FunctionOfPseudoJet.hh

#ifndef __FASTJET_FUNCTION_OF_PSEUDOJET_HH__
#define __FASTJET_FUNCTION_OF_PSEUDOJET_HH__

//STARTHEADER
// $Id: FunctionOfPseudoJet.hh 2213 2011-06-02 21:05:47Z salam $
//
// Copyright (c) 2005-2011, Matteo Cacciari, Gavin Salam and Gregory Soyez
//
//----------------------------------------------------------------------
// 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.
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//  The algorithms that underlie FastJet have required considerable
//  development and are described in hep-ph/0512210. If you use
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//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU General Public License for more details.
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//  Foundation, Inc.:
//      59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//----------------------------------------------------------------------
//ENDHEADER

#include <fastjet/PseudoJet.hh>
#include <fastjet/Selector.hh>

FASTJET_BEGIN_NAMESPACE

/// \class FunctionOfPseudoJet
/// base class providing interface for a generic function of a PseudoJet
///
/// This class serves as a base class to provide a standard interface
/// for a function that returns an object of a given (templated) type
/// that depends on a PseudoJet argument. The rationale for using a
/// class (rather than a pointer to a function) is that a class can be
/// constructed with (and store) additional arguments.
template<typename TOut>
class FunctionOfPseudoJet{
public:
  /// default ctor
  FunctionOfPseudoJet(){}

  /// ctor that creates a constant function
  FunctionOfPseudoJet(const TOut &constant_value);

  /// default dtor (virtual to allow safe polymorphism)
  virtual ~FunctionOfPseudoJet(){}

  /// returns a description of the function (an empty string by
  /// default)
  virtual std::string description() const{ return "";}

  /// the action of the function
  /// this _has_ to be overloaded in derived classes
  ///  \param pj   the PseudoJet input to the function
  virtual TOut result(const PseudoJet &pj) const = 0;

  /// apply the function using the "traditional" () operator.
  /// By default, this just calls the apply(...) method above.
  ///  \param pj   the PseudoJet input to the function
  TOut operator()(const PseudoJet &pj) const { return result(pj);}

  /// apply the function on a vector of PseudoJet, returning a vector
  /// of the results.
  /// This just calls apply on every PseudoJet in the vector.
  ///  \param pjs  the vector of PseudoJet inputs to the function
  std::vector<TOut> operator()(const std::vector<PseudoJet> &pjs) const {
    std::vector<TOut> res(pjs.size());
    for (unsigned int i=0; i<pjs.size(); i++)
      res[i] = result(pjs[i]);
    return res;
  }
};


// Selectors created from the ordering between a FunctionOfPseudoJet
// and a constant
//----------------------------------------------------------------------

/// 'larger than' operator
///
/// Select jets for which the given function returns a reult larger
/// than the specified constant
Selector operator >(const FunctionOfPseudoJet<double> & fn, const double & cut);

/// 'smaller than' operator
///
/// Select jets for which the given function returns a reult larger
/// than the specified constant
Selector operator <(const FunctionOfPseudoJet<double> & fn, const double & cut);

/// 'larger or equal' operator
///
/// Select jets for which the given function returns a reult larger
/// than the specified constant
Selector operator >=(const FunctionOfPseudoJet<double> & fn, const double & cut);

/// 'smaller or equal' operator
///
/// Select jets for which the given function returns a reult larger
/// than the specified constant
Selector operator <=(const FunctionOfPseudoJet<double> & fn, const double & cut);


FASTJET_END_NAMESPACE

#endif  // __FASTJET_FUNCTION_OF_PSEUDOJET_HH__