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/*
* list.h : list manipulation macros and structures.
* Copyright 2002-2006 Willy Tarreau <w@1wt.eu>
*
*/
#ifndef _COMMON_MINI_CLIST_H
#define _COMMON_MINI_CLIST_H
#include <common/config.h>
/* these are circular or bidirectionnal lists only. Each list pointer points to
* another list pointer in a structure, and not the structure itself. The
* pointer to the next element MUST be the first one so that the list is easily
* cast as a single linked list or pointer.
*/
struct list {
struct list *n; /* next */
struct list *p; /* prev */
};
#define LIST_HEAD(a) ((void *)(&(a)))
#define LIST_INIT(l) ((l)->n = (l)->p = (l))
/* dual linked lists :
* Start = (struct list *) pointer to the next elem's prev list entry
* For each element :
* - prev = pointer to previous element's next (or start). Cannot be NULL
* - next = pointer to next element's prev. NULL = end.
*
*/
/****** circular lists ********/
/* adds an element at the beginning of a list ; returns the element */
#define LIST_ADD(lh, el) ({ (el)->n = (lh)->n; (el)->n->p = (lh)->n = (el); (el)->p = (lh); (el); })
/* adds an element at the end of a list ; returns the element */
#define LIST_ADDQ(lh, el) ({ (el)->p = (lh)->p; (el)->p->n = (lh)->p = (el); (el)->n = (lh); (el); })
/* removes an element from a list and returns it */
#define LIST_DEL(el) ({ typeof(el) __ret = (el); (el)->n->p = (el)->p; (el)->p->n = (el)->n; (__ret); })
/* returns a pointer of type <pt> to a structure containing a list head called
* <el> at address <lh>. Note that <lh> can be the result of a function or macro
* since it's used only once.
* Example: LIST_ELEM(cur_node->args.next, struct node *, args)
*/
#define LIST_ELEM(lh, pt, el) ((pt)(((void *)(lh)) - ((void *)&((pt)NULL)->el)))
/* checks if the list head <lh> is empty or not */
#define LIST_ISEMPTY(lh) ((lh)->n == (lh))
/* returns a pointer of type <pt> to a structure following the element
* which contains list head <lh>, which is known as element <el> in
* struct pt.
* Example: LIST_NEXT(args, struct node *, list)
*/
#define LIST_NEXT(lh, pt, el) (LIST_ELEM((lh)->n, pt, el))
/* returns a pointer of type <pt> to a structure preceeding the element
* which contains list head <lh>, which is known as element <el> in
* struct pt.
*/
#define LIST_PREV(lh, pt, el) (LIST_ELEM((lh)->p, pt, el))
/*
* iterates through a list of items of type "<struct_type>" which are
* linked via a "struct list" member named <struct_member>. The head of the
* list is stored at a location designed by <list_head>, which should be a
* "struct list *". A variable <end_item> of type "<struct_type>" will
* be used as temporary end of list pointer. It can be derived from <list_head>
* since this one is only used before.
* Example: FOREACH_ITEM(cur_node, &node->args, node, struct node *, neigh) { ... };
*/
#define FOREACH_ITEM(iterator, list_head, end_item, struct_type, struct_member) \
iterator = end_item = LIST_ELEM(list_head, struct_type, struct_member); \
while (((iterator) = LIST_ELEM((iterator)->struct_member.n, \
struct_type, struct_member)) != (end_item))
/*
* idem except that this one is safe against deletion, but it needs a backup
* pointer of the element after the iterator.
* Example: FOREACH_ITEM_SAFE(cur_node, backup, &node->args, node, struct node *, neigh) { ... };
*/
#define FOREACH_ITEM_SAFE(iterator, backup, list_head, end_item, struct_type, struct_member) \
end_item = LIST_ELEM(list_head, struct_type, struct_member); \
iterator = LIST_ELEM((end_item)->struct_member.n, struct_type, struct_member); \
if ((iterator) != (end_item)) \
backup = LIST_ELEM((iterator)->struct_member.n, struct_type, struct_member); \
for ( ; (iterator) != (end_item); (iterator) = (backup), \
backup = LIST_ELEM((iterator)->struct_member.n, struct_type, struct_member))
#endif /* _COMMON_MINI_CLIST_H */