bits/new_allocator.h
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// Allocator that wraps operator new -*- C++ -*-
// Copyright (C) 2001-2024 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 3, 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.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
/** @file bits/new_allocator.h
* This is an internal header file, included by other library headers.
* Do not attempt to use it directly. @headername{memory}
*/
#ifndef _STD_NEW_ALLOCATOR_H
#define _STD_NEW_ALLOCATOR_H 1
#include <bits/c++config.h>
#include <new>
#include <bits/functexcept.h>
#include <bits/move.h>
#if __cplusplus >= 201103L
#include <type_traits>
#endif
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
/**
* @brief An allocator that uses global `new`, as per C++03 [20.4.1].
* @ingroup allocators
*
* This is precisely the allocator defined in the C++ Standard.
* - all allocation calls `operator new`
* - all deallocation calls `operator delete`
*
* This is the default base-class implementation of `std::allocator`,
* and is also the base-class of the `__gnu_cxx::new_allocator` extension.
* You should use either `std::allocator` or `__gnu_cxx::new_allocator`
* instead of using this directly.
*
* @tparam _Tp Type of allocated object.
*
* @headerfile memory
*/
template<typename _Tp>
class __new_allocator
{
public:
typedef _Tp value_type;
typedef std::size_t size_type;
typedef std::ptrdiff_t difference_type;
#if __cplusplus <= 201703L
typedef _Tp* pointer;
typedef const _Tp* const_pointer;
typedef _Tp& reference;
typedef const _Tp& const_reference;
template<typename _Tp1>
struct rebind
{ typedef __new_allocator<_Tp1> other; };
#endif
#if __cplusplus >= 201103L
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 2103. propagate_on_container_move_assignment
typedef std::true_type propagate_on_container_move_assignment;
#endif
__attribute__((__always_inline__))
_GLIBCXX20_CONSTEXPR
__new_allocator() _GLIBCXX_USE_NOEXCEPT { }
__attribute__((__always_inline__))
_GLIBCXX20_CONSTEXPR
__new_allocator(const __new_allocator&) _GLIBCXX_USE_NOEXCEPT { }
template<typename _Tp1>
__attribute__((__always_inline__))
_GLIBCXX20_CONSTEXPR
__new_allocator(const __new_allocator<_Tp1>&) _GLIBCXX_USE_NOEXCEPT { }
#if __cplusplus >= 201103L
__new_allocator& operator=(const __new_allocator&) = default;
#endif
#if __cplusplus <= 201703L
~__new_allocator() _GLIBCXX_USE_NOEXCEPT { }
pointer
address(reference __x) const _GLIBCXX_NOEXCEPT
{ return std::__addressof(__x); }
const_pointer
address(const_reference __x) const _GLIBCXX_NOEXCEPT
{ return std::__addressof(__x); }
#endif
#if __has_builtin(__builtin_operator_new) >= 201802L
# define _GLIBCXX_OPERATOR_NEW __builtin_operator_new
# define _GLIBCXX_OPERATOR_DELETE __builtin_operator_delete
#else
# define _GLIBCXX_OPERATOR_NEW ::operator new
# define _GLIBCXX_OPERATOR_DELETE ::operator delete
#endif
// NB: __n is permitted to be 0. The C++ standard says nothing
// about what the return value is when __n == 0.
_GLIBCXX_NODISCARD _Tp*
allocate(size_type __n, const void* = static_cast<const void*>(0))
{
#if __cplusplus >= 201103L
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 3308. std::allocator<void>().allocate(n)
static_assert(sizeof(_Tp) != 0, "cannot allocate incomplete types");
#endif
if (__builtin_expect(__n > this->_M_max_size(), false))
{
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 3190. allocator::allocate sometimes returns too little storage
if (__n > (std::size_t(-1) / sizeof(_Tp)))
std::__throw_bad_array_new_length();
std::__throw_bad_alloc();
}
#if __cpp_aligned_new
if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
{
std::align_val_t __al = std::align_val_t(alignof(_Tp));
return static_cast<_Tp*>(_GLIBCXX_OPERATOR_NEW(__n * sizeof(_Tp),
__al));
}
#endif
return static_cast<_Tp*>(_GLIBCXX_OPERATOR_NEW(__n * sizeof(_Tp)));
}
// __p is not permitted to be a null pointer.
