/*
- * Copyright (c) 2008, 2009, 2010 Nicira Networks.
+ * Copyright (c) 2008, 2009, 2010, 2011 Nicira, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
}
/* Adjusts pointers around 'list' to compensate for 'list' having been moved
- * around in memory (e.g. as a consequence of realloc()). */
+ * around in memory (e.g. as a consequence of realloc()).
+ *
+ * This always works if 'list' is a member of a list, or if 'list' is the head
+ * of a non-empty list. It fails badly, however, if 'list' is the head of an
+ * empty list; just use list_init() in that case. */
void
list_moved(struct list *list)
{
return back;
}
-/* Returns the front element in 'list'.
- Undefined behavior if 'list' is empty. */
+/* Returns the front element in 'list_'.
+ Undefined behavior if 'list_' is empty. */
struct list *
-list_front(struct list *list)
+list_front(const struct list *list_)
{
+ struct list *list = (struct list *) list_;
+
assert(!list_is_empty(list));
return list->next;
}
-/* Returns the back element in 'list'.
- Undefined behavior if 'list' is empty. */
+/* Returns the back element in 'list_'.
+ Undefined behavior if 'list_' is empty. */
struct list *
-list_back(struct list *list)
+list_back(const struct list *list_)
{
+ struct list *list = (struct list *) list_;
+
assert(!list_is_empty(list));
return list->prev;
}
{
return list->next == list;
}
+
+/* Returns true if 'list' has exactly 1 element, false otherwise. */
+bool
+list_is_singleton(const struct list *list)
+{
+ return list_is_short(list) && !list_is_empty(list);
+}
+
+/* Returns true if 'list' has 0 or 1 elements, false otherwise. */
+bool
+list_is_short(const struct list *list)
+{
+ return list->next == list->prev;
+}