diff --git a/src/CTree.hpp b/src/CTree.hpp
index fa99df6..3e95066 100644
--- a/src/CTree.hpp
+++ b/src/CTree.hpp
@@ -8,20 +8,22 @@
 
 #pragma once
 
+#include <boost/variant.hpp>
+#include <set>
 #include <stdexcept>
 #include <unordered_map>
 
-enum NODE_TYPE {
-    TYPE_CONTAINER,
-    TYPE_LIST,
-    TYPE_LIST_ELEMENT
-};
+namespace schema {
+    struct container {
+    };
+    struct list {
+        std::set<std::string> m_keys;
+    };
+}
 
-struct TreeNode {
-    bool operator<(const TreeNode& b) const;
-    std::string m_name;
-    NODE_TYPE m_type;
-};
+
+using NodeType = boost::variant<schema::container, schema::list>;
+
 
 class InvalidNodeException : public std::invalid_argument {
 public:
@@ -38,16 +40,20 @@
 class CTree {
 public:
     CTree();
-    bool nodeExists(const std::string& location, const std::string& node) const;
+    bool nodeExists(const std::string& location, const std::string& name) const;
 
-    bool isContainer(const std::string& location, const std::string& node) const;
-    void addContainer(const std::string& location, const std::string& node);
-    void changeNode(const std::string& node);
+    bool isContainer(const std::string& location, const std::string& name) const;
+    void addContainer(const std::string& location, const std::string& name);
+    const std::set<std::string>& listKeys(const std::string& location, const std::string& name) const;
+    bool listHasKey(const std::string& location, const std::string& name, const std::string& key) const;
+    bool isList(const std::string& location, const std::string& name) const;
+    void addList(const std::string& location, const std::string& name, const std::set<std::string>& keys);
+    void changeNode(const std::string& name);
     std::string currentNode() const;
 
 private:
-    const std::unordered_map<std::string, NODE_TYPE>& children(const std::string& node) const;
+    const std::unordered_map<std::string, NodeType>& children(const std::string& name) const;
 
-    std::unordered_map<std::string, std::unordered_map<std::string, NODE_TYPE>> m_nodes;
+    std::unordered_map<std::string, std::unordered_map<std::string, NodeType>> m_nodes;
     std::string m_curDir;
 };