list: implement list_for_each_rev()

[ccan] / ccan / list / list.h

diff --git a/ccan/list/list.h b/ccan/list/list.h
index 18f077aec20418c65711230ff051bc85670a2cbb..bda2922bc37b7b8dc22ec5482b5e6d75513c1eb7 100644 (file)
--- a/ccan/list/list.h
+++ b/ccan/list/list.h
@@ -315,6 +315,24 @@ static inline void list_del_from(struct list_head *h, struct list_node *n)
             &i->member != &(h)->n;                                     \
             i = container_of_var(i->member.next, i, member))
 
+/**
+ * list_for_each_rev - iterate through a list backwards.
+ * @h: the list_head
+ * @i: the structure containing the list_node
+ * @member: the list_node member of the structure
+ *
+ * This is a convenient wrapper to iterate @i over the entire list.  It's
+ * a for loop, so you can break and continue as normal.
+ *
+ * Example:
+ *     list_for_each_rev(&parent->children, child, list)
+ *             printf("Name: %s\n", child->name);
+ */
+#define list_for_each_rev(h, i, member)                                        \
+       for (i = container_of_var(list_debug(h)->n.prev, i, member);    \
+            &i->member != &(h)->n;                                     \
+            i = container_of_var(i->member.prev, i, member))
+
 /**
  * list_for_each_safe - iterate through a list, maybe during deletion
  * @h: the list_head