Eina_Inlist advanced usage - lists and inlists

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Eina_Inlist advanced usage - lists and inlists

This example describes the usage of Eina_Inlist mixed with Eina_List . We create and add elements to an inlist, and the even members are also added to a normal list. Later we remove the elements divisible by 3 from this normal list.

The struct that is going to be used is the same used in Eina_Inlist basic usage , since we still need the EINA_INLIST macro to declare the inlist node info:

struct my_struct {
EINA_INLIST;
int a, b;
};
EINA_INLIST
#define EINA_INLIST
Used for declaring an inlist member in a struct.
Definition: eina_inlist.h:411

The resulting node representing this struct can be exemplified by the following picture:

Now we need some pointers and auxiliary variables that will help us iterate on the lists:

struct my_struct *d, *cur;
int i;
Eina_Inlist *inlist = NULL;
Eina_List *list = NULL, *l_itr, *l_next;
_Eina_Inlist
Inlined list type.
Definition: eina_inlist.h:405
_Eina_List
Type for a generic double linked list.
Definition: eina_list.h:318

Allocating 100 elements and putting them into an inlist, and the even elements also go to the normal list:

for (i = 0; i < 100; i++)
{
d = malloc(sizeof(*d));
d->a = i;
d->b = i * 10;
inlist = eina_inlist_append(inlist, EINA_INLIST_GET(d));
if ((i % 2) == 0)
list = eina_list_prepend(list, d);
}
EINA_INLIST_GET
#define EINA_INLIST_GET(Inlist)
Utility macro to get the inlist object of a struct.
Definition: eina_inlist.h:413
eina_inlist_append
EINA_API Eina_Inlist * eina_inlist_append(Eina_Inlist *list, Eina_Inlist *new_l)
Adds a new node to end of a list.
Definition: eina_inlist.c:227
eina_list_prepend
EINA_API Eina_List * eina_list_prepend(Eina_List *list, const void *data)
Prepends the given data to the given linked list.
Definition: eina_list.c:618

After this point, what we have are two distinct lists that share some elements. The first list (inlist) is defined by the pointers inside the elements data structure, while the second list (normal list) has its own node data structure that is kept outside of the elements.

The two lists, sharing some elements, can be represented by the following picture:

Accessing both lists is done normally, as if they didn't have any elements in common:

printf("inlist=%p\n", inlist);
EINA_INLIST_FOREACH(inlist, cur)
printf("\ta=%d, b=%d\n", cur->a, cur->b);
printf("list=%p\n", list);
EINA_LIST_FOREACH(list, l_itr, cur)
printf("\ta=%d, b=%d\n", cur->a, cur->b);
printf("inlist count=%d\n", eina_inlist_count(inlist));
printf("list count=%d\n\n", eina_list_count(list));
eina_inlist_count
EINA_API unsigned int eina_inlist_count(const Eina_Inlist *list)
Gets the count of the number of items in a list.
Definition: eina_inlist.c:448
EINA_INLIST_FOREACH
#define EINA_INLIST_FOREACH(list, it)
Definition: eina_inlist.h:832
EINA_LIST_FOREACH
#define EINA_LIST_FOREACH(list, l, _data)
Definition for the macro to iterate over a list.
Definition: eina_list.h:1415

We can remove elements from the normal list, but we just don't free them because they are still stored in the inlist:

EINA_LIST_FOREACH_SAFE(list, l_itr, l_next, cur)
{
if ((cur->a % 3) == 0)
list = eina_list_remove_list(list, l_itr);
}
printf("inlist count=%d\n", eina_inlist_count(inlist));
printf("list count=%d\n\n", eina_list_count(list));
EINA_LIST_FOREACH_SAFE
#define EINA_LIST_FOREACH_SAFE(list, l, l_next, data)
Definition for the macro to iterate over a list with support for node deletion.
Definition: eina_list.h:1526
eina_list_remove_list
EINA_API Eina_List * eina_list_remove_list(Eina_List *list, Eina_List *remove_list)
Removes the specified list node.
Definition: eina_list.c:786

To finish this example, we want to free both lists, we can't just free all elements on the second list (normal list) because they are still being used in the inlist. So we first discard the normal list without freeing its elements, then we free all elements in the inlist (that contains all elements allocated until now):

eina_list_free(list);
while (inlist)
{
struct my_struct *aux = EINA_INLIST_CONTAINER_GET(inlist,
struct my_struct);
inlist = eina_inlist_remove(inlist, inlist);
free(aux);
}
EINA_INLIST_CONTAINER_GET
#define EINA_INLIST_CONTAINER_GET(ptr, type)
Utility macro to get the container object of an inlist.
Definition: eina_inlist.h:415
eina_inlist_remove
EINA_API Eina_Inlist * eina_inlist_remove(Eina_Inlist *list, Eina_Inlist *item)
Removes node from list.
Definition: eina_inlist.c:335
eina_list_free
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

Here is the full source code for this example: eina_inlist_02.c Eina_Inlist advanced usage - lists and inlists source