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

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6.7 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_POINTER_TRAITS_H
#define _LIBCPP___MEMORY_POINTER_TRAITS_H
#include <__config>
#include <__memory/addressof.h>
#include <type_traits>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#pragma GCC system_header
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
template <class _Tp, class = void>
struct __has_element_type : false_type {};
template <class _Tp>
struct __has_element_type<_Tp,
typename __void_t<typename _Tp::element_type>::type> : true_type {};
template <class _Ptr, bool = __has_element_type<_Ptr>::value>
struct __pointer_traits_element_type;
template <class _Ptr>
struct __pointer_traits_element_type<_Ptr, true>
{
typedef _LIBCPP_NODEBUG typename _Ptr::element_type type;
};
template <template <class, class...> class _Sp, class _Tp, class ..._Args>
struct __pointer_traits_element_type<_Sp<_Tp, _Args...>, true>
{
typedef _LIBCPP_NODEBUG typename _Sp<_Tp, _Args...>::element_type type;
};
template <template <class, class...> class _Sp, class _Tp, class ..._Args>
struct __pointer_traits_element_type<_Sp<_Tp, _Args...>, false>
{
typedef _LIBCPP_NODEBUG _Tp type;
};
template <class _Tp, class = void>
struct __has_difference_type : false_type {};
template <class _Tp>
struct __has_difference_type<_Tp,
typename __void_t<typename _Tp::difference_type>::type> : true_type {};
template <class _Ptr, bool = __has_difference_type<_Ptr>::value>
struct __pointer_traits_difference_type
{
typedef _LIBCPP_NODEBUG ptrdiff_t type;
};
template <class _Ptr>
struct __pointer_traits_difference_type<_Ptr, true>
{
typedef _LIBCPP_NODEBUG typename _Ptr::difference_type type;
};
template <class _Tp, class _Up>
struct __has_rebind
{
private:
struct __two {char __lx; char __lxx;};
template <class _Xp> static __two __test(...);
_LIBCPP_SUPPRESS_DEPRECATED_PUSH
template <class _Xp> static char __test(typename _Xp::template rebind<_Up>* = 0);
_LIBCPP_SUPPRESS_DEPRECATED_POP
public:
static const bool value = sizeof(__test<_Tp>(0)) == 1;
};
template <class _Tp, class _Up, bool = __has_rebind<_Tp, _Up>::value>
struct __pointer_traits_rebind
{
#ifndef _LIBCPP_CXX03_LANG
typedef _LIBCPP_NODEBUG typename _Tp::template rebind<_Up> type;
#else
typedef _LIBCPP_NODEBUG typename _Tp::template rebind<_Up>::other type;
#endif
};
template <template <class, class...> class _Sp, class _Tp, class ..._Args, class _Up>
struct __pointer_traits_rebind<_Sp<_Tp, _Args...>, _Up, true>
{
#ifndef _LIBCPP_CXX03_LANG
typedef _LIBCPP_NODEBUG typename _Sp<_Tp, _Args...>::template rebind<_Up> type;
#else
typedef _LIBCPP_NODEBUG typename _Sp<_Tp, _Args...>::template rebind<_Up>::other type;
#endif
};
template <template <class, class...> class _Sp, class _Tp, class ..._Args, class _Up>
struct __pointer_traits_rebind<_Sp<_Tp, _Args...>, _Up, false>
{
typedef _Sp<_Up, _Args...> type;
};
template <class _Ptr>
struct _LIBCPP_TEMPLATE_VIS pointer_traits
{
typedef _Ptr pointer;
typedef typename __pointer_traits_element_type<pointer>::type element_type;
typedef typename __pointer_traits_difference_type<pointer>::type difference_type;
#ifndef _LIBCPP_CXX03_LANG
template <class _Up> using rebind = typename __pointer_traits_rebind<pointer, _Up>::type;
#else
template <class _Up> struct rebind
{typedef typename __pointer_traits_rebind<pointer, _Up>::type other;};
#endif // _LIBCPP_CXX03_LANG
private:
struct __nat {};
public:
_LIBCPP_INLINE_VISIBILITY
static pointer pointer_to(typename conditional<is_void<element_type>::value,
__nat, element_type>::type& __r)
{return pointer::pointer_to(__r);}
};
template <class _Tp>
struct _LIBCPP_TEMPLATE_VIS pointer_traits<_Tp*>
{
typedef _Tp* pointer;
typedef _Tp element_type;
typedef ptrdiff_t difference_type;
#ifndef _LIBCPP_CXX03_LANG
template <class _Up> using rebind = _Up*;
#else
template <class _Up> struct rebind {typedef _Up* other;};
#endif
private:
struct __nat {};
public:
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
static pointer pointer_to(typename conditional<is_void<element_type>::value,
__nat, element_type>::type& __r) _NOEXCEPT
{return _VSTD::addressof(__r);}
};
template <class _From, class _To>
struct __rebind_pointer {
#ifndef _LIBCPP_CXX03_LANG
typedef typename pointer_traits<_From>::template rebind<_To> type;
#else
typedef typename pointer_traits<_From>::template rebind<_To>::other type;
#endif
};
// to_address
template <class _Pointer, class = void>
struct __to_address_helper;
template <class _Tp>
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
_Tp* __to_address(_Tp* __p) _NOEXCEPT {
static_assert(!is_function<_Tp>::value, "_Tp is a function type");
return __p;
}
// enable_if is needed here to avoid instantiating checks for fancy pointers on raw pointers
template <class _Pointer, class = __enable_if_t<
!is_pointer<_Pointer>::value && !is_array<_Pointer>::value && !is_function<_Pointer>::value
> >
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
typename decay<decltype(__to_address_helper<_Pointer>::__call(declval<const _Pointer&>()))>::type
__to_address(const _Pointer& __p) _NOEXCEPT {
return __to_address_helper<_Pointer>::__call(__p);
}
template <class _Pointer, class>
struct __to_address_helper {
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
static decltype(_VSTD::__to_address(declval<const _Pointer&>().operator->()))
__call(const _Pointer& __p) _NOEXCEPT {
return _VSTD::__to_address(__p.operator->());
}
};
template <class _Pointer>
struct __to_address_helper<_Pointer, decltype((void)pointer_traits<_Pointer>::to_address(declval<const _Pointer&>()))> {
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
static decltype(pointer_traits<_Pointer>::to_address(declval<const _Pointer&>()))
__call(const _Pointer& __p) _NOEXCEPT {
return pointer_traits<_Pointer>::to_address(__p);
}
};
#if _LIBCPP_STD_VER > 17
template <class _Tp>
inline _LIBCPP_INLINE_VISIBILITY constexpr
auto to_address(_Tp *__p) noexcept {
return _VSTD::__to_address(__p);
}
template <class _Pointer>
inline _LIBCPP_INLINE_VISIBILITY constexpr
auto to_address(const _Pointer& __p) noexcept {
return _VSTD::__to_address(__p);
}
#endif
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___MEMORY_POINTER_TRAITS_H