DataObjID.h

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* (c) Copyright 1998-2025 CERN for the benefit of the LHCb and ATLAS collaborations *
*                                                                                   *
* This software is distributed under the terms of the Apache version 2 licence,     *
* copied verbatim in the file "LICENSE".                                            *
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#pragma once
 
#include <GaudiKernel/ClassID.h>
#include <GaudiKernel/StatusCode.h>
 
#include <iostream>
#include <memory>
#include <mutex>
#include <string>
#include <unordered_set>
 
//---------------------------------------------------------------------------
 
//---------------------------------------------------------------------------
 
struct DataObjID_Hasher;
class IClassIDSvc;
 
class DataObjID {
public:
  friend DataObjID_Hasher;
 
  DataObjID() = default;
  DataObjID( const DataObjID& other )
      : m_clid( other.m_clid ), m_hash( other.m_hash ), m_key( other.m_key ), m_className( other.m_className ) {}
 
  DataObjID( std::string key );
  DataObjID( const CLID& clid, std::string key );
  DataObjID( std::string className, std::string key );
 
  DataObjID& operator=( const DataObjID& other ) {
    m_clid      = other.m_clid;
    m_hash      = other.m_hash;
    m_key       = other.m_key;
    m_className = other.m_className;
    return *this;
  }
 
  const std::string& key() const { return m_key; }
 
  const std::string& className() const;
 
  std::string fullKey() const;
 
  CLID        clid() const { return m_clid; }
  std::size_t hash() const { return m_hash; }
 
  void updateKey( std::string key );
 
  friend bool operator<( const DataObjID& lhs, const DataObjID& rhs ) { return lhs.m_hash < rhs.m_hash; }
  friend bool operator==( const DataObjID& lhs, const DataObjID& rhs ) { return lhs.m_hash == rhs.m_hash; }
  friend bool operator!=( const DataObjID& lhs, const DataObjID& rhs ) { return !( lhs == rhs ); }
 
  friend StatusCode    parse( DataObjID& dest, std::string_view src );
  friend std::ostream& toStream( const DataObjID& v, std::ostream& o );
  friend std::ostream& operator<<( std::ostream& os, const DataObjID& d ) { return toStream( d, os ); }
 
private:
  void hashGen();
  void setClid();
 
  CLID        m_clid{ 0 };
  std::size_t m_hash{ 0 };
 
  std::string            m_key{ "INVALID" };
  mutable std::string    m_className;
  mutable std::once_flag m_setClassName;
};
 
inline DataObjID::DataObjID( std::string key ) : m_key( std::move( key ) ) { hashGen(); }
 
inline DataObjID::DataObjID( const CLID& clid, std::string key ) : m_clid( clid ), m_key( std::move( key ) ) {
  hashGen();
}
 
inline DataObjID::DataObjID( std::string className, std::string key )
    : m_key( std::move( key ) ), m_className( std::move( className ) ) {
  setClid();
  hashGen();
}
 
inline void DataObjID::updateKey( std::string key ) {
  m_key = std::move( key );
  hashGen();
}
 
struct DataObjID_Hasher {
  std::size_t operator()( const DataObjID& k ) const { return k.m_hash; }
};
 
using DataObjIDColl   = std::unordered_set<DataObjID, DataObjID_Hasher>;
using DataObjIDVector = std::vector<DataObjID>;
 
namespace Gaudi {
  namespace Details {
    namespace Property {
      template <typename T>
      struct StringConverter;
 
      template <>
      struct StringConverter<DataObjIDColl> {
        std::string   toString( const DataObjIDColl& v );
        DataObjIDColl fromString( const DataObjIDColl&, const std::string& );
      };
 
      template <>
      struct StringConverter<DataObjIDVector> {
        std::string     toString( const DataObjIDVector& v );
        DataObjIDVector fromString( const DataObjIDVector&, const std::string& );
      };
    } // namespace Property
  }   // namespace Details
} // namespace Gaudi