AuxVariable.h

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// Dear emacs, this is -*- c++ -*-
//
// Copyright (C) 2002-2024 CERN for the benefit of the ATLAS collaboration
//
#ifndef XAODCORE_TOOLS_AUXVARIABLE_H
#define XAODCORE_TOOLS_AUXVARIABLE_H
 
// EDM include(s).
#include "AthContainers/AuxTypeRegistry.h"
#include "AthContainers/ConstAccessor.h"
#include "CxxUtils/pputils.h"
 
#define AUX_VARIABLE( VAR, ... )                              \
   do {                                                       \
      static const auxid_t auxid =                            \
      getAuxID( #VAR, VAR CXXUTILS_PP_FIRST( __VA_ARGS__ ) ); \
      regAuxVar( auxid, #VAR, VAR );                          \
   } while( false )
 
 
 
namespace xAOD { namespace detail {
 
 
template <class VARTYPE, class AUXBASE>
VARTYPE initAuxVar2( AUXBASE* auxcont,
                     std::true_type)
{
  return VARTYPE (auxcont->memResource());
}
 
 
template <class VARTYPE, class AUXBASE>
VARTYPE initAuxVar2( AUXBASE* /*auxcont*/,
                     std::false_type)
{
  return VARTYPE();
}
 
 
template <class VARTYPE, class AUXBASE>
VARTYPE initAuxVar1( AUXBASE* auxcont)
{
  return initAuxVar2<VARTYPE> ( auxcont, std::is_constructible<VARTYPE, std::pmr::memory_resource*>() );
}
 
 
template <const char* NAME, class AUXBASE, class VARTYPE>
VARTYPE initAuxVar( AUXBASE* auxcont,
                    VARTYPE& var,
                    SG::AuxVarFlags flags = SG::AuxVarFlags::None )
{
  static const SG::auxid_t auxid = auxcont->getAuxID( NAME, var, flags );
  auxcont->regAuxVar (auxid, NAME, var);
  return initAuxVar1<VARTYPE>( auxcont );
}
 
 
// Version to handle initializing a linked variable.
// ELT is the type of the variable being linked to, LINKS is the type of the
// member defined in the container for it.  LINKED is the member type
// for the linked variable, and AUXBASE is the container base class.
template <class ELT, const char* NAME, class AUXBASE, class LINKS, class LINKED>
LINKED initLinkedVar( AUXBASE* auxcont,
                      LINKS& links,
                      LINKED& linked )
{
  // Use the @c ConstAccessor specialization to get the variable
  // declared properly.
  static const SG::ConstAccessor<ELT> acc( NAME );
  auxcont->regAuxVar( acc.linkedAuxid(), SG::AuxTypeRegistry::linkedName (NAME), linked );
  auxcont->regAuxVar( acc.auxid(), NAME, links );
  return xAOD::detail::initAuxVar1<LINKED>( auxcont );
}
 
 
}} // namespace xAOD::detail
 
 
#define AUXVAR_DECL( TYPE, NAME, ... )                                  \
  static constexpr const char NAME ## __name[] = #NAME;                 \
  AuxVariable_t< TYPE AUXVAR_DECL_ALLOC_( TYPE, __VA_ARGS__ ) > NAME     \
    { xAOD::detail::initAuxVar< NAME ## __name >( this, NAME CXXUTILS_PP_SECOND( __VA_ARGS__ ) ) }
#define AUXVAR_DECL_ALLOC_( TYPE, ... ) \
  __VA_OPT__( CXXUTILS_PP_FIRST( __VA_ARGS__ )< TYPE > )
 
 
#define AUXVAR_PACKEDCONTAINER_DECL( TYPE, NAME )           \
  static constexpr const char NAME ## __name[] = #NAME; \
  SG::PackedContainer< TYPE > NAME  { xAOD::detail::initAuxVar< NAME ## __name >( this, NAME ) }
 
 
#endif // XAODCORE_TOOLS_AUXVARIABLE_H