// Class Stack:
// Stack container.
// Stack should be able to push, pop, check if is empty,
// full, check size, the topmost element on the stack, push
// pop and clear.

class Stack {
private:
	//NOTE: You will be required to keep track of the size of the stack.
	unsigned int Size;
	DLinkedList List;
public:
	Stack();

	Stack(const Stack& source);
	Stack& operator=(const Stack& RHS);

	// should return false if operation is not successful,
	bool push(const ElementD& val);

	// should return false if operation is not successful,
	// if successful set reference parameter to item poped
	bool pop(ElementD& val);

	// return element at top
	bool top(ElementD& val);

   // check if full
	bool isFull() const;

   // check if empty
	bool isEmpty() const;

   // report size
	unsigned int size() const;

   // clear stack
	void clear();

   // compare Sizes - return if equal
	bool operator==(const Stack& RHS) const;

   // compare Sizes - return if not equal
	bool operator!=(const Stack& RHS) const;

   // compare Sizes - return if lhs size greater
   // than or equal to rhs size
	bool operator>=(const Stack& RHS) const;

   // compare Sizes - return if lhs size smaller
   // than or equal to rhs size
	bool operator<=(const Stack& RHS) const;

   // compare Sizes - return if lhs size smaller
   // than rhs size
	bool operator<(const Stack& RHS) const;

   // compare Sizes - return if lhs size greater
   // than rhs size
	bool operator>(const Stack& RHS) const;
	
	//leave this in
	friend class Tester;

   ~Stack();
};