random.hpp

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/*
 * This file is part of Algorithms library toolkit.
 * Copyright (C) 2017 Jan Travnicek (jan.travnicek@fit.cvut.cz)
 
 * Algorithms library toolkit 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 3 of the License, or
 * (at your option) any later version.
 
 * Algorithms library toolkit 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 General Public License for more details.
 
 * You should have received a copy of the GNU General Public License
 * along with Algorithms library toolkit.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#pragma once
 
#include <random>
#include <limits>
 
namespace ext {
 
class random_devices {
public:
    static std::random_device & getRandom ( ) {
        static std::random_device res;
        return res;
    }
 
    static std::random_device & random;
 
private:
    class semirandom_device {
    public:
        typedef unsigned int result_type;
 
    private:
        std::mt19937 gen;
 
        std::uniform_int_distribution<unsigned int> dis;
 
    public:
        semirandom_device() : gen ( 0 ) {
        }
 
        result_type operator()() {
            return dis(gen);
        }
 
        static constexpr result_type min() {
            return 0;
        }
 
        static constexpr result_type max() {
            return std::numeric_limits<result_type>::max() ;
        }
 
        void seed ( unsigned int seed ) {
            gen.seed ( seed );
        }
    };
 
public:
    static semirandom_device & getSemirandom ( ) {
        static semirandom_device res;
        return res;
    }
 
    static semirandom_device & semirandom;
 
};
 
} /* namespace ext */