18、拷贝构造、赋值构造、移动构造的简洁代码实现

class Buffer
{
public:
    explicit Buffer(int capacity) : capacity_(capacity), len_(0), buff_(new char[capacity] {0})
    {
        std::cout << "默认的构造函数" << std::endl;
    };
    ~Buffer() {};

    Buffer(const Buffer& other) noexcept 
        : capacity_(other.capacity_), len_(other.len_), buff_(capacity_ ? new char[capacity_] {0} : nullptr)
    {
        if (capacity_)
        {
            std::copy(other.buff_, other.buff_ + other.capacity_, this->buff_);
        }
        std::cout << "拷贝构造" << std::endl;
    }

    Buffer& operator=(Buffer other) noexcept     // 
    {
        std::cout << "赋值拷贝" << std::endl;
        Swap(*this, other);
        return *this;
    }

    Buffer(Buffer&& other) noexcept: capacity_(0), len_(0), buff_(nullptr)
    {
        Swap(*this, other);
        std::cout << "移动构造" << std::endl;
    }

    static void Swap(Buffer& lns, Buffer& rhs) noexcept
    {
        std::swap(lns.buff_, rhs.buff_);
        std::swap(lns.capacity_, rhs.capacity_);
        std::swap(lns.len_, rhs.len_);
    }


private:
    int capacity_;
    int len_;
    char* buff_;

};