diff --git a/src/ast_values.hpp b/src/ast_values.hpp
new file mode 100644
index 0000000..121e760
--- /dev/null
+++ b/src/ast_values.hpp
@@ -0,0 +1,25 @@
+/*
+ * Copyright (C) 2018 CESNET, https://photonics.cesnet.cz/
+ * Copyright (C) 2018 FIT CVUT, https://fit.cvut.cz/
+ *
+ * Written by Václav Kubernát <kubervac@fit.cvut.cz>
+ *
+*/
+#pragma once
+
+#include <boost/variant.hpp>
+
+struct enum_ {
+    enum_();
+    enum_(const std::string& value);
+    bool operator==(const enum_& b) const;
+    std::string m_value;
+};
+
+using leaf_data_ = boost::variant<enum_,
+                                  double,
+                                  bool,
+                                  int32_t,
+                                  uint32_t,
+                                  std::string>;
+