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 #if __has_feature(is_trivially_copyable) 32 // If the compiler supports the is_trivially_copyable trait use it, as it 33 // matches the definition of isPodLike closely. 34 static const bool value = __is_trivially_copyable(T); 35 #else 36 // If we don't know anything else, we can (at least) assume that all non-class 37 // types are PODs. 38 static const bool value = !std::is_class<T>::value; 39 #endif 40 }; 41 42 // std::pair's are pod-like if their elements are. 43 template<typename T, typename U> 44 struct isPodLike<std::pair<T, U> > { 45 static const bool value = isPodLike<T>::value && isPodLike<U>::value; 46 }; 47 48 /// \brief Metafunction that determines whether the given type is either an 49 /// integral type or an enumeration type. 50 /// 51 /// Note that this accepts potentially more integral types than is_integral 52 /// because it is based on merely being convertible implicitly to an integral 53 /// type. 54 template <typename T> class is_integral_or_enum { 55 typedef typename std::remove_reference<T>::type UnderlyingT; 56 57 public: 58 static const bool value = 59 !std::is_class<UnderlyingT>::value && // Filter conversion operators. 60 !std::is_pointer<UnderlyingT>::value && 61 !std::is_floating_point<UnderlyingT>::value && 62 std::is_convertible<UnderlyingT, unsigned long long>::value; 63 }; 64 65 /// \brief If T is a pointer, just return it. If it is not, return T&. 66 template<typename T, typename Enable = void> 67 struct add_lvalue_reference_if_not_pointer { typedef T &type; }; 68 69 template <typename T> 70 struct add_lvalue_reference_if_not_pointer< 71 T, typename std::enable_if<std::is_pointer<T>::value>::type> { 72 typedef T type; 73 }; 74 75 /// \brief If T is a pointer to X, return a pointer to const X. If it is not, 76 /// return const T. 77 template<typename T, typename Enable = void> 78 struct add_const_past_pointer { typedef const T type; }; 79 80 template <typename T> 81 struct add_const_past_pointer< 82 T, typename std::enable_if<std::is_pointer<T>::value>::type> { 83 typedef const typename std::remove_pointer<T>::type *type; 84 }; 85 86 } 87 88 #ifdef LLVM_DEFINED_HAS_FEATURE 89 #undef __has_feature 90 #endif 91 92 #endif 93
