#include "dll.h"


class dq
{

public:
	typedef char item_type;
	dq(void)
	{
		return;
	}
	
	bool empty(void)
	{
		return list.begin() == list.end();
	}

	item_type front(void)
	{
		return list.begin()->itm;
	}

	item_type back(void)
	{
		return list.end()->itm;
	}

	void push_front(const item_type c)
	{
		list.insert (list.begin(), c);
	}

	void push_back( const item_type c)
	{
		list.insert(list.end(), c);	
	}

	item_type operator[] (unsigned int n)
	{
		return helper(n, list.begin());
	}

	item_type helper(unsigned int n, dll::link * pos)
	{
		if (n == 0)
			return pos->itm;
		else
			return helper(n-1, list.succ(pos));
	}

private:
	item_type item;
	dll list;


};