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** QList and QListIterator class documentation

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/*****************************************************************************

  QList documentation

 *****************************************************************************/

/*!

  \class QList qlist.h

  \brief The QList class is a template class that provides doubly linked lists.

  \ingroup collection

  \ingroup tools

  In Qt 2.0 QList is only implemented as a template class. Define a

  template instance QList\<X\> to create a list that operates on pointers

  to X, or X*.

  Example:

  \code

    #include <qlist.h>

    #include <qstring.h>

    #include <stdio.h>

    class Employee

    {

    public:

        Employee( const QString& name, int salary ) { n=name; s=salary; }

        QString     name()   const		 { return n; }

        int	    salary() const		 { return s; }

    private:

        QString     n;

        int         s;

    };

    void main()

    {

	QList<Employee> list;		// list of pointers to Employee

	list.setAutoDelete( TRUE );	// delete items when they are removed

	list.append( new Employee("Bill", 50000) );

	list.append( new Employee("Steve",80000) );

	list.append( new Employee("Ron",  60000) );

	Employee *emp;

	for ( emp=list.first(); emp != 0; emp=list.next() )

	    printf( "%s earns %d\n", emp->name().latin1(), emp->salary() );

    }

  \endcode

  Program output:

  \code

	Bill earns 50000

	Steve earns 80000

	Ron earns 60000

  \endcode

  The list class is indexable and has a \link at() current index\endlink

  and a \link current() current item\endlink.  The first item corresponds

  to index 0.  The current index is -1 if the current item is null.

  QList has several member functions for traversing the list, but using

  a QListIterator can be more practical. Multiple list iterators may

  traverse the same list, independent of each other and independent of

  the current list item.

  In the example above, we make the call setAutoDelete(TRUE).

  Enabling auto-deletion tells the list to delete items that are removed

  from the list.  The default is to not delete items when they are

  removed, but that would cause a memory leak in our example since we have

  no other references to the list items.

  List items are stored as \c void* in an internal QLNode, which also

  holds pointers to the next and previous list items.  The functions

  currentNode(), removeNode() and takeNode() operate directly on the

  QLNode, but they should be used with care.

  When inserting an item into a list, only the pointer is copied, not the

  item itself. This is called a shallow copy. It is possible to make the

  list copy all of the item's data (known as a deep copy) when an item is

  inserted.  insert(), inSort() and append() call the virtual function

  QCollection::newItem() for the item to be inserted.

  Inherit a list and reimplement it if you want deep copies.

  When removing an item from a list, the virtual function

  QCollection::deleteItem() is called.  QList's default implementation

  is to delete the item if auto-deletion is enabled.

  The virtual function QGList::compareItems() can be reimplemented to

  compare two list items. This function is called from all list functions

  that need to compare list items, for instance remove(const type*).

  If you only want to deal with pointers, there are functions that

  compare pointers instead, for instance removeRef(const type*).

  These functions are somewhat faster than those that call compareItems().

  The QStrList class in qstrlist.h is a list of \c char*.  QStrList is

  a good example of a list that reimplements newItem(), deleteItem() and

  compareItems()

  \sa QListIterator, \link collection.html Collection Classes\endlink

*/

/*!

  \fn QList::QList()

  Constructs an empty list.

*/

/*!

  \fn QList::QList( const QList<type> &list )

  Constructs a copy of \e list.

  Each item in \e list is \link append() appended\endlink to this list.

  Only the pointers are copied (shallow copy).

*/

/*!

  \fn QList::~QList()

  Removes all items from the list and destroys the list.

  All list iterators that access this list will be reset.

  \sa setAutoDelete()

*/

/*!

  \fn QList<type> &QList::operator=(const QList<type> &list)

  Assigns \e list to this list and returns a reference to this list.

  This list is first cleared, then each item in \e list is

  \link append() appended\endlink to this list.  Only the pointers are copied

  (shallow copy), unless newItem() has been reimplemented().

*/

/*!

  \fn bool QList::operator==(const QList<type> &list ) const

  Compares this list with \a list. Retruns TRUE if the lists

  contain the same data, else FALSE.

*/

/*!

  \fn uint QList::count() const

  Returns the number of items in the list.

  \sa isEmpty()

*/

/*!

  \fn void QList::sort()

  Sorts the list by the result of the virtual compareItems() function.

  The Heap-Sort algorithm is used for sorting.  It sorts n items with

  O(n*log n) compares.  This is the asymptotic optimal solution of the

  sorting problem.

  If the items in your list support operator< and operator== then you

  might be better off with QSortedList since it implements the

  compareItems() function for you using these two operators.

