/*
   Copyright (c) 1997 Oxford University Press. All Rights Reserved.
   This code is from "Data Structures via C++: Objects by Evolution", 
   published by Oxford University Press.  Permission is hearby granted 
   to use this code for any educational, non-commercial purpose, 
   provided this notice remains intact. 
   A. Michael Berman, Rowan University, berman@rowan.edu 
   http://www.rowan.edu/evolve
*/
// RCS $Id: cx8-2.cpp,v 1.2 1997/08/08 14:14:53 berman Exp $

// cx8-2.cpp 
// Code Example 8-2: Implementation file, stack implemented using an Array
            
#include "stack.h"

Stack::Stack()
{
   topIndex = -1;
}

void Stack::push(StackElementType item)
{
   ++topIndex;
   // ensure array bounds not exceeded
   // assert(topIndex < maxStackSize);
   stackArray[topIndex] = item;
}

StackElementType Stack::pop()
{
   // ensure array bounds not exceeded
   // assert(topIndex >= 0);
   int returnIndex(topIndex);
   --topIndex;
   return stackArray[returnIndex];
}

StackElementType Stack::top()
{
   // ensure array bounds not exceeded
   // assert(topIndex >= 0);
   return stackArray[topIndex];
}

bool Stack::isEmpty()
{
   return bool(topIndex == -1);
}