contains_none

contains_none_t kumi::contains_none {}

inlineconstexprnodiscardnoexcept

Callable object checking if a product type contains no fields based on any of the selected identifier.

Header file

#include <kumi/algorithm/contains.hpp>

Call Signature

template<product_type T, identifier... IDs>
constexpr auto contains_none(T && t, IDs const&... ids) noexcept;

Parameters

• t: The product type to inspect
• ids: The identifiers to check for

Return value

• std::true_type if t contains no field labeled with any of the ids, std::false_type otherwise.

Helper type

    template<kumi::concepts::product_type T, kumi::concepts::identifier... IDs> struct contains_none
    {
      using type = decltype(kumi::contains_none(std::declval<T>(), std::declval<IDs>()...));
    };
 
    template<kumi::concepts::product_type T, kumi::concepts::identifier... IDs>
    using contains_none_t = typename kumi::result::contains_none<T, IDs...>::type;

Computes the return type of a call to kumi:contains_none

Examples

• Tuple

  
  #include <kumi/kumi.hpp>
  #include <iostream>
   
  using namespace kumi::literals;
   
  template<kumi::concepts::product_type T>
  void check_contains(T const& )
  {
    if constexpr(kumi::contains_none(T{}, "malus"_id, "other"_id))
      std::cout << "Correct product_type\n";
    else
      std::cout << "Incorrect product type\n";
  }
   
  int main()
  {
    check_contains( kumi::tuple{"value"_id = 9  });
    check_contains( kumi::tuple{"active"_id = std::bool_constant<true>{}});
    check_contains( kumi::tuple{"malus"_id = 6.5, "value"_id = 17} );
    check_contains( kumi::tuple{"active"_id = std::bool_constant<true>{}, "value"_id = 17} );
    check_contains( kumi::tuple{"active"_id = std::bool_constant<true>{}, "value"_id = 17, "other"_id = false});
  }

• Record

  
  #include <kumi/kumi.hpp>
  #include <iostream>
   
  using namespace kumi::literals;
   
  template<kumi::concepts::product_type T>
  void check_contains(T const& )
  {
    if constexpr(kumi::contains_none(T{}, "malus"_id, "other"_id))
      std::cout << "Correct product_type\n";
    else
      std::cout << "Incorrect product type\n";
  }
   
  int main()
  {
    check_contains( kumi::record{"value"_id = 9  });
    check_contains( kumi::record{"active"_id = std::bool_constant<true>{}});
    check_contains( kumi::record{"malus"_id = 6.5, "value"_id = 17} );
    check_contains( kumi::record{"active"_id = std::bool_constant<true>{}, "value"_id = 17} );
    check_contains( kumi::record{"active"_id = std::bool_constant<true>{}, "value"_id = 17, "other"_id = false});
  }