1 //===- llvm/Support/type_traits.h - Simplfied type traits -------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file provides useful additions to the standard type_traits library.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_SUPPORT_TYPE_TRAITS_H
15 #define LLVM_SUPPORT_TYPE_TRAITS_H
17 #include <type_traits>
21 #define LLVM_DEFINED_HAS_FEATURE
22 #define __has_feature(x) 0
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.
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);
36 // If we don't know anything else, we can (at least) assume that all non-class
38 static const bool value = !std::is_class<T>::value;
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;
48 /// \brief Metafunction that determines whether the given type is either an
49 /// integral type or an enumeration type.
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
54 template <typename T> class is_integral_or_enum {
55 typedef typename std::remove_reference<T>::type UnderlyingT;
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;
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; };
70 struct add_lvalue_reference_if_not_pointer<
71 T, typename std::enable_if<std::is_pointer<T>::value>::type> {
75 /// \brief If T is a pointer to X, return a pointer to const X. If it is not,
77 template<typename T, typename Enable = void>
78 struct add_const_past_pointer { typedef const T type; };
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;
88 #ifdef LLVM_DEFINED_HAS_FEATURE