/**************************************************************************** ** ** Implementation of TQGList and TQGListIterator classes ** ** Created : 920624 ** ** Copyright (C) 2010 Timothy Pearson and (C) 1992-2008 Trolltech ASA. ** ** This file is part of the tools module of the TQt GUI Toolkit. ** ** This file may be used under the terms of the GNU General ** Public License versions 2.0 or 3.0 as published by the Free ** Software Foundation and appearing in the files LICENSE.GPL2 ** and LICENSE.GPL3 included in the packaging of this file. ** Alternatively you may (at your option) use any later version ** of the GNU General Public License if such license has been ** publicly approved by Trolltech ASA (or its successors, if any) ** and the KDE Free TQt Foundation. ** ** Please review the following information to ensure GNU General ** Public Licensing requirements will be met: ** http://trolltech.com/products/qt/licenses/licensing/opensource/. ** If you are unsure which license is appropriate for your use, please ** review the following information: ** http://trolltech.com/products/qt/licenses/licensing/licensingoverview ** or contact the sales department at sales@trolltech.com. ** ** This file may be used under the terms of the Q Public License as ** defined by Trolltech ASA and appearing in the file LICENSE.TQPL ** included in the packaging of this file. Licensees holding valid TQt ** Commercial licenses may use this file in accordance with the TQt ** Commercial License Agreement provided with the Software. ** ** This file is provided "AS IS" with NO WARRANTY OF ANY KIND, ** INCLUDING THE WARRANTIES OF DESIGN, MERCHANTABILITY AND FITNESS FOR ** A PARTICULAR PURPOSE. Trolltech reserves all rights not granted ** herein. ** **********************************************************************/ #include "tqglist.h" #include "tqgvector.h" #include "tqdatastream.h" #include "tqvaluelist.h" /*! \class TQLNode tqglist.h \reentrant \ingroup collection \brief The TQLNode class is an internal class for the TQPtrList template collection. \internal TQLNode is a doubly-linked list node. It has three pointers: \list 1 \i Pointer to the previous node. \i Pointer to the next node. \i Pointer to the actual data. \endlist It might sometimes be practical to have direct access to the list nodes in a TQPtrList, but it is seldom required. Be very careful if you want to access the list nodes. The heap can easily get corrupted if you make a mistake. \sa TQPtrList::currentNode(), TQPtrList::removeNode(), TQPtrList::takeNode() */ /*! \fn TQPtrCollection::Item TQLNode::getData() Returns a pointer (\c void*) to the actual data in the list node. */ /*! \class TQGList tqglist.h \reentrant \ingroup collection \brief The TQGList class is an internal class for implementing TQt collection classes. \internal TQGList is a strictly internal class that acts as a base class for several collection classes; TQPtrList, TQPtrQueue and TQPtrStack. TQGList has some virtual functions that can be reimplemented to customize the subclasses, namely compareItems(), read() and write. Normally, you do not have to reimplement any of these functions. If you still want to reimplement them, see the TQStrList class (tqstrlist.h) for an example. */ /* Internal helper class for TQGList. Contains some optimization for the typically case where only one iterators is activre on the list. */ class TQGListIteratorList { public: TQGListIteratorList() : list(0), iterator(0) { } ~TQGListIteratorList() { notifyClear( TRUE ); delete list; } void add( TQGListIterator* i ) { if ( !iterator ) { iterator = i; } else if ( list ) { list->push_front( i ); } else { list = new TQValueList; list->push_front( i ); } } void remove( TQGListIterator* i ) { if ( iterator == i ) { iterator = 0; } else if ( list ) { list->remove( i ); if ( list->isEmpty() ) { delete list; list = 0; } } } void notifyClear( bool zeroList ) { if ( iterator ) { if ( zeroList ) iterator->list = 0; iterator->curNode = 0; } if ( list ) { for ( TQValueList::Iterator i = list->begin(); i != list->end(); ++i ) { if ( zeroList ) (*i)->list = 0; (*i)->curNode = 0; } } } void notifyRemove( TQLNode* n, TQLNode* curNode ) { if ( iterator ) { if ( iterator->curNode == n ) iterator->curNode = curNode; } if ( list ) { for ( TQValueList::Iterator i = list->begin(); i != list->end(); ++i ) { if ( (*i)->curNode == n ) (*i)->curNode = curNode; } } } private: TQValueList* list; TQGListIterator* iterator; }; /***************************************************************************** Default implementation of virtual functions *****************************************************************************/ /*! Documented as TQPtrList::compareItems(). Compares \a item1 with \a item2. */ int TQGList::compareItems( TQPtrCollection::Item item1, TQPtrCollection::Item item2 ) { return item1 != item2; // compare pointers } #ifndef TQT_NO_DATASTREAM /*! \overload Reads a collection/list item from the stream \a s and returns a reference to the stream. The default implementation sets \a item to 0. \sa write() */ TQDataStream &TQGList::read( TQDataStream &s, TQPtrCollection::Item &item ) { item = 0; return s; } /*! \overload Writes a collection/list item to the stream \a s and returns a reference to the stream. The default implementation does nothing. \sa read() */ TQDataStream &TQGList::write( TQDataStream &s, TQPtrCollection::Item ) const { return s; } #endif // TQT_NO_DATASTREAM /***************************************************************************** TQGList member functions *****************************************************************************/ /*! Constructs an empty list. */ TQGList::TQGList() { firstNode = lastNode = curNode = 0; // initialize list numNodes = 0; curIndex = -1; iterators = 0; // initialize iterator list } /*! Constructs a copy of \a list. */ TQGList::TQGList( const TQGList & list ) : TQPtrCollection( list ) { firstNode = lastNode = curNode = 0; // initialize list numNodes = 0; curIndex = -1; iterators = 0; // initialize iterator list TQLNode *n = list.firstNode; while ( n ) { // copy all items from list append( n->data ); n = n->next; } } /*! Removes all items from the list and destroys the list. */ TQGList::~TQGList() { clear(); delete iterators; // Workaround for GCC 2.7.* bug. Compiler constructs 'static' TQGList // instances twice on the same address and therefore tries to destruct // twice on the same address! This is insane but let's try not to crash // here. iterators = 0; } /*! Assigns \a list to this list. */ TQGList& TQGList::operator=( const TQGList &list ) { if ( &list == this ) return *this; clear(); if ( list.count() > 0 ) { TQLNode *n = list.firstNode; while ( n ) { // copy all items from list append( n->data ); n = n->next; } curNode = firstNode; curIndex = 0; } return *this; } /*! Compares this list with \a list. Returns TRUE if the lists contain the same data, otherwise FALSE. */ bool TQGList::operator==( const TQGList &list ) const { if ( count() != list.count() ) return FALSE; if ( count() == 0 ) return TRUE; TQLNode *n1 = firstNode; TQLNode *n2 = list.firstNode; while ( n1 && n2 ) { // should be mutable if ( ( (TQGList*)this )->compareItems( n1->data, n2->data ) != 0 ) return FALSE; n1 = n1->next; n2 = n2->next; } return TRUE; } /*! \fn uint TQGList::count() const Returns the number of items in the list. */ /*! Returns the node at position \a index. Sets this node to current. */ TQLNode *TQGList::locate( uint index ) { if ( index == (uint)curIndex ) // current node ? return curNode; if ( !curNode && firstNode ) { // set current node curNode = firstNode; curIndex = 0; } register TQLNode *node; int distance = index - curIndex; // node distance to cur node bool forward; // direction to traverse if ( index >= numNodes ) return 0; if ( distance < 0 ) distance = -distance; if ( (uint)distance < index && (uint)distance < numNodes - index ) { node = curNode; // start from current node forward = index > (uint)curIndex; } else if ( index < numNodes - index ) { // start from first node node = firstNode; distance = index; forward = TRUE; } else { // start from last node node = lastNode; distance = numNodes - index - 1; if ( distance < 0 ) distance = 0; forward = FALSE; } if ( forward ) { // now run through nodes while ( distance-- ) node = node->next; } else { while ( distance-- ) node = node->prev; } curIndex = index; // must update index return curNode = node; } /*! Inserts item \a d at its sorted position in the list. */ void TQGList::inSort( TQPtrCollection::Item d ) { int index = 0; register TQLNode *n = firstNode; while ( n && compareItems(n->data,d) < 0 ){ // tqfind position in list n = n->next; index++; } insertAt( index, d ); } /*! Inserts item \a d at the start of the list. */ void TQGList::prepend( TQPtrCollection::Item d ) { register TQLNode *n = new TQLNode( newItem(d) ); TQ_CHECK_PTR( n ); n->prev = 0; if ( (n->next = firstNode) ) // list is not empty firstNode->prev = n; else // initialize list lastNode = n; firstNode = curNode = n; // curNode affected numNodes++; curIndex = 0; } /*! Inserts item \a d at the end of the list. */ void TQGList::append( TQPtrCollection::Item d ) { register TQLNode *n = new TQLNode( newItem(d) ); TQ_CHECK_PTR( n ); n->next = 0; if ( (n->prev = lastNode) ) // list is not empty lastNode->next = n; else // initialize list firstNode = n; lastNode = curNode = n; // curNode affected curIndex = numNodes; numNodes++; } /*! Inserts item \a d at position \a index in the list. */ bool TQGList::insertAt( uint index, TQPtrCollection::Item d ) { if ( index == 0 ) { prepend( d ); return TRUE; } else if ( index == numNodes ) { append( d ); return TRUE; } TQLNode *nextNode = locate( index ); if ( !nextNode ) return FALSE; TQLNode *prevNode = nextNode->prev; register TQLNode *n = new TQLNode( newItem(d) ); TQ_CHECK_PTR( n ); nextNode->prev = n; prevNode->next = n; n->prev = prevNode; // link new node into list n->next = nextNode; curNode = n; // curIndex set by locate() numNodes++; return TRUE; } /*! Relinks node \a n and makes it the first node in the list. */ void TQGList::relinkNode( TQLNode *n ) { if ( n == firstNode ) // already first return; curNode = n; unlink(); n->prev = 0; if ( (n->next = firstNode) ) // list is not empty firstNode->prev = n; else // initialize list lastNode = n; firstNode = curNode = n; // curNode affected numNodes++; curIndex = 0; } /*! Unlinks the current list node and returns a pointer to this node. */ TQLNode *TQGList::unlink() { if ( curNode == 0 ) // null current node return 0; register TQLNode *n = curNode; // unlink this node if ( n == firstNode ) { // removing first node ? if ( (firstNode = n->next) ) { firstNode->prev = 0; } else { lastNode = curNode = 0; // list becomes empty curIndex = -1; } } else { if ( n == lastNode ) { // removing last node ? lastNode = n->prev; lastNode->next = 0; } else { // neither last nor first node n->prev->next = n->next; n->next->prev = n->prev; } } if ( n->next ) { // change current node curNode = n->next; } else if ( n->prev ) { curNode = n->prev; curIndex--; } if ( iterators ) iterators->notifyRemove( n, curNode ); numNodes--; return n; } /*! Removes the node \a n from the list. */ bool TQGList::removeNode( TQLNode *n ) { #if defined(TQT_CHECK_NULL) if ( n == 0 || (n->prev && n->prev->next != n) || (n->next && n->next->prev != n) ) { qWarning( "TQGList::removeNode: Corrupted node" ); return FALSE; } #endif curNode = n; unlink(); // unlink node deleteItem( n->data ); // deallocate this node delete n; curNode = firstNode; curIndex = curNode ? 0 : -1; return TRUE; } /*! Removes the item \a d from the list. Uses compareItems() to tqfind the item. If \a d is 0, removes the current item. */ bool TQGList::remove( TQPtrCollection::Item d ) { if ( d && tqfind(d) == -1 ) return FALSE; TQLNode *n = unlink(); if ( !n ) return FALSE; deleteItem( n->data ); delete n; return TRUE; } /*! Removes the item \a d from the list. */ bool TQGList::removeRef( TQPtrCollection::Item d ) { if ( tqfindRef(d) == -1 ) return FALSE; TQLNode *n = unlink(); if ( !n ) return FALSE; deleteItem( n->data ); delete n; return TRUE; } /*! \fn bool TQGList::removeFirst() Removes the first item in the list. */ /*! \fn bool TQGList::removeLast() Removes the last item in the list. */ /*! Removes the item at