TTreeReaderValue.cxx

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// @(#)root/treeplayer:$Id$
// Author: Axel Naumann, 2011-09-28
 
/*************************************************************************
 * Copyright (C) 1995-2013, Rene Brun and Fons Rademakers and al.        *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/
 
#include "TTreeReaderValue.h"
 
#include "TTreeReader.h"
#include "TBranchClones.h"
#include "TBranchElement.h"
#include "TBranchRef.h"
#include "TBranchSTL.h"
#include "TBranchObject.h"
#include "TBranchProxyDirector.h"
#include "TClassEdit.h"
#include "TEnum.h"
#include "TFriendElement.h"
#include "TFriendProxy.h"
#include "TLeaf.h"
#include "TTreeProxyGenerator.h"
#include "TRegexp.h"
#include "TStreamerInfo.h"
#include "TStreamerElement.h"
#include "TNtuple.h"
#include "TROOT.h"
#include <vector>
 
// clang-format off
/**
 * \class TTreeReaderValue
 * \ingroup treeplayer
 * \brief An interface for reading values stored in ROOT columnar datasets
 *
 * The TTreeReaderValue is a type-safe tool to be used in association with a TTreeReader
 * to access the values stored in TTree, TNtuple and TChain datasets.
 * TTreeReaderValue can be also used to access collections such as `std::vector`s or TClonesArray
 * stored in columnar datasets but it is recommended to use TTreeReaderArray instead as it offers
 * several advantages.
 *
 * See the documentation of TTreeReader for more details and examples.
*/
// clang-format on
 
ClassImp(ROOT::Internal::TTreeReaderValueBase);
 
////////////////////////////////////////////////////////////////////////////////
/// Construct a tree value reader and register it with the reader object.
 
ROOT::Internal::TTreeReaderValueBase::TTreeReaderValueBase(TTreeReader* reader /*= 0*/,
                                                 const char* branchname /*= 0*/,
                                                 TDictionary* dict /*= 0*/):
   fHaveLeaf(false),
   fHaveStaticClassOffsets(false),
   fReadStatus(kReadNothingYet),
   fBranchName(branchname),
   fTreeReader(reader),
   fDict(dict)
{
   RegisterWithTreeReader();
}
 
////////////////////////////////////////////////////////////////////////////////
/// Copy-construct.
 
ROOT::Internal::TTreeReaderValueBase::TTreeReaderValueBase(const TTreeReaderValueBase& rhs):
   fHaveLeaf(rhs.fHaveLeaf),
   fHaveStaticClassOffsets(rhs.fHaveStaticClassOffsets),
   fReadStatus(rhs.fReadStatus),
   fSetupStatus(rhs.fSetupStatus),
   fBranchName(rhs.fBranchName),
   fLeafName(rhs.fLeafName),
   fTreeReader(rhs.fTreeReader),
   fDict(rhs.fDict),
   fProxy(rhs.fProxy),
   fLeaf(rhs.fLeaf),
   fStaticClassOffsets(rhs.fStaticClassOffsets)
{
   RegisterWithTreeReader();
}
 
////////////////////////////////////////////////////////////////////////////////
/// Copy-assign.
 
ROOT::Internal::TTreeReaderValueBase&
ROOT::Internal::TTreeReaderValueBase::operator=(const TTreeReaderValueBase& rhs) {
   if (&rhs != this) {
      fHaveLeaf = rhs.fHaveLeaf;
      fHaveStaticClassOffsets = rhs.fHaveStaticClassOffsets;
      fBranchName = rhs.fBranchName;
      fLeafName = rhs.fLeafName;
      if (fTreeReader != rhs.fTreeReader) {
         if (fTreeReader)
            fTreeReader->DeregisterValueReader(this);
         fTreeReader = rhs.fTreeReader;
         RegisterWithTreeReader();
      }
      fDict = rhs.fDict;
      fProxy = rhs.fProxy;
      fLeaf = rhs.fLeaf;
      fSetupStatus = rhs.fSetupStatus;
      fReadStatus = rhs.fReadStatus;
      fStaticClassOffsets = rhs.fStaticClassOffsets;
   }
   return *this;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Unregister from tree reader, cleanup.
 
