[u/mrichter/AliRoot.git] / TEvtGen / EvtGenBase / EvtPredGen.hh

/*******************************************************************************
 * Project: BaBar detector at the SLAC PEP-II B-factory
 * Package: EvtGenBase
 *    File: $Id: EvtPredGen.hh,v 1.3 2003/06/19 02:17:14 dvoretsk Exp $
 *  Author: Alexei Dvoretskii, dvoretsk@slac.stanford.edu, 2001-2002
 *
 * Copyright (C) 2002 Caltech
 *******************************************************************************/

// A predicate is applied to a generator to get another generator.
// Accept-reject can be implemented in this way.
//
//           Predicate
// Generator    ->     Generator 

#ifndef EVT_PRED_GEN_HH
#define EVT_PRED_GEN_HH

#include <stdio.h>

template <class Generator, class Predicate> 
class EvtPredGen {

public:

  typedef typename Generator::result_type result_type;
  
  EvtPredGen()
    : itsTried(0), itsPassed(0)
  {}

  EvtPredGen(Generator gen, Predicate pred)
    : itsGen(gen), itsPred(pred), itsTried(0), itsPassed(0) 
  {}

  EvtPredGen(const EvtPredGen& other)
    : itsGen(other.itsGen), itsPred(other.itsPred), 
    itsTried(other.itsTried), itsPassed(other.itsPassed)
  {}

  ~EvtPredGen()
  {}
  
  result_type operator()() {

    int i = 0;
    int MAX = 10000;
    while(i++ < MAX) {

      itsTried++;
      result_type point = itsGen();
      if(itsPred(point)) {
	itsPassed++;
	return point;
      }
    }    
    
    printf("No random point generated after %d attempts\n",MAX);
    printf("Sharp peak? Consider using pole compensation.\n");
    printf("I will now pick a point at random to return.\n");
    return itsGen();
  }
  
  inline int getTried() const { return itsTried; }
  inline int getPassed() const { return itsPassed; }

protected:

  Generator itsGen;
  Predicate itsPred;
  int itsTried;
  int itsPassed;

};

#endif
Commit	Line	Data
da0e9ce3	1	/*******************************************************************************
	2	* Project: BaBar detector at the SLAC PEP-II B-factory
	3	* Package: EvtGenBase
	4	* File: $Id: EvtPredGen.hh,v 1.3 2003/06/19 02:17:14 dvoretsk Exp $
	5	* Author: Alexei Dvoretskii, dvoretsk@slac.stanford.edu, 2001-2002
	6	*
	7	* Copyright (C) 2002 Caltech
	8	*******************************************************************************/
	9
	10	// A predicate is applied to a generator to get another generator.
	11	// Accept-reject can be implemented in this way.
	12	//
	13	// Predicate
	14	// Generator -> Generator
	15
	16	#ifndef EVT_PRED_GEN_HH
	17	#define EVT_PRED_GEN_HH
	18
	19	#include <stdio.h>
	20
	21	template <class Generator, class Predicate>
	22	class EvtPredGen {
	23
	24	public:
	25
	26	typedef typename Generator::result_type result_type;
	27
	28	EvtPredGen()
	29	: itsTried(0), itsPassed(0)
	30	{}
	31
	32	EvtPredGen(Generator gen, Predicate pred)
	33	: itsGen(gen), itsPred(pred), itsTried(0), itsPassed(0)
	34	{}
	35
	36	EvtPredGen(const EvtPredGen& other)
	37	: itsGen(other.itsGen), itsPred(other.itsPred),
	38	itsTried(other.itsTried), itsPassed(other.itsPassed)
	39	{}
	40
	41	~EvtPredGen()
	42	{}
	43
	44	result_type operator()() {
	45
	46	int i = 0;
	47	int MAX = 10000;
	48	while(i++ < MAX) {
	49
	50	itsTried++;
	51	result_type point = itsGen();
	52	if(itsPred(point)) {
	53	itsPassed++;
	54	return point;
	55	}
	56	}
	57
	58	printf("No random point generated after %d attempts\n",MAX);
	59	printf("Sharp peak? Consider using pole compensation.\n");
	60	printf("I will now pick a point at random to return.\n");
	61	return itsGen();
	62	}
	63
	64	inline int getTried() const { return itsTried; }
65	inline int getPassed() const { return itsPassed; }
66
67	protected:
68
69	Generator itsGen;
70	Predicate itsPred;
71	int itsTried;
72	int itsPassed;
73
74	};
75
76	#endif
77