X-Git-Url: https://git.ozlabs.org/?a=blobdiff_plain;f=ccan%2Flist%2Flist.h;h=ab3240871773d90ceee149c3cb30931e228326fb;hb=8216fa0be7d9bf39774a192d52fef955f6bd7cd8;hp=faad86f5c736a3a53ed08c79e74f92c39086a810;hpb=f98c408ee4e2f655e009e2499a02aeb2cc2fa905;p=ccan

diff --git a/ccan/list/list.h b/ccan/list/list.h
index faad86f5..ab324087 100644
--- a/ccan/list/list.h
+++ b/ccan/list/list.h
@@ -292,6 +292,34 @@ static inline const void *list_top_(const struct list_head *h, size_t off)
 	return (const char *)h->n.next - off;
 }
 
+/**
+ * list_pop - remove the first entry in a list
+ * @h: the list_head
+ * @type: the type of the entry
+ * @member: the list_node member of the type
+ *
+ * If the list is empty, returns NULL.
+ *
+ * Example:
+ *	struct child *one;
+ *	one = list_pop(&parent->children, struct child, list);
+ *	if (!one)
+ *		printf("Empty list!\n");
+ */
+#define list_pop(h, type, member)					\
+	((type *)list_pop_((h), list_off_(type, member)))
+
+static inline const void *list_pop_(const struct list_head *h, size_t off)
+{
+	struct list_node *n;
+
+	if (list_empty(h))
+		return NULL;
+	n = h->n.next;
+	list_del(n);
+	return (const char *)n - off;
+}
+
 /**
  * list_tail - get the last entry in a list
  * @h: the list_head
@@ -371,6 +399,68 @@ 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