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//
//
// Base type key class
//
// Jane Tinslay, September 2006
//
#ifndef G4TYPEKEY_HH
#define G4TYPEKEY_HH

#include "globals.hh"
#include <ostream>

class G4TypeKey {

public:

  using Key = unsigned long;

  // Constructor
  G4TypeKey() = default;

  // Destructor
  virtual ~G4TypeKey() = default;

  G4bool IsValid() {
    return (0 != fMyKey);
  }
  
  // Operators
  Key operator()() const {return fMyKey;}  
  G4bool operator==(const G4TypeKey& rhs) const {return fMyKey == rhs.fMyKey;}
  G4bool operator!=(const G4TypeKey& rhs) const {return !operator==(rhs);}
  G4bool operator<(const G4TypeKey& rhs) const {return fMyKey < rhs.fMyKey;}
  G4bool operator>(const G4TypeKey& rhs) const {return fMyKey > rhs.fMyKey;}

  friend std::ostream& operator<<(std::ostream& out, const G4TypeKey& key){ 
    return out<< key.fMyKey;
  }

protected:

  Key NextKey() const {
    static G4ThreadLocal Key *npKey = nullptr ;
    if (npKey == nullptr) { npKey = new Key; *npKey = 0; }
    Key &nKey = *npKey;
    return ++nKey;
  }

  Key fMyKey{0};

};

#endif
