在unordered_map中找到一个枚举并获取其值？

Question

给出以下代码：

enum Keys {
    Up,
    Down,
    Left,
    Right
};

enum KeyState {
    Down,
    Up
};

std::unordered_map<Keys, KeyState> keys;

keys[Keys::Up] = KeyState::Up;
keys[Keys::Down] = KeyState::Up;
keys[Keys::Left] = KeyState::Down;
keys[Keys::Right] = KeyState::Up;

我如何编写这样的方法：

isKeyDown(Keys key) {
   return true if key has the Up or Down state.
}

Answer 1

KeyState value = keys[key];
return value == KeyState::Up || value == KeyState::Down;

当然，这些是您为KeyState定义的唯一两个值，因此，它就是......

return true;