position \a index from the list. */ bool TQGList::removeAt( uint index ) { if ( !locate(index) ) return FALSE; TQLNode *n = unlink(); if ( !n ) return FALSE; deleteItem( n->data ); delete n; return TRUE; } /*! Replaces the item at index \a index with \a d. */ bool TQGList::tqreplaceAt( uint index, TQPtrCollection::Item d ) { TQLNode *n = locate( index ); if ( !n ) return FALSE; if ( n->data != d ) { deleteItem( n->data ); n->data = newItem( d ); } return TRUE; } /*! Takes the node \a n out of the list. */ TQPtrCollection::Item TQGList::takeNode( TQLNode *n ) { #if defined(TQT_CHECK_NULL) if ( n == 0 || (n->prev && n->prev->next != n) || (n->next && n->next->prev != n) ) { qWarning( "TQGList::takeNode: Corrupted node" ); return 0; } #endif curNode = n; unlink(); // unlink node Item d = n->data; delete n; // delete the node, not data curNode = firstNode; curIndex = curNode ? 0 : -1; return d; } /*! Takes the current item out of the list. */ TQPtrCollection::Item TQGList::take() { TQLNode *n = unlink(); // unlink node Item d = n ? n->data : 0; delete n; // delete node, keep contents return d; } /*! Takes the item at position \a index out of the list. */ TQPtrCollection::Item TQGList::takeAt( uint index ) { if ( !locate(index) ) return 0; TQLNode *n = unlink(); // unlink node Item d = n ? n->data : 0; delete n; // delete node, keep contents return d; } /*! Takes the first item out of the list. */ TQPtrCollection::Item TQGList::takeFirst() { first(); TQLNode *n = unlink(); // unlink node Item d = n ? n->data : 0; delete n; return d; } /*! Takes the last item out of the list. */ TQPtrCollection::Item TQGList::takeLast() { last(); TQLNode *n = unlink(); // unlink node Item d = n ? n->data : 0; delete n; return d; } /*! Removes all items from the list. */ void TQGList::clear() { register TQLNode *n = firstNode; firstNode = lastNode = curNode = 0; // initialize list numNodes = 0; curIndex = -1; if ( iterators ) iterators->notifyClear( FALSE ); TQLNode *prevNode; while ( n ) { // for all nodes ... deleteItem( n->data ); // deallocate data prevNode = n; n = n->next; delete prevNode; // deallocate node } } /*! Finds item \a d in the list. If \a fromStart is TRUE the search begins at the first node; otherwise it begins at the current node. */ int TQGList::tqfindRef( TQPtrCollection::Item d, bool fromStart ) { register TQLNode *n; int index; if ( fromStart ) { // start from first node n = firstNode; index = 0; } else { // start from current node n = curNode; index = curIndex; } while ( n && n->data != d ) { // tqfind exact match n = n->next; index++; } curNode = n; curIndex = n ? index : -1; return curIndex; // return position of item } /*! Finds item \a d in the list using compareItems(). If \a fromStart is TRUE the search begins at the first node; otherwise it begins at the current node. */ int TQGList::tqfind( TQPtrCollection::Item d, bool fromStart ) { register TQLNode *n; int index; if ( fromStart ) { // start from first node n = firstNode; index = 0; } else { // start from current node n = curNode; index = curIndex; } while ( n && compareItems(n->data,d) ){ // tqfind equal match n = n->next; index++; } curNode = n; curIndex = n ? index : -1; return curIndex; // return position of item } /*! Counts the number item \a d occurs in the list. */ uint TQGList::tqcontainsRef( TQPtrCollection::Item d ) const { register TQLNode *n = firstNode; uint count = 0; while ( n ) { // for all nodes... if ( n->data == d ) // count # exact matches count++; n = n->next; } return count; } /*! Counts the number of times item \a d occurs in the list. Uses compareItems(). */ uint TQGList::tqcontains( TQPtrCollection::Item d ) const { register TQLNode *n = firstNode; uint count = 0; TQGList *that = (TQGList*)this; // mutable for compareItems() while ( n ) { // for all nodes... if ( !that->compareItems(n->data,d) ) // count # equal matches count++; n = n->next; } return count; } /*! \overload TQPtrCollection::Item TQGList::at( uint index ) Sets the item at position \a index to the current item. */ /*! \fn int TQGList::at() const Returns the current index. */ /*! \fn