bt: New function bt_is_empty().

diff --git a/src/libpspp/bt.h b/src/libpspp/bt.h
index 7045632ef204e2edd228dc4dd8473174318212be..0ee29898e8263eeb434d8987192157c771fbb19a 100644 (file)
--- a/src/libpspp/bt.h
+++ b/src/libpspp/bt.h
@@ -1,5 +1,5 @@
 /* PSPP - a program for statistical analysis.
-   Copyright (C) 2007, 2009 Free Software Foundation, Inc.
+   Copyright (C) 2007, 2009, 2010 Free Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -23,6 +23,7 @@
    balancing applied to the balanced tree, as its operation is
    fully encapsulated. */
 
+#include <stdbool.h>
 #include <stddef.h>
 #include <libpspp/cast.h>
 
@@ -80,4 +81,11 @@ static inline size_t bt_count (const struct bt *bt)
   return bt->size;
 }
 
+/* Return true if BT contains no nodes,
+   false if BT contains at least one node. */
+static inline bool bt_is_empty (const struct bt *bt)
+{
+  return bt->size == 0;
+}
+
 #endif /* libpspp/bt.h */