htable: add a htable_prev method to oppose _next

[ccan] / ccan / htable / htable.h

diff --git a/ccan/htable/htable.h b/ccan/htable/htable.h
index 03193567d847a5512b31d173bcb8a21a6d54d09e..e150c2ef0958065d3e289482d78dfe8267017a9b 100644 (file)
--- a/ccan/htable/htable.h
+++ b/ccan/htable/htable.h
@@ -178,6 +178,21 @@ void *htable_first(const struct htable *htable, struct htable_iter *i);
  */
 void *htable_next(const struct htable *htable, struct htable_iter *i);
 
+/**
+ * htable_prev - find the previous entry in the hash table
+ * @ht: the hashtable
+ * @i: the struct htable_iter to use
+ *
+ * Get previous entry in the hashtable; NULL if all done.
+ *
+ * "previous" here only means the item that would have been returned by
+ * htable_next() before the item it returned most recently.
+ *
+ * This is usually used in the middle of (or after) a htable_next iteration and
+ * to "unwind" actions taken.
+ */
+void *htable_prev(const struct htable *htable, struct htable_iter *i);
+
 /**
  * htable_delval - remove an iterated pointer from a hash table
  * @ht: the htable