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#pragma once
#include <algorithm> // IWYU pragma: keep
#include <array>
#include <cstddef>
#include <tuple>
template<typename T, std::size_t N>
constexpr auto
transform_array(const std::array<T, N> & in, auto && transform)
{
std::array<decltype(transform(in.front())), N> out {};
std::transform(in.begin(), in.end(), out.begin(), transform);
return out;
}
namespace {
template<size_t... N> struct GetNth {
decltype(auto)
operator()(const auto & tup) const
{
if constexpr (sizeof...(N) == 1) {
return std::get<N...>(tup);
}
else {
return std::tie(std::get<N>(tup)...);
}
}
};
}
template<size_t... N> constexpr auto Nth = GetNth<N...> {};
constexpr auto GetFirst = Nth<0>;
constexpr auto GetSecond = Nth<1>;
constexpr auto GetSwapped = Nth<0, 1>;
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