//
//===----------------------------------------------------------------------===//
//
-// This file provides a template class that determines if a type is a class or
-// not. The basic mechanism, based on using the pointer to member function of
-// a zero argument to a function was "boosted" from the boost type_traits
-// library. See http://www.boost.org/ for all the gory details.
+// This file provides useful additions to the standard type_traits library.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_SUPPORT_TYPE_TRAITS_H
#define LLVM_SUPPORT_TYPE_TRAITS_H
-// This is actually the conforming implementation which works with abstract
-// classes. However, enough compilers have trouble with it that most will use
-// the one in boost/type_traits/object_traits.hpp. This implementation actually
-// works with VC7.0, but other interactions seem to fail when we use it.
+#include <type_traits>
+#include <utility>
-namespace llvm {
+#ifndef __has_feature
+#define LLVM_DEFINED_HAS_FEATURE
+#define __has_feature(x) 0
+#endif
-namespace dont_use
-{
- // These two functions should never be used. They are helpers to
- // the is_class template below. They cannot be located inside
- // is_class because doing so causes at least GCC to think that
- // the value of the "value" enumerator is not constant. Placing
- // them out here (for some strange reason) allows the sizeof
- // operator against them to magically be constant. This is
- // important to make the is_class<T>::value idiom zero cost. it
- // evaluates to a constant 1 or 0 depending on whether the
- // parameter T is a class or not (respectively).
- template<typename T> char is_class_helper(void(T::*)(void));
- template<typename T> double is_class_helper(...);
-}
+namespace llvm {
+/// isPodLike - This is a type trait that is used to determine whether a given
+/// type can be copied around with memcpy instead of running ctors etc.
template <typename T>
-struct is_class
-{
- // is_class<> metafunction due to Paul Mensonides (leavings@attbi.com). For
- // more details:
- // http://groups.google.com/groups?hl=en&selm=000001c1cc83%24e154d5e0%247772e50c%40c161550a&rnum=1
- public:
- enum { value = sizeof(char) == sizeof(dont_use::is_class_helper<T>(0)) };
+struct isPodLike {
+#if __has_feature(is_trivially_copyable)
+ // If the compiler supports the is_trivially_copyable trait use it, as it
+ // matches the definition of isPodLike closely.
+ static const bool value = __is_trivially_copyable(T);
+#else
+ // If we don't know anything else, we can (at least) assume that all non-class
+ // types are PODs.
+ static const bool value = !std::is_class<T>::value;
+#endif
};
-
-// enable_if_c - Enable/disable a template based on a metafunction
-template<bool Cond, typename T = void>
-struct enable_if_c {
- typedef T type;
+// std::pair's are pod-like if their elements are.
+template<typename T, typename U>
+struct isPodLike<std::pair<T, U> > {
+ static const bool value = isPodLike<T>::value && isPodLike<U>::value;
};
-template<typename T> struct enable_if_c<false, T> { };
-
-// enable_if - Enable/disable a template based on a metafunction
-template<typename Cond, typename T = void>
-struct enable_if : public enable_if_c<Cond::value, T> { };
+/// \brief Metafunction that determines whether the given type is either an
+/// integral type or an enumeration type.
+///
+/// Note that this accepts potentially more integral types than is_integral
+/// because it is based on merely being convertible implicitly to an integral
+/// type.
+template <typename T> class is_integral_or_enum {
+ typedef typename std::remove_reference<T>::type UnderlyingT;
-namespace dont_use {
- template<typename Base> char base_of_helper(const volatile Base*);
- template<typename Base> double base_of_helper(...);
-}
+public:
+ static const bool value =
+ !std::is_class<UnderlyingT>::value && // Filter conversion operators.
+ !std::is_pointer<UnderlyingT>::value &&
+ !std::is_floating_point<UnderlyingT>::value &&
+ std::is_convertible<UnderlyingT, unsigned long long>::value;
+};
+
+/// \brief If T is a pointer, just return it. If it is not, return T&.
+template<typename T, typename Enable = void>
+struct add_lvalue_reference_if_not_pointer { typedef T &type; };
-/// is_base_of - Metafunction to determine whether one type is a base class of
-/// (or identical to) another type.
-template<typename Base, typename Derived>
-struct is_base_of {
- static const bool value
- = is_class<Base>::value && is_class<Derived>::value &&
- sizeof(char) == sizeof(dont_use::base_of_helper<Base>((Derived*)0));
+template <typename T>
+struct add_lvalue_reference_if_not_pointer<
+ T, typename std::enable_if<std::is_pointer<T>::value>::type> {
+ typedef T type;
+};
+
+/// \brief If T is a pointer to X, return a pointer to const X. If it is not,
+/// return const T.
+template<typename T, typename Enable = void>
+struct add_const_past_pointer { typedef const T type; };
+
+template <typename T>
+struct add_const_past_pointer<
+ T, typename std::enable_if<std::is_pointer<T>::value>::type> {
+ typedef const typename std::remove_pointer<T>::type *type;
};
}
+#ifdef LLVM_DEFINED_HAS_FEATURE
+#undef __has_feature
+#endif
+
#endif
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