// auto_ptr implementation -*- C++ -*- // Copyright (C) 2007-2020 Free Software Foundation, Inc. // // This file is part of the GNU ISO C++ Library. This library is free // software; you can redistribute it and/or modify it under the // terms of the GNU General Public License as published by the // Free Software Foundation; either version 3, or (at your option) // any later version. // This library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // Under Section 7 of GPL version 3, you are granted additional // permissions described in the GCC Runtime Library Exception, version // 3.1, as published by the Free Software Foundation. // You should have received a copy of the GNU General Public License and // a copy of the GCC Runtime Library Exception along with this program; // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see // <http://www.gnu.org/licenses/>. /** @file backward/auto_ptr.h * This is an internal header file, included by other library headers. * Do not attempt to use it directly. @headername{memory} */ #ifndef _BACKWARD_AUTO_PTR_H #define _BACKWARD_AUTO_PTR_H 1 #include <bits/c++config.h> #include <debug/debug.h> namespace std _GLIBCXX_VISIBILITY(default) { _GLIBCXX_BEGIN_NAMESPACE_VERSION /** * A wrapper class to provide auto_ptr with reference semantics. * For example, an auto_ptr can be assigned (or constructed from) * the result of a function which returns an auto_ptr by value. * * All the auto_ptr_ref stuff should happen behind the scenes. */ template<typename _Tp1> struct auto_ptr_ref { _Tp1* _M_ptr; explicit auto_ptr_ref(_Tp1* __p): _M_ptr(__p) { } } _GLIBCXX_DEPRECATED; #pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Wdeprecated-declarations" /** * @brief A simple smart pointer providing strict ownership semantics. * * The Standard says: * <pre> * An @c auto_ptr owns the object it holds a pointer to. Copying * an @c auto_ptr copies the pointer and transfers ownership to the * destination. If more than one @c auto_ptr owns the same object * at the same time the behavior of the program is undefined. * * The uses of @c auto_ptr include providing temporary * exception-safety for dynamically allocated memory, passing * ownership of dynamically allocated memory to a function, and * returning dynamically allocated memory from a function. @c * auto_ptr does not meet the CopyConstructible and Assignable * requirements for Standard Library <a * href="tables.html#65">container</a> elements and thus * instantiating a Standard Library container with an @c auto_ptr * results in undefined behavior. * </pre> * Quoted from [20.4.5]/3. * * Good examples of what can and cannot be done with auto_ptr can * be found in the libstdc++ testsuite. * * _GLIBCXX_RESOLVE_LIB_DEFECTS * 127. auto_ptr<> conversion issues * These resolutions have all been incorporated. */ template<typename _Tp> class auto_ptr { private: _Tp* _M_ptr; public: /// The pointed-to type. typedef _Tp element_type; /** * @brief An %auto_ptr is usually constructed from a raw pointer. * @param __p A pointer (defaults to NULL). * * This object now @e owns the object pointed to by @a __p. */ explicit auto_ptr(element_type* __p = 0) throw() : _M_ptr(__p) { } /** * @brief An %auto_ptr can be constructed from another %auto_ptr. * @param __a Another %auto_ptr of the same type. * * This object now @e owns the object previously owned by @a __a, * which has given up ownership. */ auto_ptr(auto_ptr& __a) throw() : _M_ptr(__a.release()) { } /** * @brief An %auto_ptr can be constructed from another %auto_ptr. * @param __a Another %auto_ptr of a different but related type. * * A pointer-to-Tp1 must be convertible to a * pointer-to-Tp/element_type. * * This object now @e owns the object previously owned by @a __a, * which has given up ownership. */ template<typename _Tp1> auto_ptr(auto_ptr<_Tp1>& __a) throw() : _M_ptr(__a.release()) { } /** * @brief %auto_ptr assignment operator. * @param __a Another %auto_ptr of the same type. * * This object now @e owns the object previously owned by @a __a, * which has given up ownership. The object that this one @e * used to own and track has been deleted. */ auto_ptr& operator=(auto_ptr& __a) throw() { reset(__a.release()); return *this; } /** * @brief %auto_ptr assignment operator. * @param __a Another %auto_ptr of a different but related type. * * A pointer-to-Tp1 must be convertible to a pointer-to-Tp/element_type. * * This object now @e owns the object previously owned by @a __a, * which has