If this is a header file, avoid bringing std::make_unique and std::unique_ptr into the global namespace, as that will affect every file that includes the header. It's reasonably to do so inside the function bodies, but at that point it's likely better to simply use the qualified names. Including them within the scope of the type is a middle ground where opinions will differ.

If this is a header file, avoid bringing std::make_unique and std::unique_ptr into the global namespace, as that will affect every file that includes the header. It's reasonable to do so inside the function bodies, but at that point it's likely better to simply use the qualified names. Including them within the scope of the type is a middle ground where opinions will differ.

You haven't shown your unit tests here, but it's worthwhile occasionally running them with a memory checker such as Valgrind. As well as ensuring we don't leak memory, that will also help identify any uses of dangling pointers or uninitialized values, which an ordinary run might not.

Consider maintaining a balanced tree - you'll want to read up on the theory if you're not already familiar with the techniques to do this.

You haven't shown your unit tests here, but it's worthwhile occasionally running them with a memory checker such as Valgrind. As well as ensuring we don't leak memory, that will also help identify any uses of dangling pointers or uninitialized values, which an ordinary run might not.

Further directions

Try to evolve the public interface to supporting standard container operations. This probably begins with creating iterators and the member functions that return them.

You haven't shown your unit tests here, but it's worthwhile occasionally running them with a memory checker such as Valgrind. As well as ensuring we don't leak memory, that will also help identify any uses of dangling pointers or uninitialized values, which an ordinary run might not.