File SIOReader.h

namespace podio
class SIOReader
#include <podio/SIOReader.h>

The SIOReader can be used to read files that have been written with the SIO backend.

The SIOReader provides the data as SIOFrameData from which a podio::Frame can be constructed. It can be used to read files written by the SIOWriter.

Public Functions

SIOReader()

Create an SIOReader.

~SIOReader() = default

SIOReader destructor.

SIOReader(const SIOReader&) = delete

The SIOReader is not copy-able.

SIOReader &operator=(const SIOReader&) = delete

The SIOReader is not copy-able.

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

Read the next data entry for a given category.

Parameters:

name – The category name for which to read the next entry

Returns:

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

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

Read the desired data entry for a given category.

Parameters:

  • name – The category name for which to read the next entry

  • entry – The entry number to read

Returns:

FrameData from which a podio::Frame can be constructed if the category and the desired entry exist. 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 the passed file for reading.

Parameters:

filename – The path to the file to read from

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.

Returns:

The names of the available categores from the file

inline const std::string_view getDatamodelDefinition(const std::string &name) const

Get the datamodel definition for the given name.

Parameters:

name – The name of the datamodel

Returns:

The high level definition of the datamodel in JSON format

inline std::vector<std::string> getAvailableDatamodels() const

Get all names of the datamodels that are available from this reader.

Returns:

The names of the datamodels

Private Functions

void readPodioHeader()
bool readFileTOCRecord()

read the TOC record

void readEDMDefinitions()

Private Members

sio::ifstream m_stream = {}

The stream from which we read.

std::unordered_map<std::string, unsigned> m_nameCtr = {}

Count how many times each an entry of this name has been read already.

SIOFileTOCRecord m_tocRecord = {}

Table of content record where starting points of named entries can be read from.

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

The podio version that has been used to write the file.

DatamodelDefinitionHolder m_datamodelHolder = {}