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_DECAY_H 10 #define _LIBCPP___TYPE_TRAITS_DECAY_H 11 12 #include <__config> 13 #include <__type_traits/add_pointer.h> 14 #include <__type_traits/conditional.h> 15 #include <__type_traits/is_array.h> 16 #include <__type_traits/is_function.h> 17 #include <__type_traits/is_referenceable.h> 18 #include <__type_traits/remove_cv.h> 19 #include <__type_traits/remove_extent.h> 20 #include <__type_traits/remove_reference.h> 21 22 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 23 # pragma GCC system_header 24 #endif 25 26 _LIBCPP_BEGIN_NAMESPACE_STD 27 28 #if __has_builtin(__decay) 29 template <class _Tp> 30 using __decay_t _LIBCPP_NODEBUG = __decay(_Tp); 31 32 template <class _Tp> 33 struct decay { 34 using type _LIBCPP_NODEBUG = __decay_t<_Tp>; 35 }; 36 37 #else 38 template <class _Up, bool> 39 struct __decay { 40 typedef _LIBCPP_NODEBUG __remove_cv_t<_Up> type; 41 }; 42 43 template <class _Up> 44 struct __decay<_Up, true> { 45 public: 46 typedef _LIBCPP_NODEBUG typename conditional 47 < 48 is_array<_Up>::value, 49 __add_pointer_t<__remove_extent_t<_Up> >, 50 typename conditional 51 < 52 is_function<_Up>::value, 53 typename add_pointer<_Up>::type, 54 __remove_cv_t<_Up> 55 >::type 56 >::type type; 57 }; 58 59 template <class _Tp> 60 struct _LIBCPP_TEMPLATE_VIS decay 61 { 62 private: 63 typedef _LIBCPP_NODEBUG __libcpp_remove_reference_t<_Tp> _Up; 64 public: 65 typedef _LIBCPP_NODEBUG typename __decay<_Up, __libcpp_is_referenceable<_Up>::value>::type type; 66 }; 67 68 template <class _Tp> 69 using __decay_t = typename decay<_Tp>::type; 70 #endif // __has_builtin(__decay) 71 72 #if _LIBCPP_STD_VER >= 14 73 template <class _Tp> using decay_t = __decay_t<_Tp>; 74 #endif 75 76 _LIBCPP_END_NAMESPACE_STD 77 78 #endif // _LIBCPP___TYPE_TRAITS_DECAY_H 79