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// <extptr_allocator.h> -*- C++ -*-

// Copyright (C) 2008, 2009 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 ext/extptr_allocator.h

 * @author Bob Walters

 *

 * An example allocator which uses an alternative pointer type from

 * bits/pointer.h.  Supports test cases which confirm container support

 * for alternative pointers.

 */

#ifndef _EXTPTR_ALLOCATOR_H

#define _EXTPTR_ALLOCATOR_H 1

#include <memory>

#include <limits>

#include <ext/pointer.h>

_GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)

  /**

   * @brief An example allocator which uses a non-standard pointer type.

   * @ingroup allocators

   *

   * This allocator specifies that containers use a 'relative pointer' as it's

   * pointer type.  (See ext/pointer.h)  Memory allocation in this example

   * is still performed using std::allocator.

   */

  template<typename _Tp>

    class _ExtPtr_allocator

    {

    public:

      typedef std::size_t     size_type;

      typedef std::ptrdiff_t  difference_type;

      // Note the non-standard pointer types.

      typedef _Pointer_adapter<_Relative_pointer_impl<_Tp> >       pointer;

      typedef _Pointer_adapter<_Relative_pointer_impl<const _Tp> >

                                                             const_pointer;

      typedef _Tp&       reference;

      typedef const _Tp& const_reference;

      typedef _Tp        value_type;

      template<typename _Up>

        struct rebind

        { typedef _ExtPtr_allocator<_Up> other; };

      _ExtPtr_allocator() throw()

      : _M_real_alloc() { }

      _ExtPtr_allocator(const _ExtPtr_allocator &__rarg) throw()

      : _M_real_alloc(__rarg._M_real_alloc) { }

      template<typename _Up>

        _ExtPtr_allocator(const _ExtPtr_allocator<_Up>& __rarg) throw()

        : _M_real_alloc(__rarg._M_getUnderlyingImp()) { }

      ~_ExtPtr_allocator() throw()

      { }

      pointer address(reference __x) const

      { return &__x; }

      const_pointer address(const_reference __x) const

      { return &__x; }

      pointer allocate(size_type __n, void* __hint = 0)

      { return _M_real_alloc.allocate(__n,__hint); }

      void deallocate(pointer __p, size_type __n)

      { _M_real_alloc.deallocate(__p.get(), __n); }

      size_type max_size() const throw()

      { return std::numeric_limits<size_type>::max() / sizeof(_Tp); }

      void construct(pointer __p, const _Tp& __val)

      { ::new(__p.get()) _Tp(__val); }

#ifdef __GXX_EXPERIMENTAL_CXX0X__

      template<typename... _Args>

        void

        construct(pointer __p, _Args&&... __args)

        { ::new(__p.get()) _Tp(std::forward<_Args>(__args)...); }

#endif

      void destroy(pointer __p)

      { __p->~_Tp(); }

      template<typename _Up>

        inline bool

        operator==(const _ExtPtr_allocator<_Up>& __rarg)

        { return _M_real_alloc == __rarg._M_getUnderlyingImp(); }

      inline bool

      operator==(const _ExtPtr_allocator& __rarg)

      { return _M_real_alloc == __rarg._M_real_alloc; }

      template<typename _Up>

        inline bool

        operator!=(const _ExtPtr_allocator<_Up>& __rarg)

        { return _M_real_alloc != __rarg._M_getUnderlyingImp(); }

      inline bool

      operator!=(const _ExtPtr_allocator& __rarg)

      { return _M_real_alloc != __rarg._M_real_alloc; }

      template<typename _Up>

        inline friend void

        swap(_ExtPtr_allocator<_Up>&, _ExtPtr_allocator<_Up>&);

      // A method specific to this implementation.

      const std::allocator<_Tp>&

      _M_getUnderlyingImp() const

      { return _M_real_alloc; }

    private:

      std::allocator<_Tp>  _M_real_alloc;

    };

  // _ExtPtr_allocator<void> specialization.

  template<>

    class _ExtPtr_allocator<void>

    {

    public:

      typedef std::size_t      size_type;

      typedef std::ptrdiff_t   difference_type;

      typedef void             value_type;

      // Note the non-standard pointer types

      typedef _Pointer_adapter<_Relative_pointer_impl<void> >       pointer;

      typedef _Pointer_adapter<_Relative_pointer_impl<const void> >

                                                              const_pointer;

      template<typename _Up>

        struct rebind

        { typedef _ExtPtr_allocator<_Up> other; };

    private:

      std::allocator<void>  _M_real_alloc;

    };

  template<typename _Tp>

    inline void

    swap(_ExtPtr_allocator<_Tp>& __larg, _ExtPtr_allocator<_Tp>& __rarg)

    {

      std::allocator<_Tp> __tmp( __rarg._M_real_alloc );

      __rarg._M_real_alloc = __larg._M_real_alloc;

      __larg._M_real_alloc = __tmp;

    }

_GLIBCXX_END_NAMESPACE

#endif /* _EXTPTR_ALLOCATOR_H */