regret to do 对要做的事遗憾.(未做)
regret doing 对做过的事遗憾、后悔.(已做)
I regret to have to do this,but I have no choice.
我很遗憾必须这样去做,我实在没有办法.
I don't regret telling her what I thought.
我不为告诉她我的想法而后悔.
regret having done sth.对已发生的事感到遗憾
所以regret doing sth 和 regret having done sth 是可以同用的