locate()

template<typename Pred , typename... Ts>

constexpr auto kumi::locate ( tuple< Ts... > const &  t, Pred  p  )

constexprnoexcept

Return the index of a value which type satisfies a given predicate.

Parameters

t	Tuple to process
p	Unary predicate. p must return a value convertible to bool for every element of t.

Returns

Integral index of the element inside the tuple if present, kumi::size<tuple<T...>>::value otherwise.

Example:

 
#include <kumi/tuple.hpp>
#include <iostream>
#include <type_traits>
 
int main()
{
  auto t = kumi::tuple{1, 2., 0ULL, 3.f, 'z'};
 
  std::cout << std::boolalpha
            << kumi::locate( t, kumi::predicate<std::is_floating_point>() ) << "\n";
 
  std::cout << std::boolalpha << kumi::locate( t, [](auto e) { return e > 3; } ) << "\n";
}