Nested Class Accessing Classes Private Variables

I have a Tree template -

Code:

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;
};

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

Code:

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

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.