1f51a89d39
These were ignored by git accidentally. We want ALL OF THEM since they all came in the llvm/clang source distribution.
119 lines
3.7 KiB
C++
119 lines
3.7 KiB
C++
// RUN: %clang_cc1 -std=c++11 %s -fsyntax-only -fcxx-exceptions
|
|
|
|
template<typename T> struct remove_reference { typedef T type; };
|
|
template<typename T> struct remove_reference<T&> { typedef T type; };
|
|
template<typename T> struct remove_reference<T&&> { typedef T type; };
|
|
|
|
template<typename T> constexpr T &&forward(typename remove_reference<T>::type &t) noexcept { return static_cast<T&&>(t); }
|
|
template<typename T> constexpr T &&forward(typename remove_reference<T>::type &&t) noexcept { return static_cast<T&&>(t); }
|
|
template<typename T> constexpr typename remove_reference<T>::type &&move(T &&t) noexcept { return static_cast<typename remove_reference<T>::type&&>(t); }
|
|
|
|
template<typename T> T declval() noexcept;
|
|
|
|
namespace detail {
|
|
template<unsigned N> struct select {}; // : integral_constant<unsigned, N> {};
|
|
template<typename T> struct type {};
|
|
|
|
template<typename...T> union either_impl;
|
|
|
|
template<> union either_impl<> {
|
|
void get(...);
|
|
void destroy(...) { throw "logic_error"; }
|
|
};
|
|
|
|
template<typename T, typename...Ts> union either_impl<T, Ts...> {
|
|
private:
|
|
T val;
|
|
either_impl<Ts...> rest;
|
|
typedef either_impl<Ts...> rest_t;
|
|
|
|
public:
|
|
constexpr either_impl(select<0>, T &&t) : val(move(t)) {}
|
|
|
|
template<unsigned N, typename U>
|
|
constexpr either_impl(select<N>, U &&u) : rest(select<N-1>(), move(u)) {}
|
|
|
|
constexpr static unsigned index(type<T>) { return 0; }
|
|
template<typename U>
|
|
constexpr static unsigned index(type<U> t) {
|
|
return decltype(rest)::index(t) + 1;
|
|
}
|
|
|
|
void destroy(unsigned elem) {
|
|
if (elem)
|
|
rest.destroy(elem - 1);
|
|
else
|
|
val.~T();
|
|
}
|
|
|
|
constexpr const T &get(select<0>) { return val; }
|
|
template<unsigned N> constexpr const decltype(static_cast<const rest_t&>(rest).get(select<N-1>{})) get(select<N>) {
|
|
return rest.get(select<N-1>{});
|
|
}
|
|
};
|
|
}
|
|
|
|
template<typename T>
|
|
struct a {
|
|
T value;
|
|
template<typename...U>
|
|
constexpr a(U &&...u) : value{forward<U>(u)...} {}
|
|
};
|
|
template<typename T> using an = a<T>;
|
|
|
|
template<typename T, typename U> T throw_(const U &u) { throw u; }
|
|
|
|
template<typename...T>
|
|
class either {
|
|
unsigned elem;
|
|
detail::either_impl<T...> impl;
|
|
typedef decltype(impl) impl_t;
|
|
|
|
public:
|
|
template<typename U>
|
|
constexpr either(a<U> &&t) :
|
|
elem(impl_t::index(detail::type<U>())),
|
|
impl(detail::select<impl_t::index(detail::type<U>())>(), move(t.value)) {}
|
|
|
|
// Destruction disabled to allow use in a constant expression.
|
|
// FIXME: declare a destructor iff any element has a nontrivial destructor
|
|
//~either() { impl.destroy(elem); }
|
|
|
|
constexpr unsigned index() noexcept { return elem; }
|
|
|
|
template<unsigned N> using const_get_result =
|
|
decltype(static_cast<const impl_t&>(impl).get(detail::select<N>{}));
|
|
|
|
template<unsigned N>
|
|
constexpr const_get_result<N> get() {
|
|
// Can't just use throw here, since that makes the conditional a prvalue,
|
|
// which means we return a reference to a temporary.
|
|
return (elem != N ? throw_<const_get_result<N>>("bad_either_get")
|
|
: impl.get(detail::select<N>{}));
|
|
}
|
|
|
|
template<typename U>
|
|
constexpr const U &get() {
|
|
return get<impl_t::index(detail::type<U>())>();
|
|
}
|
|
};
|
|
|
|
typedef either<int, char, double> icd;
|
|
constexpr icd icd1 = an<int>(4);
|
|
constexpr icd icd2 = a<char>('x');
|
|
constexpr icd icd3 = a<double>(6.5);
|
|
|
|
static_assert(icd1.get<int>() == 4, "");
|
|
static_assert(icd2.get<char>() == 'x', "");
|
|
static_assert(icd3.get<double>() == 6.5, "");
|
|
|
|
struct non_triv {
|
|
constexpr non_triv() : n(5) {}
|
|
int n;
|
|
};
|
|
constexpr either<const icd*, non_triv> icd4 = a<const icd*>(&icd2);
|
|
constexpr either<const icd*, non_triv> icd5 = a<non_triv>();
|
|
|
|
static_assert(icd4.get<const icd*>()->get<char>() == 'x', "");
|
|
static_assert(icd5.get<non_triv>().n == 5, "");
|