given up ownership. The object that this one @e * used to own and track has been deleted. */ template<typename _Tp1> auto_ptr& operator=(auto_ptr<_Tp1>& __a) throw() { reset(__a.release()); return *this; } /** * When the %auto_ptr goes out of scope, the object it owns is * deleted. If it no longer owns anything (i.e., @c get() is * @c NULL), then this has no effect. * * The C++ standard says there is supposed to be an empty throw * specification here, but omitting it is standard conforming. Its * presence can be detected only if _Tp::~_Tp() throws, but this is * prohibited. [17.4.3.6]/2 */ ~auto_ptr() { delete _M_ptr; } /** * @brief Smart pointer dereferencing. * * If this %auto_ptr no longer owns anything, then this * operation will crash. (For a smart pointer, <em>no longer owns * anything</em> is the same as being a null pointer, and you know * what happens when you dereference one of those...) */ element_type& operator*() const throw() { __glibcxx_assert(_M_ptr != 0); return *_M_ptr; } /** * @brief Smart pointer dereferencing. * * This returns the pointer itself, which the language then will * automatically cause to be dereferenced. */ element_type* operator->() const throw() { __glibcxx_assert(_M_ptr != 0); return _M_ptr; } /** * @brief Bypassing the smart pointer. * @return The raw pointer being managed. * * You can get a copy of the pointer that this object owns, for * situations such as passing to a function which only accepts * a raw pointer. * * @note This %auto_ptr still owns the memory. */ element_type* get() const throw() { return _M_ptr; } /** * @brief Bypassing the smart pointer. * @return The raw pointer being managed. * * You can get a copy of the pointer that this object owns, for * situations such as passing to a function which only accepts * a raw pointer. * * @note This %auto_ptr no longer owns the memory. When this object * goes out of scope, nothing will happen. */ element_type* release() throw() { element_type* __tmp = _M_ptr; _M_ptr = 0; return __tmp; } /** * @brief Forcibly deletes the managed object. * @param __p A pointer (defaults to NULL). * * This object now @e owns the object pointed to by @a __p. The * previous object has been deleted. */ void reset(element_type* __p = 0) throw() { if (__p != _M_ptr) { delete _M_ptr; _M_ptr = __p; } } /** * @brief Automatic conversions * * These operations are supposed to convert an %auto_ptr into and from * an auto_ptr_ref automatically as needed. This would allow * constructs such as * @code * auto_ptr<Derived> func_returning_auto_ptr(.....); * ... * auto_ptr<Base> ptr = func_returning_auto_ptr(.....); * @endcode * * But it doesn't work, and won't be fixed. For further details see * http://cplusplus.github.io/LWG/lwg-closed.html#463 */ auto_ptr(auto_ptr_ref<element_type> __ref) throw() : _M_ptr(__ref._M_ptr) { } auto_ptr& operator=(auto_ptr_ref<element_type> __ref) throw() { if (__ref._M_ptr != this->get()) { delete _M_ptr; _M_ptr = __ref._M_ptr; } return *this; } template<typename _Tp1> operator auto_ptr_ref<_Tp1>() throw() { return auto_ptr_ref<_Tp1>(this->release()); } template<typename _Tp1> operator auto_ptr<_Tp1>() throw() { return auto_ptr<_Tp1>(this->release()); } } _GLIBCXX_DEPRECATED; // _GLIBCXX_RESOLVE_LIB_DEFECTS // 541. shared_ptr template assignment and void template<> class auto_ptr<void> { public: typedef void element_type; } _GLIBCXX_DEPRECATED; #if __cplusplus >= 201103L template<_Lock_policy _Lp> template<typename _Tp> inline __shared_count<_Lp>::__shared_count(std::auto_ptr<_Tp>&& __r) : _M_pi(new _Sp_counted_ptr<_Tp*, _Lp>(__r.get())) { __r.release(); } template<typename _Tp, _Lock_policy _Lp> template<typename _Tp1, typename> inline __shared_ptr<_Tp, _Lp>::__shared_ptr(std::auto_ptr<_Tp1>&& __r) : _M_ptr(__r.get()), _M_refcount() { __glibcxx_function_requires(_ConvertibleConcept<_Tp1*, _Tp*>) static_assert( sizeof(_Tp1) > 0, "incomplete type" ); _Tp1* __tmp = __r.get(); _M_refcount = __shared_count<_Lp>(std::move(__r)); _M_enable_shared_from_this_with(__tmp); } template<typename _Tp> template<typename _Tp1, typename> inline shared_ptr<_Tp>::shared_ptr(std::auto_ptr<_Tp1>&& __r) : __shared_ptr<_Tp>(std::move(__r)) { } template<typename _Tp, typename _Dp> template<typename _Up, typename> inline unique_ptr<_Tp, _Dp>::unique_ptr(auto_ptr<_Up>&& __u) noexcept : _M_t(__u.release(), deleter_type()) { } #endif #pragma GCC diagnostic pop _GLIBCXX_END_NAMESPACE_VERSION } // namespace #endif /* _BACKWARD_AUTO_PTR_H */