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 47 __conditional_t<is_array<_Up>::value, 48 __add_pointer_t<__remove_extent_t<_Up> >, 49 __conditional_t<is_function<_Up>::value, typename add_pointer<_Up>::type, __remove_cv_t<_Up> > > 50 type; 51 }; 52 53 template <class _Tp> 54 struct _LIBCPP_TEMPLATE_VIS decay { 55 private: 56 typedef _LIBCPP_NODEBUG __libcpp_remove_reference_t<_Tp> _Up; 57 58 public: 59 typedef _LIBCPP_NODEBUG typename __decay<_Up, __libcpp_is_referenceable<_Up>::value>::type type; 60 }; 61 62 template <class _Tp> 63 using __decay_t = typename decay<_Tp>::type; 64 #endif // __has_builtin(__decay) 65 66 #if _LIBCPP_STD_VER >= 14 67 template <class _Tp> 68 using decay_t = __decay_t<_Tp>; 69 #endif 70 71 _LIBCPP_END_NAMESPACE_STD 72 73 #endif // _LIBCPP___TYPE_TRAITS_DECAY_H 74