Adding qmake in preperation for new build system

1 files changed, 863 insertions, 0 deletions

diff --git a/qmake/tools/qgcache.cpp b/qmake/tools/qgcache.cpp
new file mode 100644
index 0000000..84180b0
--- a/dev/null
+++ b/qmake/tools/qgcache.cpp
@@ -0,0 +1,863 @@
+/****************************************************************************
+** $Id$
+**
+** Implementation of QGCache and QGCacheIterator classes
+**
+** Created : 950208
+**
+** Copyright (C) 1992-2000 Trolltech AS.  All rights reserved.
+**
+** This file is part of the tools module of the Qt GUI Toolkit.
+**
+** This file may be distributed under the terms of the Q Public License
+** as defined by Trolltech AS of Norway and appearing in the file
+** LICENSE.QPL included in the packaging of this file.
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.
+**
+** Licensees holding valid Qt Enterprise Edition or Qt Professional Edition
+** licenses may use this file in accordance with the Qt Commercial License
+** Agreement provided with the Software.
+**
+** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
+** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+**
+** See http://www.trolltech.com/pricing.html or email sales@trolltech.com for
+**   information about Qt Commercial License Agreements.
+** See http://www.trolltech.com/qpl/ for QPL licensing information.
+** See http://www.trolltech.com/gpl/ for GPL licensing information.
+**
+** Contact info@trolltech.com if any conditions of this licensing are
+** not clear to you.
+**
+**********************************************************************/
+
+#include "qgcache.h"
+#include "qptrlist.h"
+#include "qdict.h"
+#include "qstring.h"
+
+/*!
+  \class QGCache qgcache.h
+  \reentrant
+  \ingroup shared
+  \ingroup collection
+  \brief The QGCache class is an internal class for implementing QCache
+  template classes.
+
+  \internal
+
+  QGCache is a strictly internal class that acts as a base class for the
+  \link collection.html collection classes\endlink QCache and QIntCache.
+*/
+
+
+/*****************************************************************************
+  QGCacheItem class (internal cache item)
+ *****************************************************************************/
+
+struct QCacheItem
+{
+    QCacheItem( void *k, QPtrCollection::Item d, int c, short p )
+	: priority(p), skipPriority(p), cost(c), key(k), data(d), node(0) {}
+    short	priority;
+    short	skipPriority;
+    int		cost;
+    void       *key;
+    QPtrCollection::Item data;
+    QLNode     *node;
+};
+
+
+/*****************************************************************************
+  QCList class (internal list of cache items)
+ *****************************************************************************/
+
+class QCList : private QPtrList<QCacheItem>
+{
+friend class QGCacheIterator;
+friend class QCListIt;
+public:
+    QCList()	{}
+   ~QCList();
+
+    void	insert( QCacheItem * );		// insert according to priority
+    void	insert( int, QCacheItem * );
+    void	take( QCacheItem * );
+    void	reference( QCacheItem * );
+
+    void	setAutoDelete( bool del ) { QPtrCollection::setAutoDelete(del); }
+
+    bool	removeFirst()	{ return QPtrList<QCacheItem>::removeFirst(); }
+    bool	removeLast()	{ return QPtrList<QCacheItem>::removeLast(); }
+
+    QCacheItem *first()		{ return QPtrList<QCacheItem>::first(); }
+    QCacheItem *last()		{ return QPtrList<QCacheItem>::last(); }
+    QCacheItem *prev()		{ return QPtrList<QCacheItem>::prev(); }
+    QCacheItem *next()		{ return QPtrList<QCacheItem>::next(); }
+
+#if defined(QT_DEBUG)
+    int		inserts;			// variables for statistics
+    int		insertCosts;
+    int		insertMisses;
+    int		finds;
+    int		hits;
+    int		hitCosts;
+    int		dumps;
+    int		dumpCosts;
+#endif
+};
+
+
+QCList::~QCList()
+{
+#if defined(QT_DEBUG)
+    Q_ASSERT( count() == 0 );
