Boost.Coroutineでitertools.permutations

こいつをC++で書いたもの。
糞汚いコードだがとりあえずMSVCで動いた。

# include "stdafx.h"
# include <functional>
# include <boost/coroutine/all.hpp>
# include <iostream>
# include <iterator>
# include <numeric>
# include <algorithm>
# include <vector>
# include <boost/bind.hpp>

template<typename T>
void iter_permutations(typename boost::coroutines::coroutine<std::vector<T>()>::caller_type& yield, std::vector<T> pool){
	const size_t n = pool.size();
	const size_t r = n;
	if(r > n)return;
	std::vector<size_t> indices(n);
	std::iota(indices.begin(), indices.end(), 0);
	std::vector<size_t> cycles(r);
	std::iota(cycles.begin(), cycles.end(), n-r+1);
	std::reverse(cycles.begin(), cycles.end());
	{
		std::vector<T> ret(r);
		ret.assign(pool.begin(), pool.begin()+r);
		yield(ret);
	}
	while(n){
		auto fl = true;
		for(int i = r - 1; i >= 0 ; --i){
			cycles[i] -= 1;
			if(cycles[i] == 0){
				std::vector<size_t>::iterator tmp = indices.begin();
				std::advance(tmp, i);
				auto tmp_val = *tmp;
				indices.erase(tmp);
				indices.push_back(tmp_val);
				cycles[i] = n - i;
			}else{
				auto j = cycles[i];
				auto k = n - j;
				boost::swap(indices[i], indices[k]);
				{
					std::vector<T> ret(r);
					for(size_t m = 0; m < r; ++m){
						ret[m] = pool[indices[m]];
					}
					yield(ret);
				}
				fl = false;
				break;
			}
		}
		if(fl){
			break;	
		}
	}
}


int _tmain(int argc, _TCHAR* argv[])
{
	using namespace std;

	vector<int> a(3);
	iota(a.begin(), a.end(), 0);
	boost::coroutines::coroutine<std::vector<int>()> mycol(boost::bind(iter_permutations<int>, _1, a));

	while(mycol){
		auto b = mycol.get();
		copy(b.begin(), b.end(), ostream_iterator<int>(cout, ","));
		cout << endl;
		mycol();
	}
	return 0;
}