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

** 

**

** Implementation of QGList and QGListIterator classes

**

** Created : 920624

**

** 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.

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**   information about Qt Commercial License Agreements.

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

#include "qglist.h"

#include "qgvector.h"

#include "qdatastream.h"

// NOT REVISED

/*!

  \class QLNode qglist.h

  \brief The QLNode class is an internal class for the QList template collection.

  QLNode is a doubly linked list node; it has three pointers:

  <ol>

  <li> Pointer to the previous node.

  <li> Pointer to the next node.

  <li> Pointer to the actual data.

  </ol>

  Sometimes it might be practical to have direct access to the list nodes

  in a QList, but it is seldom required.

  \warning Be very careful if you want to access the list nodes. The heap

  can easily get corrupted if you make a mistake.

  \sa QList::currentNode(), QList::removeNode(), QList::takeNode()

*/

/*!

  \fn QCollection::Item QLNode::getData()

  Returns a pointer (\c void*) to the actual data in the list node.

*/

/*!

  \class QGList qglist.h

  \brief The QGList class is an internal class for implementing Qt collection classes.

  QGList is a strictly internal class that acts as a base class for several

  \link collection.html collection classes\endlink; QList, QQueue and

  QStack.

  QGList has some virtual functions that can be reimplemented to customize

  the subclasses.

  <ul>

  <li> compareItems() compares two collection/list items.

  <li> read() reads a collection/list item from a QDataStream.

  <li> write() writes a collection/list item to a QDataStream.

  </ul>

  Normally, you do not have to reimplement any of these functions.

  If you still want to reimplement them, see the QStrList class (qstrlist.h),

  which is a good example.

*/

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

  Default implementation of virtual functions

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

/*!

  This virtual function compares two list items.

  Returns:

  <ul>

  <li> 0 if \e item1 == \e item2

  <li> non-zero if \e item1 != \e item2

  </ul>

  This function returns \e int rather than \e bool so that

  reimplementations can return three values and use it to sort by:

  <ul>

  <li> 0 if \e item1 == \e item2

  <li> \> 0 (positive integer) if \e item1 \> \e item2

  <li> \< 0 (negative integer) if \e item1 \< \e item2

  </ul>

  The QList::inSort() function requires that compareItems() is implemented

  as described here.

  This function should not modify the list because some const functions

  call compareItems().

  The default implementation compares the pointers:

  \code

  \endcode

*/

int QGList::compareItems( QCollection::Item item1, QCollection::Item item2 )

{

    return item1 != item2;			// compare pointers

}

#ifndef QT_NO_DATASTREAM

/*!

  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()

*/

QDataStream &QGList::read( QDataStream &s, QCollection::Item &item )

{

    item = 0;

    return s;

}

/*!

  Writes a collection/list item to the stream \a s and returns a reference

  to the stream.

  The default implementation does nothing.

  \sa read()

*/

QDataStream &QGList::write( QDataStream &s, QCollection::Item ) const

{

    return s;

}

#endif // QT_NO_DATASTREAM

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

  QGList member functions

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

/*!

  \internal

  Constructs an empty list.

*/

QGList::QGList()

{

    firstNode = lastNode = curNode = 0;		// initialize list

    numNodes  = 0;

    curIndex  = -1;

    iterators = 0;				// initialize iterator list

}

/*!

  \internal

  Constructs a copy of \e list.

*/

QGList::QGList( const QGList & list )

    : QCollection( list )

{

    firstNode = lastNode = curNode = 0;		// initialize list

    numNodes  = 0;

    curIndex  = -1;

    iterators = 0;				// initialize iterator list

    QLNode *n = list.firstNode;

    while ( n ) {				// copy all items from list

	append( n->data );

	n = n->next;

    }

}

/*!

  \internal

  Removes all items from the list and destroys the list.

*/

QGList::~QGList()

{

    clear();

    if ( !iterators )				// no iterators for this list

	return;

    QGListIterator *i = (QGListIterator*)iterators->first();

    while ( i ) {				// notify all iterators that

	i->list = 0;				// this list is deleted

	i->curNode = 0;

	i = (QGListIterator*)iterators->next();

    }

    delete iterators;

}

/*!

  \internal

  Assigns \e list to this list.

