X-Git-Url: https://git.libre-soc.org/?a=blobdiff_plain;f=src%2Futil%2Flist.h;h=6edb750110973ed42d926a60e1cf55299236b546;hb=ce412371513c90bf9156f22c3567ee57750ef264;hp=d4b485174fc7391fc2dde6a127e7d224dc02d75f;hpb=005c8e01062e8e88a86904b955d5422742bd32e7;p=mesa.git

diff --git a/src/util/list.h b/src/util/list.h
index d4b485174fc..6edb7501109 100644
--- a/src/util/list.h
+++ b/src/util/list.h
@@ -41,6 +41,7 @@
 #include <stdbool.h>
 #include <stddef.h>
 #include <assert.h>
+#include "c99_compat.h"
 
 
 struct list_head
@@ -71,12 +72,18 @@ static inline void list_addtail(struct list_head *item, struct list_head *list)
     list->prev = item;
 }
 
+static inline bool list_empty(struct list_head *list);
+
 static inline void list_replace(struct list_head *from, struct list_head *to)
 {
-    to->prev = from->prev;
-    to->next = from->next;
-    from->next->prev = to;
-    from->prev->next = to;
+    if (list_empty(from)) {
+        list_inithead(to);
+    } else {
+        to->prev = from->prev;
+        to->next = from->next;
+        from->next->prev = to;
+        from->prev->next = to;
+    }
 }
 
 static inline void list_del(struct list_head *item)
@@ -99,6 +106,14 @@ static inline bool list_empty(struct list_head *list)
    return list->next == list;
 }
 
+/**
+ * Returns whether the list has exactly one element.
+ */
+static inline bool list_is_singular(const struct list_head *list)
+{
+   return list->next != NULL && list->next != list && list->next->next == list;
+}
+
 static inline unsigned list_length(struct list_head *list)
 {
    struct list_head *node;