podio/utilities/ArrowFrameConverter.h

0001 #ifndef PODIO_ARROWFRAMECONVERTER_H
0002 #define PODIO_ARROWFRAMECONVERTER_H
0003
0004 #include <memory>
0005 #include <string>
0006 #include <vector>
0007
0008 namespace arrow {
0009 class DataType;
0010 class Table;
0011 } // namespace arrow
0012
0013 namespace podio {
0014
0015 class Frame;
0016
0017 /**
0018  * @brief Get the standard Arrow DataType for object references/IDs.
0019  */
0020 std::shared_ptr<arrow::DataType> objectRefType();
0021
0022 /**
0023  * @brief Convert a PODIO Frame to an Arrow Table (1-row).
0024  *
0025  * Each collection specified in collsToWrite is mapped to a column of type List<Struct<...>>.
0026  * Metadata about the concrete collection value type is stored in each column field's KeyValueMetadata
0027  * under the key "value_type" (e.g. "value_type" -> "ExampleHit").
0028  *
0029  * Frame parameters (podio::GenericParameters) are converted and included under the column "frame_parameters".
0030  *
0031  * @param frame The Frame containing collections to convert.
0032  * @param collsToWrite The names of the collections to write to the Table.
0033  * @return A shared pointer to the created 1-row Arrow Table.
0034  */
0035 std::shared_ptr<arrow::Table> convertFrameToTable(const podio::Frame& frame,
0036                                                   const std::vector<std::string>& collsToWrite);
0037
0038 /**
0039  * @brief Convert a 1-row slice of an Arrow Table to a PODIO Frame.
0040  *
0041  * Reconstructs the frame parameters and all collection buffers using registered BufferReaderFuncs.
0042  *
0043  * @param table The Arrow Table containing the frame data.
0044  * @param rowIndex The index of the row to read.
0045  * @return The reconstructed Frame.
0046  */
0047 podio::Frame convertTableToFrame(const std::shared_ptr<arrow::Table>& table, int rowIndex = 0);
0048
0049 } // namespace podio
0050
0051 #endif // PODIO_ARROWFRAMECONVERTER_H