IdentifierHash.h

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/*
  Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration
*/
 
 
#ifndef IDENTIFIER_IDENTIFIERHASH_H
#define IDENTIFIER_IDENTIFIERHASH_H
 
#include "GaudiKernel/MsgStream.h"  
class IdentifierHash{
public:
    using value_type = unsigned int;
    IdentifierHash () = default;
    IdentifierHash (value_type value);
    operator value_type() const;
    value_type value() const;
    bool is_valid () const;
    IdentifierHash& operator = (value_type value);
    IdentifierHash& operator += (value_type value);
    IdentifierHash& operator -= (value_type value);
 
private:
    static constexpr value_type m_max_value = 0xFFFFFFFF;
    //
    value_type m_value = m_max_value;
};
 
 
// Define a hash functional
namespace std {
  template<>
  struct hash<IdentifierHash>{
    size_t operator()(const IdentifierHash& id) const{
      return static_cast<size_t>(id.value());
    }
  };
}
 
#include "Identifier/IdentifierHash.icc"
#endif // IDENTIFIER_IDENTIFIERHASH_H