Randomizer.hxx

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#ifndef RANDOMIZER_HXX_
#define RANDOMIZER_HXX_
 
#include <random>
#include <iterator>
#include <algorithm>
#include "../util/Singleton.hxx"
 
class Randomizer : public Singleton<Randomizer>
{
  static thread_local std::mt19937 generator;
 
  template <typename IntType> using UniformIntDist = std::uniform_int_distribution<IntType>;
 
public:
  Randomizer() = default;
 
  template <typename Iterator> void shuffle(Iterator begin, Iterator end) { std::shuffle(begin, end, generator); }
 
  template <typename Iterator> Iterator choose(Iterator begin, Iterator end)
  {
    using DiffType = typename std::iterator_traits<Iterator>::difference_type;
    DiffType upper{std::distance(begin, end) - 1};
    UniformIntDist<DiffType> distn{DiffType{0}, upper};
    std::advance(begin, distn(generator));
    return begin;
  }
};
 
#endif