Direction.h

// -*- C++ -*-
//
// Direction.h is a part of ThePEG - Toolkit for HEP Event Generation
// Copyright (C) 1999-2007 Leif Lonnblad
//
// ThePEG is licenced under version 2 of the GPL, see COPYING for details.
// Please respect the MCnet academic guidelines, see GUIDELINES for details.
//
#ifndef ThePEG_Direction_H
#define ThePEG_Direction_H
// This is the declaration of the Direction class.

#include "ThePEG/Config/ThePEG.h"
#include "Direction.xh"

namespace ThePEG {

template <int I>
class Direction {

public:

  enum Dir { Neg = -1, 
             Negative = -1, 
             Undefined = 0, 
             Pos = 1, 
             Positive = 1 
  };

public:

  Direction(Dir newDirection)
    
  {
    if ( theDirection != Undefined ) throw MultipleDirectionException(I);
    if ( newDirection == Positive ) theDirection = Positive;
    else if ( newDirection == Negative ) theDirection = Negative;
    else throw UndefinedDirectionException(I);
  }

  Direction(double rnd)
  {
    if ( theDirection != Undefined ) throw MultipleDirectionException(I);
    theDirection = rnd > 0 ? Positive : Negative;
  }

  Direction(bool p)
  {
    if ( theDirection != Undefined ) throw MultipleDirectionException(I);
    theDirection = p ? Positive : Negative;
  }

  ~Direction() { theDirection = Undefined; }

public:

  static void set(Dir newDirection) {
    if ( newDirection == Positive ) theDirection = Positive;
    else if ( newDirection == Negative ) theDirection = Negative;
    else throw UndefinedDirectionException(I);
  }

  static void reverse() {
    theDirection = pos() ? Negative : Positive;
  }

  static bool pos() {
    return dir() == Positive;
  }

  static bool neg() {
    return dir() == Negative;
  }

  static Dir dir() {
    if ( theDirection == Undefined ) throw UndefinedDirectionException(I);
    return theDirection;
  }

private:

  static Dir theDirection;

private:

  Direction();
  Direction(const Direction &);
  Direction & operator=(const Direction &);

};

template<int I>
typename Direction<I>::Dir Direction<I>::theDirection = Direction<I>::Undefined;

}

#endif /* ThePEG_Direction_H */

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