array_allocator.h

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

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