+#endif
+}
+
+
+void QCList::insert( QCacheItem *ci )
+{
+    QCacheItem *item = first();
+    while( item && item->skipPriority > ci->priority ) {
+	item->skipPriority--;
+	item = next();
+    }
+    if ( item )
+	QPtrList<QCacheItem>::insert( at(), ci );
+    else
+	append( ci );
+#if defined(QT_DEBUG)
+    Q_ASSERT( ci->node == 0 );
+#endif
+    ci->node = currentNode();
+}
+
+inline void QCList::insert( int i, QCacheItem *ci )
+{
+    QPtrList<QCacheItem>::insert( i, ci );
+#if defined(QT_DEBUG)
+    Q_ASSERT( ci->node == 0 );
+#endif
+    ci->node = currentNode();
+}
+
+
+void QCList::take( QCacheItem *ci )
+{
+    if ( ci ) {
+#if defined(QT_DEBUG)
+	Q_ASSERT( ci->node != 0 );
+#endif
+	takeNode( ci->node );
+	ci->node = 0;
+    }
+}
+
+
+inline void QCList::reference( QCacheItem *ci )
+{
+#if defined(QT_DEBUG)
+    Q_ASSERT( ci != 0 && ci->node != 0 );
+#endif
+    ci->skipPriority = ci->priority;
+    relinkNode( ci->node );			// relink as first item
+}
+
+
+class QCListIt: public QPtrListIterator<QCacheItem>
+{
+public:
+    QCListIt( const QCList *p ): QPtrListIterator<QCacheItem>( *p ) {}
+    QCListIt( const QCListIt *p ): QPtrListIterator<QCacheItem>( *p ) {}
+};
+
+
+/*****************************************************************************
+  QCDict class (internal dictionary of cache items)
+ *****************************************************************************/
+
+//
+// Since we need to decide if the dictionary should use an int or const
+// char * key (the "bool trivial" argument in the constructor below)
+// we cannot use the macro/template dict, but inherit directly from QGDict.
+//
+
+class QCDict : public QGDict
+{
+public:
+    QCDict( uint size, uint kt, bool caseSensitive, bool copyKeys )
+	: QGDict( size, (KeyType)kt, caseSensitive, copyKeys ) {}
+    ~QCDict();
+
+    void clear() { QGDict::clear(); }
+
+    QCacheItem *find_string(const QString &key) const
+	{ return (QCacheItem*)((QCDict*)this)->look_string(key, 0, 0); }
+    QCacheItem *find_ascii(const char *key) const
+	{ return (QCacheItem*)((QCDict*)this)->look_ascii(key, 0, 0); }
+    QCacheItem *find_int(long key) const
+	{ return (QCacheItem*)((QCDict*)this)->look_int(key, 0, 0); }
+
+    QCacheItem *take_string(const QString &key)
+	{ return (QCacheItem*)QGDict::take_string(key); }
+    QCacheItem *take_ascii(const char *key)
+	{ return (QCacheItem*)QGDict::take_ascii(key); }
+    QCacheItem *take_int(long key)
+	{ return (QCacheItem*)QGDict::take_int(key); }
+
+    bool  insert_string( const QString &key, const QCacheItem *ci )
+	{ return QGDict::look_string(key,(Item)ci,1)!=0;}
+    bool  insert_ascii( const char *key, const QCacheItem *ci )
+	{ return QGDict::look_ascii(key,(Item)ci,1)!=0;}
+    bool  insert_int( long key, const QCacheItem *ci )
+	{ return QGDict::look_int(key,(Item)ci,1)!=0;}
+
+    bool  remove_string( QCacheItem *item )
+	{ return QGDict::remove_string(*((QString*)(item->key)),item); }
+    bool  remove_ascii( QCacheItem *item )
+	{ return QGDict::remove_ascii((const char *)item->key,item); }
+    bool  remove_int( QCacheItem *item )
+	{ return QGDict::remove_int((long)item->key,item);}
+
+    void  statistics()			{ QGDict::statistics(); }
+
+private:
+    void deleteItem( void *item )
+	{ if ( del_item ) { QCacheItem *d = (QCacheItem*)item; delete d; } }
+};
+
+inline QCDict::~QCDict()
+{
+    clear();
+}
+
+/*****************************************************************************
+  QGDict member functions
+ *****************************************************************************/
+
+/*!
+  Constructs a cache.
+  The maximum cost of the cache is given by \a maxCost and the size by \a
+  size. The key type is \a kt which may be \c StringKey, \c AsciiKey,
+  \c IntKey or \c PtrKey. The case-sensitivity of lookups is set with
+  \a caseSensitive. Keys are copied if \a copyKeys is TRUE.
