#ifndef Stack_h
#define Stack_h

const int null = 0;

template <typename DataType>
class Stack
{
  private:
	struct Node
	{
		DataType data;
		Node* previous;

	  public:
		explicit Node(const DataType& data, Node* previous = null) : data(data), previous(previous) { }
	};

  private:
	Node* last;

  public:
	Stack() : last(null) { }
	~Stack() { clear(); }

	inline bool empty() const { return last == null; }
	void clear()
	{
		for (Node* current = last; last; current = last, last = last->previous )
			delete current;
	}

	bool push(const DataType& data)
	{
		return ( last = new Node(data, last) );
	}

	DataType pop()
	{
		DataType result = last->data;
		Node* temp = last;
		last = last->previous;
		delete temp;
		return result;
	}

  private:
	Stack(const Stack& other);
	const Stack& operator=(const Stack& other);
};

#endif