102 строки
3.4 KiB
C++
102 строки
3.4 KiB
C++
//===- llvm/Support/type_traits.h - Simplfied type traits -------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file provides useful additions to the standard type_traits library.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SUPPORT_TYPE_TRAITS_H
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#define LLVM_SUPPORT_TYPE_TRAITS_H
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#include <type_traits>
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#include <utility>
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#ifndef __has_feature
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#define LLVM_DEFINED_HAS_FEATURE
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#define __has_feature(x) 0
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#endif
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namespace llvm {
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/// isPodLike - This is a type trait that is used to determine whether a given
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/// type can be copied around with memcpy instead of running ctors etc.
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template <typename T>
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struct isPodLike {
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// std::is_trivially_copyable is available in libc++ with clang, libstdc++
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// that comes with GCC 5.
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#if (__has_feature(is_trivially_copyable) && defined(_LIBCPP_VERSION)) || \
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(defined(__GNUC__) && __GNUC__ >= 5) || \
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(_MSC_VER >= 1900) // HLSL Change
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// If the compiler supports the is_trivially_copyable trait use it, as it
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// matches the definition of isPodLike closely.
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static const bool value = std::is_trivially_copyable<T>::value;
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#elif __has_feature(is_trivially_copyable)
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// Use the internal name if the compiler supports is_trivially_copyable but we
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// don't know if the standard library does. This is the case for clang in
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// conjunction with libstdc++ from GCC 4.x.
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static const bool value = __is_trivially_copyable(T);
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#else
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// If we don't know anything else, we can (at least) assume that all non-class
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// types are PODs.
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static const bool value = !std::is_class<T>::value;
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#endif
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};
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// std::pair's are pod-like if their elements are.
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template<typename T, typename U>
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struct isPodLike<std::pair<T, U> > {
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static const bool value = isPodLike<T>::value && isPodLike<U>::value;
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};
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/// \brief Metafunction that determines whether the given type is either an
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/// integral type or an enumeration type.
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///
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/// Note that this accepts potentially more integral types than is_integral
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/// because it is based on merely being convertible implicitly to an integral
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/// type.
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template <typename T> class is_integral_or_enum {
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typedef typename std::remove_reference<T>::type UnderlyingT;
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public:
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static const bool value =
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!std::is_class<UnderlyingT>::value && // Filter conversion operators.
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!std::is_pointer<UnderlyingT>::value &&
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!std::is_floating_point<UnderlyingT>::value &&
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std::is_convertible<UnderlyingT, unsigned long long>::value;
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};
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/// \brief If T is a pointer, just return it. If it is not, return T&.
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template<typename T, typename Enable = void>
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struct add_lvalue_reference_if_not_pointer { typedef T &type; };
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template <typename T>
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struct add_lvalue_reference_if_not_pointer<
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T, typename std::enable_if<std::is_pointer<T>::value>::type> {
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typedef T type;
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};
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/// \brief If T is a pointer to X, return a pointer to const X. If it is not,
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/// return const T.
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template<typename T, typename Enable = void>
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struct add_const_past_pointer { typedef const T type; };
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template <typename T>
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struct add_const_past_pointer<
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T, typename std::enable_if<std::is_pointer<T>::value>::type> {
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typedef const typename std::remove_pointer<T>::type *type;
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};
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}
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#ifdef LLVM_DEFINED_HAS_FEATURE
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#undef __has_feature
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#endif
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#endif
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