DetectorClocksStandardTriggerLoader.h

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#ifndef LARDATA_DETECTORINFO_DETECTORCLOCKSSTANDARDTRIGGERLOADER_H
#define LARDATA_DETECTORINFO_DETECTORCLOCKSSTANDARDTRIGGERLOADER_H

// LArSoft libraries
#include "lardataalg/DetectorInfo/DetectorClocksStandard.h"
#include "lardataobj/RawData/TriggerData.h" // raw::Trigger

// framework libraries
#include "canvas/Utilities/InputTag.h"
#include "cetlib_except/exception.h"

// C++ standard libraries
#include <vector>


namespace detinfo {
  
  inline void setDetectorClocksStandardTriggersFromRawTrigger
    (detinfo::DetectorClocksStandard& detClocks, raw::Trigger const& trigger)
    { detClocks.SetTriggerTime(trigger.TriggerTime(), trigger.BeamGateTime()); }


  template <typename Event>
  bool setDetectorClocksStandardTriggersFromEvent
    (detinfo::DetectorClocksStandard& detClocks, Event const& event)
  {
    //
    // fetch the trigger data product
    //
    using TriggerHandle_t
      = typename Event::template HandleT<std::vector<raw::Trigger>>;
    
    art::InputTag const triggerTag = detClocks.TrigModuleName();
    TriggerHandle_t triggerHandle;
    if (!event.template getByLabel(triggerTag, triggerHandle)) return false;
    
    //
    // check that we do have a trigger
    // (we have already checked whether the handle is valid above)
    //
    
    auto const& triggers = *triggerHandle;
    if (triggers.empty()) return false;
    
    //
    // select which trigger to set (i.e., the only one!)
    //
    if (triggers.size() != 1) {
      throw cet::exception("setDetectorClocksStandardTrigger")
        << "Found " << triggers.size()
        << " trigger objects in '" << triggerTag.encode()
        << "' (only one trigger per event is supported)\n";
    }
        
    //
    // set the timings from the first and only trigger into the service
    //
    setDetectorClocksStandardTriggersFromRawTrigger
      (detClocks, triggers.front());
    
    // all done
    return true;
    
  } // setDetectorClocksStandardTriggersFromEvent()
  
  
  template <typename Event>
  bool setDetectorClocksStandardTrigger
    (detinfo::DetectorClocksStandard& detClocks, Event const& event)
  {
    //
    // try to read the trigger from the event
    //
    if (setDetectorClocksStandardTriggersFromEvent(detClocks, event))
      return true;
    
    //
    // if there was no trigger candidate, set it default
    //
    detClocks.SetDefaultTriggerTime();
    return false;
    
  } // setDetectorClocksStandardTrigger

} // namespace detinfo


#endif // LARDATA_DETECTORINFO_DETECTORCLOCKSSTANDARDTRIGGERLOADER_H