1 //===----------------------------------------------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #ifndef _LIBCPP___TYPE_TRAITS_IS_SWAPPABLE_H 10 #define _LIBCPP___TYPE_TRAITS_IS_SWAPPABLE_H 11 12 #include <__config> 13 #include <__type_traits/add_lvalue_reference.h> 14 #include <__type_traits/enable_if.h> 15 #include <__type_traits/is_assignable.h> 16 #include <__type_traits/is_constructible.h> 17 #include <__type_traits/is_nothrow_assignable.h> 18 #include <__type_traits/is_nothrow_constructible.h> 19 #include <__type_traits/void_t.h> 20 #include <__utility/declval.h> 21 #include <cstddef> 22 23 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 24 # pragma GCC system_header 25 #endif 26 27 _LIBCPP_BEGIN_NAMESPACE_STD 28 29 template <class _Tp, class _Up, class = void> 30 inline const bool __is_swappable_with_v = false; 31 32 template <class _Tp> 33 inline const bool __is_swappable_v = __is_swappable_with_v<_Tp&, _Tp&>; 34 35 template <class _Tp, class _Up, bool = __is_swappable_with_v<_Tp, _Up> > 36 inline const bool __is_nothrow_swappable_with_v = false; 37 38 template <class _Tp> 39 inline const bool __is_nothrow_swappable_v = __is_nothrow_swappable_with_v<_Tp&, _Tp&>; 40 41 #ifndef _LIBCPP_CXX03_LANG 42 template <class _Tp> 43 using __swap_result_t = __enable_if_t<is_move_constructible<_Tp>::value && is_move_assignable<_Tp>::value>; 44 #else 45 template <class> 46 using __swap_result_t = void; 47 #endif 48 49 template <class _Tp> 50 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __swap_result_t<_Tp> swap(_Tp& __x, _Tp& __y) 51 _NOEXCEPT_(is_nothrow_move_constructible<_Tp>::value&& is_nothrow_move_assignable<_Tp>::value); 52 53 template <class _Tp, size_t _Np, __enable_if_t<__is_swappable_v<_Tp>, int> = 0> 54 inline _LIBCPP_HIDE_FROM_ABI 55 _LIBCPP_CONSTEXPR_SINCE_CXX20 void swap(_Tp (&__a)[_Np], _Tp (&__b)[_Np]) _NOEXCEPT_(__is_nothrow_swappable_v<_Tp>); 56 57 // ALL generic swap overloads MUST already have a declaration available at this point. 58 59 template <class _Tp, class _Up> 60 inline const bool __is_swappable_with_v<_Tp, 61 _Up, 62 __void_t<decltype(swap(std::declval<_Tp>(), std::declval<_Up>())), 63 decltype(swap(std::declval<_Up>(), std::declval<_Tp>()))> > = true; 64 65 #ifndef _LIBCPP_CXX03_LANG // C++03 doesn't have noexcept, so things are never nothrow swappable 66 template <class _Tp, class _Up> 67 inline const bool __is_nothrow_swappable_with_v<_Tp, _Up, true> = 68 noexcept(swap(std::declval<_Tp>(), std::declval<_Up>())) && 69 noexcept(swap(std::declval<_Up>(), std::declval<_Tp>())); 70 #endif 71 72 #if _LIBCPP_STD_VER >= 17 73 74 template <class _Tp, class _Up> 75 inline constexpr bool is_swappable_with_v = __is_swappable_with_v<_Tp, _Up>; 76 77 template <class _Tp, class _Up> 78 struct _LIBCPP_TEMPLATE_VIS is_swappable_with : bool_constant<is_swappable_with_v<_Tp, _Up>> {}; 79 80 template <class _Tp> 81 inline constexpr bool is_swappable_v = 82 is_swappable_with_v<__add_lvalue_reference_t<_Tp>, __add_lvalue_reference_t<_Tp>>; 83 84 template <class _Tp> 85 struct _LIBCPP_TEMPLATE_VIS is_swappable : bool_constant<is_swappable_v<_Tp>> {}; 86 87 template <class _Tp, class _Up> 88 inline constexpr bool is_nothrow_swappable_with_v = __is_nothrow_swappable_with_v<_Tp, _Up>; 89 90 template <class _Tp, class _Up> 91 struct _LIBCPP_TEMPLATE_VIS is_nothrow_swappable_with : bool_constant<is_nothrow_swappable_with_v<_Tp, _Up>> {}; 92 93 template <class _Tp> 94 inline constexpr bool is_nothrow_swappable_v = 95 is_nothrow_swappable_with_v<__add_lvalue_reference_t<_Tp>, __add_lvalue_reference_t<_Tp>>; 96 97 template <class _Tp> 98 struct _LIBCPP_TEMPLATE_VIS is_nothrow_swappable : bool_constant<is_nothrow_swappable_v<_Tp>> {}; 99 100 #endif // _LIBCPP_STD_VER >= 17 101 102 _LIBCPP_END_NAMESPACE_STD 103 104 #endif // _LIBCPP___TYPE_TRAITS_IS_SWAPPABLE_H 105