Add ls

Change-Id: I86f799ff9577940c7df8e01cda6c6b7867de8e7e
diff --git a/src/parser.hpp b/src/parser.hpp
index 05e636e..0f1fd79 100644
--- a/src/parser.hpp
+++ b/src/parser.hpp
@@ -30,6 +30,7 @@
     command_ parseCommand(const std::string& line, std::ostream& errorStream);
     void changeNode(const path_& name);
     std::string currentNode() const;
+    std::set<std::string> availableNodes(const boost::optional<path_>& path) const;
 
 private:
     const std::shared_ptr<const Schema> m_schema;