102 lines
2.5 KiB
C++
102 lines
2.5 KiB
C++
//
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// Created by light on 19-12-9.
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//
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#include "../RAII/shape.h"
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template <typename T> class auto_ptr {
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public:
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explicit auto_ptr(T *ptr = nullptr) noexcept : ptr_(ptr) {}
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~auto_ptr() noexcept { delete ptr_; }
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T &operator*() const noexcept { return *ptr_; }
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T *operator->() const noexcept { return ptr_; }
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operator bool() const noexcept { return ptr_; }
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T *get() const noexcept { return ptr_; }
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// 拷贝构造,被复制放释放原来指针的所有权,交给复制方
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// 始终只有一个对象管理一块空间
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auto_ptr(auto_ptr &other) noexcept { ptr_ = other.release(); }
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// copy and swap 始终只有一个对象有管理这块空间的权限
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auto_ptr &operator=(auto_ptr &rhs) noexcept {
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// auto_ptr tmp(rhs.release());
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// tmp.swap(*this);
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// s上述两行等价于下面一行
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auto_ptr(rhs.release()).swap(*this);
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return *this;
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}
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// 原来的指针释放所有权
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T *release() noexcept {
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T *ptr = ptr_;
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ptr_ = nullptr;
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return ptr;
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}
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void swap(auto_ptr &rhs) noexcept {
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using std::swap;
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swap(ptr_, rhs.ptr_); // 转移指针所有权
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}
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private:
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T *ptr_;
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};
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template <typename T> void swap(auto_ptr<T> &lhs, auto_ptr<T> &rhs) noexcept {
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lhs.swap(rhs);
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}
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template <class T>
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class scoped_ptr // noncopyable
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{
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public:
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explicit scoped_ptr(T *ptr = 0) noexcept : ptr_(ptr) {}
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~scoped_ptr() noexcept { delete ptr_; }
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void reset(T *p = 0) noexcept { scoped_ptr(p).swap(*this); }
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T &operator*() const noexcept { return *ptr_; }
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T *operator->() const noexcept { return ptr_; }
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T *get() const noexcept { return ptr_; }
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void swap(scoped_ptr &rhs) noexcept {
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using std::swap;
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swap(ptr_, rhs.ptr_);
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}
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private:
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T *ptr_;
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scoped_ptr(scoped_ptr const &);
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scoped_ptr &operator=(scoped_ptr const &);
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};
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template <typename T>
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void swap(scoped_ptr<T> &lhs, scoped_ptr<T> &rhs) noexcept {
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lhs.swap(rhs);
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}
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int main() {
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auto_ptr<shape> ptr1{create_shape(shape_type::circle)};
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auto_ptr<shape> ptr2{ptr1};
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if (ptr1.get() == nullptr && ptr2.get())
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cout << "拷贝构造：ptr1释放了所有权,ptr2获得了所有权" << endl;
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ptr1 = ptr1;
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auto_ptr<shape> ptr3{create_shape(shape_type::rectangle)};
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ptr1 = ptr3;
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if (ptr3.get() == nullptr && ptr1.get())
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cout << "赋值操作：始终只有一个对象管理一个区块!ptr3释放了所有权,"
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"ptr1获得了所有权"
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<< endl;
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scoped_ptr<shape> sptr1{create_shape(shape_type::circle)};
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// scoped_ptr<shape> sptr2{sptr1}; // error 不可拷贝
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} |