+*/
+
+QGCache::QGCache( int maxCost, uint size, KeyType kt, bool caseSensitive,
+		  bool copyKeys )
+{
+    keytype = kt;
+    lruList = new QCList;
+    Q_CHECK_PTR( lruList );
+    lruList->setAutoDelete( TRUE );
+    copyk   = ((keytype == AsciiKey) && copyKeys);
+    dict    = new QCDict( size, kt, caseSensitive, FALSE );
+    Q_CHECK_PTR( dict );
+    mCost   = maxCost;
+    tCost   = 0;
+#if defined(QT_DEBUG)
+    lruList->inserts	  = 0;
+    lruList->insertCosts  = 0;
+    lruList->insertMisses = 0;
+    lruList->finds	  = 0;
+    lruList->hits	  = 0;
+    lruList->hitCosts	  = 0;
+    lruList->dumps	  = 0;
+    lruList->dumpCosts	  = 0;
+#endif
+}
+
+/*!
+  Cannot copy a cache.
+*/
+
+QGCache::QGCache( const QGCache & )
+    : QPtrCollection()
+{
+#if defined(QT_CHECK_NULL)
+    qFatal( "QGCache::QGCache(QGCache &): Cannot copy a cache" );
+#endif
+}
+
+/*!
+  Removes all items from the cache and destroys it.
+*/
+
+QGCache::~QGCache()
+{
+    clear();
+    delete dict;
+    delete lruList;
+}
+
+/*!
+  Cannot assign a cache.
+*/
+
+QGCache &QGCache::operator=( const QGCache & )
+{
+#if defined(QT_CHECK_NULL)
+    qFatal( "QGCache::operator=: Cannot copy a cache" );
+#endif
+    return *this;
+}
+
+
+/*!
+  Returns the number of items in the cache.
+*/
+
+uint QGCache::count() const
+{
+    return dict->count();
+}
+
+/*!
+  Returns the size of the hash array.
+*/
+
+uint QGCache::size() const
+{
+    return dict->size();
+}
+
+/*!
+  \fn int QGCache::maxCost() const
+
+  Returns the maximum cache cost.
+*/
+
+/*!
+  \fn int QGCache::totalCost() const
+
+  Returns the total cache cost.
+*/
+
+/*!
+  Sets the maximum cache cost to \a maxCost.
+*/
+
+void QGCache::setMaxCost( int maxCost )
+{
+    if ( maxCost < tCost ) {
+	if ( !makeRoomFor(tCost - maxCost) )	// remove excess cost
+	    return;
+    }
+    mCost = maxCost;
+}
+
+
+/*!
+    Inserts an item with data \a data into the cache using key \a key.
+    The item has cost \a cost and priority \a priority.
+
+  \warning If this function returns FALSE, you must delete \a data
+  yourself.  Additionally, be very careful about using \a data after
+  calling this function, as any other insertions into the cache, from
+  anywhere in the application, or within Qt itself, could cause the
+  data to be discarded from the cache, and the pointer to become
+  invalid.
+*/
+
+bool QGCache::insert_string( const QString &key, QPtrCollection::Item data,
+			     int cost, int priority)
+{
+    if ( tCost + cost > mCost ) {
+	if ( !makeRoomFor(tCost + cost - mCost, priority) ) {
+#if defined(QT_DEBUG)
+	    lruList->insertMisses++;
+#endif
+	    return FALSE;
+	}
+    }
+#if defined(QT_DEBUG)
+    Q_ASSERT( keytype == StringKey );
+    lruList->inserts++;
+    lruList->insertCosts += cost;
+#endif
+    if ( priority < -32768 )
+	priority = -32768;
+    else if ( priority > 32767 )
+	priority = 32677;
+    QCacheItem *ci = new QCacheItem( new QString(key), newItem(data),
+				     cost, (short)priority );
+    Q_CHECK_PTR( ci );
+    lruList->insert( 0, ci );
+    dict->insert_string( key, ci );
+    tCost += cost;
+    return TRUE;
+}
+
+bool QGCache::insert_other( const char *key, QPtrCollection::Item data,
+			    int cost, int priority)
+{
+    if ( tCost + cost > mCost ) {
+	if ( !makeRoomFor(tCost + cost - mCost, priority) ) {
+#if defined(QT_DEBUG)
+	    lruList->insertMisses++;
+#endif
+	    return FALSE;
+	}
+    }
+#if defined(QT_DEBUG)
+    Q_ASSERT( keytype != StringKey );
+    lruList->inserts++;
+    lruList->insertCosts += cost;
+#endif
+    if ( keytype == AsciiKey && copyk )
+	key = qstrdup( key );
+    if ( priority < -32768 )
+	priority = -32768;
+    else if ( priority > 32767 )
+	priority = 32677;
+    QCacheItem *ci = new QCacheItem( (void*)key, newItem(data), cost,
+				     (short)priority );
+    Q_CHECK_PTR( ci );
+    lruList->insert( 0, ci );
+    if ( keytype == AsciiKey )
+	dict->insert_ascii( key, ci );
+    else
+	dict->insert_int( (long)key, ci );
+    tCost += cost;
+    return TRUE;
+}
+
+
+/*!
