// File: intstack.C
//
// Implementation of class IntStack which was derived from GenStack

#include <iostream.h>
#include <iomanip.h>
#include <stdlib.h>
#include "intstack.h"

// "Local" functions
//
static void CrashOnNULL(void *ptr, char *mesg) ;

static void CrashOnNULL(void *ptr, char *mesg) {
   if (ptr == NULL) {
      cerr << "CrashOnNULL: " << mesg << endl ;
      exit(1) ;
   }
}


// Default constructor
//
IntStack::IntStack()
: GenStack(cmp, prt)        // member initializer
{
#ifndef NDEBUG
   cerr << "IntStack constructor, this = " << this << endl ;
#endif
   // Do nothing
}


// Destructor
//
IntStack::~IntStack() {
#ifndef NDEBUG
   cerr << "IntStack destructor, this = " << this << endl ;
#endif

   // Do nothing, GenStack destructor automatically called
}


// Add an int to the top of stack
//
void IntStack::push(int n) {

   int *ptr = new int(n) ;
   CrashOnNULL(ptr, "Out of memory in IntStack::push()") ;

   GenStack::push(ptr) ;
}


// Remove and return int from top of stack
//
int IntStack::pop() {
   int result, *ptr ;

   ptr = (int *) GenStack::pop() ;
   result = *ptr ;
   delete ptr ;
   return result ;
}


// Return (don't remove) int from top of stack
//
int IntStack::top() {
   int *ptr ;

   ptr = (int *) GenStack::top() ;
   return *ptr ;
}


// Compare two integers
//
int IntStack::cmp(void *vptr1, void *vptr2) {
   int *ptr1, *ptr2 ;

   ptr1 = (int *) vptr1 ;
   ptr2 = (int *) vptr2 ;

   if (ptr1 == NULL && ptr2 == NULL) return 0 ;
   if (ptr1 == NULL) return -1 ;
   if (ptr2 == NULL) return  1 ;

   if (*ptr1 < *ptr2) return -1 ;
   if (*ptr1 == *ptr2) return 0 ;
   return 1 ;
}

// print out an integer
//
void IntStack::prt(void *vptr) {
   int *ptr ;

   if (vptr == NULL) return ;

   ptr = (int *) vptr ;
   cout << *ptr << " " ;
}