/*
- * Copyright (c) 2008, 2009 Nicira Networks.
+ * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
*/
#include <config.h>
#include "list.h"
-#include <assert.h>
/* Initializes 'list' as an empty list. */
void
list->next = list->prev = list;
}
+/* Initializes 'list' with pointers that will (probably) cause segfaults if
+ * dereferenced and, better yet, show up clearly in a debugger. */
+void
+list_poison(struct list *list)
+{
+ memset(list, 0xcc, sizeof *list);
+}
+
/* Inserts 'elem' just before 'before'. */
void
list_insert(struct list *before, struct list *elem)
{
- elem->prev = before->prev;
- elem->next = before;
- before->prev->next = elem;
- before->prev = elem;
+ elem->prev = before->prev;
+ elem->next = before;
+ before->prev->next = elem;
+ before->prev = elem;
}
/* Removes elements 'first' though 'last' (exclusive) from their current list,
void
list_splice(struct list *before, struct list *first, struct list *last)
{
- if (first == last)
- return;
- last = last->prev;
-
- /* Cleanly remove 'first'...'last' from its current list. */
- first->prev->next = last->next;
- last->next->prev = first->prev;
-
- /* Splice 'first'...'last' into new list. */
- first->prev = before->prev;
- last->next = before;
- before->prev->next = first;
- before->prev = last;
+ if (first == last) {
+ return;
+ }
+ last = last->prev;
+
+ /* Cleanly remove 'first'...'last' from its current list. */
+ first->prev->next = last->next;
+ last->next->prev = first->prev;
+
+ /* Splice 'first'...'last' into new list. */
+ first->prev = before->prev;
+ last->next = before;
+ before->prev->next = first;
+ before->prev = last;
}
/* Inserts 'elem' at the beginning of 'list', so that it becomes the front in
void
list_push_front(struct list *list, struct list *elem)
{
- list_insert(list->next, elem);
+ list_insert(list->next, elem);
}
/* Inserts 'elem' at the end of 'list', so that it becomes the back in
void
list_push_back(struct list *list, struct list *elem)
{
- list_insert(list, elem);
+ list_insert(list, elem);
}
/* Puts 'elem' in the position currently occupied by 'position'.
}
/* 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)
{
list->prev->next = list->next->prev = list;
}
+/* Initializes 'dst' with the contents of 'src', compensating for moving it
+ * around in memory. The effect is that, if 'src' was the head of a list, now
+ * 'dst' is the head of a list containing the same elements. */
+void
+list_move(struct list *dst, struct list *src)
+{
+ if (!list_is_empty(src)) {
+ *dst = *src;
+ list_moved(dst);
+ } else {
+ list_init(dst);
+ }
+}
+
/* Removes 'elem' from its list and returns the element that followed it.
Undefined behavior if 'elem' is not in a list. */
struct list *
list_remove(struct list *elem)
{
- elem->prev->next = elem->next;
- elem->next->prev = elem->prev;
- return elem->next;
+ elem->prev->next = elem->next;
+ elem->next->prev = elem->prev;
+ return elem->next;
}
/* Removes the front element from 'list' and returns it. Undefined behavior if
struct list *
list_pop_front(struct list *list)
{
- struct list *front = list->next;
- list_remove(front);
- return front;
+ struct list *front = list->next;
+ list_remove(front);
+ return front;
}
/* Removes the back element from 'list' and returns it.
struct list *
list_pop_back(struct list *list)
{
- struct list *back = list->prev;
- list_remove(back);
- return back;
+ struct list *back = list->prev;
+ list_remove(back);
+ 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_)
{
- assert(!list_is_empty(list));
- return list->next;
+ struct list *list = CONST_CAST(struct list *, list_);
+
+ ovs_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_)
{
- assert(!list_is_empty(list));
- return list->prev;
+ struct list *list = CONST_CAST(struct list *, list_);
+
+ ovs_assert(!list_is_empty(list));
+ return list->prev;
}
/* Returns the number of elements in 'list'.
size_t
list_size(const struct list *list)
{
- const struct list *e;
- size_t cnt = 0;
+ const struct list *e;
+ size_t cnt = 0;
- for (e = list->next; e != list; e = e->next)
- cnt++;
- return cnt;
+ for (e = list->next; e != list; e = e->next) {
+ cnt++;
+ }
+ return cnt;
}
/* Returns true if 'list' is empty, false otherwise. */
bool
list_is_empty(const struct list *list)
{
- return list->next == list;
+ 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;
}
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