#include <iostream>

// 通过递归实现
template <int Beg, int End>
struct static_for
{
    template <typename Fn>
    void operator()(const Fn& fn) const
    {
        if (Beg < End)
        {
            fn(Beg);
            static_for<Beg+1, End>()(fn);   // 最后一次，2个数相等了，会调用下面的 static_for<N, N>
        }
    }
};

template <int N>
struct static_for<N, N>
{
    template <typename Fn>
    void operator()(Fn const& fn) const
    {
        std::cout << "static_for<N, N>" << std::endl;
    }
};


int main() {
    static_for<0, 5>()([&](int i){
        std::cout << i << std::endl;
    });
    return 0;
}