/afs/cern.ch/work/a/aaltunda/public/www/CMSSW_6_2_5/src/RecoTauTag/RecoTau/interface/RecoTauCrossCleaning.h

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#ifndef RecoTauTag_RecoTau_RecoTauCrossCleaning_h
#define RecoTauTag_RecoTau_RecoTauCrossCleaning_h

#include <boost/foreach.hpp>

#include "DataFormats/TauReco/interface/RecoTauPiZero.h"
#include "CommonTools/CandUtils/interface/AddFourMomenta.h"

namespace reco { namespace tau { namespace xclean {

template<typename PtrIter>
class CrossCleanPiZeros {
  public:
    typedef std::vector<RecoTauPiZero> PiZeroList;

    CrossCleanPiZeros(PtrIter signalTracksBegin, PtrIter signalTracksEnd) {
      // Get the list of objects we need to clean
      for (PtrIter i = signalTracksBegin; i != signalTracksEnd; ++i) {
        toRemove_.insert(reco::CandidatePtr(*i));
      }
    }

    PiZeroList operator()(const std::vector<RecoTauPiZero> &input) const {
      PiZeroList output;
      output.reserve(input.size());
      BOOST_FOREACH(const RecoTauPiZero& piZero, input) {
        const RecoTauPiZero::daughters& daughters = piZero.daughterPtrVector();
        std::set<reco::CandidatePtr> toCheck(daughters.begin(), daughters.end());
        std::vector<reco::CandidatePtr> cleanDaughters;
        std::set_difference(toCheck.begin(), toCheck.end(),
            toRemove_.begin(), toRemove_.end(), std::back_inserter(cleanDaughters));
        if (cleanDaughters.size() == daughters.size()) {
          // We don't need to clean anything, just add a pointer to current cnad
          output.push_back(piZero);
        } else {
          // Otherwise rebuild
          RecoTauPiZero newPiZero = piZero;
          newPiZero.clearDaughters();
          // Add our cleaned daughters.
          BOOST_FOREACH(const reco::CandidatePtr& ptr, cleanDaughters) {
            newPiZero.addDaughter(ptr);
          }
          // Check if the pizero is not empty.  If empty, forget it.
          if (newPiZero.numberOfDaughters()) {
            p4Builder_.set(newPiZero);
            // Make our ptr container take ownership.
            output.push_back(newPiZero);
          }
        }
      }
      return output;
    }

  private:
    AddFourMomenta p4Builder_;
    std::set<reco::CandidatePtr> toRemove_;
};

// Predicate to filter PFCandPtrs (and those compatible to this type) by the
// particle id
class FilterPFCandByParticleId {
  public:
    FilterPFCandByParticleId(int particleId):
      id_(particleId){};
    template<typename PFCandCompatiblePtrType>
      bool operator()(const PFCandCompatiblePtrType& ptr) const {
        PFCandidatePtr pfptr(ptr);
        return ptr->particleId() == id_;
      }
  private:
    int id_;
};

// Determine if a candidate is contained in a collection of PiZeros.
class CrossCleanPtrs {
  public:
    CrossCleanPtrs(const std::vector<reco::RecoTauPiZero> &piZeros) {
      BOOST_FOREACH(const PFCandidatePtr &ptr, flattenPiZeros(piZeros)) {
        toRemove_.insert(CandidatePtr(ptr));
      }
    }

    template<typename AnyPtr>
    bool operator() (const AnyPtr& ptr) const {
      if (toRemove_.count(CandidatePtr(ptr)))
        return false;
      else
        return true;
    }
  private:
    std::set<CandidatePtr> toRemove_;
};

// Create the AND of two predicates
template<typename P1, typename P2>
class PredicateAND {
  public:
    PredicateAND(const P1& p1, const P2& p2):
      p1_(p1),p2_(p2){}

    template<typename AnyPtr>
    bool operator() (const AnyPtr& ptr) const {
      return p1_(ptr) && p2_(ptr);
    }
  private:
    const P1& p1_;
    const P2& p2_;
};

// Helper function to infer template type
template<typename P1, typename P2>
PredicateAND<P1, P2> makePredicateAND(const P1& p1, const P2& p2) {
  return PredicateAND<P1, P2>(p1, p2);
}

}}}
#endif