transform_copy_if

eve::algo::transform_copy_if = function_with_traits<detail::transform_copy_if_>

inlineconstexpr

#include <eve/module/algo/algo/transform_copy_if.hpp>

Defined in header

#include <eve/module/algo.hpp>

Note

If the scalar operation is cheap enough, copy_if + views::map might be slightly faster.

For an in-place version, see transform_keep_if.

Conditionally copies values from an input range to an output range, transforming them in the process.

If the output range is too small, fills all the available space and then stops.

If the output range's element type is different from the type of the values returned by the transforming function, performs the appropriate conversions.

Callable Signatures

namespace eve::algo
{
  template <eve::algo::relaxed_range In, eve::algo::relaxed_range Out, typename Func>
  auto transform_copy_if(In&& in, Out&& out, Func func) const -> unaligned_iterator_t<Out>
}

Parameters

• in: Input range
• out: Output range
• func: Function that takes elements from in as SIMD registers and returns a pair of:
  • the transformed values
  • a logical mask.

Return value

Output iterator past the last written element.

Example

#include <eve/module/core.hpp>
#include <eve/module/algo.hpp>
#include <tts/tts.hpp>
#include <iostream>
#include <vector>
 
int main()
{
  std::vector<int> input(16);
  eve::algo::iota(input, 0);
  std::cout << "Input vector:\n  " << tts::as_string(input) << "\n\n";
 
  auto func = [](eve::like<int> auto x) {
    return kumi::make_tuple(-x, eve::is_even(x));
  };
 
  std::vector<int> output_big(42);
  output_big.erase(eve::algo::transform_copy_if(input, output_big, func), output_big.end());
  std::cout << "Output (opposites of even numbers):\n  "
            << tts::as_string(output_big)
            << "\n\n";
 
  std::vector<unsigned char> output_small(5);
  output_small.erase(eve::algo::transform_copy_if(input, output_small, func), output_small.end());
  std::cout << "Output on a range too small to hold all the results,\nwith conversion to unsigned char:\n  "
            << tts::as_string(output_small)
            << std::endl;
 
  return 0;
}

See also

keep_if

copy_if

remove_if

transform_keep_if

transform_to

views::map