force_cardinal

template<int N>

eve::algo::force_cardinal = (force_cardinal_key = eve::fixed<N>{})

inlineconstexpr

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

 
#include <eve/module/core.hpp>
#include <eve/module/algo.hpp>
 
#include <string>
#include <span>
 
#ifdef __SSSE3__
 
void remove_spaces(std::string& s)
{
  using u8x16 = eve::wide<std::uint8_t, eve::fixed<16>>;
 
  // eve only supports std::int8_t and std::uint8_t, not char.
  std::span s_bytes{reinterpret_cast<std::uint8_t*>(s.data()), s.size()};
 
  auto end = eve::algo::remove_if[eve::algo::force_cardinal<16>](
    s_bytes,[](u8x16 v) -> eve::logical<u8x16> {
    // A simd is_space we took from @aqrit
    __m128i lut = _mm_setr_epi8(' ',    0,    0,  0,
                                  0,    0,    0,  0,
                                  0, '\t', '\n',  0,
                                  0, '\r',    0,  0);
    return v == u8x16{_mm_shuffle_epi8(lut, v)};
  });
 
  auto offset = end - s_bytes.begin();
  s.erase(s.begin() + offset, s.end());
}
 
#endif  // __SSSE3__
 

See also

consider_types if maybe using some extra type is the reason you want to change cardinal.