#ifndef _LVPSTACK_H_
#define _LVPSTACK_H_

#include "cvclibdef.h"
#include "vector.h"

#define SDEFAULT_SIZE 10        // default initial stack size

template <class itemType>
class stack
{
	public:
    
	// constructors/destructor
	stackstack( ) : myTop(-1), myElements(SDEFAULT_SIZE) { }
    stack(const stack<itemType> & s) : myTop(s.myTop), myElements(s.myElements) { }
    ~stack( ) { }

	// assignment
    const stack & operator = (const stack<itemType> & rhs)
	{
		if (this != &rhs)
		{
			myTop = rhs.myTop;
			myElements = rhs.myElements;
		}
		return *this;
	}

	// accessors

    const itemType & top() const
	{
		if (isEmpty())
		{
			cerr << "error, popping an empty stack" << endl;
			exit(1);
		}    
		return myElements[myTop];
	}


    bool             isEmpty() const { return myTop == -1; }

    int              length() const { return myTop+1; }


	// modifiers
    void push(const itemType & item)   
	{
		if( myTop + 1 >= myElements.length() )   // grow vector if necessary
		{
			myElements.resize(myElements.length() * 2);
		}
		myTop++;                           // new top most element
		myElements[myTop ] = item;
	}

    void pop()
	{
		if (isEmpty())
		{
			cerr << "error, popping an empty stack" << endl;
			exit(1);
		}
		myTop--;
	}

    void pop(itemType & item)
	{
		if (isEmpty())
		{
			cerr << "error, popping an empty stack" << endl;
			exit(1);
		}
		item = myElements[myTop];
		myTop--;
	}

    void makeEmpty() { yTop = -1; }


  private:

    int myTop;                            // index of top element
	 vector<itemType> myElements;        // storage for stack
};


#endif