static bool is_empty_function(F const& f) noexcept
{
using is_pointer = std::integral_constant<bool,
std::is_pointer<F>::value
|| std::is_member_pointer<F>::value
>;
return is_empty_function(is_pointer{}, f);
}
static bool is_empty_function(F const& f) noexcept
{
std::integral_constant<bool,
std::is_pointer<F>::value
|| std::is_member_pointer<F>::value
> is_pointer;
return is_empty_function(f, is_pointer);
}
void assign(F&& f)
{
if (!is_empty_function(f))
{
typedef typename util::decay<F>::type target_type;
VTablePtr const* f_vptr = get_table_ptr<target_type>();
if (vptr == f_vptr)
{
vtable::reconstruct<target_type>(&object, std::forward<F>(f));
} else {
reset();
vtable::destruct<empty_function<Sig> >(&this->object);
vptr = f_vptr;
vtable::construct<target_type>(&object, std::forward<F>(f));
}
} else {
reset();
}
}
void assign(F&& f)
{
if (!is_empty_function(f))
{
typedef typename std::decay<F>::type target_type;
VTable const* f_vptr = get_vtable<target_type>();
if (vptr == f_vptr)
{
vtable::reconstruct<target_type>(object, std::forward<F>(f));
} else {
reset();
vtable::_delete<empty_function<R(Ts...)> >(object);
vptr = f_vptr;
vtable::construct<target_type>(object, std::forward<F>(f));
}
} else {
reset();
}
}