keep_if

eve::algo::keep_if = function_with_traits<keep_if_>[no_traits]

inlineconstexpr

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

Defined in Header

#include <eve/module/algo.hpp>

Takes values that pass the predicate, and copies them to the beginning of the range. Values past the returned sentinel are to be considered garbage.

Acts like an eager version of filter, or an in-place version of std::copy_if:

std::copy_if(r.begin(), r.end(), r.begin(), predicate);

Note

If you need to apply a transformation, you can use eve::algo::views::map or eve::algo::transform_keep_if.

Tuning

dense_output/sparse_output: if you expect very sparse output (one or two trues per register), you can call keep_if[sparse_output](...) to optimize for that scenario.

Callable Signatures

{
  template<relaxed_range Rng, typename P>
  auto keep_if(Rng&& rng, P p) -> unaligned_iterator_t<Rng>
}

Parameters

• rng: Range to modify
• p: SIMD predicate over elements of rng

Return value

Iterator past the last written element.

See also

copy_if

remove_if

transform_keep_if

transform_copy_if