list: add list_for_each_rev_safe{,_off} macros
[ccan] / ccan / list / list.h
index 983675b81f9d53877fd5d0dfaa56abc1d742a641..275442d23da05cb8fe9c462e75ffd589fa97e374 100644 (file)
@@ -522,9 +522,29 @@ static inline const void *list_tail_(const struct list_head *h, size_t off)
  *             printf("Name: %s\n", child->name);
  */
 #define list_for_each_rev(h, i, member)                                        \
-       for (i = container_of_var(list_debug(h, LIST_LOC)->n.prev, i, member); \
-            &i->member != &(h)->n;                                     \
-            i = container_of_var(i->member.prev, i, member))
+       list_for_each_rev_off(h, i, list_off_var_(i, member))
+
+/**
+ * list_for_each_rev_safe - iterate through a list backwards,
+ * maybe during deletion
+ * @h: the list_head
+ * @i: the structure containing the list_node
+ * @nxt: 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 backwards.
+ * It's a for loop, so you can break and continue as normal.  The extra
+ * variable * @nxt is used to hold the next element, so you can delete @i
+ * from the list.
+ *
+ * Example:
+ *     struct child *next;
+ *     list_for_each_rev_safe(&parent->children, child, next, list) {
+ *             printf("Name: %s\n", child->name);
+ *     }
+ */
+#define list_for_each_rev_safe(h, i, nxt, member)                      \
+       list_for_each_rev_safe_off(h, i, nxt, list_off_var_(i, member))
 
 /**
  * list_for_each_safe - iterate through a list, maybe during deletion
@@ -538,7 +558,6 @@ static inline const void *list_tail_(const struct list_head *h, size_t off)
  * @nxt is used to hold the next element, so you can delete @i from the list.
  *
  * Example:
- *     struct child *next;
  *     list_for_each_safe(&parent->children, child, next, list) {
  *             list_del(&child->list);
  *             parent->num_children--;
@@ -653,6 +672,24 @@ static inline void list_prepend_list_(struct list_head *to,
        list_head_init(from);
 }
 
+/* internal macros, do not use directly */
+#define list_for_each_off_dir_(h, i, off, dir)                         \
+       for (i = list_node_to_off_(list_debug(h, LIST_LOC)->n.dir,      \
+                                  (off));                              \
+       list_node_from_off_((void *)i, (off)) != &(h)->n;               \
+       i = list_node_to_off_(list_node_from_off_((void *)i, (off))->dir, \
+                             (off)))
+
+#define list_for_each_safe_off_dir_(h, i, nxt, off, dir)               \
+       for (i = list_node_to_off_(list_debug(h, LIST_LOC)->n.dir,      \
+                                  (off)),                              \
+       nxt = list_node_to_off_(list_node_from_off_(i, (off))->dir,     \
+                               (off));                                 \
+       list_node_from_off_(i, (off)) != &(h)->n;                       \
+       i = nxt,                                                        \
+       nxt = list_node_to_off_(list_node_from_off_(i, (off))->dir,     \
+                               (off)))
+
 /**
  * list_for_each_off - iterate through a list of memory regions.
  * @h: the list_head
@@ -683,11 +720,18 @@ static inline void list_prepend_list_(struct list_head *to,
  *             printf("Name: %s\n", child->name);
  */
 #define list_for_each_off(h, i, off)                                    \
-       for (i = list_node_to_off_(list_debug(h, LIST_LOC)->n.next,     \
-                                  (off));                              \
-       list_node_from_off_((void *)i, (off)) != &(h)->n;                \
-       i = list_node_to_off_(list_node_from_off_((void *)i, (off))->next, \
-                             (off)))
+       list_for_each_off_dir_((h),(i),(off),next)
+
+/**
+ * list_for_each_rev_off - iterate through a list of memory regions backwards
+ * @h: the list_head
+ * @i: the pointer to a memory region wich contains list node data.
+ * @off: offset(relative to @i) at which list node data resides.
+ *
+ * See list_for_each_off for details
+ */
+#define list_for_each_rev_off(h, i, off)                                    \
+       list_for_each_off_dir_((h),(i),(off),prev)
 
 /**
  * list_for_each_safe_off - iterate through a list of memory regions, maybe
@@ -706,15 +750,26 @@ static inline void list_prepend_list_(struct list_head *to,
  *             printf("Name: %s\n", child->name);
  */
 #define list_for_each_safe_off(h, i, nxt, off)                          \
-       for (i = list_node_to_off_(list_debug(h, LIST_LOC)->n.next,     \
-                                  (off)),                              \
-         nxt = list_node_to_off_(list_node_from_off_(i, (off))->next,   \
-                                 (off));                                \
-       list_node_from_off_(i, (off)) != &(h)->n;                        \
-       i = nxt,                                                         \
-         nxt = list_node_to_off_(list_node_from_off_(i, (off))->next,   \
-                                 (off)))
+       list_for_each_safe_off_dir_((h),(i),(nxt),(off),next)
 
+/**
+ * list_for_each_rev_safe_off - iterate backwards through a list of
+ * memory regions, maybe during deletion
+ * @h: the list_head
+ * @i: the pointer to a memory region wich contains list node data.
+ * @nxt: the structure containing the list_node
+ * @off: offset(relative to @i) at which list node data resides.
+ *
+ * For details see `list_for_each_rev_off' and `list_for_each_rev_safe'
+ * descriptions.
+ *
+ * Example:
+ *     list_for_each_rev_safe_off(&parent->children, child,
+ *             next, offsetof(struct child, list))
+ *             printf("Name: %s\n", child->name);
+ */
+#define list_for_each_rev_safe_off(h, i, nxt, off)                      \
+       list_for_each_safe_off_dir_((h),(i),(nxt),(off),prev)
 
 /* Other -off variants. */
 #define list_entry_off(n, type, off)           \