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/*!

    \class Q3ValueStack

    \brief The Q3ValueStack class is a value-based template class that provides a stack.

    \compat

    Define a template instance Q3ValueStack\<X\> to create a stack of

    values that all have the class X.

    Note that Q3ValueStack does not store pointers to the members of

    the stack; it holds a copy of every member. That is why these

    kinds of classes are called "value based"; Q3PtrStack, Q3PtrList,

    Q3Dict, etc., are "pointer based".

    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(). The top() function provides access to the topmost item

    without removing it.

    Example:

    \snippet doc/src/snippets/code/doc_src_q3valuestack.qdoc 0

    Q3ValueStack is a specialized Q3ValueList provided for convenience.

    All of Q3ValueList's functionality also applies to Q3PtrStack, for

    example the facility to iterate over all elements using

    Q3ValueStack<T>::Iterator. See Q3ValueListIterator for further

    details.

    Some classes cannot be used within a Q3ValueStack, for example

    everything derived from QObject and thus all classes that

    implement widgets. Only values can be used in a Q3ValueStack. To

    qualify as a value, the class must provide

    \list

    \i a copy constructor;

    \i an assignment operator;

    \i a default constructor, i.e. a constructor that does not take any arguments.

    \endlist

    Note that C++ defaults to field-by-field assignment operators and

    copy constructors if no explicit version is supplied. In many

    cases this is sufficient.

*/

/*!

    \fn Q3ValueStack::Q3ValueStack()

    Constructs an empty stack.

*/

/*!

    \fn Q3ValueStack::~Q3ValueStack()

    Destroys the stack. References to the values in the stack and all

    iterators of this stack become invalidated. Because Q3ValueStack is

    highly tuned for performance, you won't see warnings if you use

    invalid iterators because it is impossible for an iterator to

    check whether or not it is valid.

*/

/*!

    \fn void  Q3ValueStack::push( const T& d )

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

    This function is equivalent to append().

    \sa pop(), top()

*/

/*!

    \fn T& Q3ValueStack::top()

    Returns a reference to the top item of the stack or the item

    referenced by end() if no such item exists. Note that you must not

    change the value the end() iterator points to.

    This function is equivalent to last().

    \sa pop(), push(), Q3ValueList::fromLast()

*/

/*!

    \fn const T& Q3ValueStack::top() const

    \overload

    Returns a reference to the top item of the stack or the item

    referenced by end() if no such item exists.

    This function is equivalent to last().

    \sa pop(), push(), Q3ValueList::fromLast()

*/

/*!

    \fn T Q3ValueStack::pop()

    Removes the top item from the stack and returns it.

    \sa top() push()

*/