// 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 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 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 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 struct rebind { typedef __allocator<_Tp1, _Alloc> other; }; __allocator() throw() { } __allocator(const __allocator& __a) throw() : __underlying_alloc(__a.__underlying_alloc) { } template __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 struct __allocator { typedef size_t size_type; typedef ptrdiff_t difference_type; typedef void* pointer; typedef const void* const_pointer; typedef void value_type; template struct rebind { typedef __allocator<_Tp1, _Alloc> other; }; }; template inline bool operator==(const __allocator<_Tp,_Alloc>& __a1, const __allocator<_Tp,_Alloc>& __a2) { return __a1.__underlying_alloc == __a2.__underlying_alloc; } template 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 struct _Alloc_traits { static const bool _S_instanceless = false; typedef typename _Allocator::template rebind<_Tp>::other allocator_type; }; template const bool _Alloc_traits<_Tp, _Allocator>::_S_instanceless; } // namespace std #endif