Nested Class Accessing Classes Private Variables

I have a Tree template -

Code:

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template<typename T>
class Tree {
       
public:
       
        //node class
        //nodes should have value, their parent, and all of their children
        //and functions to get all of those
        class Node {
               
        public:
                //when declaring a node, give it
                //a value and a parent value
                Node(T&, Node*&);
                ~Node();
               
                bool isRoot();
               
                T& getValue();
                void setValue(T&);
               
                Node*& getParent();
                std::vector<Node*>& getChildren();
                int getNumOfChildren();
               
                std::string toString();
                std::string childrenToString();
               
                bool operator==(const Node& other);
        private:
                T value;
                Node* parent;
                std::vector<Node*> children;
        };
       
        Tree();
        Tree(T&);
        ~Tree();
       
        Node*& getRoot();
       
        void add(T&, Node*&);
       
       
private:

        //root of tree
        Node* dummyroot;
        Node* root;
};

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I want the isRoot() function to just be something like this -

Code:

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template<typename T>
bool Tree<T>::Node::isRoot() {return this == root;}

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When I do this, it tells me invalid use of nonstatic data member root. How can I access root without making it public? A couple random things I tried were-

this == &root
this == Tree<T>::root

I don't want to give a Tree variable for each Node because I don't think it makes sense. I want the Nodes to just be a Node with a value, parent, and children. Any help would be appreciated.

Since you are using a root variable without a particular association to a tree, you would get that error, since root is not a static member. I don't think making root a static member is the answer.

Incidentally, isn't this something you'd want to handle in Tree? A tree ought to know where it's root node is. I would just make this a method for tree.