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dlist: add SYS_DLIST_ITERATE_FROM_NODE()

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Like SYS_DLIST_FOR_EACH_NODE(), but __dn contains a node where to fetch
the next node from, NULL to start at the head.

Note that the function does not iterate from @a node, but from
node->next. This allows the following:

sys_dnode_t *funcA(sys_dlist_t *list, sys_dnode_t *node)
{
	SYS_DLIST_ITERATE_FROM_NODE(list, node) {
		if (node == <some condition>) {
			return node;
		}
	}
	return NULL;
}

sys_dlist_t list = &<some list>;
sys_dnode_t *node = NULL;

do {
	node = funcA(list, node)
	if (node == <some other condition>) {
		goto found;
	}
} while(node);

<handle error>

found:
<do stuff with node>

Change-Id: I17a5787594a0ed1a4745bd2e1557dd54895105ca
Signed-off-by: Benjamin Walsh <walsh.benj@gmail.com>
This commit is contained in:
Benjamin Walsh 2017-02-12 09:35:16 -05:00 committed by Anas Nashif
parent c88d0fb82f
commit d032bb88cc
1 changed files with 42 additions and 1 deletions
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43
include/misc/dlist.h
View File

@ -55,6 +55,30 @@ typedef struct _dnode sys_dnode_t;
for (__dn = sys_dlist_peek_head(__dl); __dn; \
__dn = sys_dlist_peek_next(__dl, __dn))
/**
* @brief Provide the primitive to iterate on a list, from a node in the list
* Note: the loop is unsafe and thus __dn should not be removed
*
* User _MUST_ add the loop statement curly braces enclosing its own code:
*
* SYS_DLIST_ITERATE_FROM_NODE(l, n) {
* <user code>
* }
*
* Like SYS_DLIST_FOR_EACH_NODE(), but __dn already contains a node in the list
* where to start searching for the next entry from. If NULL, it starts from
* the head.
*
* @param __dl A pointer on a sys_dlist_t to iterate on
* @param __dn A sys_dnode_t pointer to peek each node of the list;
* it contains the starting node, or NULL to start from the head
*/
#define SYS_DLIST_ITERATE_FROM_NODE(__dl, __dn) \
for (__dn = __dn ? sys_dlist_peek_next_no_check(__dl, __dn) \
: sys_dlist_peek_head(__dl); \
__dn; \
__dn = sys_dlist_peek_next(__dl, __dn))
/**
* @brief Provide the primitive to safely iterate on a list
* Note: __dn can be removed, it will not break the loop.
@ -229,6 +253,23 @@ static inline sys_dnode_t *sys_dlist_peek_head_not_empty(sys_dlist_t *list)
return list->head;
}
/**
* @brief get a reference to the next item in the list, node is not NULL
*
* Faster than sys_dlist_peek_next() if node is known not to be NULL.
*
* @param list the doubly-linked list to operate on
* @param node the node from which to get the next element in the list
*
* @return a pointer to the next element from a node, NULL if node is the tail
*/
static inline sys_dnode_t *sys_dlist_peek_next_no_check(sys_dlist_t *list,
sys_dnode_t *node)
{
return (node == list->tail) ? NULL : node->next;
}
/**
* @brief get a reference to the next item in the list
*
@ -242,7 +283,7 @@ static inline sys_dnode_t *sys_dlist_peek_head_not_empty(sys_dlist_t *list)
static inline sys_dnode_t *sys_dlist_peek_next(sys_dlist_t *list,
sys_dnode_t *node)
{
return (!node || node == list->tail) ? NULL : node->next;
return node ? sys_dlist_peek_next_no_check(list, node) : NULL;
}
/**