These functions manage accessor on containers. More...

Data Structures

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

Macros

#define FUNC_ACCESSOR_GET_AT(Function)   ((Eina_Accessor_Get_At_Callback)Function)
 Helper macro to cast Function to a Eina_Accessor_Get_At_Callback.
 
#define FUNC_ACCESSOR_GET_CONTAINER(Function)   ((Eina_Accessor_Get_Container_Callback)Function)
 Helper macro to cast Function to a Eina_Accessor_Get_Container_Callback.
 
#define FUNC_ACCESSOR_FREE(Function)   ((Eina_Accessor_Free_Callback)Function)
 Helper macro to cast Function to a Eina_Accessor_Free_Callback.
 
#define FUNC_ACCESSOR_LOCK(Function)   ((Eina_Accessor_Lock_Callback)Function)
 Helper macro to cast Function to a Eina_Iterator_Lock_Callback.
 
#define EINA_ACCESSOR_FOREACH(accessor, counter, data)
 Macro to iterate over all elements easily. More...
 

Typedefs

typedef struct _Eina_Accessor Eina_Accessor
 Abstract type for accessors.
 
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 that returns the container.
 
typedef void(* Eina_Accessor_Free_Callback) (Eina_Accessor *it)
 Type for a callback that frees the container.
 
typedef Eina_Bool(* Eina_Accessor_Lock_Callback) (Eina_Accessor *it)
 Type for a callback that lock the container.
 

Functions

EAPI void eina_accessor_free (Eina_Accessor *accessor)
 Free an accessor. More...
 
EAPI Eina_Bool eina_accessor_data_get (Eina_Accessor *accessor, unsigned int position, void **data) EINA_ARG_NONNULL(1)
 Retrieve the data of an accessor at a given position. More...
 
EAPI void * eina_accessor_container_get (Eina_Accessor *accessor) EINA_ARG_NONNULL(1) EINA_PURE
 Return the container of an accessor. More...
 
EAPI void eina_accessor_over (Eina_Accessor *accessor, Eina_Each_Cb cb, unsigned int start, unsigned int end, const void *fdata) EINA_ARG_NONNULL(2)
 Iterate over the container and execute a callback on chosen elements. More...
 
EAPI Eina_Bool eina_accessor_lock (Eina_Accessor *accessor) EINA_ARG_NONNULL(1)
 Lock the container of the accessor. More...
 
EAPI Eina_Bool eina_accessor_unlock (Eina_Accessor *accessor) EINA_ARG_NONNULL(1)
 Unlock the container of the accessor. More...
 

Detailed Description

These functions manage 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 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 with 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

◆ EINA_ACCESSOR_FOREACH

#define EINA_ACCESSOR_FOREACH (   accessor,
  counter,
  data 
)
Value:
for ((counter) = 0; \
eina_accessor_data_get((accessor), (counter), (void **)(void *)&(data)); \
(counter)++)

Macro to iterate over all elements easily.

Parameters
accessorThe accessor to use.
counterA counter used by eina_accessor_data_get() when iterating over the container.
dataWhere to store * data, must be a pointer support getting its address since * eina_accessor_data_get() requires a pointer to pointer!

This macro allows a convenient way to loop over all elements in an accessor, very similar to EINA_LIST_FOREACH().

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);
Note
if the datatype provides both iterators and accessors prefer to use iterators to iterate over, as they're likely to be more optimized for such task.
this example is not optimal algorithm to release a list since it will walk the list twice, but it serves as an example. For optimized version use EINA_LIST_FREE()
Warning
unless explicitly stated in functions returning accessors, do not modify the accessed object while you walk it, in this example using lists, do not remove list nodes or you might crash! This is not a limitation of accessors themselves, rather in the accessors implementations to keep them as simple and fast as possible.

Function Documentation

◆ eina_accessor_free()

EAPI void eina_accessor_free ( Eina_Accessor accessor)

Free an accessor.

Parameters
accessorThe accessor to free.

This function frees accessor if it is not NULL;

◆ eina_accessor_data_get()

EAPI Eina_Bool eina_accessor_data_get ( Eina_Accessor accessor,
unsigned int  position,
void **  data 
)

Retrieve the data of an accessor at a given position.

Parameters
accessorThe accessor.
positionThe position of the element.
dataThe pointer that stores the data to retrieve.
Returns
EINA_TRUE on success, EINA_FALSE otherwise.

This function retrieves the data of the element pointed by accessor at the porition position, and stores it in data. If accessor is NULL or if an error occurred, EINA_FALSE is returned, otherwise EINA_TRUE is returned.

◆ eina_accessor_container_get()

EAPI void* eina_accessor_container_get ( Eina_Accessor accessor)

Return the container of an accessor.

Parameters
accessorThe accessor.
Returns
The container which created the accessor.

This function returns the container which created accessor. If accessor is NULL, this function returns NULL.

◆ eina_accessor_over()

EAPI void eina_accessor_over ( Eina_Accessor accessor,
Eina_Each_Cb  cb,
unsigned int  start,
unsigned int  end,
const void *  fdata 
)

Iterate over the container and execute a callback on chosen elements.

Parameters
accessorThe accessor.
cbThe callback called on the chosen elements.
startThe position of the first element.
endThe position of the last element.
fdataThe data passed to the callback.

This function iterates over the elements pointed by accessor, starting from the element at position start and ending to 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 greter or equal than end, the function returns immediately.

◆ eina_accessor_lock()

EAPI Eina_Bool eina_accessor_lock ( Eina_Accessor accessor)

Lock the container of the accessor.

Parameters
accessorThe accessor.
Returns
EINA_TRUE on success, EINA_FALSE otherwise.

If the container of the accessor permits it, it will be locked. When a container is locked calling eina_accessor_over() on it will return immediately. If accessor is NULL or if a problem occurred, EINA_FALSE is returned, otherwise EINA_TRUE is returned. If the container isn't lockable, it will return EINA_TRUE.

Warning
None of the existing eina data structures are lockable.

◆ eina_accessor_unlock()

EAPI Eina_Bool eina_accessor_unlock ( Eina_Accessor accessor)

Unlock the container of the accessor.

Parameters
accessorThe accessor.
Returns
EINA_TRUE on success, EINA_FALSE otherwise.

If the container of the accessor permits it and was previously locked, it will be unlocked. If accessor is NULL or if a problem occurred, EINA_FALSE is returned, otherwise EINA_TRUE is returned. If the container is not lockable, it will return EINA_TRUE.

Warning
None of the existing eina data structures are lockable.