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| // auto_ptr implementation -*- C++ -*-
// Copyright (C) 2007-2017 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;
/**
* @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
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
#endif /* _BACKWARD_AUTO_PTR_H */
|