Function type

cpp/src/arrow/array/builder_nested.h:609–618

  ArrayBuilder* value_builder() const { return list_builder_->value_builder(); }

  std::shared_ptr<DataType> type() const override {
    // Key and Item builder may update types, but they don't contain the field names,
    // so we need to reconstruct the type. (See ARROW-13735.)
    return std::make_shared<MapType>(
        field(entries_name_,
              struct_({field(key_name_, key_builder_->type(), false),
                       field(item_name_, item_builder_->type(), item_nullable_)}),
              false),
        keys_sorted_);
  }

  Status ValidateOverflow(int64_t new_elements) {
    return list_builder_->ValidateOverflow(new_elements);