Preview: malloc_allocator.h
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/opt/rh/gcc-toolset-14/root/usr/include/c++/14/ext/malloc_allocator.h
// Allocator that wraps "C" malloc -*- 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 ext/malloc_allocator.h
* This file is a GNU extension to the Standard C++ Library.
*/
#ifndef _MALLOC_ALLOCATOR_H
#define _MALLOC_ALLOCATOR_H 1
#include <bits/requires_hosted.h> // malloc
#include <cstdlib>
#include <cstddef>
#include <new>
#include <bits/functexcept.h>
#include <bits/move.h>
#if __cplusplus >= 201103L
#include <type_traits>
#endif
namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
/**
* @brief An allocator that uses malloc.
* @ingroup allocators
*
* This is precisely the allocator defined in the C++ Standard.
* - all allocation calls malloc
* - all deallocation calls free
*/
template<typename _Tp>
class malloc_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 malloc_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
_GLIBCXX20_CONSTEXPR
malloc_allocator() _GLIBCXX_USE_NOEXCEPT { }
_GLIBCXX20_CONSTEXPR
malloc_allocator(const malloc_allocator&) _GLIBCXX_USE_NOEXCEPT { }
template<typename _Tp1>
_GLIBCXX20_CONSTEXPR
malloc_allocator(const malloc_allocator<_Tp1>&)
_GLIBCXX_USE_NOEXCEPT { }
#if __cplusplus <= 201703L
~malloc_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
// 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* = 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();
}
_Tp* __ret = 0;
#if __cpp_aligned_new
#if __cplusplus > 201402L && _GLIBCXX_HAVE_ALIGNED_ALLOC
if (alignof(_Tp) > alignof(std::max_align_t))
{
__ret = static_cast<_Tp*>(::aligned_alloc(alignof(_Tp),
__n * sizeof(_Tp)));
}
#else
# define _GLIBCXX_CHECK_MALLOC_RESULT
#endif
#endif
if (!__ret)
__ret = static_cast<_Tp*>(std::malloc(__n * sizeof(_Tp)));
if (!__ret)
std::__throw_bad_alloc();
#ifdef _GLIBCXX_CHECK_MALLOC_RESULT
#undef _GLIBCXX_CHECK_MALLOC_RESULT
if (reinterpret_cast<std::size_t>(__ret) % alignof(_Tp))
{
// Memory returned by malloc is not suitably aligned for _Tp.
deallocate(__ret, __n);
std::__throw_bad_alloc();
}
#endif
return __ret;
}
// __p is not permitted to be a null pointer.
void
deallocate(_Tp* __p, size_type)
{ std::free(static_cast<void*>(__p)); }
#if __cplusplus <= 201703L
size_type
max_size() const _GLIBCXX_USE_NOEXCEPT
{ return _M_max_size(); }
#if __cplusplus >= 201103L
template<typename _Up, typename... _Args>
void
construct(_Up* __p, _Args&&... __args)
noexcept(std::__is_nothrow_new_constructible<_Up, _Args...>)
{ ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
template<typename _Up>
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
void
construct(pointer __p, const _Tp& __val)
{ ::new((void *)__p) value_type(__val); }
void
destroy(pointer __p) { __p->~_Tp(); }
#endif
#endif // ! C++20
template<typename _Up>
friend _GLIBCXX20_CONSTEXPR bool
operator==(const malloc_allocator&, const malloc_allocator<_Up>&)
_GLIBCXX_NOTHROW
{ return true; }
#if __cpp_impl_three_way_comparison < 201907L
template<typename _Up>
friend _GLIBCXX20_CONSTEXPR bool
operator!=(const malloc_allocator&, const malloc_allocator<_Up>&)
_GLIBCXX_NOTHROW
{ return false; }
#endif
private:
_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
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