ROOT::Internal::TTreeReaderValueBase::~TTreeReaderValueBase()
{
   if (fTreeReader) fTreeReader->DeregisterValueReader(this);
   R__ASSERT((fLeafName.Length() == 0 ) == !fHaveLeaf
          && "leafness disagreement");
   R__ASSERT(fStaticClassOffsets.empty() == !fHaveStaticClassOffsets
          && "static class offset disagreement");
}
 
////////////////////////////////////////////////////////////////////////////////
/// Register with tree reader.
 
void ROOT::Internal::TTreeReaderValueBase::RegisterWithTreeReader() {
   if (fTreeReader) {
      if (!fTreeReader->RegisterValueReader(this)) {
         fTreeReader = nullptr;
      }
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Try to read the value from the TBranchProxy, returns
/// the status of the read.
 
 
 
template <ROOT::Internal::TTreeReaderValueBase::BranchProxyRead_t Func>
ROOT::Internal::TTreeReaderValueBase::EReadStatus ROOT::Internal::TTreeReaderValueBase::ProxyReadTemplate()
{
   if ((fProxy->*Func)()) {
      fReadStatus = kReadSuccess;
   } else {
      fReadStatus = kReadError;
   }
   return fReadStatus;
}
 
ROOT::Internal::TTreeReaderValueBase::EReadStatus
ROOT::Internal::TTreeReaderValueBase::ProxyReadDefaultImpl() {
   if (!fProxy) return kReadNothingYet;
   if (fProxy->IsInitialized() || fProxy->Setup()) {
 
      using EReadType = ROOT::Detail::TBranchProxy::EReadType;
      using TBranchPoxy = ROOT::Detail::TBranchProxy;
 
      EReadType readtype = EReadType::kNoDirector;
      if (fProxy) readtype = fProxy->GetReadType();
 
      switch (readtype) {
         case EReadType::kNoDirector:
            fProxyReadFunc = &TTreeReaderValueBase::ProxyReadTemplate<&TBranchPoxy::ReadNoDirector>;
            break;
         case EReadType::kReadParentNoCollection:
            fProxyReadFunc = &TTreeReaderValueBase::ProxyReadTemplate<&TBranchPoxy::ReadParentNoCollection>;
            break;
         case EReadType::kReadParentCollectionNoPointer:
            fProxyReadFunc = &TTreeReaderValueBase::ProxyReadTemplate<&TBranchPoxy::ReadParentCollectionNoPointer>;
            break;
         case EReadType::kReadParentCollectionPointer:
            fProxyReadFunc = &TTreeReaderValueBase::ProxyReadTemplate<&TBranchPoxy::ReadParentCollectionPointer>;
            break;
         case EReadType::kReadNoParentNoBranchCountCollectionPointer:
            fProxyReadFunc = &TTreeReaderValueBase::ProxyReadTemplate<&TBranchPoxy::ReadNoParentNoBranchCountCollectionPointer>;
            break;
         case EReadType::kReadNoParentNoBranchCountCollectionNoPointer:
            fProxyReadFunc = &TTreeReaderValueBase::ProxyReadTemplate<&TBranchPoxy::ReadNoParentNoBranchCountCollectionNoPointer>;
            break;
         case EReadType::kReadNoParentNoBranchCountNoCollection:
            fProxyReadFunc = &TTreeReaderValueBase::ProxyReadTemplate<&TBranchPoxy::ReadNoParentNoBranchCountNoCollection>;
            break;
         case EReadType::kReadNoParentBranchCountCollectionPointer:
            fProxyReadFunc = &TTreeReaderValueBase::ProxyReadTemplate<&TBranchPoxy::ReadNoParentBranchCountCollectionPointer>;
            break;
         case EReadType::kReadNoParentBranchCountCollectionNoPointer:
            fProxyReadFunc = &TTreeReaderValueBase::ProxyReadTemplate<&TBranchPoxy::ReadNoParentBranchCountCollectionNoPointer>;
            break;
         case EReadType::kReadNoParentBranchCountNoCollection:
            fProxyReadFunc = &TTreeReaderValueBase::ProxyReadTemplate<&TBranchPoxy::ReadNoParentBranchCountNoCollection>;
            break;
         case EReadType::kDefault:
            // intentional fall through.
         default: fProxyReadFunc = &TTreeReaderValueBase::ProxyReadDefaultImpl;
      }
      return (this->*fProxyReadFunc)();
   }
 
