OverlapLinkHelper.h

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/*
  Copyright (C) 2002-2022 CERN for the benefit of the ATLAS collaboration
*/
 
#ifndef ASSOCIATIONUTILS_OVERLAPLINKHELPER_H
#define ASSOCIATIONUTILS_OVERLAPLINKHELPER_H
 
// Framework includes
#include "AsgMessaging/StatusCode.h"
 
// EDM includes
#include "xAODBase/IParticleContainer.h"
 
// Columnar includes
#include "ColumnarCore/ColumnAccessor.h"
#include "ColumnarCore/ColumnarTool.h"
#include "ColumnarCore/LinkColumn.h"
#include "ColumnarVariant/VariantLinkColumn.h"
 
// Local includes
#include "AssociationUtils/OverlapRemovalDefs.h"
 
namespace ORUtils
{

  template<columnar::ContainerIdConcept CI>
  class OverlapLinkHelper : public columnar::ColumnarTool<>
  {
 
    public:

      OverlapLinkHelper(const std::string& linkLabel);

      template<columnar::ContainerIdConcept LT>
      StatusCode addObjectLink(columnar::ObjectId<CI> p1,
                               columnar::ObjectId<LT> p2) const;

      template<columnar::ContainerIdConcept LT>
      columnar::OptObjectId<LT> getObjectLink(columnar::ObjectId<CI> p, columnar::ObjectRange<LT> container) const;
 
    private:
 
      // we need to use a columnar variant link here, because other
      // tools may send a link to a container we are not listing here.
      // however, at the same time having a variant link here also means
      // I can point to either of my two containers without extra
      // effort.
      using LTDef = columnar::VariantContainerId<columnar::Particle1Def,columnar::Particle1Def,columnar::Particle2Def>;

      columnar::ColumnDecorator<CI,columnar::ObjectLink<LTDef>> m_linkDecorator;
      columnar::ColumnAccessor<CI,columnar::ObjectLink<LTDef>> m_linkAccessor;
 
  }; // class OverlapLinkHelper
 
  //---------------------------------------------------------------------------
  // Constructor
  //---------------------------------------------------------------------------
  template<columnar::ContainerIdConcept CI>
  OverlapLinkHelper<CI>::OverlapLinkHelper(const std::string& linkLabel)
    : m_linkDecorator(*this,linkLabel),
      m_linkAccessor(*this,linkLabel)
  {}
 
  //---------------------------------------------------------------------------
  // Link p1 to p2
  //---------------------------------------------------------------------------
  template<columnar::ContainerIdConcept CI> template<columnar::ContainerIdConcept LT>
  StatusCode OverlapLinkHelper<CI>::addObjectLink
  (columnar::ObjectId<CI> p1, columnar::ObjectId<LT> p2) const
  {
    m_linkDecorator.set (p1, p2);
    return StatusCode::SUCCESS;
  }
 
  //---------------------------------------------------------------------------
  // Retrieve an overlap-linked particle or null.
  //---------------------------------------------------------------------------
  template<columnar::ContainerIdConcept CI> template<columnar::ContainerIdConcept LT>
  columnar::OptObjectId<LT> OverlapLinkHelper<CI>::getObjectLink
  (columnar::ObjectId<CI> p, columnar::ObjectRange<LT> container) const
  {
    // Check if the decoration is present and valid
    if(!m_linkAccessor.isAvailable(p))
      return {};
    auto link = m_linkAccessor(p);
    if (!link)
      return {};
    if constexpr (columnar::ColumnarModeDefault::isXAOD)
    {
      if (link.getXAODObject()->container() != &container.getXAODObject())
        return {};
    }
    return link.template tryGetVariant<LT>();
  }
 
} // namespace ORUtils
 
#endif