Add support for identityref data type

Change-Id: I369150b83d86a4c22fadf383ee011eee619a4c15
diff --git a/src/ast_path.hpp b/src/ast_path.hpp
index 557b01f..dcd13ff 100644
--- a/src/ast_path.hpp
+++ b/src/ast_path.hpp
@@ -18,6 +18,8 @@
 #include <map>
 #include <vector>
 
+#include "ast_values.hpp"
+
 struct nodeup_ {
     bool operator==(const nodeup_&) const
     {
@@ -62,11 +64,6 @@
     std::string m_name;
 };
 
-struct module_ {
-    bool operator==(const module_& b) const;
-    std::string m_name;
-};
-
 struct schemaNode_ {
     boost::optional<module_> m_prefix;
     boost::variant<container_, list_, nodeup_, leaf_> m_suffix;