IInspector.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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* granted to it by virtue of its status as an Intergovernmental Organization        *
* or submit itself to any jurisdiction.                                             *
\***********************************************************************************/
#pragma once
 
#include <GaudiKernel/IInterface.h>
#include <string>
#include <typeinfo>

class GAUDI_API IInspector : virtual public IInterface {
public:
  DeclareInterfaceID( IInspector, 1, 0 );
 
  enum { Mutable = 1 << 1, Const = 1 << 2 };
 
protected:
  class IValue {
  protected:
    void* m_P{};
    IValue() = default;
 
  public:
    virtual ~IValue() = default;
    virtual void release() { delete this; }
    void*        ptr() { return m_P; }
    const void*  ptr() const { return m_P; }
    virtual long size() const                    = 0;
    virtual void construct( void* buffer ) const = 0;
  };
 
  struct Tag {
    long                  first;
    const std::type_info& second;
    Tag( long f, const std::type_info& s ) : first( f ), second( s ) {}
  };
 
private:
  template <class T>
  class _V : public IValue {
    T m_O;
 
  public:
    _V( const T& v ) : m_O( v ) { m_P = &m_O; }
    virtual long size() const { return sizeof( T ); }
    virtual void construct( void* b ) const { ::new ( b ) T(); }
  };
 
  template <class T>
  class _TT : public Tag {
  public:
    _TT() : Tag( sizeof( T ), typeid( T ) ) {}
  };
 
protected:
  // Referenced implementation of the IInspector interface:
  virtual StatusCode inspectByRef( const void* pObj, const Tag& typ, void* pOwner, const Tag& otag,
                                   const std::string& comment, long flag ) = 0;
  virtual StatusCode inspectByValue( IValue* pObj, const Tag& typ, void* pOwner, const Tag& oTag,
                                     const std::string& comment ) = 0;
  virtual StatusCode inspectContByRef( const void* pObj, const Tag& tag, const Tag& rtag, const Tag& vtag,
                                       const void* pOwner, const Tag& otag, const std::string& comment,
                                       long flags ) = 0;
  virtual StatusCode inspectContByValue( IValue* pObj, const Tag& tag, const Tag& rtag, const Tag& vtag,
                                         const void* pOwner, const Tag& otag, const std::string& comment ) = 0;
 
public:
  // User interface of the IInspector interface
  template <class T, class O>
  StatusCode inspectByRef( const T* pObj, const O* pOwner, const std::string& comment, long flag = Mutable ) {
    return inspectByRef( pObj, _TT<T>(), (void*)pOwner, _TT<O>(), comment, flag );
  }

  template <class T, class O>
  StatusCode inspectByValue( const T& obj, const O* pOwner, const std::string& comment ) {
    return inspectByValue( new _V<T>( obj ), _TT<T>(), (void*)pOwner, _TT<O>(), comment );
  }

  template <class T, class O>
  StatusCode inspectContByRef( const T* pObj, const O* pOwner, const std::string& comment, long flag = Mutable ) {
    typedef typename T::value_type _VVV;
    typedef typename T::value_type _TTT;
    // Unfortunately this is not implemented on G++:
    // typedef typename T::allocator_type::value_type _TTT;
    return inspectContByRef( (void*)pObj, _TT<T>(), _TT<_VVV>(), _TT<_TTT>(), (void*)pOwner, _TT<O>(), comment, flag );
  }

  template <class T, class O>
  StatusCode inspectContByValue( const T& obj, const O* pOwner, const std::string& comment ) {
    typedef typename T::value_type _VVV;
    typedef typename T::value_type _TTT;
    // Unfortunately this is not implemented on G++:
    // typedef typename T::allocator_type::value_type _TTT;
    return inspectContByValue( new _V<T>( obj ), _TT<T>(), _TT<_VVV>(), _TT<_TTT>(), (void*)pOwner, _TT<O>(), comment );
  }
};