   // If somehow the Setup fails call the original Read to
   // have the proper error handling (message only if the Setup fails
   // and the current proxy entry is different than the TTree's current entry)
   if (fProxy->Read()) {
      fReadStatus = kReadSuccess;
   } else {
      fReadStatus = kReadError;
   }
   return fReadStatus;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Stringify the template argument.
std::string ROOT::Internal::TTreeReaderValueBase::GetElementTypeName(const std::type_info& ti) {
   int err;
   char* buf = TClassEdit::DemangleTypeIdName(ti, err);
   std::string ret = buf;
   free(buf);
   return ret;
}
 
////////////////////////////////////////////////////////////////////////////////
/// The TTreeReader has switched to a new TTree. Update the leaf.
 
void ROOT::Internal::TTreeReaderValueBase::NotifyNewTree(TTree* newTree) {
   // Since the TTree structure might have change, let's make sure we
   // use the right reading function.
   fProxyReadFunc = &TTreeReaderValueBase::ProxyReadDefaultImpl;
 
   if (!fHaveLeaf || !newTree) {
      fLeaf = nullptr;
      return;
   }
 
   TBranch *myBranch = newTree->GetBranch(fBranchName);
 
   if (!myBranch) {
      fReadStatus = kReadError;
      Error("TTreeReaderValueBase::GetLeaf()", "Unable to get the branch from the tree");
      return;
   }
 
   fLeaf = myBranch->GetLeaf(fLeafName);
   if (!fLeaf) {
      Error("TTreeReaderValueBase::GetLeaf()", "Failed to get the leaf from the branch");
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Returns the memory address of the object being read.
 
void* ROOT::Internal::TTreeReaderValueBase::GetAddress() {
   if (ProxyRead() != kReadSuccess) return 0;
 
   if (fHaveLeaf){
      if (GetLeaf()){
         return fLeaf->GetValuePointer();
      }
      else {
         fReadStatus = kReadError;
         Error("TTreeReaderValueBase::GetAddress()", "Unable to get the leaf");
         return 0;
      }
   }
   if (fHaveStaticClassOffsets){ // Follow all the pointers
      Byte_t *address = (Byte_t*)fProxy->GetWhere();
 
      for (unsigned int i = 0; i < fStaticClassOffsets.size() - 1; ++i){
         address = *(Byte_t**)(address + fStaticClassOffsets[i]);
      }
 
      return address + fStaticClassOffsets.back();
   }
   return (Byte_t*)fProxy->GetWhere();
}
 
////////////////////////////////////////////////////////////////////////////////
/// \brief Search a branch the name of which contains a "."
/// \param[out] myLeaf The leaf identified by the name if found (can be untouched).
/// \param[out] branchActualType Dictionary associated to the type of the leaf (can be untouched).
/// \param[out] errMsg The error message (can be untouched).
/// \return The address of the branch if found, nullptr otherwise
/// This method allows to efficiently search for branches which have names which
/// contain "dots", for example "w.v.a" or "v.a".
/// Therefore, it allows to support names such as v.a where the branch was
/// created with this syntax:
/// ```{.cpp}
/// myTree->Branch("v", &v, "a/I:b:/I")
/// ```
/// The method has some side effects, namely it can modify fSetupStatus, fProxy
/// and fStaticClassOffsets/fHaveStaticClassOffsets.
TBranch *ROOT::Internal::TTreeReaderValueBase::SearchBranchWithCompositeName(TLeaf *&myLeaf, TDictionary *&branchActualType, std::string &errMsg)
{
   TRegexp leafNameExpression ("\\.[a-zA-Z0-9_]+$");
   TString leafName (fBranchName(leafNameExpression));
   TString branchName = fBranchName(0, fBranchName.Length() - leafName.Length());
   auto branch = fTreeReader->GetTree()->GetBranch(branchName);
   if (!branch){
      std::vector<TString> nameStack;
      nameStack.push_back(TString()); //Trust me
      nameStack.push_back(leafName.Strip(TString::kBoth, '.'));
      leafName = branchName(leafNameExpression);
      branchName = branchName(0, branchName.Length() - leafName.Length());
 
