malloc_allocator.h

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00001 // Allocator that wraps "C" malloc -*- C++ -*-
00002 
00003 // Copyright (C) 2001, 2002, 2003, 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/malloc_allocator.h
00027  *  This file is a GNU extension to the Standard C++ Library.
00028  */
00029 
00030 #ifndef _MALLOC_ALLOCATOR_H
00031 #define _MALLOC_ALLOCATOR_H 1
00032 
00033 #include <cstdlib>
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 malloc.
00045    *  @ingroup allocators
00046    *
00047    *  This is precisely the allocator defined in the C++ Standard. 
00048    *    - all allocation calls malloc
00049    *    - all deallocation calls free
00050    */
00051   template<typename _Tp>
00052     class malloc_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 malloc_allocator<_Tp1> other; };
00066 
00067       malloc_allocator() throw() { }
00068 
00069       malloc_allocator(const malloc_allocator&) throw() { }
00070 
00071       template<typename _Tp1>
00072         malloc_allocator(const malloc_allocator<_Tp1>&) throw() { }
00073 
00074       ~malloc_allocator() throw() { }
00075 
00076       pointer
00077       address(reference __x) const { return &__x; }
00078 
00079       const_pointer
00080       address(const_reference __x) const { return &__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 (__builtin_expect(__n > this->max_size(), false))
00088       std::__throw_bad_alloc();
00089 
00090     pointer __ret = static_cast<_Tp*>(std::malloc(__n * sizeof(_Tp)));
00091     if (!__ret)
00092       std::__throw_bad_alloc();
00093     return __ret;
00094       }
00095 
00096       // __p is not permitted to be a null pointer.
00097       void
00098       deallocate(pointer __p, size_type)
00099       { std::free(static_cast<void*>(__p)); }
00100 
00101       size_type
00102       max_size() const throw() 
00103       { return size_t(-1) / sizeof(_Tp); }
00104 
00105       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00106       // 402. wrong new expression in [some_] allocator::construct
00107       void 
00108       construct(pointer __p, const _Tp& __val) 
00109       { ::new((void *)__p) value_type(__val); }
00110 
00111 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00112       template<typename... _Args>
00113         void
00114         construct(pointer __p, _Args&&... __args) 
00115     { ::new((void *)__p) _Tp(std::forward<_Args>(__args)...); }
00116 #endif
00117 
00118       void 
00119       destroy(pointer __p) { __p->~_Tp(); }
00120     };
00121 
00122   template<typename _Tp>
00123     inline bool
00124     operator==(const malloc_allocator<_Tp>&, const malloc_allocator<_Tp>&)
00125     { return true; }
00126   
00127   template<typename _Tp>
00128     inline bool
00129     operator!=(const malloc_allocator<_Tp>&, const malloc_allocator<_Tp>&)
00130     { return false; }
00131 
00132 _GLIBCXX_END_NAMESPACE
00133 
00134 #endif

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