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