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// <memory> -*- C++ -*-

// Copyright (C) 2001, 2002, 2004 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 2, 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.

// You should have received a copy of the GNU General Public License along

// with this library; see the file COPYING.  If not, write to the Free

// Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,

// USA.

// As a special exception, you may use this file as part of a free software

// library without restriction.  Specifically, if other files instantiate

// templates or use macros or inline functions from this file, or you compile

// this file and link it with other files to produce an executable, this

// file does not by itself cause the resulting executable to be covered by

// the GNU General Public License.  This exception does not however

// invalidate any other reasons why the executable file might be covered by

// the GNU General Public License.

/*

 * Copyright (c) 1997-1999

 * Silicon Graphics Computer Systems, Inc.

 *

 * Permission to use, copy, modify, distribute and sell this software

 * and its documentation for any purpose is hereby granted without fee,

 * provided that the above copyright notice appear in all copies and

 * that both that copyright notice and this permission notice appear

 * in supporting documentation.  Silicon Graphics makes no

 * representations about the suitability of this software for any

 * purpose.  It is provided "as is" without express or implied warranty.

 *

 */

/** @file

 *  This is a Standard C++ Library header.

 */

#ifndef _GLIBCXX_MEMORY

#define _GLIBCXX_MEMORY 1

#pragma GCC system_header

#include <bits/stl_algobase.h>

#include <bits/allocator.h>

#include <bits/stl_construct.h>

#include <bits/stl_iterator_base_types.h> //for iterator_traits

#include <bits/stl_uninitialized.h>

#include <bits/stl_raw_storage_iter.h>

#include <debug/debug.h>

#include <limits>

namespace std

{

  /**

   *  @if maint

   *  This is a helper function.  The unused second parameter exists to

   *  permit the real get_temporary_buffer to use template parameter deduction.

   *

   *  XXX This should perhaps use the pool.

   *  @endif

   */

  template<typename _Tp>

    pair<_Tp*, ptrdiff_t>

    __get_temporary_buffer(ptrdiff_t __len, _Tp*)

    {

      const ptrdiff_t __max = numeric_limits<ptrdiff_t>::max() / sizeof(_Tp);

      if (__len > __max)

        __len = __max;

      while (__len > 0)

        {

          _Tp* __tmp = static_cast<_Tp*>(::operator new(__len * sizeof(_Tp),

                                                        nothrow));

          if (__tmp != 0)

            return pair<_Tp*, ptrdiff_t>(__tmp, __len);

          __len /= 2;

        }

      return pair<_Tp*, ptrdiff_t>(static_cast<_Tp*>(0), 0);

    }

  /**

   *  @brief Allocates a temporary buffer.

   *  @param  len  The number of objects of type Tp.

   *  @return See full description.

   *

   *  Reinventing the wheel, but this time with prettier spokes!

   *

   *  This function tries to obtain storage for @c len adjacent Tp

   *  objects.  The objects themselves are not constructed, of course.

   *  A pair<> is returned containing "the buffer s address and

   *  capacity (in the units of sizeof(Tp)), or a pair of 0 values if

   *  no storage can be obtained."  Note that the capacity obtained

   *  may be less than that requested if the memory is unavailable;

   *  you should compare len with the .second return value.

   *

   * Provides the nothrow exception guarantee.

   */

  template<typename _Tp>

    inline pair<_Tp*, ptrdiff_t>

    get_temporary_buffer(ptrdiff_t __len)

    { return std::__get_temporary_buffer(__len, static_cast<_Tp*>(0)); }

  /**

   *  @brief The companion to get_temporary_buffer().

   *  @param  p  A buffer previously allocated by get_temporary_buffer.

   *  @return   None.

   *

   *  Frees the memory pointed to by p.

   */

  template<typename _Tp>

    void

    return_temporary_buffer(_Tp* __p)

    { ::operator delete(__p, nothrow); }

  /**

   *  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) { }

    };

  /**

   *  @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.

   *

   *  @if maint

   *  _GLIBCXX_RESOLVE_LIB_DEFECTS

   *  127.  auto_ptr<> conversion issues

   *  These resolutions have all been incorporated.

   *  @endif

   */

  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 ownsership.

       */

      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 ownsership.

       */

      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 ownsership.  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 ownsership.  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.

       *

       *  @if maint

       *  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

       *  @endif

       */

      ~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, "no longer owns

       *  anything" 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()); }

  };

} // namespace std

#endif /* _GLIBCXX_MEMORY */