array_allocator.h

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00001 // array allocator -*- C++ -*-
00002 
00003 // Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009
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 <cstddef>
00034 #include <new>
00035 #include <bits/functexcept.h>
00036 #include <tr1/array>
00037 #include <bits/move.h>
00038 
00039 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
00040 
00041  using std::size_t;
00042  using std::ptrdiff_t;
00043 
00044   /// Base class.
00045  template<typename _Tp>
00046     class array_allocator_base
00047     {
00048     public:
00049       typedef size_t        size_type;
00050       typedef ptrdiff_t     difference_type;
00051       typedef _Tp*          pointer;
00052       typedef const _Tp*    const_pointer;
00053       typedef _Tp&          reference;
00054       typedef const _Tp&    const_reference;
00055       typedef _Tp           value_type;
00056 
00057       pointer
00058       address(reference __x) const { return &__x; }
00059 
00060       const_pointer
00061       address(const_reference __x) const { return &__x; }
00062 
00063       void
00064       deallocate(pointer, size_type)
00065       { 
00066     // Does nothing.
00067       }
00068 
00069       size_type
00070       max_size() const throw() 
00071       { return size_t(-1) / sizeof(_Tp); }
00072 
00073       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00074       // 402. wrong new expression in [some_] allocator::construct
00075       void 
00076       construct(pointer __p, const _Tp& __val) 
00077       { ::new((void *)__p) value_type(__val); }
00078 
00079 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00080       template<typename... _Args>
00081         void
00082         construct(pointer __p, _Args&&... __args)
00083     { ::new((void *)__p) _Tp(std::forward<_Args>(__args)...); }
00084 #endif
00085 
00086       void 
00087       destroy(pointer __p) { __p->~_Tp(); }
00088     };  
00089 
00090   /**
00091    *  @brief  An allocator that uses previously allocated memory.
00092    *  This memory can be externally, globally, or otherwise allocated.
00093    *  @ingroup allocators
00094    */
00095   template<typename _Tp, typename _Array = std::tr1::array<_Tp, 1> >
00096     class array_allocator : public array_allocator_base<_Tp>
00097     {
00098     public:
00099       typedef size_t        size_type;
00100       typedef ptrdiff_t     difference_type;
00101       typedef _Tp*          pointer;
00102       typedef const _Tp*    const_pointer;
00103       typedef _Tp&          reference;
00104       typedef const _Tp&    const_reference;
00105       typedef _Tp           value_type;
00106       typedef _Array        array_type;
00107 
00108     private:
00109       array_type*   _M_array;
00110       size_type     _M_used;
00111 
00112     public:
00113      template<typename _Tp1, typename _Array1 = _Array>
00114         struct rebind
00115         { typedef array_allocator<_Tp1, _Array1> other; };
00116 
00117       array_allocator(array_type* __array = NULL) throw() 
00118       : _M_array(__array), _M_used(size_type()) { }
00119 
00120       array_allocator(const array_allocator& __o)  throw() 
00121       : _M_array(__o._M_array), _M_used(__o._M_used) { }
00122 
00123       template<typename _Tp1, typename _Array1>
00124         array_allocator(const array_allocator<_Tp1, _Array1>&) throw()
00125     : _M_array(NULL), _M_used(size_type()) { }
00126 
00127       ~array_allocator() throw() { }
00128 
00129       pointer
00130       allocate(size_type __n, const void* = 0)
00131       {
00132     if (_M_array == 0 || _M_used + __n > _M_array->size())
00133       std::__throw_bad_alloc();
00134     pointer __ret = _M_array->begin() + _M_used;
00135     _M_used += __n;
00136     return __ret;
00137       }
00138     };
00139 
00140   template<typename _Tp, typename _Array>
00141     inline bool
00142     operator==(const array_allocator<_Tp, _Array>&,
00143            const array_allocator<_Tp, _Array>&)
00144     { return true; }
00145   
00146   template<typename _Tp, typename _Array>
00147     inline bool
00148     operator!=(const array_allocator<_Tp, _Array>&, 
00149            const array_allocator<_Tp, _Array>&)
00150     { return false; }
00151 
00152 _GLIBCXX_END_NAMESPACE
00153 
00154 #endif

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