// -*- mode: c++; c-indent-level: 4; c++-member-init-indent: 8; comment-column: 35; -*-

//-----------------------------------------------------------------------------
// eoMerge.h
//   Base class for choosing a number of guys to apply something from a popsize
// (c) Marc Schoenauer, 2000
/* 
   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2 of the License, or (at your option) any later version.

   This library 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with this library; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

   Contact: todos@geneura.ugr.es, http://geneura.ugr.es
 */
//-----------------------------------------------------------------------------

#ifndef eoHowMany_h
#define eoHowMany_h

// to be used in selection / replacement procedures to indicate whether 
// the argument (rate, a double) shoudl be treated as a rate (number=rate*popSize)
// or as an absolute integer (number=rate regardless of popsize).
// the default value shoudl ALWAYS be true (eo_as_a_rate).
//
// this construct is mandatory because in some cases you might not know the 
// population size that will enter the replacement for instance - so you 
// cannot simply have a pre-computed (double) rate of 1/popSize if you want 1 guy


class eoHowMany
{
public:
  eoHowMany(double  _rate, bool _interpret_as_rate = true):
    rate(0), howmany(0)
  {
    if (_interpret_as_rate)
      {
	rate = _rate;
      }
    else
      {
	if (_rate<0)
	  throw std::logic_error("Negative number in eoHowMany!");
	howmany = (unsigned int)_rate;
	if (howmany != _rate)
	  cout << "Warning: Number was rounded in eoHowMany";
      }
  }

  unsigned int operator()(unsigned int _size)
  {
    if (howmany == 0)
      {
	if (rate == 0.0)
	  return 0;
	else
	  return (unsigned int) (rate * _size);
      }
    return howmany;
  }
  
private :
  double rate;
  unsigned howmany;
};



#endif