//===========================================================================//=-------------------------------------------------------------------------=//= Module history:                                                         =//= - January 3 2007 - Oscar Chavarro: Original base version                =//===========================================================================package vsdk.toolkit.common;class _CircularDoubleLinkedListNode<E> extends FundamentalEntity{    /// Check the general attribute description in superclass Entity.    public static final long serialVersionUID = 20070422L;    public E data;    public _CircularDoubleLinkedListNode<E> next;    public _CircularDoubleLinkedListNode<E> previous;}public class CircularDoubleLinkedList<E> extends FundamentalEntity{    /// Check the general attribute description in superclass Entity.    public static final long serialVersionUID = 20070422L;    private _CircularDoubleLinkedListNode<E> head;    private _CircularDoubleLinkedListNode<E> window;    private int lastAccessedIndex;    private int currentSize;    public CircularDoubleLinkedList()    {        head = null;        window = null;        currentSize = 0;        lastAccessedIndex = -1;    }    public int size()    {        return currentSize;    }    public void add(E e)    {        _CircularDoubleLinkedListNode<E> newContainer;        newContainer = new _CircularDoubleLinkedListNode<E>();        newContainer.data = e;        if ( head == null ) {            head = newContainer;            newContainer.next = newContainer;            newContainer.previous = newContainer;        }        else {            newContainer.previous = head.previous;            newContainer.next = head;            head.previous.next = newContainer;            head.previous = newContainer;        }        currentSize++;    }    public void insertBefore(E newElem, E pivot)    {        locateWindowAtElem(pivot);        _CircularDoubleLinkedListNode<E> newContainer;        newContainer = new _CircularDoubleLinkedListNode<E>();        newContainer.data = newElem;        lastAccessedIndex = -1;        if ( head == null ) {            head = newContainer;            newContainer.next = newContainer;            newContainer.previous = newContainer;        }        else if ( window == null || window == head ) {            window = head;            head = newContainer;            newContainer.previous = window.previous;            newContainer.next = window;            window.previous.next = newContainer;            window.previous = newContainer;        }        else {            newContainer.previous = window.previous;            newContainer.next = window;            window.previous.next = newContainer;            window.previous = newContainer;        }        currentSize++;    }    public void locateWindowAtIndex(int index)    {        if ( index < 0 || index >= currentSize ) {            return;        }        int i;        for ( i = 0, window = head;              i < currentSize && i < index;              i++, window = window.next );        lastAccessedIndex = i;    }    public boolean locateWindowAtElem(E e)    {        int i;        lastAccessedIndex = -1;        for ( i = 0, window = head;              i < currentSize;              i++, window = window.next ) {            if ( window.data == e ) {                lastAccessedIndex = i;                return true;            }        }        window = null;        return false;    }    public void swapElements(E e1, E e2)    {        locateWindowAtElem(e1);        _CircularDoubleLinkedListNode<E> window1 = window;        locateWindowAtElem(e2);        _CircularDoubleLinkedListNode<E> window2 = window;        if ( window1 == null || window2 == null ) return;        E temp = window1.data;        window1.data = window2.data;        window2.data = temp;    }    public E next()    {        lastAccessedIndex = -1;        if ( window == null ) {            window = head;        }        E elem = window.data;        window = window.next;        return elem;    }    public E getWindow()    {        if ( head == null ) return null;        lastAccessedIndex = -1;        if ( window == null ) {            window = head;        }        return window.data;    }    public E previous()    {        lastAccessedIndex = -1;        if ( window == null ) {            window = head;        }        E elem = window.data;        window = window.previous;        return elem;    }    public E get(int index)    {        if ( index < 0 || index >= currentSize ) {            // Report index out of bounds exception!            System.out.println("<CircularDoubleLinkedList> IndexOutOfBounds Exception! - Trying to `get` with index " + index + " in a list with " + currentSize + " elements.");            try {                throw new Exception("CircularDoubleLinkedList.get");	    }	    catch ( Exception e ) {                e.printStackTrace();	    }            System.exit(1);            return null;        }        if ( lastAccessedIndex >= 0 && lastAccessedIndex == (index-1) &&             lastAccessedIndex < (currentSize-1) ) {            lastAccessedIndex++;            window = window.next;            return window.data;        }        int i;        for ( i = 0, window = head;              i < currentSize && i < index; i++, window = window.next );        lastAccessedIndex = i;        return window.data;    }    public void remove(int pos)    {        locateWindowAtIndex(pos);        removeElemAtWindow();    }    public void removeElemAtWindow()    {        if ( window == null ) return;        if ( window == head ) head = window.next;        window.previous.next = window.next;        window.next.previous = window.previous;        window = null;        currentSize--;    }    public void push(E newElem)    {        window = head;        lastAccessedIndex = 0;        _CircularDoubleLinkedListNode<E> newContainer;        newContainer = new _CircularDoubleLinkedListNode<E>();        newContainer.data = newElem;        lastAccessedIndex = -1;        if ( head == null ) {            head = newContainer;            newContainer.next = newContainer;            newContainer.previous = newContainer;        }        else if ( window == null || window == head ) {            window = head;            head = newContainer;            newContainer.previous = window.previous;            newContainer.next = window;            window.previous.next = newContainer;            window.previous = newContainer;        }        else {            newContainer.previous = window.previous;            newContainer.next = window;            window.previous.next = newContainer;            window.previous = newContainer;        }        currentSize++;    }    public void reverse()    {        _CircularDoubleLinkedListNode<E> ptr, qtr;        E tmp;        int i = 0;        ptr = head;        qtr = head.previous;        do {            tmp = ptr.data;            ptr.data = qtr.data;            qtr.data = tmp;            ptr = ptr.next;            qtr = qtr.previous;            i++;        } while ( ptr != head && i < currentSize/2 );    }}//===========================================================================//= EOF                                                                     =//===========================================================================