// ArrayStack.cpp
// minimal array implementation of Stack; no test for overflow
// wdg 2009
#include <iostream>
using namespace std;
#include "ArrayStack.h"

  // constructor
  // arbitrarily sets upper limit
  ArrayStack::ArrayStack( ) : count(0) 
  {     
    // arr not initialized
  }

  // pushes object onto stack
  // @post: reference to item placed at right-end of array
  void ArrayStack::push( StackType item )
  {
     arr[count++] = item;     // count incremented after array access
  }

  //@ returns whether stack is empty or not
  bool ArrayStack::isEmpty( ) const
  {
     return (count==0);
  }

  // pops top element from stack
  // @returns: previous top element or ERROR if problem
  // @post: the top element is removed
  StackType ArrayStack::pop( ) 
  {
     if( isEmpty() )
        return ERROR;
     else
        return arr[--count];    // count decremented before array access
  }

  // @returns reference to data on top of stack
  //     or ERROR (constant in header) if stack is empty
  StackType ArrayStack::peek( ) const
  {
     if( isEmpty() )
        return ERROR;
     else
        return arr[count-1];
  }

  // outputs representation
  void ArrayStack::dump() const
  {
     if( isEmpty() )
       cout << "-empty-" << endl;
     else {
       for(int x=0; x<count; x++)
         cout << arr[x] << " ";
       cout << endl;
     }
  }