272 lines
8.9 KiB
C++
272 lines
8.9 KiB
C++
// -*- C++ -*-
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//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___MEMORY_POINTER_TRAITS_H
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#define _LIBCPP___MEMORY_POINTER_TRAITS_H
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#include <__config>
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#include <__cstddef/ptrdiff_t.h>
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#include <__memory/addressof.h>
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#include <__type_traits/conditional.h>
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#include <__type_traits/conjunction.h>
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#include <__type_traits/decay.h>
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#include <__type_traits/detected_or.h>
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#include <__type_traits/enable_if.h>
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#include <__type_traits/integral_constant.h>
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#include <__type_traits/is_class.h>
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#include <__type_traits/is_function.h>
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#include <__type_traits/is_void.h>
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#include <__type_traits/nat.h>
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#include <__type_traits/void_t.h>
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#include <__utility/declval.h>
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#include <__utility/forward.h>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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_LIBCPP_PUSH_MACROS
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#include <__undef_macros>
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_LIBCPP_BEGIN_NAMESPACE_STD
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template <class _Ptr>
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struct __pointer_traits_element_type_impl {};
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template <template <class, class...> class _Sp, class _Tp, class... _Args>
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struct __pointer_traits_element_type_impl<_Sp<_Tp, _Args...> > {
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using type _LIBCPP_NODEBUG = _Tp;
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};
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template <class _Ptr, class = void>
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struct __pointer_traits_element_type : __pointer_traits_element_type_impl<_Ptr> {};
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template <class _Ptr>
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struct __pointer_traits_element_type<_Ptr, __void_t<typename _Ptr::element_type> > {
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using type _LIBCPP_NODEBUG = typename _Ptr::element_type;
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};
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template <class _Tp, class _Up>
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struct __pointer_traits_rebind_impl {
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static_assert(false, "Cannot rebind pointer; did you forget to add a rebind member to your pointer?");
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};
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template <template <class, class...> class _Sp, class _Tp, class... _Args, class _Up>
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struct __pointer_traits_rebind_impl<_Sp<_Tp, _Args...>, _Up> {
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using type _LIBCPP_NODEBUG = _Sp<_Up, _Args...>;
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};
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template <class _Tp, class _Up, class = void>
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struct __pointer_traits_rebind : __pointer_traits_rebind_impl<_Tp, _Up> {};
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template <class _Tp, class _Up>
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struct __pointer_traits_rebind<_Tp, _Up, __void_t<typename _Tp::template rebind<_Up> > > {
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#ifndef _LIBCPP_CXX03_LANG
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using type _LIBCPP_NODEBUG = typename _Tp::template rebind<_Up>;
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#else
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using type _LIBCPP_NODEBUG = typename _Tp::template rebind<_Up>::other;
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#endif
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};
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template <class _Tp>
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using __difference_type_member _LIBCPP_NODEBUG = typename _Tp::difference_type;
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template <class _Ptr, class = void>
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struct __pointer_traits_impl {};
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template <class _Ptr>
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struct __pointer_traits_impl<_Ptr, __void_t<typename __pointer_traits_element_type<_Ptr>::type> > {
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typedef _Ptr pointer;
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typedef typename __pointer_traits_element_type<pointer>::type element_type;
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using difference_type = __detected_or_t<ptrdiff_t, __difference_type_member, pointer>;
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#ifndef _LIBCPP_CXX03_LANG
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template <class _Up>
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using rebind = typename __pointer_traits_rebind<pointer, _Up>::type;
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#else
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template <class _Up>
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struct rebind {
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typedef typename __pointer_traits_rebind<pointer, _Up>::type other;
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};
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#endif // _LIBCPP_CXX03_LANG
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public:
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_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 static pointer
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pointer_to(__conditional_t<is_void<element_type>::value, __nat, element_type>& __r) {
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return pointer::pointer_to(__r);
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}
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};
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template <class _Ptr>
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struct pointer_traits : __pointer_traits_impl<_Ptr> {};
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template <class _Tp>
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struct pointer_traits<_Tp*> {
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typedef _Tp* pointer;
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typedef _Tp element_type;
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typedef ptrdiff_t difference_type;
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#ifndef _LIBCPP_CXX03_LANG
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template <class _Up>
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using rebind = _Up*;
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#else
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template <class _Up>
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struct rebind {
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typedef _Up* other;
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};
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#endif
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public:
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_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 static pointer
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pointer_to(__conditional_t<is_void<element_type>::value, __nat, element_type>& __r) _NOEXCEPT {
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return std::addressof(__r);
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}
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};
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#ifndef _LIBCPP_CXX03_LANG
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template <class _From, class _To>
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using __rebind_pointer_t _LIBCPP_NODEBUG = typename pointer_traits<_From>::template rebind<_To>;
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#else
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template <class _From, class _To>
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using __rebind_pointer_t _LIBCPP_NODEBUG = typename pointer_traits<_From>::template rebind<_To>::other;
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#endif
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// to_address
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template <class _Pointer, class = void>
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struct __to_address_helper;
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template <class _Tp>
