#ifndef BOUNDED_STACK_H
#define BOUNDED_STACK_H

#include "BoundedStackEmptyException.h"

/**
 * Interface for a bounded stack: A collection of objects that are inserted
 * and removed according to the last-in first-out principle, but with
 * overflow handled by the removal of the least-recently accessed item.
 */
class BoundedStack {
 public:
  /**
   * Returns number of objects in the stack.
   */
  virtual size_t size() const =0;

  /** 
   * Returns true if the stack is empty, false otherwise.
   */
  virtual bool empty() const =0;

  /** 
   * Returns constant reference to the top object in the stack.
   * Throws BoundedStackEmptyException if the stack is empty. 
   */
  virtual const string& top() const throw(BoundedStackEmptyException) =0; 

  /**
   * Inserts an object at the top of the stack, making room if
   * necessary by removing the item at the bottom of the stack.
   */
  virtual void push(const string& obj) =0; 

  /** 
   * Removes the top object from the stack.  
   * Throws BoundedStackEmptyException if the stack is empty.
   */
  virtual void pop() throw(BoundedStackEmptyException) =0;

  /**
   * Virtual Destructor
   */
  virtual ~BoundedStack() {};
};


#endif