Add enum completion

Change-Id: I5ee7d6359812535d0eef9f70e1b66e205d93cf39
diff --git a/src/yang_schema.hpp b/src/yang_schema.hpp
index e4d6d5d..e56c853 100644
--- a/src/yang_schema.hpp
+++ b/src/yang_schema.hpp
@@ -39,6 +39,7 @@
     bool nodeExists(const std::string& location, const std::string& node) const override;
     const std::set<std::string> listKeys(const schemaPath_& location, const ModuleNodePair& node) const override;
     yang::LeafDataTypes leafType(const schemaPath_& location, const ModuleNodePair& node) const override;
+    const std::set<std::string> enumValues(const schemaPath_& location, const ModuleNodePair& node) const override;
     std::set<std::string> childNodes(const schemaPath_& path, const Recursion recursion) const override;
 
     void registerModuleCallback(const std::function<std::string(const char*, const char*, const char*)>& clb);