#include <iostream.h>
class StackException
{
  char * message;
public:
  StackException(char *msg)
    : message(msg)
  {
  }
  inline friend ostream & operator << (ostream & out, StackException & e)
  {
    return out << "StackException: " << e.message;
  }
};
 #define STACK_SIZE 1024
class StackMemento
{
  friend class ArrayStack;
  int top;
  char buf[STACK_SIZE];
  StackMemento(char * curBuf, int curTop)
  {
    top = curTop;
    for ( int i = 0; i < curTop; ++i )
      buf[i] = curBuf[i];
  }
  void restore( char * curBuf, int & curTop )
  {
    curTop = top;
    for ( int i = 0; i < top; ++i )
      curBuf[i] = buf[i];
  }
};
class StackIter;
class ArrayStack
{
  friend class StackIter;
  // static const int STACK_SIZE = 1024;
  char buf[STACK_SIZE];
  int top;
public:
  ArrayStack()
    : top(0)
  {
  }
  void push(char c)
    throw (StackException)
  {
    if ( isFull() )
      throw StackException("Full");
    buf[top++] = c;
  }
  char pop()
    throw (StackException)
  {
    if ( isEmpty() )
      throw StackException("Empty");
    return buf[--top];
  }
  bool isEmpty()
  {
    return top <= 0;
  }
  bool isFull()
  {
    return top >= STACK_SIZE;
  }
  StackMemento * createMemento()
  {
    return new StackMemento(buf, top);
  }
  void restoreState( StackMemento * m )
  {
    m->restore(buf, top);
  }
  StackIter * createIter();
};
class StackIter
{
  ArrayStack * stk;
  int index;
public:
  StackIter( ArrayStack * s )
  {
    stk = s;
    reset();
  }
  void reset()
  {
    index = 0;
  }
  void advance()
  {
    ++index;
  }
  bool hasMore()
  {
    return index < stk->top;
  }
  char current()
  {
    return stk->buf[index];
  }
};
StackIter * ArrayStack::createIter()
{
  return new StackIter( this );
}
ostream & operator << (ostream & out, ArrayStack & stk)
{
  for ( StackIter & i = *stk.createIter(); i.hasMore(); i.advance() )
    out << i.current();
  return out;
}
int main()
{
  ArrayStack & stk = *new ArrayStack();
  try
  {
    for ( char c = 'A'; c <= 'Z'; ++c )
      stk.push(c);
    cout << "Stack: " << stk << endl;
    StackMemento * m = stk.createMemento();
    cout << "Stack: " << stk << endl;
    cout << "Stack: ";
    while ( !stk.isEmpty() )
      cout << stk.pop();
    cout << endl;
    cout << "Stack: " << stk << endl;
    stk.restoreState( m );
    cout << "Stack: " << stk << endl;
  }
  catch (StackException & e)
  {
    cout << e << endl;
  }
}