array_utils.h

#pragma once
#include "gaia/config/config.h"
 
#include "gaia/core/utility.h"
#include "gaia/mem/mem_utils.h"
 
namespace gaia {
  namespace cnt {
    enum class ResizePolicy : uint8_t {
      Exact,
      Scale,
    };
 
    namespace detail {
      template <typename SizeType>
      GAIA_NODISCARD constexpr SizeType resize_capacity(ResizePolicy policy, SizeType cap, SizeType count) noexcept {
        return policy == ResizePolicy::Scale ? core::get_max(count, (SizeType)((cap * 3 + 1) / 2)) : count;
      }
 
      template <bool SOA, typename Array, typename Func>
      uint32_t retain_array(Array& arr, uint32_t& count, Func&& func) {
        using T = typename Array::value_type;
        uint32_t erased = 0;
        uint32_t idxDst = 0;
        uint32_t idxSrc = 0;
 
        while (idxSrc < count) {
          if (func(arr[idxSrc])) {
            if (idxDst < idxSrc) {
              auto* ptr = (uint8_t*)arr.data();
              mem::move_element<T, SOA>(ptr, ptr, idxDst, idxSrc, arr.capacity(), arr.capacity());
            }
            ++idxDst;
          } else {
            ++erased;
          }
          ++idxSrc;
        }
 
        if constexpr (!SOA) {
          if (erased != 0)
            core::call_dtor_n(arr.data() + idxDst, erased);
        }
        count -= erased;
        return idxDst;
      }
    } // namespace detail
  } // namespace cnt
} // namespace gaia