Hi,
I didn’t take a good look
at current iterate functions in Grub 2, yet.
Most iterations needs a “init”
(before treatment of first item) and a “fini” (after treatment of
last item).
Further more, one might want to
make iteration functions “re-entrant” (or recursive), or call-back
other functions in a generic way.
One way to get to such behavior
easily cost a bit more than the example you provided :
you may just add an argument
(let’s call it the context object) to the call of the iterate function :
#define grub_iterate_list(list, func, context) \
{typeof(list) el = list; while (el) {func(context, el); el=el->next;}
func(context, NULL)}
or
#define grub_iterate_list(list, func) \
{void * context = NULL; typeof(list) el = list; while (el) {func(&context,
el); el=el->next;} func(&context, NULL)}
but I prefer the first define as it allows transmission of a full context to
the iteration function.
my_struct
* my_ctxt;
my_ctxt
= NULL; grub_iterate_list(list, my_func, &my_ctxt);
void my_func
(my_struct ** ctxt, my_item * item) {
if
(item == NULL) {
/* End of iteration : Do any cleanup */
if (*ctxt == NULL) return;
free (*ctxt) ……
…..
return;
}
if
(*ctxt == NULL) {
/* First iteration : Do any initialization */
*ctxt = malloc (sizeof (my_struct)); ….
…..
}
/* Do the iteration stuff */
…..
return;
}
In grub_iterate_list_brk, you
can use context to send a patern or model object to compare each item of the
list with.
The draw back is it makes
iteration function a bit less readable, but a lot more powerful.
_________________________________________
Eric Salomé – Paris, France
-----Message d'origine-----
De :
[EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] De la part de Guffens, Vincent
Envoyé : lundi 8 mai 2006
01:14
À : grub-devel@gnu.org
Objet : a simple list
Hi,
I need to use a simple list to register the pci devices, drivers and so on. I
notice that there are lists like that already in the code so what would you
think about having a list.h file like that ?
/* A very simple list.
*
* If you want a list of struct myitem
* you do
*
* struct myitem *item_list;
*
* where myitem MUST have its next pointer as the FIRST field
*
* and you can then add, delete the EL item,
* grub_add_list (&item_list, el);
* grub_del_list (&item_list, el);
*
* or call HOOK(item) for each element of the list
* grub_iterate_list (item_list, hook);
*
* This brk version will point el to the list item for which
* HOOK(EL) returns a non-null value
* grub_iterate_list_brk (item_list, hook, el);
*
*/
struct obj {
struct obj *next; /* MUST BE FIRST */
};
#define grub_del_list(list, el) _grub_del_list((struct obj**) list, (struct
obj*) el)
#define grub_add_list(list, el) _grub_add_list((struct obj**) list, (struct
obj*) el)
#define grub_find_list(list, el) \
(typeof(list)) _grub_find_list((struct obj*) list, (struct obj*) el)
#define grub_iterate_list(list, func) \
{typeof(list) el = list; while (el) {func(el); el=el->next;}}
#define grub_iterate_list_brk(list, func, it) \
{typeof(list) el = list; it = 0; \
while (el) {if (func(el)) {it = el; break;} el=el->next;
}}
static inline struct obj* _grub_find_list (struct obj *list, struct obj
*el)
{
struct obj *it = list;
for (it = list; it; it=it->next)
{
if (it == el) return el;
}
return 0;
};
static inline void _grub_add_list (struct obj **list, struct obj *el)
{
if ( (!el) || (_grub_find_list (*list, el)) )
return;
el->next = *list;
*list = el;
};
static inline void _grub_del_list (struct obj **list, struct obj *el)
{
struct obj **p;
struct obj *q;
for (p = list, q = *p; q; p = &(q->next), q = q->next)
if (q == el)
{
*p = q->next;
break;
}
};