simcore::hepmc::HepMCReader Class Reference

Reads HepMC event data into a HepMCEvent object. More...

#include <HepMCReader.h>

Public Member Functions
	HepMCReader (std::string &fileName)
	Class constructor.
virtual	~HepMCReader ()=default
	Class destructor.
std::unique_ptr< HepMCEvent >	readNextEvent ()
	Read the next event.

Private Attributes
std::shared_ptr< HepMC3::Reader >	reader_
	The HepMC3 reader.
int	event_counter_ {0}
	Event counter for tracking progress.

Detailed Description

Reads HepMC event data into a HepMCEvent object.

Definition at line 27 of file HepMCReader.h.

Constructor & Destructor Documentation

HepMCReader()

simcore::hepmc::HepMCReader::HepMCReader

(

std::string &

fileName

)

Class constructor.

Parameters

fileName

The input file name.

Definition at line 16 of file HepMCReader.cxx.

                                            {
  ldmx_log(info) << "Opening HepMC file " << filename;
 
  // ROOT files start with the "root" magic bytes
  std::string magic(4, '\0');
  std::ifstream(filename, std::ios::binary).read(magic.data(), magic.size());
  if (magic == "root") {
    // WriterRootTree stores a TTree, WriterRoot one object per event
    std::unique_ptr<TFile> file{TFile::Open(filename.c_str())};
    if (file && file->Get<TTree>("hepmc3_tree")) {
      ldmx_log(info) << "Detected HepMC3 ROOT tree format";
      reader_ = std::make_shared<HepMC3::ReaderRootTree>(filename);
    } else {
      ldmx_log(info) << "Detected HepMC3 ROOT format";
      reader_ = std::make_shared<HepMC3::ReaderRoot>(filename);
    }
  } else {
    // HepMC2/3 ascii, LHEF or HEPEVT
    reader_ = HepMC3::deduce_reader(filename);
  }
 
  if (!reader_ || reader_->failed()) {
    EXCEPTION_RAISE("BadFile", "Failed to open HepMC file: " + filename);
  }
}

References reader_.

Member Function Documentation

readNextEvent()

std::unique_ptr< HepMCEvent > simcore::hepmc::HepMCReader::readNextEvent

(

)

Read the next event.

Returns

The next HepMC event.

Definition at line 42 of file HepMCReader.cxx.

                                                     {
  // Create a new HepMC3 GenEvent
  auto gen_event = std::make_shared<HepMC3::GenEvent>();
 
  // Read the next event from the file
  if (!reader_->read_event(*gen_event)) {
    ldmx_log(warn) << "No next event was found by the HepMC reader.";
    return nullptr;
  }
 
  // Geant4 expects GeV and mm
  gen_event->set_units(HepMC3::Units::GEV, HepMC3::Units::MM);
 
  // Check if the event is empty
  if (gen_event->particles().empty()) {
    ldmx_log(warn) << "Empty event found by HepMC reader.";
    return nullptr;
  }
 
  // Increment event counter and log progress every 100 events
  event_counter_++;
  if (event_counter_ % 100 == 0) {
    ldmx_log(debug) << "HepMCReader: Read " << event_counter_ << " events";
  }
 
  // Create and return the wrapped event
  return std::make_unique<HepMCEvent>(gen_event);
}

References event_counter_, and reader_.

Referenced by simcore::generators::HepMCPrimaryGenerator::GeneratePrimaryVertex().

Member Data Documentation

event_counter_

int simcore::hepmc::HepMCReader::event_counter_ {0}

mutableprivate

Event counter for tracking progress.

Definition at line 55 of file HepMCReader.h.

{0};

Referenced by readNextEvent().

reader_

std::shared_ptr<HepMC3::Reader> simcore::hepmc::HepMCReader::reader_

private

The HepMC3 reader.

Definition at line 50 of file HepMCReader.h.

Referenced by HepMCReader(), and readNextEvent().

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The documentation for this class was generated from the following files:

• SimCore/include/SimCore/HepMC/HepMCReader.h
• SimCore/src/SimCore/HepMC/HepMCReader.cxx