So I am trying to validate if all elements of a std::tuple
meet a certain condition. My current solution uses C++17 fold epxressions:
template <typename F, typename Tuple, size_t...Is>
_CR_INLINE bool tuple_all_of(F&& fn, Tuple&& t, std::index_sequence<Is...>) {
return (std::forward<F>(fn)(std::get<Is>(std::forward<Tuple>(t))) && ...);
}
template <typename F, typename Tuple>
_CR_INLINE bool tuple_all_of(F&& fn, Tuple&& t) {
return tuple_all_of(std::forward<F>(fn), std::forward<Tuple>(t),
std::make_index_sequence<std::tuple_size_v<std::remove_reference_t<Tuple>>>());
}
It compiles in latest clang and gcc, but fails in MSVC, because fold expressions are not (yet) implemented. (http://ift.tt/2q3O3xq)
So is there a similar solution without using fold expressions?
This is how it's supposed to be used:
template<typename...Components, typename Callable>
void FindComponents(Callable&& fn) {
for (auto& node : m_Entities) {
auto tp = std::make_tuple(node.GetComponent<Components>()...);
if (!tuple_all_of([](auto& p) { return p != nullptr; }, tp))
continue;
apply_from_tuple(fn, tp);
}
}
So I am calling fn
only if a node has the requested components attached (i.e. GetComponent
!= nullptr). Maybe there is a better solution?
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