*/

QGList& QGList::operator=( const QGList &list )

{

    clear();

    if ( list.count() > 0 ) {

	QLNode *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. Retruns TRUE if the lists

  contain the same data, else FALSE.

*/

bool QGList::operator==( const QGList &list ) const

{

    if ( count() != list.count() )

	return FALSE;

    if ( count() == 0 )

	return TRUE;

    QLNode *n1 = firstNode;

    QLNode *n2 = list.firstNode;

    while ( n1 && n2 ) {

	// should be mutable

	if ( ( (QGList*)this )->compareItems( n1->data, n2->data ) != 0 )

	    return FALSE;

	n1 = n1->next;

	n2 = n2->next;

    }

    return TRUE;

}

/*!

  \fn uint QGList::count() const

  \internal

  Returns the number of items in the list.

*/

/*!

  \internal

  Returns the node at position \e index.  Sets this node to current.

*/

QLNode *QGList::locate( uint index )

{

    if ( index == (uint)curIndex )		// current node ?

	return curNode;

    if ( !curNode && firstNode ) {		// set current node

	curNode	 = firstNode;

	curIndex = 0;

    }

    register QLNode *node;

    int	 distance = index - curIndex;		// node distance to cur node

    bool forward;				// direction to traverse

    if ( index >= numNodes ) {

#if defined(CHECK_RANGE)

	qWarning( "QGList::locate: Index %d out of range", index );

#endif

	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;

}

/*!

  \internal

  Inserts an item at its sorted position in the list.

*/

void QGList::inSort( QCollection::Item d )

{

    int index = 0;

    register QLNode *n = firstNode;

    while ( n && compareItems(n->data,d) < 0 ){ // find position in list

	n = n->next;

	index++;

    }

    insertAt( index, d );

}

/*!

  \internal

  Inserts an item at the start of the list.

*/

void QGList::prepend( QCollection::Item d )

{

    register QLNode *n = new QLNode( newItem(d) );

    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;

}

/*!

  \internal

  Inserts an item at the end of the list.

*/

void QGList::append( QCollection::Item d )

{

    register QLNode *n = new QLNode( newItem(d) );

    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++;

}

/*!

  \internal

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

*/

bool QGList::insertAt( uint index, QCollection::Item d )

{

    if ( index == 0 ) {				// insert at head of list

	prepend( d );

	return TRUE;

    } else if ( index == numNodes ) {		// append at tail of list

	append( d );

	return TRUE;

    }

    QLNode *nextNode = locate( index );

    if ( !nextNode )				// illegal position

	return FALSE;

    QLNode *prevNode = nextNode->prev;

    register QLNode *n = new QLNode( newItem(d) );

    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;

}

/*!

  \internal

  Relinks node \e n and makes it the first node in the list.

*/

void QGList::relinkNode( QLNode *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;

}

/*!

  \internal

  Unlinks the current list node and returns a pointer to this node.

*/

QLNode *QGList::unlink()

{

    if ( curNode == 0 )				// null current node

	return 0;

    register QLNode *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->count() ) {	// update iterators

	QGListIterator *i = (QGListIterator*)iterators->first();

	while ( i ) {				// fix all iterators that

	    if ( i->curNode == n )		// refers to pending node

		i->curNode = curNode;

	    i = (QGListIterator*)iterators->next();

	}

    }

    numNodes--;

    return n;

}

/*!

  \internal

  Removes the node \e n from the list.

*/

bool QGList::removeNode( QLNode *n )

{

#if defined(CHECK_NULL)

    if ( n == 0 || (n->prev && n->prev->next != n) ||

	 (n->next && n->next->prev != n) ) {

	qWarning( "QGList::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;

}

/*!

  \internal

  Removes the item \e d from the list.	Uses compareItems() to find the item.

*/

bool QGList::remove( QCollection::Item d )

{

    if ( d ) {					// find the item

	if ( find(d) == -1 )

	    return FALSE;

    }

    QLNode *n = unlink();			// unlink node

    if ( !n )

	return FALSE;

    deleteItem( n->data );			// deallocate this node

    delete n;

    return TRUE;

}

/*!

  \internal

  Removes the item \e d from the list.

*/

bool QGList::removeRef( QCollection::Item d )

{

    if ( d ) {					// find the item

	if ( findRef(d) == -1 )

	    return FALSE;

    }