  \sa inSort()

*/

/*!

  \fn bool QList::isEmpty() const

  Returns TRUE if the list is empty, i.e. count() == 0. Returns FALSE

   otherwise.

  \sa count()

*/

/*!

  \fn bool QList::insert( uint index, const type *item )

  Inserts the \e item at the position \e index in the list.

  Returns TRUE if successful, or FALSE if \e index is out of range.

  The valid range is 0 .. count() inclusive.

  The item is appended if \e index == count().

  The inserted item becomes the current list item.

  The \e item must not be a null pointer.

  \sa append(), current()

*/

/*!

  \fn void QList::inSort( const type *item )

  Inserts the \e item at its sorted position in the list.

  The sort order depends on the virtual QGList::compareItems() function.

  All items must be inserted with inSort() to maintain the sorting order.

  The inserted item becomes the current list item.

  The \e item must not be a null pointer.

  Please note that inSort is slow. If you want to insert lots of items

  in a list and sort after inserting then you should use sort().

  inSort() takes up to O(n) compares. That means inserting n items in

  your list will need O(n^2) compares while sort() only needs O(n*logn)

  for the same task. So you inSort() only if you already have a pre-sorted

  list and want to insert only few additional items.

  \sa insert(), QGList::compareItems(), current(), sort()

*/

/*!

  \fn void QList::append( const type *item )

  Inserts the \e item at the end of the list.

  The inserted item becomes the current list item.

  This is equivalent to \c insert(count(),item).

  The \e item must not be a null pointer.

  \sa insert(), current(), prepend()

*/

/*!

  \fn void QList::prepend( const type *item )

  Inserts the \e item at the start of the list.

  The inserted item becomes the current list item.

  This is equivalent to \c insert(0,item).

  The \e item must not be a null pointer.

  \sa append(), insert(), current()

*/

/*!

  \fn bool QList::remove( uint index )

  Removes the item at position \e index in the list.

  Returns TRUE if successful, or FALSE if \e index is out of range.

  The valid range is 0 .. (count() - 1) inclusive.

  The removed item is deleted if \link QCollection::setAutoDelete()

  auto-deletion\endlink is enabled.

  The item after the removed item becomes the new current list item if

  the removed item is not the last item in the list.  If the last item

  is removed, the new last item becomes the current item in Qt 2.x.

  In 3.0, the current item will be set to null.  The current item is

  set to null if the list becomes empty.

  All list iterators that refer to the removed item will be set to point

  to the new current item.

  \sa take(), clear(), setAutoDelete(), current() removeRef()

*/

/*!

  \fn bool QList::remove()

  Removes the current list item.

  Returns TRUE if successful, or FALSE if the current item is null.

  The removed item is deleted if \link QCollection::setAutoDelete()

  auto-deletion\endlink is enabled.

  The item after the removed item becomes the new current list item if

  the removed item is not the last item in the list.  If the last item

  is removed, the new last item becomes the current item in Qt 2.x.

  In 3.0, the current item will be set to null.  The current item is

  set to null if the list becomes empty.

  All list iterators that refer to the removed item will be set to point

  to the new current item.

  \sa take(), clear(), setAutoDelete(), current() removeRef()

*/

/*!

  \fn bool QList::remove( const type *item )

  Removes the first occurrence of \e item from the list.

  Returns TRUE if successful, or FALSE if the item could not be found in the

  list.

  The removed item is deleted if \link QCollection::setAutoDelete()

  auto-deletion\endlink is enabled.

  The compareItems() function is called when searching for the item

  in the list. If compareItems() is not reimplemented, it is more

  efficient to call removeRef().

  The item after the removed item becomes the new current list item if

  the removed item is not the last item in the list.  If the last item

  is removed, the new last item becomes the current item in Qt 2.x.

  In 3.0, the current item will be set to null.  The current item is

  set to null if the list becomes empty.

  All list iterators that refer to the removed item will be set to point

  to the new current item.

  \sa removeRef(), take(), clear(), setAutoDelete(), compareItems(), current()

*/

/*!

  \fn bool QList::removeRef( const type *item )

  Removes the first occurrence of \e item from the list.

  Returns TRUE if successful, or FALSE if the item cannot be found in the

  list.

  The removed item is deleted if \link QCollection::setAutoDelete()

  auto-deletion\endlink is enabled.

  The list is scanned until the pointer \e item is found.  It is removed

  if it is found.

  Equivalent to:

  \code

    if ( list.findRef(item) != -1 )

	list.remove();

  \endcode

  The item after the removed item becomes the new current list item if

  the removed item is not the last item in the list.  If the last item

  is removed, the new last item becomes the current item in Qt 2.x.

