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