template<class T>
class Shared_pointer{
private:
ssize_t *_ref_count; // 计数器的指针
T *_ptr; // 元素的指针
std::mutex *mtx; // 计数器的锁
public:
explicit Shared_pointer(T *ptr = nullptr)
: _ptr(ptr), _ref_count(new ssize_t(1)), mtx(new std::mutex)
{}
explicit Shared_pointer(const Shared_pointer<T> & sp)
: _ptr(sp._ptr), _ref_count(sp._ref_count), mtx(sp.mtx)
{
std::lock_guard<std::mutex> lg(*mtx);
++(*_ref_count);
}
~Shared_pointer(){
std::lock_guard<std::mutex> lg(*mtx);
if(--(*_ref_count) == 0){
delete _ref_count;
delete _ptr;
delete mtx;
}
}
ssize_t use_count(){ return *_ref_count; }
T* operator->(){
return _ptr;
}
T& operator*(){
return *_ptr;
}
Shared_pointer<T>& operator=( Shared_pointer<T> &other ){
std::unique_lock<std::mutex> ul(this->mtx);
// 析构掉当前对象
if(this->_ptr && --(*_ref_count) == 0){
delete _ref_count;
delete _ptr;
delete mtx;
}
ul.unlock();
std::lock_guard<std::mutex> lg(other.mtx);
// 用对象other给当前对象赋值
this->_ptr = other._ptr;
this->_ref_count = &(++(*other._ref_count));
this->mtx = other.mtx;
return *this;
}
};
C++ | 智能指针之模仿实现shared_ptr
发布时间 2023-09-22 16:59:24作者: C111-CR