RVariationReader.hxx

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// Author: Enrico Guiraud CERN 11/2021
 
/*************************************************************************
 * Copyright (C) 1995-2021, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/
 
#ifndef ROOT_RDF_RVARIATIONREADER
#define ROOT_RDF_RVARIATIONREADER
 
#include "RColumnReaderBase.hxx"
#include "RVariationBase.hxx"
#include <Rtypes.h> // Long64_t, R__CLING_PTRCHECK
 
#include <limits>
#include <type_traits>
 
namespace ROOT {
namespace Internal {
namespace RDF {
 
/// Column reader that reads the value for a specific column, variation and slot.
class R__CLING_PTRCHECK(off) RVariationReader final : public ROOT::Detail::RDF::RColumnReaderBase {
   RVariationBase *fVariation;
 
   /// Non-owning ptr to the value of the variation.
   void *fValuePtr = nullptr;
 
   /// The slot this value belongs to.
   unsigned int fSlot = std::numeric_limits<unsigned int>::max();
 
   void *GetImpl(Long64_t entry) final
   {
      fVariation->Update(fSlot, entry);
      return fValuePtr;
   }
 
public:
   RVariationReader(unsigned int slot, const std::string &colName, const std::string &variationName,
                    RVariationBase &variation)
      : fVariation(&variation), fValuePtr(variation.GetValuePtr(slot, colName, variationName)), fSlot(slot)
   {
   }
};
 
class RVariationsWithReaders {
   // this is a shared_ptr only because we have to track its lifetime with a weak_ptr that we pass to jitted code
   // (see BookVariationJit). it is never null.
   std::shared_ptr<RVariationBase> fVariation;
   // Column readers for this RVariation for a given variation (map key) and a given slot (vector element).
   std::vector<std::unordered_map<std::string, std::unique_ptr<RVariationReader>>> fReadersPerVariation;
 
public:
   RVariationsWithReaders(std::shared_ptr<RVariationBase> variation, unsigned int nSlots);
   RVariationBase &GetVariation() const { return *fVariation; }
   RVariationReader &GetReader(unsigned int slot, const std::string &colName, const std::string &variationName);
};
 
} // namespace RDF
} // namespace Internal
} // namespace ROOT
 
#endif