1 files changed, 23 insertions, 0 deletions
diff --git a/util.h b/util.h
index 7a73d22..71dc3d6 100644
--- a/util.h
+++ b/util.h
@@ -1,3 +1,6 @@
+#include "runtime-compatibility.h"
+#include <Foundation/NSNull.h>
+
 #define DEFINE_GMP_OPERATION(SIGNATURE, TYPE, GMPOP, OBJTYPE, CONSTRUCTOR) \
   -(OBJTYPE *) SIGNATURE                                                \
   {                                                                     \
@@ -11,3 +14,23 @@
                                                                         \
     return result;                                                      \
   }
+
+
+static id nullify (id value) __attribute__ ((pure, unused));
+static id denullify (id value) __attribute__ ((pure, unused));
+
+static id nullify (id value)
+{
+  if (value)
+    return value;
+  else
+    return [NSNull null];
+}
+
+static id denullify (id value)
+{
+  if (value == [NSNull null])
+    return nil;
+  else
+    return value;
+}