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211 lines
5.9 KiB
211 lines
5.9 KiB
3 years ago
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// Allocator that wraps operator new -*- C++ -*-
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// Copyright (C) 2001-2021 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 3, 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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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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/** @file ext/new_allocator.h
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* This file is a GNU extension to the Standard C++ Library.
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*/
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#ifndef _NEW_ALLOCATOR_H
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#define _NEW_ALLOCATOR_H 1
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#include <bits/c++config.h>
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#include <new>
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#include <bits/functexcept.h>
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#include <bits/move.h>
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#if __cplusplus >= 201103L
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#include <type_traits>
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#endif
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namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
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{
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_GLIBCXX_BEGIN_NAMESPACE_VERSION
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/**
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* @brief An allocator that uses global new, as per C++03 [20.4.1].
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* @ingroup allocators
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*
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* This is precisely the allocator defined in the C++ Standard.
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* - all allocation calls operator new
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* - all deallocation calls operator delete
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*
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* @tparam _Tp Type of allocated object.
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*/
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template<typename _Tp>
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class new_allocator
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{
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public:
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typedef _Tp value_type;
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typedef std::size_t size_type;
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typedef std::ptrdiff_t difference_type;
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#if __cplusplus <= 201703L
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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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template<typename _Tp1>
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struct rebind
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{ typedef new_allocator<_Tp1> other; };
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#endif
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#if __cplusplus >= 201103L
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// _GLIBCXX_RESOLVE_LIB_DEFECTS
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// 2103. propagate_on_container_move_assignment
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typedef std::true_type propagate_on_container_move_assignment;
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#endif
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_GLIBCXX20_CONSTEXPR
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new_allocator() _GLIBCXX_USE_NOEXCEPT { }
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_GLIBCXX20_CONSTEXPR
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new_allocator(const new_allocator&) _GLIBCXX_USE_NOEXCEPT { }
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template<typename _Tp1>
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_GLIBCXX20_CONSTEXPR
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new_allocator(const new_allocator<_Tp1>&) _GLIBCXX_USE_NOEXCEPT { }
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#if __cplusplus <= 201703L
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~new_allocator() _GLIBCXX_USE_NOEXCEPT { }
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pointer
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address(reference __x) const _GLIBCXX_NOEXCEPT
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{ return std::__addressof(__x); }
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const_pointer
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address(const_reference __x) const _GLIBCXX_NOEXCEPT
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{ return std::__addressof(__x); }
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#endif
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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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_GLIBCXX_NODISCARD _Tp*
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allocate(size_type __n, const void* = static_cast<const void*>(0))
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{
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#if __cplusplus >= 201103L
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// _GLIBCXX_RESOLVE_LIB_DEFECTS
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// 3308. std::allocator<void>().allocate(n)
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static_assert(sizeof(_Tp) != 0, "cannot allocate incomplete types");
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#endif
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if (__builtin_expect(__n > this->_M_max_size(), false))
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{
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// _GLIBCXX_RESOLVE_LIB_DEFECTS
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// 3190. allocator::allocate sometimes returns too little storage
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if (__n > (std::size_t(-1) / sizeof(_Tp)))
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std::__throw_bad_array_new_length();
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std::__throw_bad_alloc();
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}
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#if __cpp_aligned_new
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if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
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{
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std::align_val_t __al = std::align_val_t(alignof(_Tp));
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return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp), __al));
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}
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#endif
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return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp)));
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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(_Tp* __p, size_type __t __attribute__ ((__unused__)))
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{
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#if __cpp_aligned_new
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if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
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{
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::operator delete(__p,
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# if __cpp_sized_deallocation
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__t * sizeof(_Tp),
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# endif
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std::align_val_t(alignof(_Tp)));
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return;
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}
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#endif
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::operator delete(__p
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#if __cpp_sized_deallocation
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, __t * sizeof(_Tp)
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#endif
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);
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}
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#if __cplusplus <= 201703L
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size_type
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max_size() const _GLIBCXX_USE_NOEXCEPT
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{ return _M_max_size(); }
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#if __cplusplus >= 201103L
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template<typename _Up, typename... _Args>
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void
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construct(_Up* __p, _Args&&... __args)
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noexcept(std::is_nothrow_constructible<_Up, _Args...>::value)
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{ ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
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template<typename _Up>
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void
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destroy(_Up* __p)
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noexcept(std::is_nothrow_destructible<_Up>::value)
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{ __p->~_Up(); }
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#else
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// _GLIBCXX_RESOLVE_LIB_DEFECTS
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// 402. wrong new expression in [some_] allocator::construct
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void
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construct(pointer __p, const _Tp& __val)
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{ ::new((void *)__p) _Tp(__val); }
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void
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destroy(pointer __p) { __p->~_Tp(); }
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#endif
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#endif // ! C++20
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template<typename _Up>
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friend _GLIBCXX20_CONSTEXPR bool
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operator==(const new_allocator&, const new_allocator<_Up>&)
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_GLIBCXX_NOTHROW
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{ return true; }
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#if __cpp_impl_three_way_comparison < 201907L
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template<typename _Up>
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friend _GLIBCXX20_CONSTEXPR bool
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operator!=(const new_allocator&, const new_allocator<_Up>&)
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_GLIBCXX_NOTHROW
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{ return false; }
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#endif
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private:
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_GLIBCXX_CONSTEXPR size_type
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_M_max_size() const _GLIBCXX_USE_NOEXCEPT
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{
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#if __PTRDIFF_MAX__ < __SIZE_MAX__
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return std::size_t(__PTRDIFF_MAX__) / sizeof(_Tp);
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#else
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return std::size_t(-1) / sizeof(_Tp);
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#endif
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}
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};
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_GLIBCXX_END_NAMESPACE_VERSION
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} // namespace
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#endif
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