quickcpplib::_xxx::algorithm::small_prng Namespace Reference

Classes
class	small_prng
	From http://burtleburtle.net/bob/rand/smallprng.html, a not awful fast random number source. More...

Functions
small_prng &	thread_local_prng ()
	A thread safe small prng seeded with the thread id.
template<class RandomIt >
void	random_shuffle (RandomIt first, RandomIt last, small_prng &r=thread_local_prng())
	A random_shuffle implementation which uses the small prng.

Function Documentation

thread_local_prng()

small_prng & quickcpplib::_xxx::algorithm::small_prng::thread_local_prng ( )

inline

A thread safe small prng seeded with the thread id.

    {
#ifdef QUICKCPPLIB_THREAD_LOCAL_IS_CXX11
      static thread_local small_prng v(utils::thread::this_thread_id());
      return v;
#else
      static QUICKCPPLIB_THREAD_LOCAL small_prng *v;
      if(!v)
        v = new small_prng(utils::thread::this_thread_id());  // leaks memory
      return *v;
#endif
    }

random_shuffle()

template<class RandomIt >

void quickcpplib::_xxx::algorithm::small_prng::random_shuffle	(	RandomIt	first,
		RandomIt	last,
		small_prng &	r = thread_local_prng()
	)

A random_shuffle implementation which uses the small prng.

    {
      typename std::iterator_traits<RandomIt>::difference_type i, n;
      n = last - first;
      for(i = n - 1; i > 0; --i)
      {
        using std::swap;
        swap(first[i], first[r() % (i + 1)]);
      }
    }