+  Removes the item with key \a key from the cache. Returns TRUE if the
+  item was removed; otherwise returns FALSE.
+*/
+
+bool QGCache::remove_string( const QString &key )
+{
+    Item d = take_string( key );
+    if ( d )
+	deleteItem( d );
+    return d != 0;
+}
+
+bool QGCache::remove_other( const char *key )
+{
+    Item d = take_other( key );
+    if ( d )
+	deleteItem( d );
+    return d != 0;
+}
+
+
+/*!
+  Takes the item with key \a key out of the cache. The item is not
+  deleted. If no item has this \a key 0 is returned.
+*/
+
+QPtrCollection::Item QGCache::take_string( const QString &key )
+{
+    QCacheItem *ci = dict->take_string( key );	// take from dict
+    Item d;
+    if ( ci ) {
+	d = ci->data;
+	tCost -= ci->cost;
+	lruList->take( ci );			// take from list
+	delete (QString*)ci->key;
+	delete ci;
+    } else {
+	d = 0;
+    }
+    return d;
+}
+
+/*!
+  Takes the item with key \a key out of the cache. The item is not
+  deleted. If no item has this \a key 0 is returned.
+*/
+
+QPtrCollection::Item QGCache::take_other( const char *key )
+{
+    QCacheItem *ci;
+    if ( keytype == AsciiKey )
+	ci = dict->take_ascii( key );
+    else
+	ci = dict->take_int( (long)key );
+    Item d;
+    if ( ci ) {
+	d = ci->data;
+	tCost -= ci->cost;
+	lruList->take( ci );			// take from list
+	if ( copyk )
+	    delete [] (char *)ci->key;
+	delete ci;
+    } else {
+	d = 0;
+    }
+    return d;
+}
+
+
+/*!
+  Clears the cache.
+*/
+
+void QGCache::clear()
+{
+    QCacheItem *ci;
+    while ( (ci = lruList->first()) ) {
+	switch ( keytype ) {
+	    case StringKey:
+		dict->remove_string( ci );
+		delete (QString*)ci->key;
+		break;
+	    case AsciiKey:
+		dict->remove_ascii( ci );
+		if ( copyk )
+		    delete [] (char*)ci->key;
+		break;
+	    case IntKey:
+		dict->remove_int( ci );
+		break;
+	    case PtrKey:			// unused
+		break;
+	}
+	deleteItem( ci->data );			// delete data
+	lruList->removeFirst();			// remove from list
+    }
+    tCost = 0;
+}
+
+
+/*!
+  Finds an item for \a key in the cache and adds a reference if \a ref is TRUE.
+*/
+
+QPtrCollection::Item QGCache::find_string( const QString &key, bool ref ) const
+{
+    QCacheItem *ci = dict->find_string( key );
+#if defined(QT_DEBUG)
+    lruList->finds++;
+#endif
+    if ( ci ) {
+#if defined(QT_DEBUG)
+	lruList->hits++;
+	lruList->hitCosts += ci->cost;
+#endif
+	if ( ref )
+	    lruList->reference( ci );
+	return ci->data;
+    }
+    return 0;
+}
+
+
+/*!
+  Finds an item for \a key in the cache and adds a reference if \a ref is TRUE.
