#ifndef LEAKY_STACK_H
#define LEAKY_STACK_H

#include <string>

/**
 * Interface for a leaky 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 LeakyStack {
public:
    /**
     * Return the number of objects in the stack.
     * \return number of elements
     */
    virtual int size() const =0;

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

    /**
     * Return a const reference to the top object in the stack.
     * \return const reference to top element
     * \throw runtime_error if the stack is empty
     */
    virtual const std::string& top() const =0; 

    /**
     * Insert an object at the top of the stack. If the stack
     * is already at capacity, the oldest element will be lost.
     * \param the new element
     */
    virtual void push(const std::string& e) =0; 

    /**
     *  Remove the top object from the stack.
     *  \throw runtime_error if the stack is empty.
     */
    virtual void pop() =0;

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


#endif