#ifndef BOXH
#define BOXH
#include <iostream>
#include <cassert>
#include <set>
#include <algorithm>
using namespace std;

class sudoku;
class row;
class col;
class reg;

class box {
	static const size_t root = 3;
	static const size_t n = root * root;
	static const size_t all[n];

	sudoku *p;
	size_t x;
	size_t y;
	set<size_t> s;

	bool operator[](size_t i) const {
		assert(i < n);
		return s.find(i) != s.end();
	}

	size_t size() const {return s.size();}
public:
	box(): s(all, all + n) {}

	void set(size_t i);
	void reset(size_t i);

	operator row&() const;
	operator col&() const;
	operator reg&() const;

	template <class ZONE>
	void mow_down(size_t i) const;

	template <class ZONE>
	void only(size_t i) const;

	template <class ZONE1, class ZONE2>
	void herd(size_t i) const;

	template <class ZONE>
	void contingency() const;

	friend ostream& operator<<(ostream& ost, const box& bo);
	friend class sudoku;
};
#endif