RNTupleBrowseProvider.cxx

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/*************************************************************************
 * 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.             *
 *************************************************************************/
 
#include <ROOT/Browsable/RElement.hxx>
#include <ROOT/Browsable/RProvider.hxx>
#include <ROOT/Browsable/RLevelIter.hxx>
#include <ROOT/Browsable/RItem.hxx>
 
#include <ROOT/RNTupleReader.hxx>
#include <ROOT/RNTupleDescriptor.hxx>
 
#include "TClass.h"
#include "RFieldHolder.hxx"
 
 
using namespace std::string_literals;
 
using namespace ROOT::Browsable;
 
 
// ==============================================================================================
 
/** \class RFieldElement
\ingroup rbrowser
\brief Browsing element representing of RField
\author Sergey Linev <S.Linev@gsi.de>
\date 2021-03-08
\warning This is part of the ROOT 7 prototype! It will change without notice. It might trigger earthquakes. Feedback is welcome!
*/
 
class RFieldElement : public RElement {
protected:
   std::shared_ptr<ROOT::Experimental::RNTupleReader> fNtplReader;
 
   std::string fParentName;
 
   ROOT::DescriptorId_t fFieldId;
 
public:
   RFieldElement(std::shared_ptr<ROOT::Experimental::RNTupleReader> ntplReader, const std::string &parent_name,
                 const ROOT::DescriptorId_t id)
      : RElement(), fNtplReader(ntplReader), fParentName(parent_name), fFieldId(id)
   {
   }
 
   virtual ~RFieldElement() = default;
 
   /** Name of RField */
   std::string GetName() const override
   {
      return fNtplReader->GetDescriptor().GetFieldDescriptor(fFieldId).GetFieldName();
   }
 
   /** Title of RField */
   std::string GetTitle() const override
   {
      auto &fld = fNtplReader->GetDescriptor().GetFieldDescriptor(fFieldId);
      return "RField name "s + fld.GetFieldName() + " type "s + fld.GetTypeName();
   }
 
   std::unique_ptr<RLevelIter> GetChildsIter() override;
 
   /** Return class of field  - for a moment using RNTuple class as dummy */
   const TClass *GetClass() const { return TClass::GetClass<ROOT::RNTuple>(); }
 
   std::unique_ptr<RHolder> GetObject() override
   {
      return std::make_unique<RFieldHolder>(fNtplReader, fParentName, fFieldId);
   }
 
   EActionKind GetDefaultAction() const override
   {
      auto range = fNtplReader->GetDescriptor().GetFieldIterable(fFieldId);
      if (range.begin() != range.end()) return kActNone;
      return kActDraw7;
   }
 
   bool IsCapable(EActionKind kind) const override
   {
      if ((kind == kActDraw6) || (kind == kActDraw7))
         return GetDefaultAction() == kActDraw7;
 
      return false;
   }
 
};
 
// ==============================================================================================
 
/** \class RNTupleElement
\ingroup rbrowser
\brief Browsing element representing of RNTuple
\author Sergey Linev <S.Linev@gsi.de>
\date 2021-03-08
\warning This is part of the ROOT 7 prototype! It will change without notice. It might trigger earthquakes. Feedback is welcome!
*/
 
class RNTupleElement : public RElement {
protected:
   std::shared_ptr<ROOT::Experimental::RNTupleReader> fNtplReader;
 
public:
   RNTupleElement(const std::string &ntplName, const std::string &filename)
   {
      fNtplReader = ROOT::Experimental::RNTupleReader::Open(ntplName, filename);
   }
 
   virtual ~RNTupleElement() = default;
 
   /** Returns true if no ntuple found */
   bool IsNull() const { return !fNtplReader; }
 
   /** Name of NTuple */
   std::string GetName() const override { return fNtplReader->GetDescriptor().GetName(); }
 
   /** Title of NTuple */
   std::string GetTitle() const override { return "RNTuple title"s; }
 
   /** Create iterator for childs elements if any */
   std::unique_ptr<RLevelIter> GetChildsIter() override;
 
   const TClass *GetClass() const { return TClass::GetClass<ROOT::RNTuple>(); }
 
   std::unique_ptr<RItem> CreateItem() const override
   {
      auto item = std::make_unique<RItem>(GetName(), -1, "sap-icon://table-chart");
      item->SetTitle(GetTitle());
      return item;
   }
 
   //EActionKind GetDefaultAction() const override;
 
   //bool IsCapable(EActionKind) const override;
};
 
