ClosestPair2DBase.hh

//STARTHEADER
// $Id: ClosestPair2DBase.hh 1761 2010-09-16 10:43:18Z soyez $
//
// Copyright (c) 2005-2006, Matteo Cacciari and Gavin Salam
//
//----------------------------------------------------------------------
// This file is part of FastJet.
//
//  FastJet is free software; you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation; either version 2 of the License, or
//  (at your option) any later version.
//
//  The algorithms that underlie FastJet have required considerable
//  development and are described in hep-ph/0512210. If you use
//  FastJet as part of work towards a scientific publication, please
//  include a citation to the FastJet paper.
//
//  FastJet is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  along with FastJet; if not, write to the Free Software
//  Foundation, Inc.:
//      59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//----------------------------------------------------------------------
//ENDHEADER

#ifndef __FASTJET_CLOSESTPAIR2DBASE__HH__
#define __FASTJET_CLOSESTPAIR2DBASE__HH__

#include<vector>
#include "fastjet/internal/base.hh"

FASTJET_BEGIN_NAMESPACE      // defined in fastjet/internal/base.hh

//----------------------------------------------------------------------
class Coord2D {
public:
  double x, y;

  Coord2D() {};

  Coord2D(double a, double b): x(a), y(b) {};

  Coord2D operator-(const Coord2D & other) const {
    return Coord2D(x - other.x,  y - other.y);};

  Coord2D operator+(const Coord2D & other) const {
    return Coord2D(x + other.x,  y + other.y);};

  Coord2D operator*(double factor) const {return Coord2D(factor*x,factor*y);};
  friend Coord2D operator*(double factor, const Coord2D & coord) {
    return Coord2D(factor*coord.x,factor*coord.y);
  }

  Coord2D operator/(double divisor) const {
    return Coord2D(x / divisor,  y / divisor);};

  friend double distance2(const Coord2D & a, const Coord2D & b) {
    double dx = a.x - b.x, dy = a.y-b.y;
    return dx*dx+dy*dy;
  };
  double distance2(const Coord2D & b) const {
    double dx = x - b.x, dy = y-b.y;
    return dx*dx+dy*dy;
  };
};


//----------------------------------------------------------------------
class ClosestPair2DBase {
public:
  virtual void closest_pair(unsigned int & ID1, unsigned int & ID2, 
                            double & distance2) const = 0;
  
  virtual void remove(unsigned int ID) = 0;
 
  virtual unsigned int insert(const Coord2D & position) = 0;

  virtual unsigned int replace(unsigned int ID1, unsigned int ID2, 
                               const Coord2D & position) {
    remove(ID1); 
    remove(ID2); 
    unsigned new_ID = insert(position);
    return(new_ID);
  };

  virtual void replace_many(const std::vector<unsigned int> & IDs_to_remove,
                       const std::vector<Coord2D> & new_positions,
                       std::vector<unsigned int> & new_IDs) {
    for(unsigned i = 0; i < IDs_to_remove.size(); i++) {
      remove(IDs_to_remove[i]);}
    new_IDs.resize(0);
    for(unsigned i = 0; i < new_positions.size(); i++) {
      new_IDs.push_back(insert(new_positions[i]));}
  }

  virtual unsigned int size() = 0;

  virtual ~ClosestPair2DBase() {};
  
};


FASTJET_END_NAMESPACE

#endif // __FASTJET_CLOSESTPAIR2DBASE__HH__