Method SetMembers

cpp/src/arrow/array/data.cc:286–338

// Methods for ArraySpan

void ArraySpan::SetMembers(const ArrayData& data) {
  this->type = data.type.get();
  this->length = data.length;
  if (this->type->id() == Type::NA) {
    this->null_count = this->length;
  } else {
    this->null_count = data.null_count.load();
  }
  this->offset = data.offset;

  for (int i = 0; i < std::min(static_cast<int>(data.buffers.size()), 3); ++i) {
    const std::shared_ptr<Buffer>& buffer = data.buffers[i];
    // It is the invoker-of-kernels's responsibility to ensure that
    // const buffers are not written to accidentally.
    if (buffer) {
      SetBuffer(i, buffer);
    } else {
      this->buffers[i] = {};
    }
  }

  Type::type type_id = this->type->id();
  if (type_id == Type::EXTENSION) {
    auto* ext_type = checked_cast<const ExtensionType*>(this->type);
    type_id = ext_type->storage_type()->id();
  }

  if ((data.buffers.size() == 0 || data.buffers[0] == nullptr) && type_id != Type::NA &&
      type_id != Type::SPARSE_UNION && type_id != Type::DENSE_UNION) {
    // This should already be zero but we make for sure
    this->null_count = 0;
  }

  // Makes sure any other buffers are seen as null / nonexistent
  for (int i = static_cast<int>(data.buffers.size()); i < 3; ++i) {
    this->buffers[i] = {};
  }

  if (type_id == Type::STRING_VIEW || type_id == Type::BINARY_VIEW) {
    // store the span of data buffers in the third buffer
    this->buffers[2] = internal::PackVariadicBuffers(std::span(data.buffers).subspan(2));
  }

  if (type_id == Type::DICTIONARY) {
    this->child_data.resize(1);
    this->child_data[0].SetMembers(*data.dictionary);
  } else {
    this->child_data.resize(data.child_data.size());
    for (size_t child_index = 0; child_index < data.child_data.size(); ++child_index) {
      this->child_data[child_index].SetMembers(*data.child_data[child_index]);
    }
  }
}

namespace {