gistfile1.cpp

template<class T>
class TreeNode {
public:
    TreeNode(T data, TreeNode<T>* left, TreeNode<T>* right)
    : data(data), left(left), right(right) { }

    void show() { std::cout << data; }
    T get() { return data; }
    void set(const T& data) { this->data = data; }

    TreeNode<T>* clone() {
        return new TreeNode(
            data,
            left ? left->clone() : nullptr,
            right ? right->clone() : nullptr
        );
    }

    friend class Tree<T>;

protected:
    T data;
    std::unique_ptr<TreeNode<T>> left;
    std::unique_ptr<TreeNode<T>> right;
};


template<class T>
class BSTreeNode : public TreeNode<T> {
    using TreeNode<T>::TreeNode;

    // extra functionality

    friend class BSTree<T>;
};