File SIOLegacyReader.h

namespace podio

class SIOLegacyReader

#include <podio/SIOLegacyReader.h>

A SIO reader for reading legacy podio .sio files that have been written using the legacy, non Frame based I/O model.

This reader grants Frame based access to those files, by mimicking Frame I/O functionality and the interfaces of those readers.

Note

Since there was only one category (“events”) for those legacy podio files this reader will really only work if you try to read that category, and will simply return no data if you try to read anything else.

Public Functions

SIOLegacyReader(): Create a SIOLegacyReader.

~SIOLegacyReader() = default: Destructor.

SIOLegacyReader(const SIOLegacyReader&) = delete: The SIOLegacyReader is not copy-able.

SIOLegacyReader &operator=(const SIOLegacyReader&) = delete: The SIOLegacyReader is not copy-able.

std::unique_ptr<podio::SIOFrameData> readNextEntry(const std::string&)

Read the next data entry from which a Frame can be constructed.

In case there are no more entries left, this returns a nullptr.

Note

the category name has to be “events” in this case, as only that category is available for legacy files.

Returns:: FrameData from which a podio::Frame can be constructed if there are still entries left to read. Otherwise a nullptr

std::unique_ptr<podio::SIOFrameData> readEntry(const std::string&, const unsigned entry)

Read the desired data entry from which a Frame can be constructed.

Note

the category name has to be “events” in this case, as only that category is available for legacy files.

Returns:: FrameData from which a podio::Frame can be constructed if the desired entry exists. Otherwise a nullptr

unsigned getEntries(const std::string &name) const

Get the number of entries for the given name.

Parameters:: name – The name of the category
Returns:: The number of entries that are available for the category

void openFile(const std::string &filename)

Open a single file for reading.

Parameters:: filename – The name of the input file

inline podio::version::Version currentFileVersion() const

Get the build version of podio that has been used to write the current file.

Returns:: The podio build version

std::vector<std::string_view> getAvailableCategories() const

Get the names of all the available Frame categories in the current file(s).

Returns:: The names of the available categores from the file

Private Functions

bool readFileTOCRecord(): read the TOC record

void readCollectionIDTable()

Private Members

sio::ifstream m_stream = {}

std::vector<std::string> m_typeNames = {}

std::vector<short> m_subsetCollectionBits = {}

sio::buffer m_tableBuffer = {1}: The buffer holding the compressed CollectionIDTable.

unsigned m_tableUncLength = {0}: The uncompressed length of the tableBuffer.

std::shared_ptr<podio::CollectionIDTable> m_table = {nullptr}

unsigned m_eventNumber = {0}

SIOFileTOCRecord m_tocRecord = {}

podio::version::Version m_fileVersion = {0}

Private Static Attributes

static constexpr auto m_categoryName = "events"