Class RecordBatchReaderIterator

cpp/src/arrow/record_batch.h:379–434

  virtual DeviceAllocationType device_type() const { return DeviceAllocationType::kCPU; }

  class RecordBatchReaderIterator {
   public:
    using iterator_category = std::input_iterator_tag;
    using difference_type = std::ptrdiff_t;
    using value_type = std::shared_ptr<RecordBatch>;
    using pointer = const value_type*;
    using reference = const value_type&;

    RecordBatchReaderIterator() : batch_(RecordBatchEnd()), reader_(NULLPTR) {}

    explicit RecordBatchReaderIterator(RecordBatchReader* reader)
        : batch_(RecordBatchEnd()), reader_(reader) {
      Next();
    }

    bool operator==(const RecordBatchReaderIterator& other) const {
      return batch_ == other.batch_;
    }

    bool operator!=(const RecordBatchReaderIterator& other) const {
      return !(*this == other);
    }

    Result<std::shared_ptr<RecordBatch>> operator*() {
      ARROW_RETURN_NOT_OK(batch_);

      return batch_;
    }

    RecordBatchReaderIterator& operator++() {
      Next();
      return *this;
    }

    RecordBatchReaderIterator operator++(int) {
      RecordBatchReaderIterator tmp(*this);
      Next();
      return tmp;
    }

   private:
    std::shared_ptr<RecordBatch> RecordBatchEnd() {
      return std::shared_ptr<RecordBatch>(NULLPTR);
    }

    void Next() {
      if (reader_ == NULLPTR) {
        batch_ = RecordBatchEnd();
        return;
      }
      batch_ = reader_->Next();
    }

    Result<std::shared_ptr<RecordBatch>> batch_;
    RecordBatchReader* reader_;
  };
  /// \brief Return an iterator to the first record batch in the stream
  RecordBatchReaderIterator begin() { return RecordBatchReaderIterator(this); }