks the container of the accessor.

Parameters
[in]accessorThe 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. If accessor is NULL 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.

References EINA_FALSE, EINA_SAFETY_ON_NULL_RETURN_VAL, EINA_TRUE, and _Eina_Accessor::unlock.

Referenced by eina_accessor_over().

◆ eina_carray_length_accessor_new()

EINA_API Eina_Accessor * eina_carray_length_accessor_new ( void **  array,
unsigned int  step,
unsigned int  length 
)

Creates an Eina_Accessor that wraps a plain fixed size C array.

Parameters
[in]arrayThe array
[in]stepThe size of one element in the array
[in]lengthThe 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));

Since
1.23

References EINA_MAGIC_SET, FUNC_ACCESSOR_FREE, FUNC_ACCESSOR_GET_AT, and FUNC_ACCESSOR_GET_CONTAINER.

◆ eina_carray_length_ptr_accessor_new()

EINA_API 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]arrayThe array
[in]stepThe size of one element in the array
[in]lengthThe 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
1.24

References EINA_MAGIC_SET, FUNC_ACCESSOR_FREE, FUNC_ACCESSOR_GET_AT, and FUNC_ACCESSOR_GET_CONTAINER.