296 lines
9.2 KiB
C++
296 lines
9.2 KiB
C++
// auto_ptr implementation -*- C++ -*-
|
|
|
|
// Copyright (C) 2007, 2008, 2009, 2010, 2011 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_DEBUG_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_DEBUG_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 convert an %auto_ptr into and from an auto_ptr_ref
|
|
* automatically as needed. This allows constructs such as
|
|
* @code
|
|
* auto_ptr<Derived> func_returning_auto_ptr(.....);
|
|
* ...
|
|
* auto_ptr<Base> ptr = func_returning_auto_ptr(.....);
|
|
* @endcode
|
|
*/
|
|
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;
|
|
|
|
_GLIBCXX_END_NAMESPACE_VERSION
|
|
} // namespace
|
|
|
|
#endif /* _BACKWARD_AUTO_PTR_H */
|