Eina_Iterator_Group(3)

NAME
Eina_Iterator_Group - Iterator Functions

 - These functions manage iterators on containers.

SYNOPSIS

  Data Structures
struct _Eina_Iterator
structure of an iterator

  Macros
#define FUNC_ITERATOR_NEXT(Function) ((Eina_Iterator_Next_Callback)Function)
Helper macro to cast Function to a Eina_Iterator_Next_Callback.
#define FUNC_ITERATOR_GET_CONTAINER(Function) ((Eina_Iterator_Get_Container_Callback)Function)
Helper macro to cast Function to a Eina_Iterator_Get_Container_Callback.
#define FUNC_ITERATOR_FREE(Function) ((Eina_Iterator_Free_Callback)Function)
Helper macro to cast Function to a Eina_Iterator_Free_Callback.
#define FUNC_ITERATOR_LOCK(Function) ((Eina_Iterator_Lock_Callback)Function)
Helper macro to cast Function to a Eina_Iterator_Lock_Callback.
#define EINA_C_ARRAY_ITERATOR_NEW(Array) eina_carray_length_iterator_new((void**) Array, sizeof (Array[0]), EINA_C_ARRAY_LENGTH(Array))
Creates an Eina_Iterator that iterates through a NUL-terminated C array.
#define eina_multi_iterator_new(It, ...) eina_multi_iterator_internal_new(It, ##__VA_ARGS__, NULL)
Creates an Eina_Iterator that iterates through a series of Eina_Iterator.
#define EINA_ITERATOR_FOREACH(itr, data)
Definition for the macro to iterate over all elements easily.

  Typedefs
typedef struct _Eina_Iterator Eina_Iterator
Abstract type for iterators.
typedef Eina_Bool(* Eina_Iterator_Next_Callback) (Eina_Iterator *it, void **data)
Type for a callback that returns the next element in a container.
typedef void *(* Eina_Iterator_Get_Container_Callback) (Eina_Iterator *it)
Type for a callback that returns the container.
typedef void(* Eina_Iterator_Free_Callback) (Eina_Iterator *it)
Type for a callback that frees the container.
typedef Eina_Bool(* Eina_Iterator_Lock_Callback) (Eina_Iterator *it)
Type for a callback that lock the container.

  Functions
EINA_API void eina_iterator_free (Eina_Iterator *iterator)
Frees an iterator.
EINA_API void * eina_iterator_container_get (Eina_Iterator *iterator)
Returns the container of an iterator.
EINA_API Eina_Bool eina_iterator_next (Eina_Iterator *iterator, void **data)
Returns the value of the current element and go to the next one.
EINA_API void eina_iterator_foreach (Eina_Iterator *iterator, Eina_Each_Cb callback, const void *fdata)
Iterates over the container and execute a callback on each element.
EINA_API Eina_Bool eina_iterator_lock (Eina_Iterator *iterator)
Locks the container of the iterator.
EINA_API Eina_Bool eina_iterator_unlock (Eina_Iterator *iterator)
Unlocks the container of the iterator.
EINA_API Eina_Iterator * eina_carray_iterator_new (void **array)
Creates an Eina_Iterator that iterates through a NUL-terminated C array.
EINA_API Eina_Iterator * eina_carray_length_iterator_new (void **array, unsigned int step, unsigned int length)
Creates an Eina_Iterator that iterates through a C array of specified size.
EINA_API Eina_Iterator * eina_iterator_filter_new (Eina_Iterator *original, Eina_Each_Cb filter, Eina_Free_Cb free_cb, void *data)
Creates a new iterator which which iterates through all elements with are accepted by the filter callback.
EINA_API Eina_Iterator * eina_multi_iterator_internal_new (Eina_Iterator *it,...)
Creates an Eina_Iterator that iterates through a series of Eina_Iterator.
EINA_API Eina_Iterator * eina_iterator_processed_new (Eina_Iterator *iterator, Eina_Process_Cb process, Eina_Free_Cb free_cb, void *fdata)
Calls the process method on each node of iterator, producing new 'processed' nodes and returning a new iterator which contains them.

Detailed Description

These functions manage iterators on containers. These functions allow accessing elements of a container in a generic way, without knowing which container is used (a bit like iterators in the C++ STL). Iterators only allow sequential access (that is, from one element to the next one). For random access, see Accessor Functions.

Getting an iterator to access elements of a given container is done through the functions of that particular container. There is no function to create a generic iterator as iterators absolutely depend on the container. This means you won't find an iterator creation function here, those can be found with the documentation of the container type you're using. Though created with container specific functions iterators are always deleted with the same function: eina_iterator_free().

To get the data and iterate, use eina_iterator_next(). To call a function on all the elements of a container, use eina_iterator_foreach().

Here an example

Macro Definition Documentation

  #define EINA_C_ARRAY_ITERATOR_NEW(Array) eina_carray_length_iterator_new((void**) Array, sizeof (Array[0]), EINA_C_ARRAY_LENGTH(Array))

Creates an Eina_Iterator that iterates through a NUL-terminated C array.

