filter

template<template< typename > typename Pred>

filter_t<Pred> kumi::filter {}

inlineconstexprnodiscardnoexcept

Callable object filtering a product type over a predicate.

On a record type, Pred is applied directly to the underlying elements of the fields.

Header file

#include <kumi/algorithm/partition.hpp>

Call Signature

template<product_type T>
constexpr auto filter<Pred>(T && t) noexcept;

Template Parameters

• Pred: Compile-time predicate

Parameters

• t: Product Type to process

Return value

• A Product type containing all values of t which types satisfies Pred.

Helper type

    template<template<typename> typename Pred, kumi::concepts::product_type T> struct filter
    {
      using type = decltype(kumi::filter<Pred>(std::declval<T>()));
    };
 
    template<template<typename> typename Pred, kumi::concepts::product_type T>
    using filter_t = typename kumi::result::filter<Pred, T>::type;
 

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

Examples

Tuple

#include <kumi/kumi.hpp>
#include <type_traits>
#include <iostream>
 
int main()
{
  int     a = 4;
  double  b = 3.1415;
  float   c = 0.01f;
 
  auto original = kumi::tuple{a,&a,b,&b,c,&c,'z',nullptr};
  std::cout << original << "\n";
 
  std::cout << "Pointers : " << kumi::filter<std::is_pointer>(original) << "\n";
  std::cout << "Real     : " << kumi::filter<std::is_floating_point>(original) << "\n";
  std::cout << "nullptr  : " << kumi::filter<std::is_null_pointer>(original) << "\n";
}

Record

#include <kumi/kumi.hpp>
#include <type_traits>
#include <iostream>
 
int main()
{
  using namespace kumi::literals;
 
  int     a = 4;
  double  b = 3.1415;
  float   c = 0.01f;
 
  auto original = kumi::record{"a"_id=a,"b"_id=&a,"c"_id=b,"d"_id=&b,"e"_id=c,"f"_id=&c,"g"_id='z',"h"_id=nullptr};
  std::cout << original << "\n";
 
  std::cout << "Pointers : " << kumi::filter<std::is_pointer>(original) << "\n";
  std::cout << "Real     : " << kumi::filter<std::is_floating_point>(original) << "\n";
  std::cout << "nullptr  : " << kumi::filter<std::is_null_pointer>(original) << "\n";
}