Add some type traits that are used for Clang's statically-checked

canonical types.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@78076 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Douglas Gregor 2009-08-04 17:04:52 +00:00
parent 7d35249e89
commit c7a6da6e14

View File

@ -49,6 +49,33 @@ struct is_class
enum { value = sizeof(char) == sizeof(dont_use::is_class_helper<T>(0)) }; enum { value = sizeof(char) == sizeof(dont_use::is_class_helper<T>(0)) };
}; };
// 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));
};
} }
#endif #endif