random.hpp

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/*
Copyright© 2014 Akihiro Nishimura

This software is released under the MIT License.
http://opensource.org/licenses/mit-license.php
*/

#ifndef SIG_UTIL_RANDOM_HPP
#define SIG_UTIL_RANDOM_HPP

#include "../helper/container_traits.hpp"
#include <random>



namespace sig
{

template <class T, class Engine = std::mt19937>
class SimpleRandom 
{
    mutable Engine engine_;     // 乱数生成アルゴリズム 
    
    mutable typename std::conditional <
        std::is_integral<T>::value,
        std::uniform_int_distribution<T>,
        std::uniform_real_distribution<T>
    > ::type dist_;     // 一様分布

public:

    SimpleRandom(T min, T max, bool debug) : engine_(
        [debug](){
        std::random_device rnd;
        std::vector<unsigned long> v(10);
        if (debug) std::fill(v.begin(), v.end(), 0);
        else std::generate(v.begin(), v.end(), std::ref(rnd));
        std::seed_seq seq(v.begin(), v.end());

        return Engine{seq};
    }()
        ),
        dist_(min, max){}

    T operator()() const
    {
        return dist_(engine_);
    }
};



template <class C = std::vector<int>>
C make_unique_numbers(uint n, int min, int max, bool debug)
{
    std::unordered_set<int> match;
    C result = impl::container_traits<C>::make(n);
    SimpleRandom<int> Rand(0, max - min, debug);

    int r;
    for (uint i = 0; i < n; ++i){
        do{
            r = min + Rand();
        } while (match.find(r) != match.end());

        match.insert(r);
        result.push_back(r);
    }

    return result;
}

}

#endif