+*/
+
+QPtrCollection::Item QGCache::find_other( const char *key, bool ref ) const
+{
+    QCacheItem *ci = keytype == AsciiKey ? dict->find_ascii(key)
+					 : dict->find_int((long)key);
+#if defined(QT_DEBUG)
+    lruList->finds++;
+#endif
+    if ( ci ) {
+#if defined(QT_DEBUG)
+	lruList->hits++;
+	lruList->hitCosts += ci->cost;
+#endif
+	if ( ref )
+	    lruList->reference( ci );
+	return ci->data;
+    }
+    return 0;
+}
+
+
+/*!
+  Allocates cache space for one or more items.
+*/
+
+bool QGCache::makeRoomFor( int cost, int priority )
+{
+    if ( cost > mCost )				// cannot make room for more
+	return FALSE;				//   than maximum cost
+    if ( priority == -1 )
+	priority = 32767;
+    register QCacheItem *ci = lruList->last();
+    int cntCost = 0;
+    int dumps	= 0;				// number of items to dump
+    while ( cntCost < cost && ci && ci->skipPriority <= priority ) {
+	cntCost += ci->cost;
+	ci	 = lruList->prev();
+	dumps++;
+    }
+    if ( cntCost < cost )			// can enough cost be dumped?
+	return FALSE;				// no
+#if defined(QT_DEBUG)
+    Q_ASSERT( dumps > 0 );
+#endif
+    while ( dumps-- ) {
+	ci = lruList->last();
+#if defined(QT_DEBUG)
+	lruList->dumps++;
+	lruList->dumpCosts += ci->cost;
+#endif
+	switch ( keytype ) {
+	    case StringKey:
+		dict->remove_string( ci );
+		delete (QString*)ci->key;
+		break;
+	    case AsciiKey:
+		dict->remove_ascii( ci );
+		if ( copyk )
+		    delete [] (char *)ci->key;
+		break;
+	    case IntKey:
+		dict->remove_int( ci );
+		break;
+	    case PtrKey:			// unused
+		break;
+	}
+	deleteItem( ci->data );			// delete data
+	lruList->removeLast();			// remove from list
+    }
+    tCost -= cntCost;
+    return TRUE;
+}
+
+
+/*!
+  Outputs debug statistics.
+*/
+
+void QGCache::statistics() const
+{
+#if defined(QT_DEBUG)
+    QString line;
+    line.fill( '*', 80 );
+    qDebug( line.ascii() );
+    qDebug( "CACHE STATISTICS:" );
+    qDebug( "cache contains %d item%s, with a total cost of %d",
+	   count(), count() != 1 ? "s" : "", tCost );
+    qDebug( "maximum cost is %d, cache is %d%% full.",
+	   mCost, (200*tCost + mCost) / (mCost*2) );
+    qDebug( "find() has been called %d time%s",
+	   lruList->finds, lruList->finds != 1 ? "s" : "" );
+    qDebug( "%d of these were hits, items found had a total cost of %d.",
+	   lruList->hits,lruList->hitCosts );
+    qDebug( "%d item%s %s been inserted with a total cost of %d.",
+	   lruList->inserts,lruList->inserts != 1 ? "s" : "",
+	   lruList->inserts != 1 ? "have" : "has", lruList->insertCosts );
+    qDebug( "%d item%s %s too large or had too low priority to be inserted.",
+	   lruList->insertMisses, lruList->insertMisses != 1 ? "s" : "",
+	   lruList->insertMisses != 1 ? "were" : "was" );
+    qDebug( "%d item%s %s been thrown away with a total cost of %d.",
+	   lruList->dumps, lruList->dumps != 1 ? "s" : "",
+	   lruList->dumps != 1 ? "have" : "has", lruList->dumpCosts );
+    qDebug( "Statistics from internal dictionary class:" );
+    dict->statistics();
+    qDebug( line.ascii() );
+#endif
+}
+
+
+/*****************************************************************************
+  QGCacheIterator member functions
+ *****************************************************************************/
+
+/*!
+  \class QGCacheIterator qgcache.h
+  \reentrant
+  \ingroup shared
+  \ingroup collection
+  \brief The QGCacheIterator class is an internal class for implementing QCacheIterator and
+  QIntCacheIterator.
