TreeReader.cxx

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/*
 Copyright (C) 2002-2022 CERN for the benefit of the ATLAS collaboration
 */
 
#include "TTreeFormula.h"
#include "TTreeFormulaManager.h"
#include "TString.h"
#include <iostream>
#include <TChain.h>
#include <vector>
#include "ISF_FastCaloSimParametrization/TreeReader.h"
 
//
//      Class TreeReader
//      TreeReader.cpp
//
 
//______________________________________________________________________________
/*
 Class for Tree reading through TFormula.
 ______________________________________________________________________________*/
 
 
TreeReader::TreeReader()
{
  // Default constructor.
  m_isChain = false;
  m_currentTree = -1;
  m_tree = nullptr;
  m_currentEntry = -1;
  m_entries = -1;
}
 
TreeReader::~TreeReader()
{
  m_formulae.clear();
}
 
 
//============================================================
TreeReader::TreeReader(TTree* n)
//============================================================
{
  // Constructor.
  m_tree = nullptr;
  m_entries = -1;
  SetTree(n);
}
 
//============================================================
void TreeReader::SetTree(TTree* n)
//============================================================
{
  // check for null pointer BEFORE trying to use it
  if(!n) return;
  // Set tree.
  m_tree = n;
  m_currentEntry = -1;
  m_formulae.clear();
  m_formulae["__DUMMY__"] = new TTreeFormula("__DUMMY__","0",m_tree);
  m_isChain = (n->IsA() == TClass::GetClass("TChain"));
  m_currentTree = 0;
  m_entries = (int) m_tree->GetEntries();
}
 
//=============================================================
double TreeReader::GetVariable(const char* c, int entry)
//============================================================
{
  // Get vaviable.
  // Return variable for a given entry (<0 -> current entry).
  if(entry>=0 && entry!=m_currentEntry) this->GetEntry(entry);
  std::string s = c;
  TTreeFormula *f = m_formulae[s];
  if(!f)
  {
    f = new TTreeFormula(c,c,m_tree);
    f->SetQuickLoad(kTRUE);
    //   fManager->Add(f);
    //   fManager->Sync();
    if(f->GetNdim()!=1)  //invalid fomula
    {
      delete f;
      f = m_formulae["__DUMMY__"];
      std::cout << "in [TreeReader] : " << s << " is not valid -> return 0" << std::endl;
    }
    //  else {f->Notify();}
    m_formulae[s] = f;
  }
  if(f == m_formulae["__DUMMY__"]) return 0;
  int valid = f->GetNdata()  ;
  if(!valid) return 0;
  // std::cout << "Evaluating formula : " << s << std::flush;
  // std::cout << "  " << f->EvalInstance(0) << std::endl;
  return f->EvalInstance(0);
}
 
 
//============================================================
int TreeReader::GetEntry(int entry)
//============================================================
{
  // Read a given entry in the buffer (-1 -> next entry).
  // Return kFALSE if not found.
  //   entry += 1;
  if(m_entries==0) return 0;
  if(entry==-1) entry = m_currentEntry+1;
  if(entry<m_entries)
  {
    int entryNumber = m_tree->GetEntryNumber(entry);
    if (entryNumber < 0) return 0;
    Long64_t localEntry = m_tree->LoadTree(entryNumber);
    if (localEntry < 0) return 0;
    m_currentEntry = entry;
    if(m_isChain) // check file change in chain
    {
      int I = static_cast<TChain*>(m_tree)->GetTreeNumber();
      if(I!=m_currentTree)
      {
        m_currentTree = I;
        //fManager->Clear();
        std::map<std::string, TTreeFormula*>::iterator itr = m_formulae.begin();
        std::map<std::string, TTreeFormula*>::iterator itrE= m_formulae.end();
        TTreeFormula* dummy = m_formulae["__DUMMY__"];
        for(;itr!=itrE;++itr)
        {
          if(itr->second!=dummy) itr->second->Notify(); //itr->second->UpdateFormulaLeaves();
        }
      }
    }
    return 1;
  }
  return 0;
}
 
 
 
//ClassImp(TreeReader) // Integrate this class into ROOT