| // 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 */ |