手撕c++ unique

#include <iostream> #include <memory> using namespace std; namespace smart_pointer { template <typename T> struct defaultDeleter { void operator()(const T *ptr) { if(ptr) { delete ptr; ptr = nullptr; } } }; template <typename T, typename Deleter=defaultDeleter<T> > class unique_ptr { public: unique_ptr(); unique_ptr(T *ptr); unique_ptr(unique_ptr &&p); //移动构造 ~unique_ptr(); //non-copyable private: unique_ptr(const unique_ptr &p); unique_ptr &operator=(const unique_ptr &p); public: T& operator* (); T* operator-> (); unique_ptr &operator=(unique_ptr &&p); //移动赋值，右值 operator bool() const; //返回原始指针 T* get() const; //返回指针，释放所有权 T* release(); //替换被管理的对象 void reset(T *ptr); //交换被管理的对象 void swap(unique_ptr &p); private: T *ptr; }; template <typename T, typename Deleter> unique_ptr<T, Deleter>::unique_ptr() : ptr(nullptr) {} template <typename T, typename Deleter> unique_ptr<T, Deleter>::unique_ptr(T *_ptr) : ptr(_ptr) {} //移交所有权 template <typename T, typename Deleter> unique_ptr<T, Deleter>::unique_ptr(unique_ptr &&p) : ptr(p.ptr) { p.ptr = nullptr; } template <typename T, typename Deleter> unique_ptr<T, Deleter>::~unique_ptr() { Deleter()(ptr); cout << "unique_ptr dctor" << endl; } template <typename T, typename Deleter> T& unique_ptr<T, Deleter>::operator* () { return *ptr; } template <typename T, typename Deleter> T* unique_ptr<T, Deleter>::operator-> () { return ptr; } template <typename T, typename Deleter> unique_ptr<T, Deleter> &unique_ptr<T, Deleter>::operator=(unique_ptr &&p) { std::swap(ptr, p.ptr); return *this; } template <typename T, typename Deleter> unique_ptr<T, Deleter>::operator bool() const { return ptr != nullptr; } template <typename T, typename Deleter> T* unique_ptr<T, Deleter>::get() const { return ptr; } template <typename T, typename Deleter> T* unique_ptr<T, Deleter>::release() { T *pointer = ptr; ptr = nullptr; return pointer; } template <typename T, typename Deleter> void unique_ptr<T, Deleter>::reset(T *_ptr) { unique_ptr<T, Deleter>().swap(*this); ptr = _ptr; } template <typename T, typename Deleter> void unique_ptr<T, Deleter>::swap(unique_ptr &p) { std::swap(ptr, p.ptr); } }; //namespace smart_pointer int main(int argc, char *argv[]) { { smart_pointer::unique_ptr<int> p(new int(10)); //smart_pointer::unique_ptr<int> p1 = p; //编译不过的 //mart_pointer::unique_ptr<int> p2(p); //编译不过的 cout << *p << endl; int *p3 = p.release(); if(!p) cout << "p is released" << endl; cout << *p3 << endl; delete p3; //手动释放 p = smart_pointer::unique_ptr<int>(new int(11)); //移动赋值 smart_pointer::unique_ptr<int> p4(new int(12)); p4.swap(p); cout << *p << endl; p.reset(new int(13)); cout << *p << endl; } return 0; }