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481668695a
2003-07-06 Phil Edwards <pme@gcc.gnu.org> * include/bits/allocator_traits.h: Fix doxygen markup. * include/ext/mt_allocator.h: Likewise. From-SVN: r68994
236 lines
8.2 KiB
C++
236 lines
8.2 KiB
C++
// Allocators -*- C++ -*-
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// Copyright (C) 2001, 2002, 2003 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 2, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License along
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// with this library; see the file COPYING. If not, write to the Free
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// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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// USA.
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// As a special exception, you may use this file as part of a free software
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// library without restriction. Specifically, if other files instantiate
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// templates or use macros or inline functions from this file, or you compile
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// this file and link it with other files to produce an executable, this
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// file does not by itself cause the resulting executable to be covered by
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// the GNU General Public License. This exception does not however
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// invalidate any other reasons why the executable file might be covered by
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// the GNU General Public License.
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/*
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* Copyright (c) 1996-1997
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* Silicon Graphics Computer Systems, Inc.
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*
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* Permission to use, copy, modify, distribute and sell this software
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* and its documentation for any purpose is hereby granted without fee,
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* provided that the above copyright notice appear in all copies and
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* that both that copyright notice and this permission notice appear
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* in supporting documentation. Silicon Graphics makes no
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* representations about the suitability of this software for any
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* purpose. It is provided "as is" without express or implied warranty.
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*/
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#ifndef _ALLOCATOR_TRAITS_H
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#define _ALLOCATOR_TRAITS_H 1
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#include <cstddef>
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namespace std
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{
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/**
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* @if maint
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* This is used primarily (only?) in _Alloc_traits and other places to
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* help provide the _Alloc_type typedef. All it does is forward the
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* requests after some minimal checking.
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*
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* This is neither "standard"-conforming nor "SGI". The _Alloc parameter
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* must be "SGI" style.
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* @endif
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* (See @link Allocators allocators info @endlink for more.)
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*/
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template<typename _Tp, typename _Alloc>
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class __simple_alloc
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{
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public:
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static _Tp*
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allocate(size_t __n)
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{
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_Tp* __ret = 0;
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if (__n)
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__ret = static_cast<_Tp*>(_Alloc::allocate(__n * sizeof(_Tp)));
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return __ret;
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}
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static _Tp*
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allocate()
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{ return (_Tp*) _Alloc::allocate(sizeof (_Tp)); }
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static void
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deallocate(_Tp* __p, size_t __n)
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{ if (0 != __n) _Alloc::deallocate(__p, __n * sizeof (_Tp)); }
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static void
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deallocate(_Tp* __p)
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{ _Alloc::deallocate(__p, sizeof (_Tp)); }
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};
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/**
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* @if maint
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* Allocator adaptor to turn an "SGI" style allocator (e.g.,
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* __alloc, __malloc_alloc) into a "standard" conforming
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* allocator. Note that this adaptor does *not* assume that all
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* objects of the underlying alloc class are identical, nor does it
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* assume that all of the underlying alloc's member functions are
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* static member functions. Note, also, that __allocator<_Tp,
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* __alloc> is essentially the same thing as allocator<_Tp>.
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* @endif
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* (See @link Allocators allocators info @endlink for more.)
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*/
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template<typename _Tp, typename _Alloc>
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struct __allocator
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{
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_Alloc __underlying_alloc;
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typedef size_t size_type;
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typedef ptrdiff_t difference_type;
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typedef _Tp* pointer;
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typedef const _Tp* const_pointer;
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typedef _Tp& reference;
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typedef const _Tp& const_reference;
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typedef _Tp value_type;
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template<typename _Tp1>
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struct rebind
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{ typedef __allocator<_Tp1, _Alloc> other; };
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__allocator() throw() { }
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__allocator(const __allocator& __a) throw()
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: __underlying_alloc(__a.__underlying_alloc) { }
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template<typename _Tp1>
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__allocator(const __allocator<_Tp1, _Alloc>& __a) throw()
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: __underlying_alloc(__a.__underlying_alloc) { }
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~__allocator() throw() { }
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pointer
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address(reference __x) const { return &__x; }
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const_pointer
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address(const_reference __x) const { return &__x; }
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// NB: __n is permitted to be 0. The C++ standard says nothing
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// about what the return value is when __n == 0.