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_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _Tp* __to_address(_Tp* __p) _NOEXCEPT {
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static_assert(!is_function<_Tp>::value, "_Tp is a function type");
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return __p;
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}
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template <class _Pointer, class = void>
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struct _HasToAddress : false_type {};
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template <class _Pointer>
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struct _HasToAddress<_Pointer, decltype((void)pointer_traits<_Pointer>::to_address(std::declval<const _Pointer&>())) >
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: true_type {};
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template <class _Pointer, class = void>
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struct _HasArrow : false_type {};
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template <class _Pointer>
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struct _HasArrow<_Pointer, decltype((void)std::declval<const _Pointer&>().operator->()) > : true_type {};
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template <class _Pointer>
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struct _IsFancyPointer {
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static const bool value = _HasArrow<_Pointer>::value || _HasToAddress<_Pointer>::value;
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};
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// enable_if is needed here to avoid instantiating checks for fancy pointers on raw pointers
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template <class _Pointer, __enable_if_t< _And<is_class<_Pointer>, _IsFancyPointer<_Pointer> >::value, int> = 0>
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_LIBCPP_HIDE_FROM_ABI
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_LIBCPP_CONSTEXPR __decay_t<decltype(__to_address_helper<_Pointer>::__call(std::declval<const _Pointer&>()))>
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__to_address(const _Pointer& __p) _NOEXCEPT {
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return __to_address_helper<_Pointer>::__call(__p);
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}
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template <class _Pointer, class>
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struct __to_address_helper {
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_LIBCPP_HIDE_FROM_ABI
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_LIBCPP_CONSTEXPR static decltype(std::__to_address(std::declval<const _Pointer&>().operator->()))
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__call(const _Pointer& __p) _NOEXCEPT {
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return std::__to_address(__p.operator->());
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}
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};
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template <class _Pointer>
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struct __to_address_helper<_Pointer,
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decltype((void)pointer_traits<_Pointer>::to_address(std::declval<const _Pointer&>()))> {
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_LIBCPP_HIDE_FROM_ABI
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_LIBCPP_CONSTEXPR static decltype(pointer_traits<_Pointer>::to_address(std::declval<const _Pointer&>()))
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__call(const _Pointer& __p) _NOEXCEPT {
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return pointer_traits<_Pointer>::to_address(__p);
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}
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};
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#if _LIBCPP_STD_VER >= 20
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template <class _Tp>
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inline _LIBCPP_HIDE_FROM_ABI constexpr auto to_address(_Tp* __p) noexcept {
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return std::__to_address(__p);
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}
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template <class _Pointer>
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inline _LIBCPP_HIDE_FROM_ABI constexpr auto to_address(const _Pointer& __p) noexcept
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-> decltype(std::__to_address(__p)) {
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return std::__to_address(__p);
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}
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#endif
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#if _LIBCPP_STD_VER >= 23
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template <class _Tp>
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struct __pointer_of {};
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template <class _Tp>
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concept __has_pointer_member = requires { typename _Tp::pointer; };
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template <class _Tp>
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concept __has_element_type_member = requires { typename _Tp::element_type; };
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template <class _Tp>
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requires __has_pointer_member<_Tp>
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struct __pointer_of<_Tp> {
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using type _LIBCPP_NODEBUG = typename _Tp::pointer;
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};
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template <class _Tp>
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requires(!__has_pointer_member<_Tp> && __has_element_type_member<_Tp>)
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struct __pointer_of<_Tp> {
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using type _LIBCPP_NODEBUG = typename _Tp::element_type*;
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};
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template <class _Tp>
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requires(!__has_pointer_member<_Tp> && !__has_element_type_member<_Tp> &&
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__has_element_type_member<pointer_traits<_Tp>>)
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struct __pointer_of<_Tp> {
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using type _LIBCPP_NODEBUG = typename pointer_traits<_Tp>::element_type*;
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};
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template <typename _Tp>
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using __pointer_of_t _LIBCPP_NODEBUG = typename __pointer_of<_Tp>::type;
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template <typename _Tp, typename _Up>
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using __pointer_of_or_t _LIBCPP_NODEBUG = __detected_or_t<_Up, __pointer_of_t, _Tp>;
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template <class _Smart>
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concept __resettable_smart_pointer = requires(_Smart __s) { __s.reset(); };
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template <class _Smart, class _Pointer, class... _Args>
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concept __resettable_smart_pointer_with_args = requires(_Smart __s, _Pointer __p, _Args... __args) {
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__s.reset(static_cast<__pointer_of_or_t<_Smart, _Pointer>>(__p), std::forward<_Args>(__args)...);
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};
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#endif
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// This function ensures safe conversions between fancy pointers at compile-time, where we avoid casts from/to
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// `__void_pointer` by obtaining the underlying raw pointer from the fancy pointer using `std::to_address`,
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// then dereferencing it to retrieve the pointed-to object, and finally constructing the target fancy pointer
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// to that object using the `std::pointer_traits<>::pinter_to` function.
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template <class _PtrTo, class _PtrFrom>
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_LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI _PtrTo __static_fancy_pointer_cast(const _PtrFrom& __p) {
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using __ptr_traits = pointer_traits<_PtrTo>;
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using __element_type = typename __ptr_traits::element_type;
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return __p ? __ptr_traits::pointer_to(*static_cast<__element_type*>(std::addressof(*__p)))
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: static_cast<_PtrTo>(nullptr);
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}
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_LIBCPP_END_NAMESPACE_STD
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_LIBCPP_POP_MACROS
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#endif // _LIBCPP___MEMORY_POINTER_TRAITS_H
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