  In 3.0, the current item will be set to null.  The current item is

  set to null if the list becomes empty.

  All list iterators that refer to the removed item will be set to point

  to the new current item.

  \sa remove(), clear(), setAutoDelete(), current()

*/

/*!

  \fn void QList::removeNode( QLNode *node )

  Removes the \e node from the list.

  This node must exist in the list, otherwise the program may crash.

  The removed item is deleted if \link QCollection::setAutoDelete()

  auto-deletion\endlink is enabled.

  The first item in the list will become the new current list item.

  The current item is set to null if the list becomes empty.

  All list iterators that refer to the removed item will be set to point to

  the item succeeding this item, or the preceding item if the removed item

  was the last item.

  \warning Do not call this function unless you are an expert.

  \sa takeNode(), currentNode() remove() removeRef()

*/

/*!

  \fn bool QList::removeFirst()

  Removes the first item from the list.

  Returns TRUE if successful, or FALSE if the list is empty.

  The removed item is deleted if \link QCollection::setAutoDelete()

  auto-deletion\endlink is enabled.

  The first item in the list becomes the new current list item.

  The current item is set to null if the list becomes empty.

  All list iterators that refer to the removed item will be set to point

  to the new current item.

  \sa removeLast(), setAutoDelete(), current() remove()

*/

/*!

  \fn bool QList::removeLast()

  Removes the last item from the list.

  Returns TRUE if successful, or FALSE if the list is empty.

  The removed item is deleted if \link QCollection::setAutoDelete()

  auto-deletion\endlink is enabled.

  The last item in the list becomes the new current list item.

  The current item is set to null if the list becomes empty.

  All list iterators that refer to the removed item will be set to point

  to the new current item.

  \sa removeFirst(), setAutoDelete(), current()

*/

/*!

  \fn type *QList::take( uint index )

  Takes the item at position \e index out of the list without

  deleting it (even if \link QCollection::setAutoDelete()

  auto-deletion\endlink is enabled).

  Returns a pointer to the item taken out of the list, or null if

  the index is out of range.

  The valid range is 0 .. (count() - 1) inclusive.

  The item after the taken item becomes the new current list item if

  the taken item is not the last item in the list.  If the last item

  is taken, the new last item becomes the current item in Qt 2.x.  In

  3.0, the current item will be set to null.  The current item is set

  to null if the list becomes empty.

  All list iterators that refer to the taken item will be set to point to

  the new current item.

  \sa remove(), clear(), current()

*/

/*!

  \fn type *QList::take()

  Takes the current item out of the list without deleting it (even if

  \link QCollection::setAutoDelete() auto-deletion\endlink is enabled).

  Returns a pointer to the item taken out of the list, or null if

  the current item is null.

  The item after the taken item becomes the new current list item if

  the taken item is not the last item in the list.  If the last item

  is taken, the new last item becomes the current item in Qt 2.x.  In

  3.0, the current item will be set to null.  The current item is set

  to null if the list becomes empty.

  All list iterators that refer to the taken item will be set to point to

  the new current item.

  \sa remove(), clear(), current()

*/

/*!

  \fn type *QList::takeNode( QLNode *node )

  Takes the \e node out of the list without deleting its item (even if

  \link QCollection::setAutoDelete() auto-deletion\endlink is enabled).

  Returns a pointer to the item taken out of the list.

  This node must exist in the list, otherwise the program may crash.

  The first item in the list becomes the new current list item.

  All list iterators that refer to the taken item will be set to point to

  the item succeeding this item, or the preceding item if the taken item

  was the last item.

  \warning Do not call this function unless you are an expert.

  \sa removeNode(), currentNode()

*/

/*!

  \fn void QList::clear()

  Removes all items from the list.

  The removed items are deleted if \link QCollection::setAutoDelete()

  auto-deletion\endlink is enabled.

  All list iterators that access this list will be reset.

  \sa remove(), take(), setAutoDelete()

*/

/*!

  \fn int QList::find( const type *item )

  Finds the first occurrence of \e item in the list.

  If the item is found, the list sets the current item to point to

  the found item and returns the index of this item.

  If the item is not found, the list sets the current item to null,

  the current index to -1 and returns -1.

  The compareItems() function is called when searching for the item

  in the list. If compareItems() is not reimplemented, it is more

  efficient to call findRef().

  \sa findNext(), findRef(), compareItems(), current()

*/

/*!

  \fn int QList::findNext( const type *item )

  Finds the next occurrence of \e item in the list, starting from

  the current list item.