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_Tp*
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allocate(size_type __n, const void* = 0)
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{
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_Tp* __ret = 0;
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if (__n)
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__ret = static_cast<_Tp*>(_Alloc::allocate(__n * sizeof(_Tp)));
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return __ret;
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}
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// __p is not permitted to be a null pointer.
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void
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deallocate(pointer __p, size_type __n)
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{ __underlying_alloc.deallocate(__p, __n * sizeof(_Tp)); }
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size_type
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max_size() const throw() { return size_t(-1) / sizeof(_Tp); }
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void
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construct(pointer __p, const _Tp& __val) { new(__p) _Tp(__val); }
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void
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destroy(pointer __p) { __p->~_Tp(); }
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};
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template<typename _Alloc>
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struct __allocator<void, _Alloc>
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{
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typedef size_t size_type;
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typedef ptrdiff_t difference_type;
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typedef void* pointer;
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typedef const void* const_pointer;
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typedef void value_type;
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template<typename _Tp1>
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struct rebind
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{ typedef __allocator<_Tp1, _Alloc> other; };
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};
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template<typename _Tp, typename _Alloc>
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inline bool
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operator==(const __allocator<_Tp,_Alloc>& __a1,
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const __allocator<_Tp,_Alloc>& __a2)
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{ return __a1.__underlying_alloc == __a2.__underlying_alloc; }
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template<typename _Tp, typename _Alloc>
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inline bool
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operator!=(const __allocator<_Tp, _Alloc>& __a1,
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const __allocator<_Tp, _Alloc>& __a2)
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{ return __a1.__underlying_alloc != __a2.__underlying_alloc; }
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/**
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* @if maint
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* Another allocator adaptor: _Alloc_traits. This serves two purposes.
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* First, make it possible to write containers that can use either "SGI"
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* style allocators or "standard" allocators. Second, provide a mechanism
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* so that containers can query whether or not the allocator has distinct
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* instances. If not, the container can avoid wasting a word of memory to
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* store an empty object. For examples of use, see stl_vector.h, etc, or
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* any of the other classes derived from this one.
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*
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* This adaptor uses partial specialization. The general case of
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* _Alloc_traits<_Tp, _Alloc> assumes that _Alloc is a
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* standard-conforming allocator, possibly with non-equal instances and
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* non-static members. (It still behaves correctly even if _Alloc has
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* static member and if all instances are equal. Refinements affect
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* performance, not correctness.)
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*
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* There are always two members: allocator_type, which is a standard-
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* conforming allocator type for allocating objects of type _Tp, and
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* _S_instanceless, a static const member of type bool. If
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* _S_instanceless is true, this means that there is no difference
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* between any two instances of type allocator_type. Furthermore, if
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* _S_instanceless is true, then _Alloc_traits has one additional
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* member: _Alloc_type. This type encapsulates allocation and
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* deallocation of objects of type _Tp through a static interface; it
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* has two member functions, whose signatures are
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*
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* - static _Tp* allocate(size_t)
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* - static void deallocate(_Tp*, size_t)
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*
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* The size_t parameters are "standard" style (see top of
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* allocator.h) in that they take counts, not sizes.
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*
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* @endif
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* (See @link Allocators allocators info @endlink for more.)
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*/
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// The fully general version.
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template<typename _Tp, typename _Allocator>
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struct _Alloc_traits
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{
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static const bool _S_instanceless = false;
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typedef typename _Allocator::template rebind<_Tp>::other allocator_type;
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};
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template<typename _Tp, typename _Allocator>
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const bool _Alloc_traits<_Tp, _Allocator>::_S_instanceless;
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} // namespace std
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#endif
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