VariantDef.h

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/*
  Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration
*/

 
 
#ifndef COLUMNAR_VARIANT_VARIANT_DEF_H
#define COLUMNAR_VARIANT_VARIANT_DEF_H
 
#include <ColumnarCore/ContainerId.h>
 
#include <boost/mp11/list.hpp>
#include <boost/mp11/algorithm.hpp>
#include <array>
#include <tuple>
 
namespace columnar
{
 
  template<ContainerIdConcept CIBase,ContainerIdConcept... CIList>
  struct VariantContainerId
  {
    static_assert (sizeof...(CIList) > 0, "need to have at least one variant container type for VariantContainerId");

    static constexpr bool isContainerId = true;

    static constexpr bool isMutable = CIBase::isMutable;

    static constexpr bool perEventRange = false;

    static constexpr bool perEventId = false;

    using xAODObjectIdType = typename CIBase::xAODObjectIdType;

    using xAODObjectRangeType = typename CIBase::xAODObjectRangeType;

    using xAODElementLinkType = typename CIBase::xAODElementLinkType;
 

 
    using baseId = CIBase;
 
    static constexpr std::size_t numVariants = sizeof...(CIList);
 
    static constexpr std::array<std::string_view,numVariants> idNameArray = {CIList::idName...};
 
    template<ContainerIdConcept CI>
    static constexpr bool isValidContainer ()
    {
      return (... || std::is_same_v<CI,CIList>);
    }

    template<ContainerIdConcept CI>
    static constexpr unsigned getVariantIndex ()
    {
      constexpr unsigned index = boost::mp11::mp_find<std::tuple<CIList...>,CI>::value;
      return index;
    }
 
    using mpCIList = boost::mp11::mp_list<CIList...>;
  };
}
 
#endif