random.h

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// -*-c++-*-
 
/*
 *Copyright:
 
 Copyright (C) Hidehisa AKIYAMA
 
 This code 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 3 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
 
 *EndCopyright:
 */
 
 
#ifndef RCSC_UTIL_RANDOM_H
#define RCSC_UTIL_RANDOM_H
 
#include <random>
#include <algorithm> // min, max
#include <iostream>
#include <ctime>
 
namespace rcsc {
 
/*-------------------------------------------------------------------*/
class RandomEngine {
public:
    typedef std::mt19937 base_type;
private:
    base_type M_engine;
 
    RandomEngine()
        : M_engine( std::random_device()() )
      { }
 
    RandomEngine( const RandomEngine & ) = delete;
    RandomEngine & operator=( const RandomEngine & ) = delete;
 
public:
 
    static
    RandomEngine & instance()
      {
          static RandomEngine s_instance;
          return s_instance;
      }
 
    void seed( base_type::result_type value )
      {
          M_engine.seed( value );
      }
 
    base_type & get()
      {
          return M_engine;
      }
};
 
/*-------------------------------------------------------------------*/
template < typename DstType >
class UniformRNG {
public:
    typedef typename DstType::result_type result_type;
 
private:
    DstType M_dst;
 
    UniformRNG();
public:
    UniformRNG( result_type min,
                result_type max )
        : M_dst( min, max )
      { }
 
    result_type operator()()
      {
          return M_dst( RandomEngine::instance().get() );
      }
};
 
typedef UniformRNG< std::uniform_int_distribution<> > UniformInt;
typedef UniformRNG< std::uniform_real_distribution<> > UniformReal;
 
}
 
#endif