Function ReadOptional

cpp/src/parquet/stream_reader.h:247–264

  template <typename ReaderType, typename ReadType = typename ReaderType::T, typename T>
  void ReadOptional(optional<T>* v) {
    const auto& node = nodes_[column_index_];
    auto reader = static_cast<ReaderType*>(column_readers_[column_index_++].get());
    int16_t def_level;
    int16_t rep_level;
    ReadType tmp;
    int64_t values_read;

    reader->ReadBatch(kBatchSizeOne, &def_level, &rep_level, &tmp, &values_read);

    if (values_read == 1) {
      *v = T(tmp);
    } else if ((values_read == 0) && (def_level == 0)) {
      v->reset();
    } else {
      ThrowReadFailedException(node);
    }
  }

  void ReadFixedLength(char* ptr, int len);