  If the item is found, the list sets the current item to point to

  the found item and returns the index of this item.

  If the item is not found, the list sets the current item to null,

  the current index to -1 and returns -1.

  The compareItems() function is called when searching for the item

  in the list. If compareItems() is not reimplemented, it is more

  efficient to call findNextRef().

  \sa find(), findNextRef(), compareItems(), current()

*/

/*!

  \fn int QList::findRef( const type *item )

  Finds the first occurrence of \e item in the list.

  If the item is found, the list sets the current item to point to

  the found item and returns the index of this item.

  If the item is not found, the list sets the current item to null,

  the current index to -1 and returns -1.

  Calling this function is must faster than find(), because find()

  compares \e item with each list item using compareItems().

  This function only compares the pointers.

  \sa findNextRef(), find(), current()

*/

/*!

  \fn int QList::findNextRef( const type *item )

  Finds the next occurrence of \e item in the list, starting from the

  current list item.

  If the item is found, the list sets the current item to point to

  the found item and returns the index of this item.

  If the item is not found, the list sets the current item to null,

  the current index to -1 and returns -1.

  Calling this function is must faster than findNext(), because findNext()

  compares \e item with each list item using compareItems().

  This function only compares the pointers.

  \sa findRef(), findNext(), current()

*/

/*!

  \fn uint QList::contains( const type *item ) const

  Counts and returns the number of occurrences of \e item in the list.

  The compareItems() function is called when looking for the \e item

  in the list. If compareItems() is not reimplemented, it is more

  efficient to call containsRef().

  Does not affect the current list item.

  \sa containsRef(), compareItems()

*/

/*!

  \fn uint QList::containsRef( const type *item ) const

  Counts and returns the number of occurrences of \e item in the list.

  Calling this function is must faster than contains(), because contains()

  compares \e item with each list item using compareItems().

  This function only compares the pointers.

  Does not affect the current list item.

  \sa contains()

*/

/*!

  \fn type *QList::at( uint index )

  Returns a pointer to the item at position \e index in the list, or

  null if the index is out of range.

  Sets the current list item to this item if \e index is valid.

  The valid range is 0 .. (count() - 1) inclusive.

  This function is very efficient.  It starts scanning from the first

  item, last item or current item, whichever is closest to \e index.

  \sa current()

*/

/*!

  \fn int QList::at() const

  Returns the index of the current list item.  The returned value is -1

  if the current item is null.

  \sa current()

*/

/*!

  \fn type *QList::current() const

  Returns a pointer to the current list item.  The current item may be

  null (implies that the current index is -1).

  \sa at()

*/

/*!

  \fn QLNode *QList::currentNode() const

  Returns a pointer to the current list node.

  The node can be kept and removed later using removeNode().

  The advantage is that the item can be removed directly without

  searching the list.

  \warning Do not call this function unless you are an expert.

  \sa removeNode(), takeNode(), current()

*/

/*!

  \fn type *QList::getFirst() const

  Returns a pointer to the first item in the list, or null if the

  list is empty.

  Does not affect the current list item.

  \sa first(), getLast()

*/

/*!

  \fn type *QList::getLast() const

  Returns a pointer to the last item in the list, or null if the

  list is empty.

  Does not affect the current list item.

  \sa last(), getFirst()

*/

/*!

  \fn type *QList::first()

  Returns a pointer to the first item in the list and makes this the

  current list item, or null if the list is empty.

  \sa getFirst(), last(), next(), prev(), current()

*/

/*!

  \fn type *QList::last()

  Returns a pointer to the last item in the list and makes this the

  current list item, or null if the list is empty.

  \sa getLast(), first(), next(), prev(), current()

*/

/*!

  \fn type *QList::next()

  Returns a pointer to the item succeeding the current item.

  Returns null if the current item is null or equal to the last item.

  Makes the succeeding item current. If the current item before this

  function call was the last item, the current item will be set to null.

  If the current item was null, this function does nothing.

  \sa first(), last(), prev(), current()

*/

/*!

  \fn type *QList::prev()

  Returns a pointer to the item preceding the current item.

  Returns null if the current item is null or equal to the first item.

  Makes the preceding item current. If the current item before this

  function call was the first item, the current item will be set to null.

  If the current item was null, this function does nothing.

  \sa first(), last(), next(), current()

*/

/*!

  \fn void QList::toVector( QGVector *vec ) const

  Stores all list items in the vector \e vec.

  The vector must be have the same item type, otherwise the result

  will be undefined.

*/

/*****************************************************************************

  QListIterator documentation

 *****************************************************************************/

/*!

