Viewing file:  pr70971.C (1.13 KB) -rw-r--r--
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// { dg-additional-options "-std=c++14 -Wno-return-type" }
template<typename Signature>
class function;
template<typename R, typename... Args>
class invoker_base
{
public:
virtual ~invoker_base() { }
};
template<typename F, typename R, typename... Args>
class functor_invoker : public invoker_base<R, Args...>
{
public:
explicit functor_invoker(const F& f) : f(f) { }
private:
F f;
};
template<typename R, typename... Args>
class function<R (Args...)> {
public:
template<typename F>
function(const F& f) : invoker(0) {
invoker = new functor_invoker<F, R, Args...>(f);
}
~function() {
if (invoker)
delete invoker;
}
private:
invoker_base<R, Args...>* invoker;
};
template<typename>
struct unique_ptr { };
struct A {};
template <class...> struct typelist {};
template <class... Cs> unique_ptr<A> chooseB(typelist<Cs...>);
template <class... Cs, class Idx, class... Rest>
unique_ptr<A> chooseB(typelist<Cs...> choices, Idx, Rest... rest) {
auto f = [=](auto) { return [=] { return chooseB(choices, rest...); }; };
function<unique_ptr<A>()> fs[]{f(Cs{})...};
}
main() { chooseB(typelist<double, char>{}, 0, 1, 2); }
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