E.V.E
v2023.02.15
 
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◆ keep_if

auto 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>
}
unaligned_t< iterator_t< R > > unaligned_iterator_t
Unaligned iterator for a relaxed range.
Definition ranges_types.hpp:68
constexpr auto keep_if
In-place version of std::copy_if
Definition keep_if.hpp:118

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