/*!
  \class Q3PtrStack
  \brief The Q3PtrStack class is a template class that provides a stack.
  \compat

  Q3ValueStack is an STL-compatible alternative to this class.

  Define a template instance Q3PtrStack\<X\> to create a stack that
  operates on pointers to X, (X*). 

  A stack is a last in, first out (LIFO) structure. Items are added
  to the top of the stack with push() and retrieved from the top
  with pop(). Use top() to get a reference to the top element
  without changing the stack.

  You can control the stack's deletion policy with setAutoDelete().

  For compatibility with the Q3PtrCollection classes current() and
  remove() are provided; they both operate on the top().

  \sa Q3PtrList Q3PtrQueue
*/

/*!
  \fn Q3PtrStack::Q3PtrStack () 

  Creates an empty stack.
*/

/*!
  \fn Q3PtrStack::Q3PtrStack (const Q3PtrStack<type>& s) 

  Creates a stack by making a shallow copy of another stack \a s.
*/

/*!
  \fn Q3PtrStack::~Q3PtrStack () 

  Destroys the stack. All items will be deleted if autoDelete() is
  true.
*/

/*!
  \fn Q3PtrStack<type>& Q3PtrStack::operator= (const Q3PtrStack<type>& s) 

  Sets the contents of this stack by making a shallow copy of
  another stack \a s. Elements currently in this stack will be
  deleted if autoDelete() is true.
*/

/*!
  \fn bool Q3PtrStack::isEmpty () const 

  Returns true if the stack contains no elements; otherwise returns
  false.
*/

/*!
  \fn void Q3PtrStack::push (const type* d) 

  Adds an element \a d to the top of the stack. Last in, first out.
*/

/*!
  \fn type* Q3PtrStack::pop () 

  Removes the top item from the stack and returns it. The stack must
  not be empty.
*/

/*!
  \fn bool Q3PtrStack::remove () 

  Removes the top item from the stack and deletes it if autoDelete()
  is true. Returns true if there was an item to pop; otherwise
  returns false.

  \sa clear()
*/

/*!
  \fn void Q3PtrStack::clear()

  Removes all items from the stack, deleting them if autoDelete() is
  true.

  \sa remove()
*/

/*!
  \fn uint Q3PtrStack::count() const

  Returns the number of items in the stack.

  \sa isEmpty()
*/

/*!
  \fn type* Q3PtrStack::top () const 

  Returns a pointer to the top item on the stack (most recently
  pushed). The stack is not changed. Returns 0 if the stack is
  empty.
*/

/*!
  \fn Q3PtrStack::operator type* ()const 

  Returns a pointer to the top item on the stack (most recently
  pushed). The stack is not changed. Returns 0 if the stack is
  empty.
*/

/*!
  \fn type* Q3PtrStack::current () const 

  Returns a pointer to the top item on the stack (most recently
  pushed). The stack is not changed. Returns 0 if the stack is
  empty.
*/

/*!
  \fn bool Q3PtrStack::autoDelete() const

  The same as Q3PtrCollection::autoDelete(). Returns true if 
  the auto-delete option is set. If the option is set, the 
  stack auto-deletes its contents. 

  \sa setAutoDelete()
*/

/*!
  \fn void Q3PtrStack::setAutoDelete(bool enable) 

  Defines whether this stack auto-deletes its contents. The same as
  Q3PtrCollection::setAutoDelete(). If \a enable is true, auto-delete
  is turned on.

  If auto-deleting is turned on, all the items in the stack are
  deleted when the stack itself is deleted. This is convenient if
  the stack has the only pointers to the items.

  The default setting is false, for safety. If you turn it on, be
  careful about copying the stack, or you might find yourself with
  two stacks deleting the same items.

  Note that the auto-delete setting may also affect other functions in
  subclasses. For example, a subclass that has a remove() function
  will remove the item from its data structure, and if auto-delete is
  enabled, will also delete the item.
  
  \sa autoDelete()
*/

/*!
  \fn QDataStream& Q3PtrStack::read(QDataStream& s, Q3PtrCollection::Item& item)

  Reads a stack item, \a item, from the stream \a s and returns a
  reference to the stream.

  The default implementation sets \a item to 0.

  \sa write()
*/

/*!
  \fn QDataStream& Q3PtrStack::write(QDataStream& s,
				     Q3PtrCollection::Item item) const

  Writes a stack item, \a item, to the stream \a s and returns a
  reference to the stream.

  The default implementation does nothing.

  \sa read()
*/