Parameters
    Array The NUL-terminated array

Returns
    The iterator that will walk over the array.

You can create it like this: int array[] = {1, 2, 3, 4};

Eina_Iterator* iterator = EINA_C_ARRAY_ITERATOR_NEW(array);

Since
    1.22

  #define eina_multi_iterator_new(It, ...) eina_multi_iterator_internal_new(It, ##__VA_ARGS__, NULL)

Creates an Eina_Iterator that iterates through a series of Eina_Iterator.

Parameters
    It The first Eina_Iterator to iterate over

Returns
    The iterator that will walk all the other iterator

Eina_Iterator* iterator = eina_multi_iterator_new(it1, it2, it3);

Note
    The returned array will destroy iterator given to it once they are not necessary anymore. Taking ownership of those iterator.

Since
    1.22

  #define EINA_ITERATOR_FOREACH(itr, data)
Value:

                                                              while (eina_iterator_next((itr),                                                               (void **)(void *)&(data)))

Definition for the macro to iterate over all elements easily.

Parameters
    itr The iterator to use.
    data Where to store * data, must be a pointer support getting its address since * eina_iterator_next() requires a pointer to pointer!

This macro is a convenient way to use iterators, 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 iterators:

Eina_List     *list;
Eina_Iterator *itr;
char          *data;
// list is already filled,
// its elements are just duplicated strings
itr = eina_list_iterator_new(list);
EINA_ITERATOR_FOREACH(itr, data)
  free(data);
eina_iterator_free(itr);
eina_list_free(list);

Note
    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
    The order in which the elements will be traversed depends on the underlying container and shouldn't be relied upon.

    unless explicitly stated in functions returning iterators, do not modify the iterated 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 iterators themselves, rather in the iterators implementations to keep them as simple and fast as possible.

Examples
ecore_con_client_example.c, ecore_thread_example.c, eet-data-file_descriptor_01.c, eina_file_01.c, eina_list_03.c, and eina_tiler_01.c.

Function Documentation

  EINA_API void eina_iterator_free (Eina_Iterator * iterator)

Frees an iterator.

Parameters
    iterator The iterator to free.

This function frees iterator if it is not NULL;

References EINA_SAFETY_ON_NULL_RETURN, and _Eina_Iterator::free.

Referenced by ecore_file_dir_is_empty(), ecore_file_ls(), ecore_file_recursive_rm(), ecore_wl_window_surface_find(), edje_available_modules_get(), edje_edit_clean_save_as(), edje_edit_data_list_get(), edje_edit_data_source_generate(), edje_edit_font_path_get(), edje_edit_fonts_list_get(), edje_edit_group_add(), edje_edit_group_aliased_get(), edje_edit_group_aliases_get(), edje_edit_group_copy(), edje_edit_group_data_list_get(), edje_edit_image_replace(), edje_edit_image_set_del(), edje_edit_set_usage_list_get(), edje_edit_vector_usage_list_get(), edje_mmap_collection_list(), edje_mmap_group_exists(), edje_object_access_part_list_get(), eina_cow_gc(), eina_file_dir_list(), eina_file_flush(), eina_hash_foreach(), eina_promise_all_iterator(), eina_tiler_equal(), eina_tiler_intersection(), eina_tiler_subtract(), eina_tiler_union(), eio_monitoring_interval_set(), elm_color_class_editor_add(), and elm_color_class_util_edje_file_list().

  EINA_API void* eina_iterator_container_get (Eina_Iterator * iterator)

Returns the container of an iterator.

Parameters
    iterator The iterator.

Returns
    The container which created the iterator.

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

References EINA_SAFETY_ON_NULL_RETURN_VAL, and _Eina_Iterator::get_container.

  EINA_API Eina_Bool eina_iterator_next (Eina_Iterator * iterator, void ** data)

Returns the value of the current element and go to the next one.

Parameters
    iterator The iterator.
    data The data of the element.

Returns
    EINA_TRUE on success, EINA_FALSE otherwise.

This function returns the value of the current element pointed by iterator in data, then goes to the next element. If iterator is NULL or if a problem occurred, EINA_FALSE is returned, otherwise EINA_TRUE is returned.

References EINA_FALSE, EINA_SAFETY_ON_NULL_RETURN_VAL, and _Eina_Iterator::next.

Referenced by ecore_wl_window_surface_find(), eina_cow_gc(), eina_promise_all_iterator(), eina_tiler_equal(), and eina_tiler_intersection().

  EINA_API void eina_iterator_foreach (Eina_Iterator * iterator, Eina_Each_Cb callback, const void * fdata)

Iterates over the container and execute a callback on each element.

Parameters
    iterator The iterator.
    callback The callback called on each iteration.
    fdata The data passed to the callback.

This function iterates over the elements pointed by iterator, beginning with the current element. For each element, the callback cb is called with the data fdata. If iterator is NULL, the function returns immediately. Also, if cb returns EINA_FALSE, the iteration stops at that point, if cb returns EINA_TRUE the iteration continues.

