Relation.h

/**************************************************************************
 * basf2 (Belle II Analysis Software Framework)                           *
 * Author: The Belle II Collaboration                                     *
 *                                                                        *
 * See git log for contributors and copyright holders.                    *
 * This file is licensed under LGPL-3.0, see LICENSE.md.                  *
 **************************************************************************/
#pragma once
 
#include <utility>
 
namespace Belle2 {
  namespace TrackFindingCDC {
 
    template <class AFrom, class ATo = AFrom>
    class Relation : public std::pair<AFrom*, ATo*> {
 
    private:
      using Super = std::pair<AFrom*, ATo*>;
 
    public:
      using From = AFrom;
 
      using To = ATo;
 
    public:
      using Super::Super;
 
      bool operator<(const Relation<From, To>& rhs) const
      {
        return (getFrom() < rhs.getFrom() or
                (not(rhs.getFrom() < getFrom()) and
                 (getTo() < rhs.getTo())));
      }
 
      friend bool operator<(const From* ptrFrom, const Relation<From, To>& relation)
      {
        return ptrFrom < relation.getFrom();
      }
 
      friend bool operator<(const Relation<From, To>& relation, const From* ptrFrom)
      {
        return relation.getFrom() < ptrFrom;
      }
 
      From* getFrom() const
      {
        return this->first;
      }
 
      To* getTo() const
      {
        return this->second;
      }
 
      Relation<To, From> reversed() const
      {
        return Relation<To, From>(getTo(), getFrom());
      }
    };
  }
}