void
deallocate(_Tp* __p, size_type __n __attribute__ ((__unused__)))
{
#if __cpp_sized_deallocation
# define _GLIBCXX_SIZED_DEALLOC(p, n) (p), (n) * sizeof(_Tp)
#else
# define _GLIBCXX_SIZED_DEALLOC(p, n) (p)
#endif
#if __cpp_aligned_new
if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
{
_GLIBCXX_OPERATOR_DELETE(_GLIBCXX_SIZED_DEALLOC(__p, __n),
std::align_val_t(alignof(_Tp)));
return;
}
#endif
_GLIBCXX_OPERATOR_DELETE(_GLIBCXX_SIZED_DEALLOC(__p, __n));
}
#undef _GLIBCXX_SIZED_DEALLOC
#undef _GLIBCXX_OPERATOR_DELETE
#undef _GLIBCXX_OPERATOR_NEW
#if __cplusplus <= 201703L
__attribute__((__always_inline__))
size_type
max_size() const _GLIBCXX_USE_NOEXCEPT
{ return _M_max_size(); }
#if __cplusplus >= 201103L
template<typename _Up, typename... _Args>
__attribute__((__always_inline__))
void
construct(_Up* __p, _Args&&... __args)
noexcept(std::is_nothrow_constructible<_Up, _Args...>::value)
{ ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
template<typename _Up>
__attribute__((__always_inline__))
void
destroy(_Up* __p)
noexcept(std::is_nothrow_destructible<_Up>::value)
{ __p->~_Up(); }
#else
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 402. wrong new expression in [some_] allocator::construct
__attribute__((__always_inline__))
void
construct(pointer __p, const _Tp& __val)
{ ::new((void *)__p) _Tp(__val); }
__attribute__((__always_inline__))
void
destroy(pointer __p) { __p->~_Tp(); }
#endif
#endif // ! C++20
template<typename _Up>
friend __attribute__((__always_inline__)) _GLIBCXX20_CONSTEXPR bool
operator==(const __new_allocator&, const __new_allocator<_Up>&)
_GLIBCXX_NOTHROW
{ return true; }
#if __cpp_impl_three_way_comparison < 201907L
template<typename _Up>
friend __attribute__((__always_inline__)) _GLIBCXX20_CONSTEXPR bool
operator!=(const __new_allocator&, const __new_allocator<_Up>&)
_GLIBCXX_NOTHROW
{ return false; }
#endif
private:
__attribute__((__always_inline__))
_GLIBCXX_CONSTEXPR size_type
_M_max_size() const _GLIBCXX_USE_NOEXCEPT
{
#if __PTRDIFF_MAX__ < __SIZE_MAX__
return std::size_t(__PTRDIFF_MAX__) / sizeof(_Tp);
#else
return std::size_t(-1) / sizeof(_Tp);
#endif
}
};
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
#endif
new
type_traits
move.h
functexcept.h
c++config.h
std::true_type
__bool_constant< true > true_type
The type used as a compile-time boolean with true value.
Definition type_traits:111
std::__addressof
constexpr _Tp * __addressof(_Tp &__r) noexcept
Same as C++11 std::addressof.
Definition move.h:51
std
ISO C++ entities toplevel namespace is std.
std::is_nothrow_destructible
is_nothrow_destructible
Definition type_traits:1102
std::is_nothrow_constructible
is_nothrow_constructible
Definition type_traits:1185
std::__new_allocator
An allocator that uses global new, as per C++03 [20.4.1].
Definition bits/new_allocator.h:64
std::auto_ptr_ref
Definition auto_ptr.h:49