namespace details
{
template <std::size_t TRem>
class TupleAccumulateHelper
{
public:
template <typename TTuple, typename TValue, typename TFunc>
static constexpr TValue exec(TTuple&& tuple, const TValue& value, TFunc&& func)
{
using Tuple = typename std::decay<TTuple>::type;
static_assert(TRem <= std::tuple_size<Tuple>::value, "Incorrect TRem");
return TupleAccumulateHelper<TRem - 1>::exec(
std::forward<TTuple>(tuple),
func(value, std::get<std::tuple_size<Tuple>::value - TRem>(std::forward<TTuple>(tuple))),
std::forward<TFunc>(func));
}
};
template <>
class TupleAccumulateHelper<0>
{
public:
template <typename TTuple, typename TValue, typename TFunc>
static constexpr TValue exec(TTuple&& tuple, const TValue& value, TFunc&& func)
{
return value;
}
};
} // namespace details
template <typename TTuple, typename TValue, typename TFunc>
constexpr TValue tupleAccumulate(TTuple&& tuple, const TValue& value, TFunc&& func)
{
using Tuple = typename std::decay<TTuple>::type;
return details::TupleAccumulateHelper<std::tuple_size<Tuple>::value>::exec(
std::forward<TTuple>(tuple),
value,
std::forward<TFunc>(func));
}