      branch = fTreeReader->GetTree()->GetBranch(branchName);
      if (!branch) branch = fTreeReader->GetTree()->GetBranch(branchName + ".");
      if (leafName.Length()) nameStack.push_back(leafName.Strip(TString::kBoth, '.'));
 
      while (!branch && branchName.Contains(".")){
         leafName = branchName(leafNameExpression);
         branchName = branchName(0, branchName.Length() - leafName.Length());
         branch = fTreeReader->GetTree()->GetBranch(branchName);
         if (!branch) branch = fTreeReader->GetTree()->GetBranch(branchName + ".");
         nameStack.push_back(leafName.Strip(TString::kBoth, '.'));
      }
 
      if (branch && branch->IsA() == TBranchElement::Class()){
         TBranchElement *myBranchElement = (TBranchElement*)branch;
 
         TString traversingBranch = nameStack.back();
         nameStack.pop_back();
 
         bool found = true;
 
         TDataType *finalDataType = 0;
 
         std::vector<Long64_t> offsets;
         Long64_t offset = 0;
         TClass *elementClass = 0;
 
         TObjArray *myObjArray = myBranchElement->GetInfo()->GetElements();
         TVirtualStreamerInfo *myInfo = myBranchElement->GetInfo();
 
         while (nameStack.size() && found){
            found = false;
 
            for (int i = 0; i < myObjArray->GetEntries(); ++i){
 
               TStreamerElement *tempStreamerElement = (TStreamerElement*)myObjArray->At(i);
 
               if (!strcmp(tempStreamerElement->GetName(), traversingBranch.Data())){
                  offset += myInfo->GetElementOffset(i);
 
                  traversingBranch = nameStack.back();
                  nameStack.pop_back();
 
                  elementClass = tempStreamerElement->GetClass();
                  if (elementClass) {
                     myInfo = elementClass->GetStreamerInfo(0);
                     myObjArray = myInfo->GetElements();
                     // FIXME: this is odd, why is 'i' not also reset????
                  }
                  else {
                     finalDataType = TDataType::GetDataType((EDataType)tempStreamerElement->GetType());
                     if (!finalDataType) {
                        TDictionary* seType = TDictionary::GetDictionary(tempStreamerElement->GetTypeName());
                        if (seType && seType->IsA() == TDataType::Class()) {
                           finalDataType = TDataType::GetDataType((EDataType)((TDataType*)seType)->GetType());
                        }
                     }
                  }
 
                  if (tempStreamerElement->IsaPointer()){
                     offsets.push_back(offset);
                     offset = 0;
                  }
 
                  found = true;
                  break;
               }
            }
         }
 
         offsets.push_back(offset);
 
         if (found){
            fStaticClassOffsets = offsets;
            fHaveStaticClassOffsets = true;
 
            if (fDict != finalDataType && fDict != elementClass){
               errMsg = "Wrong data type ";
               errMsg += finalDataType ? finalDataType->GetName() : elementClass ? elementClass->GetName() : "UNKNOWN";
               fSetupStatus = kSetupMismatch;
               fProxy = 0;
               return nullptr;
            }
         }
      }
 
