/** @file StackA.cpp
 * Implementation of the stack ADT using arrays.
 */

#include "C6-StackA.h"  // Stack class specification file

// Default constructor
Stack::Stack() : top(-1)
{
}

bool Stack::isEmpty() const
{
   return top < 0;
}

void Stack::push(const StackItemType& newItem)
            throw(StackException)
{
  // if stack has no more room for another item
  if (top >= MAX_STACK-1)
    throw StackException("StackException: stack full on push");
  else{
    ++top;
    items[top] = newItem;
  }
}

void Stack::pop() throw(StackException)
{
  if (isEmpty())
    throw StackException("StackException: stack empty on pop");
  else
    --top;     // stack is not empty; pop top
}

void Stack::pop(StackItemType& stackTop) throw(StackException)
{
  if (isEmpty())
    throw StackException("StackException: stack empty on pop");
  else{
    // stack is not empty; retrieve top
    stackTop = items[top];
    --top;     // pop top
  }
}

void Stack::getTop(StackItemType& stackTop) const throw(StackException)
{
  if (isEmpty())
    throw StackException("StackException: stack empty on getTop");
  else
    // stack is not empty; retrieve top
    stackTop = items[top];
}