GenBase.h

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/*
  Copyright (C) 2002-2026 CERN for the benefit of the ATLAS collaboration
*/
 
#ifndef GENERATORMODULES_GENBASE_H
#define GENERATORMODULES_GENBASE_H
 
#include "AthenaBaseComps/AthAlgorithm.h"
#include "GaudiKernel/ServiceHandle.h"
#include "GaudiKernel/IIncidentSvc.h"
#include "AthenaKernel/errorcheck.h"
#include "CxxUtils/checker_macros.h"
#include "StoreGate/ReadHandleKey.h"
#include "GeneratorObjects/McEventCollection.h"
 
#include "AtlasHepMC/GenEvent.h"
#include "AtlasHepMC/GenVertex.h"
#include "TruthUtils/MagicNumbers.h"
 
 
#include <string>
#include <vector>
#include <map>
 

class GenBase : public AthAlgorithm {
public:



  GenBase(const std::string& name, ISvcLocator* pSvcLocator);

  virtual ~GenBase() { }

 


  virtual StatusCode initialize() override;
  virtual StatusCode execute(const EventContext&) override { return StatusCode::SUCCESS; }
 



  HepMC::GenEvent* event ATLAS_NOT_CONST_THREAD_SAFE () {
    if (events()->empty())
      ATH_MSG_ERROR("McEventCollection is empty during first event access");
    return *(events()->begin());
  }

  const HepMC::GenEvent* event_const( const EventContext& ctx ) const {
    const McEventCollection* coll = events_const(ctx);
    if (coll->empty())
      ATH_MSG_ERROR("Const McEventCollection is empty during first event access");
    return *(coll->begin());
  }

  McEventCollection* events ATLAS_NOT_CONST_THREAD_SAFE ();

  const McEventCollection* events_const( const EventContext& ctx ) const {
    SG::ReadHandle<McEventCollection> ret = SG::makeHandle(m_mcevents_const, ctx);
    if (!ret.isValid())
      ATH_MSG_ERROR("No McEventCollection found in StoreGate with key " << m_mcevents_const.key());
    return ret.cptr();
  }

 
 
protected:



  std::string m_mcEventKey{};
  BooleanProperty m_mkMcEvent{this, "MakeMcEvent", false, "Create a new MC event collection if it doesn't exist"};
 
private:
 

  SG::ReadHandleKey<McEventCollection> m_mcevents_const{ this, "McEventKey", "GEN_EVENT", "StoreGate key of the MC event collection" };
 
};
 
 
#endif