array_allocator.h

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00001 // array allocator -*- C++ -*-
00002 
00003 // Copyright (C) 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
00004 //
00005 // This file is part of the GNU ISO C++ Library.  This library is free
00006 // software; you can redistribute it and/or modify it under the
00007 // terms of the GNU General Public License as published by the
00008 // Free Software Foundation; either version 2, or (at your option)
00009 // any later version.
00010 
00011 // This library is distributed in the hope that it will be useful,
00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00014 // GNU General Public License for more details.
00015 
00016 // You should have received a copy of the GNU General Public License along
00017 // with this library; see the file COPYING.  If not, write to the Free
00018 // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
00019 // USA.
00020 
00021 // As a special exception, you may use this file as part of a free software
00022 // library without restriction.  Specifically, if other files instantiate
00023 // templates or use macros or inline functions from this file, or you compile
00024 // this file and link it with other files to produce an executable, this
00025 // file does not by itself cause the resulting executable to be covered by
00026 // the GNU General Public License.  This exception does not however
00027 // invalidate any other reasons why the executable file might be covered by
00028 // the GNU General Public License.
00029 
00030 /** @file ext/array_allocator.h
00031  *  This file is a GNU extension to the Standard C++ Library.
00032  */
00033 
00034 #ifndef _ARRAY_ALLOCATOR_H
00035 #define _ARRAY_ALLOCATOR_H 1
00036 
00037 #include <cstddef>
00038 #include <new>
00039 #include <bits/functexcept.h>
00040 #include <tr1/array>
00041 #include <bits/stl_move.h>
00042 
00043 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
00044 
00045  using std::size_t;
00046  using std::ptrdiff_t;
00047 
00048   /// Base class.
00049  template<typename _Tp>
00050     class array_allocator_base
00051     {
00052     public:
00053       typedef size_t        size_type;
00054       typedef ptrdiff_t     difference_type;
00055       typedef _Tp*          pointer;
00056       typedef const _Tp*    const_pointer;
00057       typedef _Tp&          reference;
00058       typedef const _Tp&    const_reference;
00059       typedef _Tp           value_type;
00060 
00061       pointer
00062       address(reference __x) const { return &__x; }
00063 
00064       const_pointer
00065       address(const_reference __x) const { return &__x; }
00066 
00067       void
00068       deallocate(pointer, size_type)
00069       { 
00070     // Does nothing.
00071       }
00072 
00073       size_type
00074       max_size() const throw() 
00075       { return size_t(-1) / sizeof(_Tp); }
00076 
00077       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00078       // 402. wrong new expression in [some_] allocator::construct
00079       void 
00080       construct(pointer __p, const _Tp& __val) 
00081       { ::new((void *)__p) value_type(__val); }
00082 
00083 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00084       template<typename... _Args>
00085         void
00086         construct(pointer __p, _Args&&... __args)
00087     { ::new((void *)__p) _Tp(std::forward<_Args>(__args)...); }
00088 #endif
00089 
00090       void 
00091       destroy(pointer __p) { __p->~_Tp(); }
00092     };  
00093 
00094   /**
00095    *  @brief  An allocator that uses previously allocated memory.
00096    *  This memory can be externally, globally, or otherwise allocated.
00097    */
00098   template<typename _Tp, typename _Array = std::tr1::array<_Tp, 1> >
00099     class array_allocator : public array_allocator_base<_Tp>
00100     {
00101     public:
00102       typedef size_t        size_type;
00103       typedef ptrdiff_t     difference_type;
00104       typedef _Tp*          pointer;
00105       typedef const _Tp*    const_pointer;
00106       typedef _Tp&          reference;
00107       typedef const _Tp&    const_reference;
00108       typedef _Tp           value_type;
00109       typedef _Array        array_type;
00110 
00111     private:
00112       array_type*   _M_array;
00113       size_type     _M_used;
00114 
00115     public:
00116      template<typename _Tp1, typename _Array1 = _Array>
00117         struct rebind
00118         { typedef array_allocator<_Tp1, _Array1> other; };
00119 
00120       array_allocator(array_type* __array = NULL) throw() 
00121       : _M_array(__array), _M_used(size_type()) { }
00122 
00123       array_allocator(const array_allocator& __o)  throw() 
00124       : _M_array(__o._M_array), _M_used(__o._M_used) { }
00125 
00126       template<typename _Tp1, typename _Array1>
00127         array_allocator(const array_allocator<_Tp1, _Array1>&) throw()
00128     : _M_array(NULL), _M_used(size_type()) { }
00129 
00130       ~array_allocator() throw() { }
00131 
00132       pointer
00133       allocate(size_type __n, const void* = 0)
00134       {
00135     if (_M_array == 0 || _M_used + __n > _M_array->size())
00136       std::__throw_bad_alloc();
00137     pointer __ret = _M_array->begin() + _M_used;
00138     _M_used += __n;
00139     return __ret;
00140       }
00141     };
00142 
00143   template<typename _Tp, typename _Array>
00144     inline bool
00145     operator==(const array_allocator<_Tp, _Array>&,
00146            const array_allocator<_Tp, _Array>&)
00147     { return true; }
00148   
00149   template<typename _Tp, typename _Array>
00150     inline bool
00151     operator!=(const array_allocator<_Tp, _Array>&, 
00152            const array_allocator<_Tp, _Array>&)
00153     { return false; }
00154 
00155 _GLIBCXX_END_NAMESPACE
00156 
00157 #endif

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