c++元编程打印二叉树

#include
using namespace std;

template
struct Tree {};

template
struct Print {};
template
struct Print >{
	static void print() {
		cout << val<<' ';
		if constexpr (is_void::value == false) {
			Print::print();
		}
		if constexpr (is_void::value == false) {
			Print::print();
		}
	}
};

int main() {
	Print, Tree>>::print();
}