 
      if (!fHaveStaticClassOffsets) {
         errMsg = "The tree does not have a branch called ";
         errMsg += fBranchName;
         errMsg += ". You could check with TTree::Print() for available branches.";
         fSetupStatus = kSetupMissingBranch;
         fProxy = 0;
         return nullptr;
      }
   }
   else {
      myLeaf = branch->GetLeaf(TString(leafName(1, leafName.Length())));
      if (!myLeaf){
         errMsg = "The tree does not have a branch, nor a sub-branch called ";
         errMsg += fBranchName;
         errMsg += ". You could check with TTree::Print() for available branches.";
         fSetupStatus = kSetupMissingBranch;
         fProxy = 0;
         return nullptr;
      }
      else {
         TDataType *tempDict = gROOT->GetType(myLeaf->GetTypeName());
         if (tempDict && fDict->IsA() == TDataType::Class() && tempDict->GetType() == ((TDataType*)fDict)->GetType()) {
            //fLeafOffset = myLeaf->GetOffset() / 4;
            branchActualType = fDict;
            fLeaf = myLeaf;
            fBranchName = branchName;
            fLeafName = leafName(1, leafName.Length());
            fHaveLeaf = fLeafName.Length() > 0;
            fSetupStatus = kSetupMatchLeaf;
         }
         else {
            errMsg = "Leaf of type ";
            errMsg += myLeaf->GetTypeName();
            errMsg += " cannot be read by TTreeReaderValue<";
            errMsg += fDict->GetName();
            errMsg += ">.";
            fSetupStatus = kSetupMismatch;
            return nullptr;
         }
      }
   }
 
   return branch;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Create the proxy object for our branch.
 
void ROOT::Internal::TTreeReaderValueBase::CreateProxy() {
 
   constexpr const char* errPrefix = "TTreeReaderValueBase::CreateProxy()";
 
   if (fProxy) {
      return;
   }
 
   fSetupStatus = kSetupInternalError; // Fallback; set to something concrete below.
   if (!fTreeReader) {
      Error(errPrefix, "TTreeReader object not set / available for branch %s!",
            fBranchName.Data());
      fSetupStatus = kSetupTreeDestructed;
      return;
   }
 
   auto branchFromFullName = fTreeReader->GetTree()->GetBranch(fBranchName);
   if (branchFromFullName == nullptr) // use the slower but more thorough FindBranch as fallback
      branchFromFullName = fTreeReader->GetTree()->FindBranch(fBranchName);
 
   if (!fDict) {
      const char* brDataType = "{UNDETERMINED}";
      if (branchFromFullName) {
         TDictionary* brDictUnused = 0;
         brDataType = GetBranchDataType(branchFromFullName, brDictUnused, fDict);
      }
      Error(errPrefix, "The template argument type T of %s accessing branch %s (which contains data of type %s) is not known to ROOT. You will need to create a dictionary for it.",
            GetDerivedTypeName(), fBranchName.Data(), brDataType);
      fSetupStatus = kSetupMissingDictionary;
      return;
   }
 
   // Search for the branchname, determine what it contains, and wire the
   // TBranchProxy representing it to us so we can access its data.
 
   TNamedBranchProxy* namedProxy = fTreeReader->FindProxy(fBranchName);
   if (namedProxy && namedProxy->GetDict() == fDict) {
      fProxy = namedProxy->GetProxy();
      // But go on: we need to set fLeaf etc!
   }
 
   const std::string originalBranchName = fBranchName.Data();
 
   TLeaf *myLeaf = nullptr;
   TDictionary* branchActualType = nullptr;
   std::string errMsg;
 
   TBranch *branch = nullptr;
   // If the branch name contains at least a dot, we analyse it in detail and
   // we give priority to the branch identified over the one which is found
   // with the TTree::GetBranch method. This allows to correctly pick the desired
   // branch in cases where a TTree has two branches, one called for example
   // "w.v.a" and another one called "v.a".
   // This behaviour is described in ROOT-9312.
   if (fBranchName.Contains(".")) {
      branch = SearchBranchWithCompositeName(myLeaf, branchActualType, errMsg);
      // In rare cases where leaves contain the name of the branch as part of their
      // name and a dot in the branch name (such as: branch "b." and leaf "b.a")
      // the previous method may return the branch name ("b.") rather than the
      // leaf name ("b.a") as we expect.
      // For these cases, we do not have to give priority to the previously
      // identified branch since we are in a different situation.
      // This behaviour is described in ROOT-9757.
      if (branch && branch->IsA() == TBranchElement::Class() && branchFromFullName){
        branch = branchFromFullName;
        fStaticClassOffsets = {};
        fHaveStaticClassOffsets = false;
      }
   }
 