 
// ==============================================================================================
 
/** \class RFieldsIterator
\ingroup rbrowser
\brief Iterator over RNTuple fields
\author Sergey Linev <S.Linev@gsi.de>
\date 2021-03-08
\warning This is part of the ROOT 7 prototype! It will change without notice. It might trigger earthquakes. Feedback is welcome!
*/
 
 
class RFieldsIterator : public RLevelIter {
 
   std::shared_ptr<ROOT::Experimental::RNTupleReader> fNtplReader;
   std::vector<ROOT::DescriptorId_t> fFieldIds;
   std::string fParentName;
   int fCounter{-1};
 
public:
   RFieldsIterator(std::shared_ptr<ROOT::Experimental::RNTupleReader> ntplReader,
                   std::vector<ROOT::DescriptorId_t> &&ids, const std::string &parent_name = ""s)
      : fNtplReader(ntplReader), fFieldIds(ids), fParentName(parent_name)
   {
   }
 
   virtual ~RFieldsIterator() = default;
 
   bool Next() override
   {
      return ++fCounter < (int) fFieldIds.size();
   }
 
   std::string GetItemName() const override
   {
      return fNtplReader->GetDescriptor().GetFieldDescriptor(fFieldIds[fCounter]).GetFieldName();
   }
 
   bool CanItemHaveChilds() const override
   {
      auto subrange = fNtplReader->GetDescriptor().GetFieldIterable(fFieldIds[fCounter]);
      return subrange.begin() != subrange.end();
   }
 
   /** Create element for the browser */
   std::unique_ptr<RItem> CreateItem() override
   {
      int nchilds = 0;
      for (auto &sub : fNtplReader->GetDescriptor().GetFieldIterable(fFieldIds[fCounter])) {
         (void)sub;
         nchilds++;
      }
 
      const auto &field = fNtplReader->GetDescriptor().GetFieldDescriptor(fFieldIds[fCounter]);
 
      auto item =
         std::make_unique<RItem>(field.GetFieldName(), nchilds, nchilds > 0 ? "sap-icon://split" : "sap-icon://e-care");
 
      item->SetTitle("RField name "s + field.GetFieldName() + " type "s + field.GetTypeName());
 
      return item;
   }
 
   std::shared_ptr<RElement> GetElement() override
   {
      return std::make_shared<RFieldElement>(fNtplReader, fParentName, fFieldIds[fCounter]);
   }
};
 
 
std::unique_ptr<RLevelIter> RFieldElement::GetChildsIter()
{
   std::vector<ROOT::DescriptorId_t> ids;
   std::string prefix;
 
   for (auto &f : fNtplReader->GetDescriptor().GetFieldIterable(fFieldId))
      ids.emplace_back(f.GetId());
 
   if (ids.size() == 0)
      return nullptr;
 
   prefix = fParentName;
   const auto &fld = fNtplReader->GetDescriptor().GetFieldDescriptor(fFieldId);
   prefix.append(fld.GetFieldName());
   prefix.append(".");
 
   return std::make_unique<RFieldsIterator>(fNtplReader, std::move(ids), prefix);
}
 
std::unique_ptr<RLevelIter> RNTupleElement::GetChildsIter()
{
   std::vector<ROOT::DescriptorId_t> ids;
 
   for (auto &f : fNtplReader->GetDescriptor().GetTopLevelFields())
      ids.emplace_back(f.GetId());
 
   if (ids.size() == 0) return nullptr;
   return std::make_unique<RFieldsIterator>(fNtplReader, std::move(ids));
}
 
 
// ==============================================================================================
 
/** \class RNTupleBrowseProvider
\ingroup rbrowser
\brief Provider for browsing RNTuple classes
\author Sergey Linev <S.Linev@gsi.de>
\date 2021-03-08
\warning This is part of the ROOT 7 prototype! It will change without notice. It might trigger earthquakes. Feedback is welcome!
*/
 
class RNTupleBrowseProvider : public RProvider {
 
public:
 
   RNTupleBrowseProvider()
   {
      RegisterNTupleFunc([](const std::string &tuple_name, const std::string &filename) -> std::shared_ptr<RElement> {
         auto elem = std::make_shared<RNTupleElement>(tuple_name, filename);
         return elem->IsNull() ? nullptr : elem;
      });
   }
 
   virtual ~RNTupleBrowseProvider()
   {
      RegisterNTupleFunc(nullptr);
   }
 
} newRNTupleBrowseProvider;