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/*!

  \class QAbstractXmlForwardIterator

  \brief The QAbstractXmlForwardIterator class is a base class for forward iterators.

  \reentrant

  \since 4.4

  \ingroup xml-tools

  \internal

  This abstract base class is for creating iterators for

  traversing custom data structures modeled to look like XML.

  An item can be instantiated in QAbstractXmlForwardIterator if:

  \list

  \o It has a default constructor, a copy constructor, and an

  assignment operator, and

  \o It has an appropriate qIsForwardIteratorEnd() function.

  \endlist

   @ingroup Patternist_iterators

   @author Frans Englich <frans.englich@nokia.com>

 */

/*!

 \typedef QAbstractXmlForwardIterator::Ptr

 A smart pointer wrapping an instance of a QAbstractXmlForwardIterator subclass.

 */

/*!

 \typedef QAbstractXmlForwardIterator::List

 A QList containing QAbstractXmlForwardIterator::Ptr instances.

 */

/*!

 \typedef QAbstractXmlForwardIterator::Vector

 A QVector containing QAbstractXmlForwardIterator::Ptr instances.

 */

/*!

  \fn QAbstractXmlForwardIterator::QAbstractXmlForwardIterator()

  Default constructor.

 */

/*!

  \fn QAbstractXmlForwardIterator::~QAbstractXmlForwardIterator()

  Destructor.

 */

/*!

  \fn T QAbstractXmlForwardIterator::next() = 0;

 Returns the next item in the sequence, or

 a null object if the end has been reached.

 */

/*!

  \fn T QAbstractXmlForwardIterator::current() const = 0;

  Returns the current item in the sequence. If this function is called

  before the first call to next(), a null object is returned. If the

  end of the sequence has been reached, a null object is returned.

 */

/*!

  \fn qint64 QAbstractXmlForwardIterator::position() const = 0;

   Returns the current position in the sequence represented

   by \e this.

   The first position is 1, not 0. If next() hasn't been called, 0 is

   returned. If \e this has reached the end, -1 is returned.

 */

/*!

  \fn bool qIsForwardIteratorEnd(const T &unit)

  \since 4.4

  \relates QAbstractXmlForwardIterator

  The Callback QAbstractXmlForwardIterator uses for determining

  whether \a unit is the end of a sequence.

  If \a unit is a value that would signal the end of a sequence

  (typically a default constructed value), this function returns \c

  true, otherwise \c false.

  This implementation works for any type that has a boolean operator.

  For example, this function should work satisfactory for pointers.

 */

/*!

  \fn qint64 QAbstractXmlForwardIterator::count()

  \internal

   Determines the number of items this QAbstractXmlForwardIterator

   represents.

   Note that this function is not \c const. It modifies the

   QAbstractXmlForwardIterator. The reason for this is efficiency. If

   this QAbstractXmlForwardIterator must not be changed, get a copy()

   before performing the count.

   The default implementation simply calls next() until the end is

   reached. Hence, it may be of interest to override this function if

   the sub-class knows a better way of computing its count.

   The number of items in the sequence is returned.

 */

/*!

  \fn QAbstractXmlForwardIterator<T>::Ptr QAbstractXmlForwardIterator::toReversed();

  \internal

  Returns a reverse iterator for the sequence.

  This function may modify the iterator, it can be considered a

  function that evaluates this QAbstractXmlForwardIterator. It is not

  a \e getter, but potentially alters the iterator in the same way the

  next() function does. If this QAbstractXmlForwardIterator must not

  be modified, such that it can be used for evaluation with next(),

  use a copy().

 */

/*!

  \fn QList<T> QAbstractXmlForwardIterator<T>::toList();

  \internal

   Performs a copy of this QAbstractXmlForwardIterator(with copy()),

   and returns its items in a QList. Thus, this function acts as a

   conversion function, converting the sequence to a QList.

   This function may modify the iterator. It is not a \e getter, but

   potentially alters the iterator in the same way the next() function

   does. If this QAbstractXmlForwardIterator must not be modified,

   such that it can be used for evaluation with next(), use a copy().

 */

/*!

  \fn T QAbstractXmlForwardIterator::last();

  \internal

   Returns the item at the end of this QAbstractXmlForwardIterator.

   The default implementation calls next() until the end is reached.

 */

/*!

  \fn T QAbstractXmlForwardIterator::isEmpty();

  \internal

  Returns true if the sequence is empty.

 */

/*!

  \fn qint64 QAbstractXmlForwardIterator::sizeHint() const;

  \internal

  Gives a hint to the size of the contained sequence. The hint is

  assumed to be as close as possible to the actual size.

  If no sensible estimate can be computed, -1 should be returned.

 */

/*!

  \fn typename QAbstractXmlForwardIterator<T>::Ptr QAbstractXmlForwardIterator::copy() const;

  \internal

   Copies this QAbstractXmlForwardIterator and returns the copy.

   A copy and the original instance are completely independent of each

   other. Because evaluating an QAbstractXmlForwardIterator modifies

   it, one should always use a copy when an

   QAbstractXmlForwardIterator needs to be used several times.

 */

/*!

  \class QPatternist::ListIteratorPlatform

  \brief Helper class for ListIterator, and should only be instantiated through sub-classing.

  \reentrant

  \since 4.4

  \internal

  \ingroup xml-tools

   ListIteratorPlatform iterates an InputList with instances

   of InputType. For every item in it, it returns an item from it,

   that is converted to OutputType by calling a function on Derived

   that has the following signature:

   \snippet doc/src/snippets/code/src_xmlpatterns_api_qabstractxmlforwarditerator.cpp 0

   TODO Document why this class doesn't duplicate ItemMappingIterator.

 */

/*!

  \fn QPatternist::ListIteratorPlatform::ListIteratorPlatform(const ListType &list);

  Constructs a ListIteratorPlatform that walks the given \a list.

 */

/*!

  \class QPatternist::ListIterator

  \brief Bridges values in Qt's QList container class into an QAbstractXmlForwardIterator.

  \reentrant

  \since 4.4

  \internal

  \ingroup xml-tools

   ListIterator takes a reference to a QList<T> instance and allows

   access to that list via its QAbstractXmlForwardIterator interface.

   ListIterator is parameterized with the type to iterate over, e.g.,

   Item or Expression::Ptr.

   ListIterator is used by the ExpressionSequence to create an

   iterator over its operands. The iterator will be passed to a

   MappingIterator.

 */

/*!

   \fn QPatternist::makeListIterator(const QList<T> &qList)

   \relates QPatternist::ListIterator

   An object generator for ListIterator.

   makeListIterator() is a convenience function to avoid specifying

   the full template instantiation for ListIterator.  Conceptually, it

   is identical to Qt's qMakePair().

 */