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- //===- llvm/Support/type_traits.h - Simplfied type traits -------*- C++ -*-===//
- //
- // The LLVM Compiler Infrastructure
- //
- // This file is distributed under the University of Illinois Open Source
- // License. See LICENSE.TXT for details.
- //
- //===----------------------------------------------------------------------===//
- //
- // 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.
- //
- //===----------------------------------------------------------------------===//
- // Taken from llvmCore-3425.0.31.
- #ifndef LLVM_SUPPORT_TYPE_TRAITS_H
- #define LLVM_SUPPORT_TYPE_TRAITS_H
- #include <cstddef>
- #include <utility>
- #ifndef __has_feature
- #define LLVM_DEFINED_HAS_FEATURE
- #define __has_feature(x) 0
- #endif
- // 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.
- namespace objc {
-
- 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::*)());
- template<typename T> double is_class_helper(...);
- }
- 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:
- static const bool value =
- sizeof(char) == sizeof(dont_use::is_class_helper<T>(0));
- };
-
-
- /// 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 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 = !is_class<T>::value;
- #endif
- };
- // 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 <class T, T v>
- struct integral_constant {
- typedef T value_type;
- static const value_type value = v;
- typedef integral_constant<T,v> type;
- operator value_type() { return value; }
- };
- typedef integral_constant<bool, true> true_type;
- typedef integral_constant<bool, false> false_type;
- /// \brief Metafunction that determines whether the two given types are
- /// equivalent.
- template<typename T, typename U> struct is_same : public false_type {};
- template<typename T> struct is_same<T, T> : public true_type {};
- /// \brief Metafunction that removes const qualification from a type.
- template <typename T> struct remove_const { typedef T type; };
- template <typename T> struct remove_const<const T> { typedef T type; };
- /// \brief Metafunction that removes volatile qualification from a type.
- template <typename T> struct remove_volatile { typedef T type; };
- template <typename T> struct remove_volatile<volatile T> { typedef T type; };
- /// \brief Metafunction that removes both const and volatile qualification from
- /// a type.
- template <typename T> struct remove_cv {
- typedef typename remove_const<typename remove_volatile<T>::type>::type type;
- };
- /// \brief Helper to implement is_integral metafunction.
- template <typename T> struct is_integral_impl : false_type {};
- template <> struct is_integral_impl< bool> : true_type {};
- template <> struct is_integral_impl< char> : true_type {};
- template <> struct is_integral_impl< signed char> : true_type {};
- template <> struct is_integral_impl<unsigned char> : true_type {};
- template <> struct is_integral_impl< wchar_t> : true_type {};
- template <> struct is_integral_impl< short> : true_type {};
- template <> struct is_integral_impl<unsigned short> : true_type {};
- template <> struct is_integral_impl< int> : true_type {};
- template <> struct is_integral_impl<unsigned int> : true_type {};
- template <> struct is_integral_impl< long> : true_type {};
- template <> struct is_integral_impl<unsigned long> : true_type {};
- template <> struct is_integral_impl< long long> : true_type {};
- template <> struct is_integral_impl<unsigned long long> : true_type {};
- /// \brief Metafunction that determines whether the given type is an integral
- /// type.
- template <typename T>
- struct is_integral : is_integral_impl<T> {};
- /// \brief Metafunction to remove reference from a type.
- template <typename T> struct remove_reference { typedef T type; };
- template <typename T> struct remove_reference<T&> { typedef T type; };
- /// \brief Metafunction that determines whether the given type is a pointer
- /// type.
- template <typename T> struct is_pointer : false_type {};
- template <typename T> struct is_pointer<T*> : true_type {};
- template <typename T> struct is_pointer<T* const> : true_type {};
- template <typename T> struct is_pointer<T* volatile> : true_type {};
- template <typename T> struct is_pointer<T* const volatile> : true_type {};
- /// \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 we whitelist
- /// above for is_integral because it is based on merely being convertible
- /// implicitly to an integral type.
- template <typename T> class is_integral_or_enum {
- // Provide an overload which can be called with anything implicitly
- // convertible to an unsigned long long. This should catch integer types and
- // enumeration types at least. We blacklist classes with conversion operators
- // below.
- static double check_int_convertible(unsigned long long);
- static char check_int_convertible(...);
- typedef typename remove_reference<T>::type UnderlyingT;
- static UnderlyingT &nonce_instance;
- public:
- static const bool
- value = (!is_class<UnderlyingT>::value && !is_pointer<UnderlyingT>::value &&
- !is_same<UnderlyingT, float>::value &&
- !is_same<UnderlyingT, double>::value &&
- sizeof(char) != sizeof(check_int_convertible(nonce_instance)));
- };
- // enable_if_c - Enable/disable a template based on a metafunction
- template<bool Cond, typename T = void>
- struct enable_if_c {
- typedef T type;
- };
- 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> { };
- namespace dont_use {
- template<typename Base> char base_of_helper(const volatile Base*);
- template<typename Base> double base_of_helper(...);
- }
- /// 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));
- };
- // remove_pointer - Metafunction to turn Foo* into Foo. Defined in
- // C++0x [meta.trans.ptr].
- template <typename T> struct remove_pointer { typedef T type; };
- template <typename T> struct remove_pointer<T*> { typedef T type; };
- template <typename T> struct remove_pointer<T*const> { typedef T type; };
- template <typename T> struct remove_pointer<T*volatile> { typedef T type; };
- template <typename T> struct remove_pointer<T*const volatile> {
- typedef T type; };
- template <bool, typename T, typename F>
- struct conditional { typedef T type; };
- template <typename T, typename F>
- struct conditional<false, T, F> { typedef F type; };
- }
- #ifdef LLVM_DEFINED_HAS_FEATURE
- #undef __has_feature
- #endif
- #endif
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