RNTupleView.cxx

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/// \file RNTupleView.cxx
/// \ingroup NTuple ROOT7
/// \author Jakob Blomer <jblomer@cern.ch>
/// \date 2024-10-28
/// \warning This is part of the ROOT 7 prototype! It will change without notice. It might trigger earthquakes. Feedback
/// is welcome!
 
/*************************************************************************
 * Copyright (C) 1995-2024, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/
 
#include <ROOT/RError.hxx>
#include <ROOT/RFieldBase.hxx>
#include <ROOT/RNTupleDescriptor.hxx>
#include <ROOT/RNTupleView.hxx>
#include <ROOT/RPageStorage.hxx>
 
ROOT::Experimental::RNTupleGlobalRange
ROOT::Experimental::Internal::GetFieldRange(const RFieldBase &field, const RPageSource &pageSource)
{
   const auto &desc = pageSource.GetSharedDescriptorGuard().GetRef();
 
   auto fnGetPrincipalColumnId = [&desc](ROOT::DescriptorId_t fieldId) -> ROOT::DescriptorId_t {
      auto columnIterable = desc.GetColumnIterable(fieldId);
      return (columnIterable.size() > 0) ? columnIterable.begin()->GetPhysicalId() : ROOT::kInvalidDescriptorId;
   };
 
   auto columnId = fnGetPrincipalColumnId(field.GetOnDiskId());
   if (columnId == ROOT::kInvalidDescriptorId) {
      for (const auto &f : field) {
         columnId = fnGetPrincipalColumnId(f.GetOnDiskId());
         if (columnId != ROOT::kInvalidDescriptorId)
            break;
      }
   }
 
   if (columnId == ROOT::kInvalidDescriptorId) {
      return RNTupleGlobalRange(ROOT::kInvalidNTupleIndex, ROOT::kInvalidNTupleIndex);
   }
 
   auto arraySize = std::max(std::uint64_t(1), desc.GetFieldDescriptor(field.GetOnDiskId()).GetNRepetitions());
   return RNTupleGlobalRange(0, desc.GetNElements(columnId) / arraySize);
}