new_allocator.h

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00001 // Allocator that wraps operator new -*- C++ -*-
00002 
00003 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 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/new_allocator.h
00027  *  This file is a GNU extension to the Standard C++ Library.
00028  */
00029 
00030 #ifndef _NEW_ALLOCATOR_H
00031 #define _NEW_ALLOCATOR_H 1
00032 
00033 #include <bits/c++config.h>
00034 #include <new>
00035 #include <bits/functexcept.h>
00036 #include <bits/move.h>
00037 
00038 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
00039 
00040   using std::size_t;
00041   using std::ptrdiff_t;
00042 
00043   /**
00044    *  @brief  An allocator that uses global new, as per [20.4].
00045    *  @ingroup allocators
00046    *
00047    *  This is precisely the allocator defined in the C++ Standard. 
00048    *    - all allocation calls operator new
00049    *    - all deallocation calls operator delete
00050    */
00051   template<typename _Tp>
00052     class new_allocator
00053     {
00054     public:
00055       typedef size_t     size_type;
00056       typedef ptrdiff_t  difference_type;
00057       typedef _Tp*       pointer;
00058       typedef const _Tp* const_pointer;
00059       typedef _Tp&       reference;
00060       typedef const _Tp& const_reference;
00061       typedef _Tp        value_type;
00062 
00063       template<typename _Tp1>
00064         struct rebind
00065         { typedef new_allocator<_Tp1> other; };
00066 
00067       new_allocator() throw() { }
00068 
00069       new_allocator(const new_allocator&) throw() { }
00070 
00071       template<typename _Tp1>
00072         new_allocator(const new_allocator<_Tp1>&) throw() { }
00073 
00074       ~new_allocator() throw() { }
00075 
00076       pointer
00077       address(reference __x) const { return std::__addressof(__x); }
00078 
00079       const_pointer
00080       address(const_reference __x) const { return std::__addressof(__x); }
00081 
00082       // NB: __n is permitted to be 0.  The C++ standard says nothing
00083       // about what the return value is when __n == 0.
00084       pointer
00085       allocate(size_type __n, const void* = 0)
00086       { 
00087     if (__n > this->max_size())
00088       std::__throw_bad_alloc();
00089 
00090     return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp)));
00091       }
00092 
00093       // __p is not permitted to be a null pointer.
00094       void
00095       deallocate(pointer __p, size_type)
00096       { ::operator delete(__p); }
00097 
00098       size_type
00099       max_size() const throw() 
00100       { return size_t(-1) / sizeof(_Tp); }
00101 
00102       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00103       // 402. wrong new expression in [some_] allocator::construct
00104       void 
00105       construct(pointer __p, const _Tp& __val) 
00106       { ::new((void *)__p) _Tp(__val); }
00107 
00108 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00109       template<typename... _Args>
00110         void
00111         construct(pointer __p, _Args&&... __args)
00112     { ::new((void *)__p) _Tp(std::forward<_Args>(__args)...); }
00113 #endif
00114 
00115       void 
00116       destroy(pointer __p) { __p->~_Tp(); }
00117     };
00118 
00119   template<typename _Tp>
00120     inline bool
00121     operator==(const new_allocator<_Tp>&, const new_allocator<_Tp>&)
00122     { return true; }
00123   
00124   template<typename _Tp>
00125     inline bool
00126     operator!=(const new_allocator<_Tp>&, const new_allocator<_Tp>&)
00127     { return false; }
00128 
00129 _GLIBCXX_END_NAMESPACE
00130 
00131 #endif