source: svn/trunk/Utilities/ExRootAnalysis/interface/TSimpleBranch.h@ 13

#ifndef TSimpleBranch_h
#define TSimpleBranch_h

#include "TTree.h"
#include "TClonesArray.h"

class TBaseBranch
{
public:

  class OverFlow{};

  TBaseBranch() : fSize(0), fMaxSize(0), fData(0) {}

  ~TBaseBranch() { if(fData) delete fData; }

  void Clear()
  {
    fSize = 0;
    if(fData) fData->Clear();
  }

protected:

  Int_t fSize, fMaxSize;
  TClonesArray *fData;
};

//------------------------------------------------------------------------------

template<typename T>
class TSimpleBranch: public TBaseBranch
{
public:

  TSimpleBranch(const TString &name, Int_t maxsize, TTree *tree)
  {
    fMaxSize = maxsize;

    if(fMaxSize > 1)
    {
      tree->Branch(name + "_size", &fSize, name + "_size/I");
    }
    else
    {
      fMaxSize = 1;
    }

    T::Class()->IgnoreTObjectStreamer();
    fData = new TClonesArray(T::Class(), maxsize);
    fData->ExpandCreateFast(maxsize);

    tree->Branch(name, &fData, 64000, 2);
  }

  T *NewEntry()
  {
    if(fSize >= fMaxSize) throw OverFlow();
    return fData ? static_cast<T*>(fData->AddrAt(fSize++)) : 0;
  }
};

#endif /* TSimpleBranch */