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shared_ptr

news 2025/7/5 10:04:46

源码路径：

/opt/rh/devtoolset-10/root/usr/include/c++/10/bits/shared_ptr_base.h

D:\wsl-ubuntu20.04\rootfs\usr\include\c++\9\bits\shared_ptr_base.h

类原型：

    template<typename _Tp, _Lock_policy _Lp>class __shared_ptr: public __shared_ptr_access<_Tp, _Lp>{public:using element_type = typename remove_extent<_Tp>::type;private:// Constraint for taking ownership of a pointer of type _Yp*:template<typename _Yp>using _SafeConv= typename enable_if<__sp_is_constructible<_Tp, _Yp>::value>::type;// Constraint for construction from shared_ptr and weak_ptr:template<typename _Yp, typename _Res = void>using _Compatible = typenameenable_if<__sp_compatible_with<_Yp*, _Tp*>::value, _Res>::type;// Constraint for assignment from shared_ptr and weak_ptr:template<typename _Yp>using _Assignable = _Compatible<_Yp, __shared_ptr&>;// Constraint for construction from unique_ptr:template<typename _Yp, typename _Del, typename _Res = void,typename _Ptr = typename unique_ptr<_Yp, _Del>::pointer>using _UniqCompatible = typename enable_if<__and_<__sp_compatible_with<_Yp*, _Tp*>, is_convertible<_Ptr, element_type*>>::value, _Res>::type;// Constraint for assignment from unique_ptr:template<typename _Yp, typename _Del>using _UniqAssignable = _UniqCompatible<_Yp, _Del, __shared_ptr&>;public:#if __cplusplus > 201402Lusing weak_type = __weak_ptr<_Tp, _Lp>;
#endifconstexpr __shared_ptr() noexcept: _M_ptr(0), _M_refcount(){ }template<typename _Yp, typename = _SafeConv<_Yp>>explicit__shared_ptr(_Yp* __p): _M_ptr(__p), _M_refcount(__p, typename is_array<_Tp>::type()){static_assert( !is_void<_Yp>::value, "incomplete type" );static_assert( sizeof(_Yp) > 0, "incomplete type" );_M_enable_shared_from_this_with(__p);}template<typename _Yp, typename _Deleter, typename = _SafeConv<_Yp>>__shared_ptr(_Yp* __p, _Deleter __d): _M_ptr(__p), _M_refcount(__p, std::move(__d)){static_assert(__is_invocable<_Deleter&, _Yp*&>::value,"deleter expression d(p) is well-formed");_M_enable_shared_from_this_with(__p);}template<typename _Yp, typename _Deleter, typename _Alloc,typename = _SafeConv<_Yp>>__shared_ptr(_Yp* __p, _Deleter __d, _Alloc __a): _M_ptr(__p), _M_refcount(__p, std::move(__d), std::move(__a)){static_assert(__is_invocable<_Deleter&, _Yp*&>::value,"deleter expression d(p) is well-formed");_M_enable_shared_from_this_with(__p);}template<typename _Deleter>__shared_ptr(nullptr_t __p, _Deleter __d): _M_ptr(0), _M_refcount(__p, std::move(__d)){ }template<typename _Deleter, typename _Alloc>__shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a): _M_ptr(0), _M_refcount(__p, std::move(__d), std::move(__a)){ }template<typename _Yp>__shared_ptr(const __shared_ptr<_Yp, _Lp>& __r,element_type* __p) noexcept: _M_ptr(__p), _M_refcount(__r._M_refcount) // never throws{ }__shared_ptr(const __shared_ptr&) noexcept = default;__shared_ptr& operator=(const __shared_ptr&) noexcept = default;~__shared_ptr() = default;template<typename _Yp, typename = _Compatible<_Yp>>__shared_ptr(const __shared_ptr<_Yp, _Lp>& __r) noexcept: _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount){ }__shared_ptr(__shared_ptr&& __r) noexcept: _M_ptr(__r._M_ptr), _M_refcount(){_M_refcount._M_swap(__r._M_refcount);__r._M_ptr = 0;}template<typename _Yp, typename = _Compatible<_Yp>>__shared_ptr(__shared_ptr<_Yp, _Lp>&& __r) noexcept: _M_ptr(__r._M_ptr), _M_refcount(){_M_refcount._M_swap(__r._M_refcount);__r._M_ptr = 0;}template<typename _Yp, typename = _Compatible<_Yp>>explicit __shared_ptr(const __weak_ptr<_Yp, _Lp>& __r): _M_refcount(__r._M_refcount) // may throw{// It is now safe to copy __r._M_ptr, as// _M_refcount(__r._M_refcount) did not throw._M_ptr = __r._M_ptr;}// If an exception is thrown this constructor has no effect.template<typename _Yp, typename _Del,typename = _UniqCompatible<_Yp, _Del>>__shared_ptr(unique_ptr<_Yp, _Del>&& __r): _M_ptr(__r.get()), _M_refcount(){auto __raw = __to_address(__r.get());_M_refcount = __shared_count<_Lp>(std::move(__r));_M_enable_shared_from_this_with(__raw);}#if __cplusplus <= 201402L && _GLIBCXX_USE_DEPRECATEDprotected:// If an exception is thrown this constructor has no effect.template<typename _Tp1, typename _Del,typename enable_if<__and_<__not_<is_array<_Tp>>, is_array<_Tp1>,is_convertible<typename unique_ptr<_Tp1, _Del>::pointer, _Tp*>>::value, bool>::type = true>__shared_ptr(unique_ptr<_Tp1, _Del>&& __r, __sp_array_delete): _M_ptr(__r.get()), _M_refcount(){auto __raw = __to_address(__r.get());_M_refcount = __shared_count<_Lp>(std::move(__r));_M_enable_shared_from_this_with(__raw);}public:
#endif#if _GLIBCXX_USE_DEPRECATED
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wdeprecated-declarations"// Postcondition: use_count() == 1 and __r.get() == 0template<typename _Yp, typename = _Compatible<_Yp>>__shared_ptr(auto_ptr<_Yp>&& __r);
#pragma GCC diagnostic pop
#endifconstexpr __shared_ptr(nullptr_t) noexcept : __shared_ptr() { }template<typename _Yp>_Assignable<_Yp>operator=(const __shared_ptr<_Yp, _Lp>& __r) noexcept{_M_ptr = __r._M_ptr;_M_refcount = __r._M_refcount; // __shared_count::op= doesn't throwreturn *this;}#if _GLIBCXX_USE_DEPRECATED
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wdeprecated-declarations"template<typename _Yp>_Assignable<_Yp>operator=(auto_ptr<_Yp>&& __r){__shared_ptr(std::move(__r)).swap(*this);return *this;}
#pragma GCC diagnostic pop
#endif__shared_ptr&operator=(__shared_ptr&& __r) noexcept{__shared_ptr(std::move(__r)).swap(*this);return *this;}template<class _Yp>_Assignable<_Yp>operator=(__shared_ptr<_Yp, _Lp>&& __r) noexcept{__shared_ptr(std::move(__r)).swap(*this);return *this;}template<typename _Yp, typename _Del>_UniqAssignable<_Yp, _Del>operator=(unique_ptr<_Yp, _Del>&& __r){__shared_ptr(std::move(__r)).swap(*this);return *this;}voidreset() noexcept{ __shared_ptr().swap(*this); }template<typename _Yp>_SafeConv<_Yp>reset(_Yp* __p) // _Yp must be complete.{// Catch self-reset errors.