EventImporter.cpp

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/*
 *  CepGen: a central exclusive processes event generator
 *  Copyright (C) 2024  Laurent Forthomme
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#include <TFile.h>
 
#include "CepGen/Core/Exception.h"
#include "CepGen/Core/RunParameters.h"
#include "CepGen/Event/Event.h"
#include "CepGen/EventFilter/EventImporter.h"
#include "CepGen/Modules/EventImporterFactory.h"
#include "CepGen/Utils/Value.h"
#include "CepGenAddOns/ROOTWrapper/ROOTTreeInfo.h"
 
namespace cepgen {
  namespace root {
    class EventImporter : public cepgen::EventImporter {
    public:
      explicit EventImporter(const ParametersList& params)
          : cepgen::EventImporter(params), file_(TFile::Open(steer<std::string>("filename").data())) {
        if (!file_)
          throw CG_FATAL("root::EventImporter")
              << "Failed to load the ROOT file '" << steer<std::string>("filename") << "'.";
        run_tree_.attach(file_.get());
        evt_tree_.attach(file_.get());
      }
 
      static ParametersDescription description() {
        auto desc = cepgen::EventImporter::description();
        desc.setDescription("ROOT TTree importer module");
        desc.add<std::string>("filename", "output.root").setDescription("Input filename");
        return desc;
      }
 
      bool operator>>(Event& evt) override { return evt_tree_.next(evt); }
 
    private:
      void initialise() override { setCrossSection(Value{run_tree_.xsect, run_tree_.errxsect}); }
 
      const std::unique_ptr<TFile> file_;
      ROOT::CepGenRun run_tree_;
      ROOT::CepGenEvent evt_tree_;
    };
  }  // namespace root
}  // namespace cepgen
using ROOTEventImporter = cepgen::root::EventImporter;
REGISTER_EVENT_IMPORTER("root_tree", ROOTEventImporter);