Pair_Table.h

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//
//
// File: hitfit/private/Pair_Table.h
// Purpose: Helper for Fourvec_Constrainer.
// Created: Jul, 2000, sss, based on run 1 mass analysis code.
//
// Build a lookup table to speed up constraint evaluation.
//
// We have a set of constraints, which reference labels, like
//
//    (1 2) = 80
//    (1 2) = (3 4)
//
// We also have a Fourvec_Event, which has a set of objects, each of which
// has a label.  A label may correspond to multiple objects.
//
// We'll be evaluating the mass constraints by considering each
// pair of objects o_1 o_2 and finding its contribution to each
// constraint.  (We get pairs because the constraints are quadratic
// in the objects.)
//
// We build a Pair_Table by calling the constructor, giving it the event
// and the set of constraints.  We can then get back from it a list
// of Objpair's, each representing a pair of objects that are
// used in some constraint.  The Objpair will be able to tell us
// in which constraints the pair is used (and on which side of the
// equation).
//
// CMSSW File      : interface/Pair_Table.h
// Original Author : Scott Stuart Snyder <snyder@bnl.gov> for D0
// Imported to CMSSW by Haryo Sumowidagdo <Suharyo.Sumowidagdo@cern.ch>
//

#ifndef HITFIT_PAIR_TABLE_H
#define HITFIT_PAIR_TABLE_H

#include <vector>
#include <iosfwd>
#include "TopQuarkAnalysis/TopHitFit/interface/Constraint.h"
#include "TopQuarkAnalysis/TopHitFit/interface/Objpair.h"

namespace hitfit {

  class Fourvec_Event;

  class Pair_Table
  //
  // Purpose: Helper for Fourvec_Constrainer.
  //
  {
  public:
    // Constructor.  Give it the event and the list of constraints.
    Pair_Table(const std::vector<Constraint>& cv, const Fourvec_Event& ev);

    // The number of pairs in the table.

    int npairs() const;

    // Get one of the pairs from the table.
    const Objpair& get_pair(std::vector<Objpair>::size_type pairno) const;

  private:
    //The table of pairs.
    std::vector<Objpair> _pairs;
  };

  // Dump out the table.
  std::ostream& operator<<(std::ostream& s, const Pair_Table& p);

}  // namespace hitfit

#endif  // not PAIR_TABLE_H