map_field()

template<concepts::record_type T, typename Function, concepts::sized_product_type< size_v< T > >... Ts>
requires (concepts::compatible_product_types<T, Ts...>)

auto kumi::map_field ( Function f, T && t0, Ts &&... others )

inlinenodiscardconstexpr

Applies the Callable object f on each records' fields and their associated names.

Applies the given function to all the records passed as arguments along with their names and stores the result in another records, keeping the original elements order.

Note

Does not participate in overload resolution if records' size are not equal or if f can't be called on each record's fields and their names.

Parameters

f	Callable function to apply
t0	Record to operate on
others	Records to operate on

Returns

The record of f calls results.

Helper type

namespace kumi::result
{
  template<typename Function, product_type T, product_type... Ts> struct map_field;
 
  template<typename Function, product_type T, product_type... Ts>
  using map_field_t = typename map_field<Function,T>::type;
}

Computes the return type of a call to kumi::map_field

See also

kumi::map

kumi::map_index

Example:

#include <kumi/kumi.hpp>
#include <iostream>
 
using namespace kumi::literals;
 
int main()
{
  auto lhs = kumi::record{"a"_id = 1  , "b"_id = 2  , "c"_id = 3  };
  auto rhs = kumi::record{"a"_id = 2.4, "b"_id = 4.6, "c"_id = 6.8};
 
  auto res = kumi::map_field( [](auto name, auto l, auto r) 
  { 
    if (name == "a")    return l + r;
    else                return 1000*+(l*r); 
  }
  , lhs, rhs
  );
 
  std::cout << res << "\n";
}