TQLNode *TQGList::currentNode() const Returns the current node. */ /*! \fn TQPtrCollection::Item TQGList::get() const Returns the current item. */ /*! \fn TQPtrCollection::Item TQGList::cfirst() const Returns the first item in the list. */ /*! \fn TQPtrCollection::Item TQGList::clast() const Returns the last item in the list. */ /*! Returns the first list item. Sets this to current. */ TQPtrCollection::Item TQGList::first() { if ( firstNode ) { curIndex = 0; return (curNode=firstNode)->data; } return 0; } /*! Returns the last list item. Sets this to current. */ TQPtrCollection::Item TQGList::last() { if ( lastNode ) { curIndex = numNodes-1; return (curNode=lastNode)->data; } return 0; } /*! Returns the next list item (after current). Sets this to current. */ TQPtrCollection::Item TQGList::next() { if ( curNode ) { if ( curNode->next ) { curIndex++; curNode = curNode->next; return curNode->data; } curIndex = -1; curNode = 0; } return 0; } /*! Returns the previous list item (before current). Sets this to current. */ TQPtrCollection::Item TQGList::prev() { if ( curNode ) { if ( curNode->prev ) { curIndex--; curNode = curNode->prev; return curNode->data; } curIndex = -1; curNode = 0; } return 0; } /*! Converts the list to a vector, \a vector. */ void TQGList::toVector( TQGVector *vector ) const { vector->clear(); if ( !vector->resize( count() ) ) return; register TQLNode *n = firstNode; uint i = 0; while ( n ) { vector->insert( i, n->data ); n = n->next; i++; } } void TQGList::heapSortPushDown( TQPtrCollection::Item* heap, int first, int last ) { int r = first; while( r <= last/2 ) { // Node r has only one child ? if ( last == 2*r ) { // Need for swapping ? if ( compareItems( heap[r], heap[ 2*r ] ) > 0 ) { TQPtrCollection::Item tmp = heap[r]; heap[ r ] = heap[ 2*r ]; heap[ 2*r ] = tmp; } // That's it ... r = last; } else { // Node has two tqchildren if ( compareItems( heap[r], heap[ 2*r ] ) > 0 && compareItems( heap[ 2*r ], heap[ 2*r+1 ] ) <= 0 ) { // Swap with left child TQPtrCollection::Item tmp = heap[r]; heap[ r ] = heap[ 2*r ]; heap[ 2*r ] = tmp; r *= 2; } else if ( compareItems( heap[r], heap[ 2*r+1 ] ) > 0 && compareItems( heap[ 2*r+1 ], heap[ 2*r ] ) < 0 ) { // Swap with right child TQPtrCollection::Item tmp = heap[r]; heap[ r ] = heap[ 2*r+1 ]; heap[ 2*r+1 ] = tmp; r = 2*r+1; } else { // We are done r = last; } } } } /*! 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. */ void TQGList::sort() { uint n = count(); if ( n < 2 ) return; // Create the heap TQPtrCollection::Item* realheap = new TQPtrCollection::Item[ n ]; // Wow, what a fake. But I want the heap to be indexed as 1...n TQPtrCollection::Item* heap = realheap - 1; int size = 0; TQLNode* insert = firstNode; for( ; insert != 0; insert = insert->next ) { heap[++size] = insert->data; int i = size; while( i > 1 && compareItems( heap[i], heap[ i / 2 ] ) < 0 ) { TQPtrCollection::Item tmp = heap[ i ]; heap[ i ] = heap[ i/2 ]; heap[ i/2 ] = tmp; i /= 2; } } insert = firstNode; // Now do the sorting for ( int i = n; i > 0; i-- ) { insert->data = heap[1]; insert = insert->next; if ( i > 1 ) { heap[1] = heap[i]; heapSortPushDown( heap, 1, i - 1 ); } } delete [] realheap; } /***************************************************************************** TQGList stream functions *****************************************************************************/ #ifndef TQT_NO_DATASTREAM TQDataStream &operator>>( TQDataStream &s, TQGList &list ) { // read list return list.read( s ); } TQDataStream &operator<<( TQDataStream &s, const TQGList &list ) { // write list return list.write( s ); } /*! Reads a list from the stream \a s. */ TQDataStream &TQGList::read( TQDataStream &s ) { uint num; s >> num; // read number of items clear(); // clear list while ( num-- ) { // read all items Item d; read( s, d ); TQ_CHECK_PTR( d ); if ( !d ) // no memory break; TQLNode *n = new TQLNode( d ); TQ_CHECK_PTR( n ); if ( !n ) // no memory break; n->next = 0; if ( (n->prev = lastNode) ) // list is not empty lastNode->next = n; else // initialize list firstNode = n; lastNode = n; numNodes++; } curNode = firstNode; curIndex = curNode ? 