X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=lib%2Flist.c;h=e341d45bd432e5cfe1178260eba1c276629f9b1f;hb=cfc50ae514f805dcd9c14589f21158185424daf6;hp=6d5f6fe069fb9acec22f5c657777ed718ba40b8f;hpb=47ab7668cc7c57543a645b870855b0e763b1d0da;p=sliver-openvswitch.git

diff --git a/lib/list.c b/lib/list.c
index 6d5f6fe06..e341d45bd 100644
--- a/lib/list.c
+++ b/lib/list.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2009, 2010 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.
@@ -15,7 +15,6 @@
  */
 #include <config.h>
 #include "list.h"
-#include <assert.h>
 
 /* Initializes 'list' as an empty list. */
 void
@@ -47,8 +46,9 @@ list_insert(struct list *before, struct list *elem)
 void
 list_splice(struct list *before, struct list *first, struct list *last)
 {
-    if (first == last)
+    if (first == last) {
         return;
+    }
     last = last->prev;
 
     /* Cleanly remove 'first'...'last' from its current list. */
@@ -90,13 +90,31 @@ list_replace(struct list *element, const struct list *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 *
@@ -127,21 +145,25 @@ list_pop_back(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_)
 {
-    assert(!list_is_empty(list));
+    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));
+    struct list *list = CONST_CAST(struct list *, list_);
+
+    ovs_assert(!list_is_empty(list));
     return list->prev;
 }
 
@@ -153,8 +175,9 @@ list_size(const struct list *list)
     const struct list *e;
     size_t cnt = 0;
 
-    for (e = list->next; e != list; e = e->next)
+    for (e = list->next; e != list; e = e->next) {
         cnt++;
+    }
     return cnt;
 }
 
@@ -164,3 +187,17 @@ list_is_empty(const struct list *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;
+}