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