Method Decode

cpp/src/parquet/decoder.cc:1714–1748

  }

  int Decode(ByteArray* buffer, int max_values) override {
    // Decode up to `max_values` strings into an internal buffer
    // and reference them into `buffer`.
    max_values = std::min(max_values, num_valid_values_);
    DCHECK_GE(max_values, 0);
    if (max_values == 0) {
      return 0;
    }

    int32_t data_size = 0;
    const int32_t* length_ptr = buffered_length_->data_as<int32_t>() + length_idx_;
    int bytes_offset = len_ - decoder_->bytes_left();
    for (int i = 0; i < max_values; ++i) {
      int32_t len = length_ptr[i];
      if (ARROW_PREDICT_FALSE(len < 0)) {
        throw ParquetException("negative string delta length");
      }
      buffer[i].len = len;
      if (AddWithOverflow(data_size, len, &data_size)) {
        throw ParquetException("excess expansion in DELTA_(LENGTH_)BYTE_ARRAY");
      }
    }
    length_idx_ += max_values;
    if (ARROW_PREDICT_FALSE(!decoder_->Advance(8 * static_cast<int64_t>(data_size)))) {
      ParquetException::EofException();
    }
    const uint8_t* data_ptr = data_ + bytes_offset;
    for (int i = 0; i < max_values; ++i) {
      buffer[i].ptr = data_ptr;
      data_ptr += buffer[i].len;
    }
    this->num_values_ -= max_values;
    num_valid_values_ -= max_values;
    return max_values;
  }

  int DecodeArrow(int num_values, int null_count, const uint8_t* valid_bits,
                  int64_t valid_bits_offset,