ClosestPair2DBase.hh

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//STARTHEADER
// $Id: ClosestPair2DBase.hh 293 2006-08-17 19:38:38Z salam $
//
// Copyright (c) 2005-2006, Matteo Cacciari and Gavin Salam
//
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#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__