   if (!branch) {
      // We had an error, the branch name had no "." or we simply did not find anything.
      // We check if we had a branch found with the full name with a dot in it.
      branch = branchFromFullName;
      if (!branch) {
         // Also that one was empty. We need to error out. We do it properly: at
         // first we check if the routine to find branches with names with a "."
         // provided a specific error message. If not, we go with a generic message.
         if (errMsg.empty()) {
            errMsg = "The tree does not have a branch called ";
            errMsg += fBranchName.Data();
            errMsg += ". You could check with TTree::Print() for available branches.";
         }
#if !defined(_MSC_VER)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wformat-security"
#endif
         Error(errPrefix, errMsg.c_str());
#if !defined(_MSC_VER)
#pragma GCC diagnostic pop
#endif
         return;
      } else {
         // The branch found with the simplest search approach was successful.
         // We reset the state, we continue
         fSetupStatus = kSetupInternalError;
         fStaticClassOffsets = {};
         fHaveStaticClassOffsets = false;
      }
   }
 
   if (!myLeaf && !fHaveStaticClassOffsets) {
      // The following two lines cannot be swapped. The GetBranchDataType can
      // change the value of branchActualType
      const char* branchActualTypeName = GetBranchDataType(branch, branchActualType, fDict);
      if (!branchActualType) {
         Error(errPrefix, "The branch %s contains data of type %s, which does not have a dictionary.",
               fBranchName.Data(), branchActualTypeName ? branchActualTypeName : "{UNDETERMINED TYPE}");
         fProxy = 0;
         return;
      }
 
      // Check if the dictionaries are TClass instances and if there is inheritance
      // because in this case, we can read the values.
      auto dictAsClass = dynamic_cast<TClass*>(fDict);
      auto branchActualTypeAsClass = dynamic_cast<TClass*>(branchActualType);
      auto inheritance = dictAsClass && branchActualTypeAsClass && branchActualTypeAsClass->InheritsFrom(dictAsClass);
 
      if (fDict != branchActualType && !inheritance) {
         TDataType *dictdt = dynamic_cast<TDataType*>(fDict);
         TDataType *actualdt = dynamic_cast<TDataType*>(branchActualType);
         TEnum *dictenum = dynamic_cast<TEnum*>(fDict);
         TEnum *actualenum = dynamic_cast<TEnum*>(branchActualType);
         bool complainAboutMismatch = true;
         if (dictdt && actualdt) {
            if (dictdt->GetType() > 0 && dictdt->GetType() == actualdt->GetType()) {
               // Same numerical type but different TDataType, likely Long64_t
               complainAboutMismatch = false;
            } else if ((actualdt->GetType() == kDouble32_t && dictdt->GetType() == kDouble_t)
                       || (actualdt->GetType() == kFloat16_t && dictdt->GetType() == kFloat_t)) {
               // Double32_t and Float16_t never "decay" to their underlying type;
               // we need to identify them manually here (ROOT-8731).
               complainAboutMismatch = false;
            }
         } else if ( (dictdt || dictenum) && (actualdt || actualenum) ) {
            if ((dictdt && dictdt->GetType() == kInt_t && actualenum)
                ||(actualdt && actualdt->GetType() == kInt_t && dictenum))
               complainAboutMismatch = false;
         }
         if (complainAboutMismatch) {
            Error(errPrefix,
                  "The branch %s contains data of type %s. It cannot be accessed by a TTreeReaderValue<%s>",
                  fBranchName.Data(), branchActualType->GetName(),
                  fDict->GetName());
            return;
         }
      }
   }
 
   if (!namedProxy) {
      // Search for the branchname, determine what it contains, and wire the
      // TBranchProxy representing it to us so we can access its data.
      // A proxy for branch must not have been created before (i.e. check
      // fProxies before calling this function!)
 
