libstdc++-v3/include/ext/extptr_allocator.h

   1 // <extptr_allocator.h> -*- C++ -*-
   2
   3 // Copyright (C) 2008, 2009, 2010 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10
  11 // This library is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15
  16 // Under Section 7 of GPL version 3, you are granted additional
  17 // permissions described in the GCC Runtime Library Exception, version
  18 // 3.1, as published by the Free Software Foundation.
  19
  20 // You should have received a copy of the GNU General Public License and
  21 // a copy of the GCC Runtime Library Exception along with this program;
  22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 // <http://www.gnu.org/licenses/>.
  24
  25 /**
  26  *  @file ext/extptr_allocator.h
  27  *  This file is a GNU extension to the Standard C++ Library.
  28  *
  29  *  @author Bob Walters
  30  *
  31  * An example allocator which uses an alternative pointer type from
  32  * bits/pointer.h.  Supports test cases which confirm container support
  33  * for alternative pointers.
  34  */
  35
  36 #ifndef _EXTPTR_ALLOCATOR_H
  37 #define _EXTPTR_ALLOCATOR_H 1
  38
  39 #include <memory>
  40 #include <limits>
  41 #include <ext/pointer.h>
  42
  43 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
  44
  45   /**
  46    * @brief An example allocator which uses a non-standard pointer type.
  47    * @ingroup allocators
  48    *
  49    * This allocator specifies that containers use a 'relative pointer' as it's
  50    * pointer type.  (See ext/pointer.h)  Memory allocation in this example
  51    * is still performed using std::allocator.
  52    */
  53   template<typename _Tp>
  54     class _ExtPtr_allocator
  55     {
  56     public:
  57       typedef std::size_t     size_type;
  58       typedef std::ptrdiff_t  difference_type;
  59
  60       // Note the non-standard pointer types.
  61       typedef _Pointer_adapter<_Relative_pointer_impl<_Tp> >       pointer;
  62       typedef _Pointer_adapter<_Relative_pointer_impl<const _Tp> >
  63                                                              const_pointer;
  64
  65       typedef _Tp&       reference;
  66       typedef const _Tp& const_reference;
  67       typedef _Tp        value_type;
  68
  69       template<typename _Up>
  70         struct rebind
  71         { typedef _ExtPtr_allocator<_Up> other; };
  72
  73       _ExtPtr_allocator() throw()
  74       : _M_real_alloc() { }
  75
  76       _ExtPtr_allocator(const _ExtPtr_allocator &__rarg) throw()
  77       : _M_real_alloc(__rarg._M_real_alloc) { }
  78
  79       template<typename _Up>
  80         _ExtPtr_allocator(const _ExtPtr_allocator<_Up>& __rarg) throw()
  81         : _M_real_alloc(__rarg._M_getUnderlyingImp()) { }
  82
  83       ~_ExtPtr_allocator() throw()
  84       { }
  85
  86       pointer address(reference __x) const
  87       { return std::__addressof(__x); }
  88
  89       const_pointer address(const_reference __x) const
  90       { return std::__addressof(__x); }
  91
  92       pointer allocate(size_type __n, void* __hint = 0)
  93       { return _M_real_alloc.allocate(__n,__hint); }
  94
  95       void deallocate(pointer __p, size_type __n)
  96       { _M_real_alloc.deallocate(__p.get(), __n); }
  97
  98       size_type max_size() const throw()
  99       { return std::numeric_limits<size_type>::max() / sizeof(_Tp); }
 100
 101       void construct(pointer __p, const _Tp& __val)
 102       { ::new(__p.get()) _Tp(__val); }
 103
 104 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 105       template<typename... _Args>
 106         void
 107         construct(pointer __p, _Args&&... __args)
 108         { ::new(__p.get()) _Tp(std::forward<_Args>(__args)...); }
 109 #endif
 110
 111       void destroy(pointer __p)
 112       { __p->~_Tp(); }
 113
 114       template<typename _Up>
 115         inline bool
 116         operator==(const _ExtPtr_allocator<_Up>& __rarg)
 117         { return _M_real_alloc == __rarg._M_getUnderlyingImp(); }
 118
 119       inline bool
 120       operator==(const _ExtPtr_allocator& __rarg)
 121       { return _M_real_alloc == __rarg._M_real_alloc; }
 122
 123       template<typename _Up>
 124         inline bool
 125         operator!=(const _ExtPtr_allocator<_Up>& __rarg)
 126         { return _M_real_alloc != __rarg._M_getUnderlyingImp(); }
 127
 128       inline bool
 129       operator!=(const _ExtPtr_allocator& __rarg)
 130       { return _M_real_alloc != __rarg._M_real_alloc; }
 131
 132       template<typename _Up>
 133         inline friend void
 134         swap(_ExtPtr_allocator<_Up>&, _ExtPtr_allocator<_Up>&);
 135
 136       // A method specific to this implementation.
 137       const std::allocator<_Tp>&
 138       _M_getUnderlyingImp() const
 139       { return _M_real_alloc; }
 140
 141     private:
 142       std::allocator<_Tp>  _M_real_alloc;
 143     };
 144
 145   // _ExtPtr_allocator<void> specialization.
 146   template<>
 147     class _ExtPtr_allocator<void>
 148     {
 149     public:
 150       typedef std::size_t      size_type;
 151       typedef std::ptrdiff_t   difference_type;
 152       typedef void             value_type;
 153
 154       // Note the non-standard pointer types
 155       typedef _Pointer_adapter<_Relative_pointer_impl<void> >       pointer;
 156       typedef _Pointer_adapter<_Relative_pointer_impl<const void> >
 157                                                               const_pointer;
 158
 159       template<typename _Up>
 160         struct rebind
 161         { typedef _ExtPtr_allocator<_Up> other; };
 162
 163     private:
 164       std::allocator<void>  _M_real_alloc;
 165     };
 166
 167   template<typename _Tp>
 168     inline void
 169     swap(_ExtPtr_allocator<_Tp>& __larg, _ExtPtr_allocator<_Tp>& __rarg)
 170     {
 171       std::allocator<_Tp> __tmp( __rarg._M_real_alloc );
 172       __rarg._M_real_alloc = __larg._M_real_alloc;
 173       __larg._M_real_alloc = __tmp;
 174     }
 175
 176 _GLIBCXX_END_NAMESPACE
 177
 178 #endif /* _EXTPTR_ALLOCATOR_H */