Function copyNulls

bolt/dwio/common/FlatMapHelper.cpp:365–399

copy nulls from source to target, return number of nulls copied

// copy nulls from source to target, return number of nulls copied
vector_size_t copyNulls(
    BaseVector& target,
    vector_size_t targetIndex,
    const BaseVector& source,
    vector_size_t sourceIndex,
    vector_size_t count) {
  vector_size_t nulls = 0;
  // it's assumed that initVector is called before calling this method to
  // properly allocate/clear nulls buffer. So we only need to check against
  // target vector here.
  target.resize(targetIndex + count, false);
  if (target.mayHaveNulls()) {
    auto tgtNulls = const_cast<uint64_t*>(target.rawNulls());
    if (source.isConstantEncoding()) {
      for (vector_size_t i = 0; i < count; ++i) {
        bits::setNull(tgtNulls, targetIndex + i);
      }
      nulls += count;
    } else if (auto srcNulls = source.rawNulls()) {
      for (vector_size_t i = 0; i < count; ++i) {
        if (bits::isBitNull(srcNulls, sourceIndex + i)) {
          ++nulls;
          bits::setNull(tgtNulls, targetIndex + i);
        } else {
          bits::clearNull(tgtNulls, targetIndex + i);
        }
      }
    } else {
      for (vector_size_t i = 0; i < count; ++i) {
        bits::clearNull(tgtNulls, targetIndex + i);
      }
    }
  }
  return nulls;
}

template <TypeKind K>
void copyImpl(