_baselist_sublist_listiterator.java

Java的面向对象数据库系统的源代码

/*
 * $Id: _BaseList_SubList_listIterator.java,v 1.1 2003/10/02 09:01:39 leomekenkamp Exp $
 * This file is based on AbstractList.java from GNU Classpath. Quote:

AbstractList.java -- Abstract implementation of most of List
Copyright (C) 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Classpath is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
conditions of the GNU General Public License cover the whole
combination.

As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
modules, and to copy and distribute the resulting executable under
terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
module.  An independent module is a module which is not derived from
or based on this library.  If you modify this library, you may extend
this exception to your version of the library, but you are not
obligated to do so.  If you do not wish to do so, delete this
exception statement from your version.

 * end quote.
 *
 * This file is licenced under the same conditions as its original (GPL +
 * "special exception").
 */

package org.ozoneDB.collections;

import java.util.NoSuchElementException;
import org.ozoneDB.OzoneObject;

/**
 * @author Original author unknown
 * @author Eric Blake <[e-mail]>
 * @author ported to Ozone by Leo Mekenkamp
 */
public class _BaseList_SubList_listIterator extends OzoneObject implements OzoneListIterator {

    private _BaseList_SubList subList;
    private OzoneListIterator wrapped;

    private int position;

    public _BaseList_SubList_listIterator(_BaseList_SubList subList, OzoneListIterator wrapped) {
        this.subList = subList;
        this.wrapped = wrapped;
        position = wrapped.nextIndex();
    }

    public boolean hasNext() {
        subList._org_ozoneDB_checkMod();
        return position < subList.size();
    }

    public boolean hasPrevious() {
        subList._org_ozoneDB_checkMod();
        return position > 0;
    }

    public Object next() {
        if (position >= subList.size()) {
            throw new NoSuchElementException();
        }
        position++;
        return wrapped.next();
    }

    public Object previous() {
        if (position <= 0) {
            throw new NoSuchElementException();
        }
        position--;
        return wrapped.previous();
    }

    public int nextIndex() {
        return wrapped.nextIndex() - subList._org_ozoneDB_getOffset();
    }

    public int previousIndex() {
        return wrapped.previousIndex() - subList._org_ozoneDB_getOffset();
    }

    public void remove() {
        wrapped.remove();
        subList._org_ozoneDB_incSize(-1);
        position = nextIndex();
        subList._org_ozoneDB_syncModCountWithBackingList();
    }

    public void set(Object o) {
        wrapped.set(o);
    }

    public void add(Object o) {
        wrapped.add(o);
        subList._org_ozoneDB_incSize(1);
        position++;
        subList._org_ozoneDB_syncModCountWithBackingList();
    }

    // Here is the reason why the various modCount fields are mostly
    // ignored in this wrapper listIterator.
    // If the backing listIterator is failfast, then the following holds:
    //   Using any other method on this list will call a corresponding
    //   method on the backing list *after* the backing listIterator
    //   is created, which will in turn cause a ConcurrentModException
    //   when this listIterator comes to use the backing one. So it is
    //   implicitly failfast.
    // If the backing listIterator is NOT failfast, then the whole of
    //   this list isn't failfast, because the modCount field of the
    //   backing list is not valid. It would still be *possible* to
    //   make the iterator failfast wrt modifications of the sublist
    //   only, but somewhat pointless when the list can be changed under
    //   us.
    // Either way, no explicit handling of modCount is needed.
    // However modCount = backingList.modCount must be executed in add
    // and remove, and size must also be updated in these two methods,
    // since they do not go through the corresponding methods of the subList.
}