RandomSelector.h

#pragma once
#ifndef __RANDOMSELECTOR__
#define __RANDOMSELECTOR__

#include <random>
#include <iterator>

template <typename RandomGenerator = std::default_random_engine>
struct RandomSelector
{
	//On most platforms, you probably want to use std::random_device("/dev/urandom")()
	RandomSelector(RandomGenerator g = RandomGenerator(std::random_device()()))
		: gen(g) {}

	template <typename Iter>
	Iter select(Iter start, Iter end) 
	{
		std::uniform_int_distribution<> dis(0, std::distance(start, end) - 1);
		std::advance(start, dis(gen));
		return start;
	}

	//convenience function
	template <typename Iter>
	Iter operator()(Iter start, Iter end) 
	{
		return select(start, end);
	}

	//convenience function that works on anything with a sensible begin() and end(), and returns with a ref to the value type
	template <typename Container>
	auto operator()(const Container& c) -> decltype(*begin(c)) & 
	{
		return *select(begin(c), end(c));
	}

private:
	RandomGenerator gen;
};

#endif // __RANDOMSELECTOR__