IAuxElement.h

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// This file's extension implies that it's C, but it's really -*- C++ -*-.
/*
  Copyright (C) 2002-2024 CERN for the benefit of the ATLAS collaboration
*/
#ifndef ATHCONTAINERSINTERFACES_IAUXELEMENT_H
#define ATHCONTAINERSINTERFACES_IAUXELEMENT_H
 
 
#include <cstdlib>
#include <cstdint>
#include <cassert>
 
 
// If set, we need to write data that's forward-compatible with r21.
#define ATHCONTAINERS_R21_COMPAT
 
 
namespace SG {
 
 
class ConstAuxElement;
class AuxElement;
 
 
class IAuxElement
{
public:
  IAuxElement();
 
 
  IAuxElement(size_t index);
 
 
  size_t index() const;
 
 
protected:
  bool noPrivateData() const;
 
 
  bool havePrivateData() const;
 
 
  bool hadPrivateData() const;
 
 
 
private:
  // These functions are for the use of SG::*AuxElement, but should not
  // be accessible to any further derived classes.  So make them private
  // with friendship rather than protected.
  friend class SG::ConstAuxElement;
  friend class SG::AuxElement;
 
 
  void setIndex (size_t index);
 
 
  void setNoPrivateData();
 
 
  void setHavePrivateData();
 
 
  void setHadPrivateData();
 
 
  size_t m_index;
 
  enum class PrivateStoreState : uint8_t
  {
    NO_PRIVATE = 0,
    HAVE_PRIVATE = 1,
    HAD_PRIVATE = 2,
  };
  PrivateStoreState m_privateStoreState;
 
  // We have 7 bytes of padding here.  It's tempting to pack the two
  // fields above into 64 bits, but that's observed to spoil opimizations.
};
 
 
} // namespace SG
 
 
#include "AthContainersInterfaces/IAuxElement.icc"
 
 
#endif // not ATHCONTAINERSINTERFACES_IAUXELEMENT_H