+
+  \internal
+
+  QGCacheIterator is a strictly internal class that does the heavy work for
+  QCacheIterator and QIntCacheIterator.
+*/
+
+/*!
+  Constructs an iterator that operates on the cache \a c.
+*/
+
+QGCacheIterator::QGCacheIterator( const QGCache &c )
+{
+    it = new QCListIt( c.lruList );
+#if defined(QT_DEBUG)
+    Q_ASSERT( it != 0 );
+#endif
+}
+
+/*!
+  Constructs an iterator that operates on the same cache as \a ci.
+*/
+
+QGCacheIterator::QGCacheIterator( const QGCacheIterator &ci )
+{
+    it = new QCListIt( ci.it );
+#if defined(QT_DEBUG)
+    Q_ASSERT( it != 0 );
+#endif
+}
+
+/*!
+  Destroys the iterator.
+*/
+
+QGCacheIterator::~QGCacheIterator()
+{
+    delete it;
+}
+
+/*!
+  Assigns the iterator \a ci to this cache iterator.
+*/
+
+QGCacheIterator &QGCacheIterator::operator=( const QGCacheIterator &ci )
+{
+    *it = *ci.it;
+    return *this;
+}
+
+/*!
+  Returns the number of items in the cache.
+*/
+
+uint QGCacheIterator::count() const
+{
+    return it->count();
+}
+
+/*!
+  Returns TRUE if the iterator points to the first item.
+*/
+
+bool  QGCacheIterator::atFirst() const
+{
+    return it->atFirst();
+}
+
+/*!
+  Returns TRUE if the iterator points to the last item.
+*/
+
+bool QGCacheIterator::atLast() const
+{
+    return it->atLast();
+}
+
+/*!
+  Sets the list iterator to point to the first item in the cache.
+*/
+
+QPtrCollection::Item QGCacheIterator::toFirst()
+{
+    QCacheItem *item = it->toFirst();
+    return item ? item->data : 0;
+}
+
+/*!
+  Sets the list iterator to point to the last item in the cache.
+*/
+
+QPtrCollection::Item QGCacheIterator::toLast()
+{
+    QCacheItem *item = it->toLast();
+    return item ? item->data : 0;
+}
+
+/*!
+  Returns the current item.
+*/
+
+QPtrCollection::Item QGCacheIterator::get() const
+{
+    QCacheItem *item = it->current();
+    return item ? item->data : 0;
+}
+
+/*!
+  Returns the key of the current item.
+*/
+
+QString QGCacheIterator::getKeyString() const
+{
+    QCacheItem *item = it->current();
+    return item ? *((QString*)item->key) : QString::null;
+}
+
+/*!
+  Returns the key of the current item, as a \0-terminated C string.
+*/
+
+const char *QGCacheIterator::getKeyAscii() const
+{
+    QCacheItem *item = it->current();
+    return item ? (const char *)item->key : 0;
+}
+
+/*!
+  Returns the key of the current item, as a long.
+*/
+
+long QGCacheIterator::getKeyInt() const
+{
+    QCacheItem *item = it->current();
+    return item ? (long)item->key : 0;
+}
+
+/*!
+  Moves to the next item (postfix).
+*/
+
+QPtrCollection::Item QGCacheIterator::operator()()
+{
+    QCacheItem *item = it->operator()();
+    return item ? item->data : 0;
+}
+
+/*!
+  Moves to the next item (prefix).
+*/
+
+QPtrCollection::Item QGCacheIterator::operator++()
+{
+    QCacheItem *item = it->operator++();
+    return item ? item->data : 0;
+}
+
+/*!
+  Moves \a jump positions forward.
+*/
+
+QPtrCollection::Item QGCacheIterator::operator+=( uint jump )
+{
+    QCacheItem *item = it->operator+=(jump);
+    return item ? item->data : 0;
+}
+
+/*!
+  Moves to the previous item (prefix).
+*/
+
+QPtrCollection::Item QGCacheIterator::operator--()
+{
+    QCacheItem *item = it->operator--();
+    return item ? item->data : 0;
+}
+
+/*!
+  Moves \a jump positions backward.
+*/
+
+QPtrCollection::Item QGCacheIterator::operator-=( uint jump )
+{
+    QCacheItem *item = it->operator-=(jump);
+    return item ? item->data : 0;
+}