      TString membername;
 
      bool isTopLevel = branch->GetMother() == branch;
      if (!isTopLevel) {
         membername = strrchr(branch->GetName(), '.');
         if (membername.IsNull()) {
            membername = branch->GetName();
         }
      }
      auto director = fTreeReader->fDirector;
      // Determine if the branch is actually in a Friend TTree and if so which.
      if (branch->GetTree() != fTreeReader->GetTree()->GetTree()) {
         // It is in a friend, let's find the 'index' in the list of friend ...
         int index = -1;
         int current = 0;
         TFriendElement *fe_found = nullptr;
         for(auto fe : TRangeDynCast<TFriendElement>( fTreeReader->GetTree()->GetTree()->GetListOfFriends())) {
            if (branch->GetTree() == fe->GetTree()) {
               index = current;
               fe_found = fe;
               break;
            }
            ++current;
         }
         if (index == -1) {
            Error(errPrefix, "The branch %s is contained in a Friend TTree that is not directly attached to the main.\n"
                  "This is not yet supported by TTreeReader.",
                  fBranchName.Data());
            return;
         }
         const char *localBranchName =  originalBranchName.c_str();
         if (branch != branch->GetTree()->GetBranch(localBranchName)) {
            // Try removing the name of the TTree.
            auto len = strlen( branch->GetTree()->GetName());
            if (strncmp(localBranchName, branch->GetTree()->GetName(), len) == 0
                && localBranchName[len] == '.'
                && branch != branch->GetTree()->GetBranch(localBranchName+len+1)) {
               localBranchName = localBranchName + len + 1;
            } else {
               len = strlen(fe_found->GetName());
               if (strncmp(localBranchName, fe_found->GetName(), len) == 0
                  && localBranchName[len] == '.'
                  && branch != branch->GetTree()->GetBranch(localBranchName+len+1)) {
                  localBranchName = localBranchName + len + 1;
               }
            }
         }
         TFriendProxy *feproxy = nullptr;
         if ((size_t)index < fTreeReader->fFriendProxies.size()) {
            feproxy = fTreeReader->fFriendProxies.at(index);
         }
         if (!feproxy) {
            feproxy = new ROOT::Internal::TFriendProxy(director, fTreeReader->GetTree(), index);
            fTreeReader->fFriendProxies.resize(index+1);
            fTreeReader->fFriendProxies.at(index) = feproxy;
         }
         namedProxy = new TNamedBranchProxy(feproxy->GetDirector(), branch, originalBranchName.c_str(), branch->GetName(), membername);
      } else {
         namedProxy = new TNamedBranchProxy(director, branch, originalBranchName.c_str(), membername);
      }
      fTreeReader->AddProxy(namedProxy);
   }
 
   // Update named proxy's dictionary
   if (!namedProxy->GetDict())
      namedProxy->SetDict(fDict);
 
   fProxy = namedProxy->GetProxy();
   if (fProxy) {
      fSetupStatus = kSetupMatch;
   } else {
      fSetupStatus = kSetupMismatch;
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Retrieve the type of data stored by branch; put its dictionary into
/// dict, return its type name. If no dictionary is available, at least
/// its type name should be returned.
 
const char* ROOT::Internal::TTreeReaderValueBase::GetBranchDataType(TBranch* branch,
                                           TDictionary* &dict,
                                           TDictionary const *curDict)
{
   dict = 0;
   if (branch->IsA() == TBranchElement::Class()) {
      TBranchElement* brElement = (TBranchElement*)branch;
 
      auto ResolveTypedef = [&]() -> void {
         if (dict->IsA() != TDataType::Class())
            return;
         // Resolve the typedef.
         dict = TDictionary::GetDictionary(((TDataType*)dict)->GetTypeName());
         if (dict->IsA() != TDataType::Class()) {
            // Might be a class.
            if (dict != curDict) {
               dict = TClass::GetClass(brElement->GetTypeName());
            }
            if (dict != curDict) {
               dict = brElement->GetCurrentClass();
            }
         }
      };
 
      if (brElement->GetType() == TBranchElement::kSTLNode ||
            brElement->GetType() == TBranchElement::kLeafNode ||
            brElement->GetType() == TBranchElement::kObjectNode) {
 
