llvm-project/libcxx/include/__memory/base.h

128 lines
2.9 KiB
C++

// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___MEMORY_BASE_H
#define _LIBCPP___MEMORY_BASE_H
#include <__config>
#include <__debug>
#include <type_traits>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#pragma GCC system_header
#endif
_LIBCPP_PUSH_MACROS
#include <__undef_macros>
_LIBCPP_BEGIN_NAMESPACE_STD
// addressof
#ifndef _LIBCPP_HAS_NO_BUILTIN_ADDRESSOF
template <class _Tp>
inline _LIBCPP_CONSTEXPR_AFTER_CXX14
_LIBCPP_NO_CFI _LIBCPP_INLINE_VISIBILITY
_Tp*
addressof(_Tp& __x) _NOEXCEPT
{
return __builtin_addressof(__x);
}
#else
template <class _Tp>
inline _LIBCPP_NO_CFI _LIBCPP_INLINE_VISIBILITY
_Tp*
addressof(_Tp& __x) _NOEXCEPT
{
return reinterpret_cast<_Tp *>(
const_cast<char *>(&reinterpret_cast<const volatile char &>(__x)));
}
#endif // _LIBCPP_HAS_NO_BUILTIN_ADDRESSOF
#if defined(_LIBCPP_HAS_OBJC_ARC) && !defined(_LIBCPP_PREDEFINED_OBJC_ARC_ADDRESSOF)
// Objective-C++ Automatic Reference Counting uses qualified pointers
// that require special addressof() signatures. When
// _LIBCPP_PREDEFINED_OBJC_ARC_ADDRESSOF is defined, the compiler
// itself is providing these definitions. Otherwise, we provide them.
template <class _Tp>
inline _LIBCPP_INLINE_VISIBILITY
__strong _Tp*
addressof(__strong _Tp& __x) _NOEXCEPT
{
return &__x;
}
#ifdef _LIBCPP_HAS_OBJC_ARC_WEAK
template <class _Tp>
inline _LIBCPP_INLINE_VISIBILITY
__weak _Tp*
addressof(__weak _Tp& __x) _NOEXCEPT
{
return &__x;
}
#endif
template <class _Tp>
inline _LIBCPP_INLINE_VISIBILITY
__autoreleasing _Tp*
addressof(__autoreleasing _Tp& __x) _NOEXCEPT
{
return &__x;
}
template <class _Tp>
inline _LIBCPP_INLINE_VISIBILITY
__unsafe_unretained _Tp*
addressof(__unsafe_unretained _Tp& __x) _NOEXCEPT
{
return &__x;
}
#endif
#if !defined(_LIBCPP_CXX03_LANG)
template <class _Tp> _Tp* addressof(const _Tp&&) noexcept = delete;
#endif
// construct_at
#if _LIBCPP_STD_VER > 17
template<class _Tp, class ..._Args, class = decltype(
::new (_VSTD::declval<void*>()) _Tp(_VSTD::declval<_Args>()...)
)>
_LIBCPP_INLINE_VISIBILITY
constexpr _Tp* construct_at(_Tp* __location, _Args&& ...__args) {
_LIBCPP_ASSERT(__location, "null pointer given to construct_at");
return ::new ((void*)__location) _Tp(_VSTD::forward<_Args>(__args)...);
}
#endif
// destroy_at
#if _LIBCPP_STD_VER > 14
template <class _Tp>
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
void destroy_at(_Tp* __loc) {
_LIBCPP_ASSERT(__loc, "null pointer given to destroy_at");
__loc->~_Tp();
}
#endif
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
#endif // _LIBCPP___MEMORY_BASE_H