0 : -1; return s; } /*! Writes the list to the stream \a s. */ TQDataStream &TQGList::write( TQDataStream &s ) const { s << count(); // write number of items TQLNode *n = firstNode; while ( n ) { // write all items write( s, n->data ); n = n->next; } return s; } #endif // TQT_NO_DATASTREAM /*! \internal */ TQLNode* TQGList::erase( TQLNode* it ) { TQLNode* n = it; it = it->next; removeNode( n ); return it; } /***************************************************************************** TQGListIterator member functions *****************************************************************************/ /*! \class TQGListIterator tqglist.h \reentrant \ingroup collection \brief The TQGListIterator class is an internal class for implementing TQPtrListIterator. \internal TQGListIterator is a strictly internal class that does the heavy work for TQPtrListIterator. */ /*! \internal Constructs an iterator that operates on the list \a l. */ TQGListIterator::TQGListIterator( const TQGList &l ) { list = (TQGList *)&l; // get reference to list curNode = list->firstNode; // set to first node if ( !list->iterators ) { list->iterators = new TQGListIteratorList; // create iterator list TQ_CHECK_PTR( list->iterators ); } list->iterators->add( this ); // attach iterator to list } /*! \internal Constructs a copy of the iterator \a it. */ TQGListIterator::TQGListIterator( const TQGListIterator &it ) { list = it.list; curNode = it.curNode; if ( list ) list->iterators->add( this ); // attach iterator to list } /*! \internal Assigns a copy of the iterator \a it and returns a reference to this iterator. */ TQGListIterator &TQGListIterator::operator=( const TQGListIterator &it ) { if ( list ) // detach from old list list->iterators->remove( this ); list = it.list; curNode = it.curNode; if ( list ) list->iterators->add( this ); // attach to new list return *this; } /*! \internal Destroys the iterator. */ TQGListIterator::~TQGListIterator() { if ( list ) // detach iterator from list list->iterators->remove(this); } /*! \fn bool TQGListIterator::atFirst() const \internal Returns TRUE if the iterator points to the first item, otherwise FALSE. */ /*! \fn bool TQGListIterator::atLast() const \internal Returns TRUE if the iterator points to the last item, otherwise FALSE. */ /*! \internal Sets the list iterator to point to the first item in the list. */ TQPtrCollection::Item TQGListIterator::toFirst() { if ( !list ) { #if defined(TQT_CHECK_NULL) qWarning( "TQGListIterator::toFirst: List has been deleted" ); #endif return 0; } return list->firstNode ? (curNode = list->firstNode)->getData() : 0; } /*! \internal Sets the list iterator to point to the last item in the list. */ TQPtrCollection::Item TQGListIterator::toLast() { if ( !list ) { #if defined(TQT_CHECK_NULL) qWarning( "TQGListIterator::toLast: List has been deleted" ); #endif return 0; } return list->lastNode ? (curNode = list->lastNode)->getData() : 0; } /*! \fn TQPtrCollection::Item TQGListIterator::get() const \internal Returns the iterator item. */ /*! \internal Moves to the next item (postfix). */ TQPtrCollection::Item TQGListIterator::operator()() { if ( !curNode ) return 0; TQPtrCollection::Item d = curNode->getData(); curNode = curNode->next; return d; } /*! \internal Moves to the next item (prefix). */ TQPtrCollection::Item TQGListIterator::operator++() { if ( !curNode ) return 0; curNode = curNode->next; return curNode ? curNode->getData() : 0; } /*! \internal Moves \a jumps positions forward. */ TQPtrCollection::Item TQGListIterator::operator+=( uint jumps ) { while ( curNode && jumps-- ) curNode = curNode->next; return curNode ? curNode->getData() : 0; } /*! \internal Moves to the previous item (prefix). */ TQPtrCollection::Item TQGListIterator::operator--() { if ( !curNode ) return 0; curNode = curNode->prev; return curNode ? curNode->getData() : 0; } /*! \internal Moves \a jumps positions backward. */ TQPtrCollection::Item TQGListIterator::operator-=( uint jumps ) { while ( curNode && jumps-- ) curNode = curNode->prev; return curNode ? curNode->getData() : 0; }