  \class QListIterator qlist.h

  \brief The QListIterator class provides an iterator for QList collections.

  \ingroup collection

  \ingroup tools

  Define a template instance QListIterator\<X\> to create a list iterator

  that operates on QList\<X\> (list of X*).

  Example:

  \code

    #include <qlist.h>

    #include <qstring.h>

    #include <stdio.h>

    class Employee

    {

    public:

        Employee( const char *name, int salary ) { n=name; s=salary; }

        const char *name()   const		 { return n; }

        int	    salary() const		 { return s; }

    private:

        QString     n;

        int         s;

    };

    void main()

    {

	QList<Employee> list;		  // list of pointers to Employee

	list.setAutoDelete( TRUE );	  // delete items when they are removed

	list.append( new Employee("Bill", 50000) );

	list.append( new Employee("Steve",80000) );

	list.append( new Employee("Ron",  60000) );

	QListIterator<Employee> it(list); // iterator for employee list

	for ( ; it.current(); ++it ) {

	    Employee *emp = it.current();

	    printf( "%s earns %d\n", emp->name().latin1(), emp->salary() );

        }

    }

  \endcode

  Program output:

  \code

	Bill earns 50000

	Steve earns 80000

	Ron earns 60000

  \endcode

  Although QList has member functions to traverse the doubly linked list

  structure, using a list iterator is a much more robust way of traversing

  the list, because multiple list iterators can operate on the same list,

  independent of each other and independent of the QList's current item.

  An iterator has its own current list item and can get the next and

  previous list items.  It can only traverse the list, never modify it.

  A QList knows about all list iterators that are operating on the list.

  When an item is removed from the list, the list update all iterators

  that are pointing the removed item to point to the new current list item.

  Example:

  \code

    #include <qlist.h>

    #include <qstring.h>

    #include <stdio.h>

    class Employee

    {

	...	// same as above

    };

    void main()

    {

	QList<Employee> list;		  // list of pointers to Employee

	list.setAutoDelete( TRUE );	  // delete items when they are removed

	list.append( new Employee("Bill", 50000) );

	list.append( new Employee("Steve",80000) );

	list.append( new Employee("Ron",  60000) );

	QListIterator<Employee> it(list);

	list.at( 1 );			  // current list item: "Steve"

        it.toLast();			  // it: "Ron"

	--it;				  // it: "Steve"

	  // Now, both the list and the iterator are referring the same item

	list.remove();

	printf( "%s\n", it.current()->name().latin1() );

    }

  \endcode

  Program output:

  \code

	Ron

  \endcode

  \sa QList, \link collection.html collection classes\endlink

*/

/*!

  \fn QListIterator::QListIterator( const QList<type> &list )

  Constructs an iterator for \e list.  The current iterator item is

  set to point on the first item in the \e list.

*/

/*!

  \fn QListIterator::~QListIterator()

  Destroys the iterator.

*/

/*!

  \fn uint QListIterator::count() const

  Returns the number of items in the list this iterator operates on.

  \sa isEmpty()

*/

/*!

  \fn bool QListIterator::isEmpty() const

  Returns TRUE if the list is empty, i.e. count() == 0, otherwise FALSE.

  \sa count()

*/

/*!

  \fn bool QListIterator::atFirst() const

  Returns TRUE if the current iterator item is the first list item, otherwise

  FALSE.

  \sa toFirst(), atLast()

*/

/*!

  \fn bool QListIterator::atLast() const

  Returns TRUE if the current iterator item is the last list item, otherwise

  FALSE.

  \sa toLast(), atFirst()

*/

/*!

  \fn type *QListIterator::toFirst()

  Sets the current iterator item to point to the first list item and returns

  a pointer to the item.  Sets the current item to null and returns null

  if the list is empty.

  \sa toLast(), atFirst()

*/

/*!

  \fn type *QListIterator::toLast()

  Sets the current iterator item to point to the last list item and returns

  a pointer to the item.  Sets the current item to null and returns null

  if the list is empty.

  \sa toFirst(), atLast()

*/

/*!

  \fn QListIterator::operator type *() const

  Cast operator. Returns a pointer to the current iterator item.

  Same as current().

*/

/*!

  \fn type *QListIterator::operator*()

  Asterix operator. Returns a pointer to the current iterator item.

  Same as current().

*/

/*!

  \fn type *QListIterator::current() const

  Returns a pointer to the current iterator item.

*/

/*!

  \fn type *QListIterator::operator()()

  Makes the succeeding item current and returns the original current item.

  If the current iterator item was the last item in the list or if it was

  null, null is returned.

*/

/*!

  \fn char *QStrListIterator::operator()()