1 //===- llvm/Support/type_traits.h - Simplfied type traits -------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file provides useful additions to the standard type_traits library. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_SUPPORT_TYPE_TRAITS_H 15 #define LLVM_SUPPORT_TYPE_TRAITS_H 16 17 #include "llvm/Support/Compiler.h" 18 #include <type_traits> 19 #include <utility> 20 21 #ifndef __has_feature 22 #define LLVM_DEFINED_HAS_FEATURE 23 #define __has_feature(x) 0 24 #endif 25 26 namespace llvm { 27 28 /// isPodLike - This is a type trait that is used to determine whether a given 29 /// type can be copied around with memcpy instead of running ctors etc. 30 template <typename T> 31 struct isPodLike { 32 // std::is_trivially_copyable is available in libc++ with clang, libstdc++ 33 // that comes with GCC 5. 34 #if (__has_feature(is_trivially_copyable) && defined(_LIBCPP_VERSION)) || \ 35 (defined(__GNUC__) && __GNUC__ >= 5) 36 // If the compiler supports the is_trivially_copyable trait use it, as it 37 // matches the definition of isPodLike closely. 38 static const bool value = std::is_trivially_copyable<T>::value; 39 #elif __has_feature(is_trivially_copyable) 40 // Use the internal name if the compiler supports is_trivially_copyable but we 41 // don't know if the standard library does. This is the case for clang in 42 // conjunction with libstdc++ from GCC 4.x. 43 static const bool value = __is_trivially_copyable(T); 44 #else 45 // If we don't know anything else, we can (at least) assume that all non-class 46 // types are PODs. 47 static const bool value = !std::is_class<T>::value; 48 #endif 49 }; 50 51 // std::pair's are pod-like if their elements are. 52 template<typename T, typename U> 53 struct isPodLike<std::pair<T, U>> { 54 static const bool value = isPodLike<T>::value && isPodLike<U>::value; 55 }; 56 57 /// \brief Metafunction that determines whether the given type is either an 58 /// integral type or an enumeration type, including enum classes. 59 /// 60 /// Note that this accepts potentially more integral types than is_integral 61 /// because it is based on being implicitly convertible to an integral type. 62 /// Also note that enum classes aren't implicitly convertible to integral types, 63 /// the value may therefore need to be explicitly converted before being used. 64 template <typename T> class is_integral_or_enum { 65 using UnderlyingT = typename std::remove_reference<T>::type; 66 67 public: 68 static const bool value = 69 !std::is_class<UnderlyingT>::value && // Filter conversion operators. 70 !std::is_pointer<UnderlyingT>::value && 71 !std::is_floating_point<UnderlyingT>::value && 72 (std::is_enum<UnderlyingT>::value || 73 std::is_convertible<UnderlyingT, unsigned long long>::value); 74 }; 75 76 /// \brief If T is a pointer, just return it. If it is not, return T&. 77 template<typename T, typename Enable = void> 78 struct add_lvalue_reference_if_not_pointer { using type = T &; }; 79 80 template <typename T> 81 struct add_lvalue_reference_if_not_pointer< 82 T, typename std::enable_if<std::is_pointer<T>::value>::type> { 83 using type = T; 84 }; 85 86 /// \brief If T is a pointer to X, return a pointer to const X. If it is not, 87 /// return const T. 88 template<typename T, typename Enable = void> 89 struct add_const_past_pointer { using type = const T; }; 90 91 template <typename T> 92 struct add_const_past_pointer< 93 T, typename std::enable_if<std::is_pointer<T>::value>::type> { 94 using type = const typename std::remove_pointer<T>::type *; 95 }; 96 97 template <typename T, typename Enable = void> 98 struct const_pointer_or_const_ref { 99 using type = const T &; 100 }; 101 template <typename T> 102 struct const_pointer_or_const_ref< 103 T, typename std::enable_if<std::is_pointer<T>::value>::type> { 104 using type = typename add_const_past_pointer<T>::type; 105 }; 106 107 } // end namespace llvm 108 109 // If the compiler supports detecting whether a class is final, define 110 // an LLVM_IS_FINAL macro. If it cannot be defined properly, this 111 // macro will be left undefined. 112 #if __cplusplus >= 201402L 113 #define LLVM_IS_FINAL(Ty) std::is_final<Ty>() 114 #elif __has_feature(is_final) || LLVM_GNUC_PREREQ(4, 7, 0) 115 #define LLVM_IS_FINAL(Ty) __is_final(Ty) 116 #endif 117 118 #ifdef LLVM_DEFINED_HAS_FEATURE 119 #undef __has_feature 120 #endif 121 122 #endif // LLVM_SUPPORT_TYPE_TRAITS_H 123
