add function checking if a tree is empty to psplay

diff --git a/psplay.h b/psplay.h
index e2c38b8..ea65417 100644 (file)
--- a/psplay.h
+++ b/psplay.h
@@ -61,6 +61,12 @@ psplay_init_root (PSplayroot self, psplay_cmp_t cmp, psplay_delete_t delete);
 PSplayroot
 psplay_destroy_root (PSplayroot self);
 
+static inline int
+psplay_isempty_root (PSplayroot root)
+{
+  return !root->tree;
+}
+
 #define PSPLAYROOT_INITIALIZER(cmp, delete) {NULL, cmp, delete, 0}
 
 //