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