__glibcxx_assert(__p == 0 || __p != _M_ptr);__shared_ptr(__p).swap(*this);}template<typename _Yp, typename _Deleter>_SafeConv<_Yp>reset(_Yp* __p, _Deleter __d){ __shared_ptr(__p, std::move(__d)).swap(*this); }template<typename _Yp, typename _Deleter, typename _Alloc>_SafeConv<_Yp>reset(_Yp* __p, _Deleter __d, _Alloc __a){ __shared_ptr(__p, std::move(__d), std::move(__a)).swap(*this); }element_type*get() const noexcept{ return _M_ptr; }explicit operator bool() const // never throws{ return _M_ptr == 0 ? false : true; }boolunique() const noexcept{ return _M_refcount._M_unique(); }longuse_count() const noexcept{ return _M_refcount._M_get_use_count(); }voidswap(__shared_ptr<_Tp, _Lp>& __other) noexcept{std::swap(_M_ptr, __other._M_ptr);_M_refcount._M_swap(__other._M_refcount);}template<typename _Tp1>boolowner_before(__shared_ptr<_Tp1, _Lp> const& __rhs) const noexcept{ return _M_refcount._M_less(__rhs._M_refcount); }template<typename _Tp1>boolowner_before(__weak_ptr<_Tp1, _Lp> const& __rhs) const noexcept{ return _M_refcount._M_less(__rhs._M_refcount); }protected:// This constructor is non-standard, it is used by allocate_shared.template<typename _Alloc, typename... _Args>__shared_ptr(_Sp_alloc_shared_tag<_Alloc> __tag, _Args&&... __args): _M_ptr(), _M_refcount(_M_ptr, __tag, std::forward<_Args>(__args)...){ _M_enable_shared_from_this_with(_M_ptr); }template<typename _Tp1, _Lock_policy _Lp1, typename _Alloc,typename... _Args>friend __shared_ptr<_Tp1, _Lp1>__allocate_shared(const _Alloc& __a, _Args&&... __args);// This constructor is used by __weak_ptr::lock() and// shared_ptr::shared_ptr(const weak_ptr&, std::nothrow_t).__shared_ptr(const __weak_ptr<_Tp, _Lp>& __r, std::nothrow_t): _M_refcount(__r._M_refcount, std::nothrow){_M_ptr = _M_refcount._M_get_use_count() ? __r._M_ptr : nullptr;}friend class __weak_ptr<_Tp, _Lp>;private:template<typename _Yp>using __esft_base_t = decltype(__enable_shared_from_this_base(std::declval<const __shared_count<_Lp>&>(),std::declval<_Yp*>()));// Detect an accessible and unambiguous enable_shared_from_this base.template<typename _Yp, typename = void>struct __has_esft_base: false_type { };template<typename _Yp>struct __has_esft_base<_Yp, __void_t<__esft_base_t<_Yp>>>: __not_<is_array<_Tp>> { }; // No enable shared_from_this for arraystemplate<typename _Yp, typename _Yp2 = typename remove_cv<_Yp>::type>typename enable_if<__has_esft_base<_Yp2>::value>::type_M_enable_shared_from_this_with(_Yp* __p) noexcept{if (auto __base = __enable_shared_from_this_base(_M_refcount, __p))__base->_M_weak_assign(const_cast<_Yp2*>(__p), _M_refcount);}template<typename _Yp, typename _Yp2 = typename remove_cv<_Yp>::type>typename enable_if<!__has_esft_base<_Yp2>::value>::type_M_enable_shared_from_this_with(_Yp*) noexcept{ }void*_M_get_deleter(const std::type_info& __ti) const noexcept{ return _M_refcount._M_get_deleter(__ti); }template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr;template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr;template<typename _Del, typename _Tp1, _Lock_policy _Lp1>friend _Del* get_deleter(const __shared_ptr<_Tp1, _Lp1>&) noexcept;template<typename _Del, typename _Tp1>friend _Del* get_deleter(const shared_ptr<_Tp1>&) noexcept;element_type*	   _M_ptr;         // Contained pointer.__shared_count<_Lp>  _M_refcount;    // Reference counter.};

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