Method operator()

cpp/src/arrow/json/reader.cc:185–214

 private:
  Result<TransformFlow<ChunkedBlock>> operator()(std::shared_ptr<Buffer> next_buffer) {
    if (!buffer_) {
      if (ARROW_PREDICT_TRUE(!next_buffer)) {
        DCHECK_EQ(partial_, nullptr) << "Logic error: non-null partial with null buffer";
        return TransformFinish();
      }
      partial_ = std::make_shared<Buffer>("");
      buffer_ = std::move(next_buffer);
      return TransformSkip();
    }
    DCHECK_NE(partial_, nullptr);

    std::shared_ptr<Buffer> whole, completion, next_partial;
    if (!next_buffer) {
      // End of file reached => compute completion from penultimate block
      RETURN_NOT_OK(chunker_->ProcessFinal(partial_, buffer_, &completion, &whole));
    } else {
      std::shared_ptr<Buffer> starts_with_whole;
      // Get completion of partial from previous block.
      RETURN_NOT_OK(chunker_->ProcessWithPartial(partial_, buffer_, &completion,
                                                 &starts_with_whole));
      // Get all whole objects entirely inside the current buffer
      RETURN_NOT_OK(chunker_->Process(starts_with_whole, &whole, &next_partial));
    }

    buffer_ = std::move(next_buffer);
    return TransformYield(ChunkedBlock{std::exchange(partial_, next_partial),
                                       std::move(completion), std::move(whole),
                                       index_++});
  }

  std::unique_ptr<Chunker> chunker_;
  std::shared_ptr<Buffer> partial_;