X-Git-Url: http://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Flist%2Flist.h;h=8e2f6df0273998764bb89cb69fb4c25d6e5b1070;hp=0091ea4b655216754a347cb4ccb655aa8823177e;hb=c35fcafc261eb9c0f5aff1a608568b38ddc01f66;hpb=e59b7388d8b2b56dc759be7c2dbf63100d2e131f

diff --git a/ccan/list/list.h b/ccan/list/list.h
index 0091ea4b..8e2f6df0 100644
--- a/ccan/list/list.h
+++ b/ccan/list/list.h
@@ -1,4 +1,4 @@
-/* Licensed under LGPLv2.1+ - see LICENSE file for details */
+/* Licensed under BSD-MIT - see LICENSE file for details */
 #ifndef CCAN_LIST_H
 #define CCAN_LIST_H
 #include <stdbool.h>
@@ -279,6 +279,8 @@ static inline void list_del_from(struct list_head *h, struct list_node *n)
  * Example:
  *	struct child *first;
  *	first = list_top(&parent->children, struct child, list);
+ *	if (!first)
+ *		printf("Empty list!\n");
  */
 #define list_top(h, type, member)					\
 	((type *)list_top_((h), list_off_(type, member)))
@@ -301,6 +303,8 @@ static inline const void *list_top_(const struct list_head *h, size_t off)
  * Example:
  *	struct child *last;
  *	last = list_tail(&parent->children, struct child, list);
+ *	if (!last)
+ *		printf("Empty list!\n");
  */
 #define list_tail(h, type, member) \
 	((type *)list_tail_((h), list_off_(type, member)))
@@ -367,6 +371,68 @@ static inline const void *list_tail_(const struct list_head *h, size_t off)
 #define list_for_each_safe(h, i, nxt, member)				\
 	list_for_each_safe_off(h, i, nxt, list_off_var_(i, member))
 
+/**
+ * list_append_list - empty one list onto the end of another.
+ * @to: the list to append into
+ * @from: the list to empty.
+ *
+ * This takes the entire contents of @from and moves it to the end of
+ * @to.  After this @from will be empty.
+ *
+ * Example:
+ *	struct list_head adopter;
+ *
+ *	list_append_list(&adopter, &parent->children);
+ *	assert(list_empty(&parent->children));
+ *	parent->num_children = 0;
+ */
+static inline void list_append_list(struct list_head *to,
+				    struct list_head *from)
+{
+	struct list_node *from_tail = list_debug(from)->n.prev;
+	struct list_node *to_tail = list_debug(to)->n.prev;
+
+	/* Sew in head and entire list. */
+	to->n.prev = from_tail;
+	from_tail->next = &to->n;
+	to_tail->next = &from->n;
+	from->n.prev = to_tail;
+
+	/* Now remove head. */
+	list_del(&from->n);
+	list_head_init(from);
+}
+
+/**
+ * list_prepend_list - empty one list into the start of another.
+ * @to: the list to prepend into
+ * @from: the list to empty.
+ *
+ * This takes the entire contents of @from and moves it to the start
+ * of @to.  After this @from will be empty.
+ *
+ * Example:
+ *	list_prepend_list(&adopter, &parent->children);
+ *	assert(list_empty(&parent->children));
+ *	parent->num_children = 0;
+ */
+static inline void list_prepend_list(struct list_head *to,
+				     struct list_head *from)
+{
+	struct list_node *from_tail = list_debug(from)->n.prev;
+	struct list_node *to_head = list_debug(to)->n.next;
+
+	/* Sew in head and entire list. */
+	to->n.next = &from->n;
+	from->n.prev = &to->n;
+	to_head->prev = from_tail;
+	from_tail->next = to_head;
+
+	/* Now remove head. */
+	list_del(&from->n);
+	list_head_init(from);
+}
+
 /**
  * list_for_each_off - iterate through a list of memory regions.
  * @h: the list_head