References eina_iterator_lock(), eina_iterator_unlock(), EINA_SAFETY_ON_NULL_RETURN, EINA_TRUE, _Eina_Iterator::get_container, and _Eina_Iterator::next.

Referenced by eina_hash_foreach().

  EINA_API Eina_Bool eina_iterator_lock (Eina_Iterator * iterator)

Locks the container of the iterator.

Parameters
    iterator The iterator.

Returns
    EINA_TRUE on success, EINA_FALSE otherwise.

If the container of the iterator permits it, it will be locked. When a container is locked calling eina_iterator_foreach() on it will return immediately. If iterator 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.

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

Referenced by eina_iterator_foreach().

  EINA_API Eina_Bool eina_iterator_unlock (Eina_Iterator * iterator)

Unlocks the container of the iterator.

Parameters
    iterator The iterator.

Returns
    EINA_TRUE on success, EINA_FALSE otherwise.

If the container of the iterator permits it and was previously locked, it will be unlocked. If iterator 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.

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

Referenced by eina_iterator_foreach().

  EINA_API Eina_Iterator* eina_carray_iterator_new (void ** array)

Creates an Eina_Iterator that iterates through a NUL-terminated C array.

Parameters
    array The NUL-terminated array

Returns
    The iterator that will walk over the array.

You can create it like this: int array[] = {1, 2, 3, 4}; int* array2[] = {&array[0], &array[1], &array[2], &array[3], NULL};

Eina_Iterator* iterator = eina_carray_iterator_new((void**)array2);

Since
    1.18

References EINA_MAGIC_SET, FUNC_ITERATOR_FREE, FUNC_ITERATOR_GET_CONTAINER, and FUNC_ITERATOR_NEXT.

  EINA_API Eina_Iterator* eina_carray_length_iterator_new (void ** array, unsigned int step, unsigned int length)

Creates an Eina_Iterator that iterates through a C array of specified size.

Parameters
    array The array

Returns
    The iterator that will walk over the array.

You can create it like this: int array[] = {1, 2, 3, 4};

Eina_Iterator* iterator = eina_carray_length_iterator_new((void**)array, sizeof (array[0]), (EINA_C_ARRAY_LENGTH(array));

Since
    1.22

References EINA_MAGIC_SET, FUNC_ITERATOR_FREE, FUNC_ITERATOR_GET_CONTAINER, and FUNC_ITERATOR_NEXT.

  EINA_API Eina_Iterator* eina_iterator_filter_new (Eina_Iterator * original, Eina_Each_Cb filter, Eina_Free_Cb free_cb, void * data)

Creates a new iterator which which iterates through all elements with are accepted by the filter callback.

Parameters
    original the iterator the use as original set
    filter if the callback returns true the element from the original set is taken into the the new set.
    free_cb when the iterator is gone this callback will be called with data as argument
    data the data which is passed to the filter callback

The iterator is filtered while it is being iterated. The original iterator you pass in here is is then owned and will be freed once the the new iterator is freed.

Since
    1.19

References EINA_MAGIC_SET, EINA_SAFETY_ON_NULL_RETURN_VAL, _Eina_Iterator::free, FUNC_ITERATOR_FREE, FUNC_ITERATOR_GET_CONTAINER, and FUNC_ITERATOR_NEXT.

  EINA_API Eina_Iterator* eina_multi_iterator_internal_new (Eina_Iterator * it, ...)

Creates an Eina_Iterator that iterates through a series of Eina_Iterator.

Parameters
    it The first Eina_Iterator to iterate over

Returns
    The iterator that will walk all the other iterator

Eina_Iterator* iterator = eina_multi_iterator_new(it1, it2, it3, NULL);

Note
    The returned array will destroy iterator given to it once they are not necessary anymore. Taking ownership of those iterator.

Since
    1.22

References eina_list_append(), EINA_MAGIC_SET, FUNC_ITERATOR_FREE, FUNC_ITERATOR_GET_CONTAINER, and FUNC_ITERATOR_NEXT.

  EINA_API Eina_Iterator* eina_iterator_processed_new (Eina_Iterator * iterator, Eina_Process_Cb process, Eina_Free_Cb free_cb, void * fdata)

Calls the process method on each node of iterator, producing new 'processed' nodes and returning a new iterator which contains them.

Parameters
    iterator Iterator containing the nodes to process.
    process Method to call on each node.
    free_cb Method called when all nodes have been processed. It receives 'data' as a parameter.
    fdata Additional data passed to the process method.

Processes every node in the input iterator and returns a new iterator containing the processed nodes. This is akin to a Map function: https://en.wikipedia.org/wiki/Map_(higher-order_function)

Since
    1.24

References EINA_MAGIC_SET, EINA_SAFETY_ON_NULL_RETURN_VAL, FUNC_ITERATOR_FREE, FUNC_ITERATOR_GET_CONTAINER, and FUNC_ITERATOR_NEXT.

Author

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