libstdc++
array_allocator.h
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00001 // array allocator -*- C++ -*-
00002 
00003 // Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010
00004 // Free Software Foundation, Inc.
00005 //
00006 // This file is part of the GNU ISO C++ Library.  This library is free
00007 // software; you can redistribute it and/or modify it under the
00008 // terms of the GNU General Public License as published by the
00009 // Free Software Foundation; either version 3, or (at your option)
00010 // any later version.
00011 
00012 // This library is distributed in the hope that it will be useful,
00013 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00014 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00015 // GNU General Public License for more details.
00016 
00017 // Under Section 7 of GPL version 3, you are granted additional
00018 // permissions described in the GCC Runtime Library Exception, version
00019 // 3.1, as published by the Free Software Foundation.
00020 
00021 // You should have received a copy of the GNU General Public License and
00022 // a copy of the GCC Runtime Library Exception along with this program;
00023 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00024 // <http://www.gnu.org/licenses/>.
00025 
00026 /** @file ext/array_allocator.h
00027  *  This file is a GNU extension to the Standard C++ Library.
00028  */
00029 
00030 #ifndef _ARRAY_ALLOCATOR_H
00031 #define _ARRAY_ALLOCATOR_H 1
00032 
00033 #include <bits/c++config.h>
00034 #include <new>
00035 #include <bits/functexcept.h>
00036 #include <tr1/array>
00037 #include <bits/move.h>
00038 
00039 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
00040 {
00041 _GLIBCXX_BEGIN_NAMESPACE_VERSION
00042 
00043  using std::size_t;
00044  using std::ptrdiff_t;
00045 
00046   /// Base class.
00047  template<typename _Tp>
00048     class array_allocator_base
00049     {
00050     public:
00051       typedef size_t        size_type;
00052       typedef ptrdiff_t     difference_type;
00053       typedef _Tp*          pointer;
00054       typedef const _Tp*    const_pointer;
00055       typedef _Tp&          reference;
00056       typedef const _Tp&    const_reference;
00057       typedef _Tp           value_type;
00058 
00059       pointer
00060       address(reference __x) const { return std::__addressof(__x); }
00061 
00062       const_pointer
00063       address(const_reference __x) const { return std::__addressof(__x); }
00064 
00065       void
00066       deallocate(pointer, size_type)
00067       { 
00068     // Does nothing.
00069       }
00070 
00071       size_type
00072       max_size() const throw() 
00073       { return size_t(-1) / sizeof(_Tp); }
00074 
00075       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00076       // 402. wrong new expression in [some_] allocator::construct
00077       void 
00078       construct(pointer __p, const _Tp& __val) 
00079       { ::new((void *)__p) value_type(__val); }
00080 
00081 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00082       template<typename... _Args>
00083         void
00084         construct(pointer __p, _Args&&... __args)
00085     { ::new((void *)__p) _Tp(std::forward<_Args>(__args)...); }
00086 #endif
00087 
00088       void 
00089       destroy(pointer __p) { __p->~_Tp(); }
00090     };  
00091 
00092   /**
00093    *  @brief  An allocator that uses previously allocated memory.
00094    *  This memory can be externally, globally, or otherwise allocated.
00095    *  @ingroup allocators
00096    */
00097   template<typename _Tp, typename _Array = std::tr1::array<_Tp, 1> >
00098     class array_allocator : public array_allocator_base<_Tp>
00099     {
00100     public:
00101       typedef size_t        size_type;
00102       typedef ptrdiff_t     difference_type;
00103       typedef _Tp*          pointer;
00104       typedef const _Tp*    const_pointer;
00105       typedef _Tp&          reference;
00106       typedef const _Tp&    const_reference;
00107       typedef _Tp           value_type;
00108       typedef _Array        array_type;
00109 
00110     private:
00111       array_type*   _M_array;
00112       size_type     _M_used;
00113 
00114     public:
00115      template<typename _Tp1, typename _Array1 = _Array>
00116         struct rebind
00117         { typedef array_allocator<_Tp1, _Array1> other; };
00118 
00119       array_allocator(array_type* __array = 0) throw() 
00120       : _M_array(__array), _M_used(size_type()) { }
00121 
00122       array_allocator(const array_allocator& __o)  throw() 
00123       : _M_array(__o._M_array), _M_used(__o._M_used) { }
00124 
00125       template<typename _Tp1, typename _Array1>
00126         array_allocator(const array_allocator<_Tp1, _Array1>&) throw()
00127     : _M_array(0), _M_used(size_type()) { }
00128 
00129       ~array_allocator() throw() { }
00130 
00131       pointer
00132       allocate(size_type __n, const void* = 0)
00133       {
00134     if (_M_array == 0 || _M_used + __n > _M_array->size())
00135       std::__throw_bad_alloc();
00136     pointer __ret = _M_array->begin() + _M_used;
00137     _M_used += __n;
00138     return __ret;
00139       }
00140     };
00141 
00142   template<typename _Tp, typename _Array>
00143     inline bool
00144     operator==(const array_allocator<_Tp, _Array>&,
00145            const array_allocator<_Tp, _Array>&)
00146     { return true; }
00147   
00148   template<typename _Tp, typename _Array>
00149     inline bool
00150     operator!=(const array_allocator<_Tp, _Array>&, 
00151            const array_allocator<_Tp, _Array>&)
00152     { return false; }
00153 
00154 _GLIBCXX_END_NAMESPACE_VERSION
00155 } // namespace
00156 
00157 #endif