random_number_generator.h

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// Pallas Solver
// Copyright 2015. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice,
//   this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright notice,
//   this list of conditions and the following disclaimer in the documentation
//   and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//
// Author: ryan.latture@gmail.com (Ryan Latture)

#ifndef PALLAS_RANDOM_NUMBER_GENERATOR_H
#define PALLAS_RANDOM_NUMBER_GENERATOR_H

#include <random>
#include <type_traits>

namespace pallas {
    namespace internal {
        template <class T, class Enable = void> class RandomNumberGenerator;

        template<class T>
        class RandomNumberGenerator<T, typename std::enable_if<std::is_integral<T>::value >::type> {
            typedef std::mt19937 Engine;
            typedef std::uniform_int_distribution<T> Distribution;

        private:
            Engine *_eng;
            Distribution *_dist;
            std::random_device rd;
        public:
            RandomNumberGenerator(T minVal, T maxVal) {
                std::random_device rd;
                _eng = new Engine(rd());
                _dist = new Distribution(minVal, maxVal);
            };

            RandomNumberGenerator(T minVal, T maxVal, int seed) {
                std::random_device rd;
                _eng = new Engine(seed);
                _dist = new Distribution(minVal, maxVal);
            };

            RandomNumberGenerator() {
                std::random_device rd;
                _eng = new Engine(rd());
                _dist = new Distribution(0, 1);
            };

            RandomNumberGenerator(int seed) {
                std::random_device rd;
                _eng = new Engine(seed);
                _dist = new Distribution(0, 1);
            };

            ~RandomNumberGenerator() {
                delete _dist;
                delete _eng;
            };

            inline T operator()() {
                return (*_dist)(*_eng);
            };
        };

        template<class T>
        class RandomNumberGenerator<T, typename std::enable_if<std::is_floating_point<T>::value >::type> {
            typedef std::mt19937 Engine;
            typedef std::uniform_real_distribution<T> Distribution;

        private:
            Engine *_eng;
            Distribution *_dist;
            std::random_device rd;
        public:
            RandomNumberGenerator(T minVal, T maxVal) {
                std::random_device rd;
                _eng = new Engine(rd());
                _dist = new Distribution(minVal, maxVal);
            };

            RandomNumberGenerator(T minVal, T maxVal, int seed) {
                std::random_device rd;
                _eng = new Engine(seed);
                _dist = new Distribution(minVal, maxVal);
            };

            RandomNumberGenerator() {
                std::random_device rd;
                _eng = new Engine(rd());
                _dist = new Distribution(0, 1);
            };

            RandomNumberGenerator(int seed) {
                std::random_device rd;
                _eng = new Engine(seed);
                _dist = new Distribution(0, 1);
            };

            ~RandomNumberGenerator() {
                delete _dist;
                delete _eng;
            };

            inline T operator()() {
                return (*_dist)(*_eng);
            };
        };

    } // namespace internal
} // namespace pallas

#endif //PALLAS_RANDOM_NUMBER_GENERATOR_H