         TStreamerInfo *streamerInfo = brElement->GetInfo();
         Int_t id = brElement->GetID();
 
         if (id >= 0){
            TStreamerElement *element = (TStreamerElement*)streamerInfo->GetElements()->At(id);
            if (element->IsA() == TStreamerSTL::Class()){
               TStreamerSTL *myStl = (TStreamerSTL*)element;
               dict = myStl->GetClass();
               return 0;
            }
         }
 
         if (brElement->GetType() == 3 || brElement->GetType() == 4) {
            dict = brElement->GetCurrentClass();
            return brElement->GetTypeName();
         }
 
         if (brElement->GetTypeName())
            dict = TDictionary::GetDictionary(brElement->GetTypeName());
 
         if (dict)
            ResolveTypedef();
         else
            dict = brElement->GetCurrentClass();
 
         return brElement->GetTypeName();
      } else if (brElement->GetType() == TBranchElement::kClonesNode) {
         dict = TClonesArray::Class();
         return "TClonesArray";
      } else if (brElement->GetType() == 31
                 || brElement->GetType() == 41) {
         // it's a member, extract from GetClass()'s streamer info
         Error("TTreeReaderValueBase::GetBranchDataType()", "Must use TTreeReaderArray to access a member of an object that is stored in a collection.");
      } else if (brElement->GetType() == -1 && brElement->GetTypeName()) {
         dict = TDictionary::GetDictionary(brElement->GetTypeName());
         ResolveTypedef();
         return brElement->GetTypeName();
      } else {
         Error("TTreeReaderValueBase::GetBranchDataType()", "Unknown type and class combination: %i, %s", brElement->GetType(), brElement->GetClassName());
      }
      return 0;
   } else if (branch->IsA() == TBranch::Class()
              || branch->IsA() == TBranchObject::Class()
              || branch->IsA() == TBranchSTL::Class()) {
      if (branch->GetTree()->IsA() == TNtuple::Class()){
         dict = TDataType::GetDataType(kFloat_t);
         return dict->GetName();
      }
      const char* dataTypeName = branch->GetClassName();
      if ((!dataTypeName || !dataTypeName[0])
          && branch->IsA() == TBranch::Class()) {
         TLeaf *myLeaf = branch->GetLeaf(branch->GetName());
         if (!myLeaf) {
            myLeaf = branch->FindLeaf(branch->GetName());
         }
         if (!myLeaf && branch->GetListOfLeaves()->GetEntries() == 1) {
            myLeaf = static_cast<TLeaf *>(branch->GetListOfLeaves()->UncheckedAt(0));
         }
         if (myLeaf){
            TDictionary *myDataType = TDictionary::GetDictionary(myLeaf->GetTypeName());
            if (myDataType && myDataType->IsA() == TDataType::Class()){
               if (myLeaf->GetLeafCount() != nullptr || myLeaf->GetLenStatic() > 1) {
                  Error("TTreeReaderValueBase::GetBranchDataType()", "Must use TTreeReaderArray to read branch %s: it contains an array or a collection.", branch->GetName());
                  return 0;
               }
               dict = TDataType::GetDataType((EDataType)((TDataType*)myDataType)->GetType());
               return myLeaf->GetTypeName();
            }
         }
 
         // leaflist. Can't represent.
         Error("TTreeReaderValueBase::GetBranchDataType()", "The branch %s was created using a leaf list and cannot be represented as a C++ type. Please access one of its siblings using a TTreeReaderArray:", branch->GetName());
         TIter iLeaves(branch->GetListOfLeaves());
         TLeaf* leaf = 0;
         while ((leaf = (TLeaf*) iLeaves())) {
            Error("TTreeReaderValueBase::GetBranchDataType()", "   %s.%s", branch->GetName(), leaf->GetName());
         }
         return 0;
      }
      if (dataTypeName) dict = TDictionary::GetDictionary(dataTypeName);
      return dataTypeName;
   } else if (branch->IsA() == TBranchClones::Class()) {
      dict = TClonesArray::Class();
      return "TClonesArray";
   } else if (branch->IsA() == TBranchRef::Class()) {
      // Can't represent.
      Error("TTreeReaderValueBase::GetBranchDataType()", "The branch %s is a TBranchRef and cannot be represented as a C++ type.", branch->GetName());
      return 0;
   } else {
      Error("TTreeReaderValueBase::GetBranchDataType()", "The branch %s is of type %s - something that is not handled yet.", branch->GetName(), branch->IsA()->GetName());
      return 0;
   }
 
   return 0;
}