/* * Distributed as part of c3p0 v.0.9.1-pre6 * * Copyright (C) 2005 Machinery For Change, Inc. * * Author: Steve Waldman <swaldman@mchange.com> * * This library is free software; you can redistribute it and/or modify * it under the terms of the GNU Lesser General Public License version 2.1, as  * published by the Free Software Foundation. * * This software 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 Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public License * along with this software; see the file LICENSE.  If not, write to the * Free Software Foundation, Inc., 59 Temple Place, Suite 330, * Boston, MA 02111-1307, USA. */package com.mchange.v1.util;import java.util.*;import com.mchange.v1.util.DebugUtils;/** *  This implementation does not yet support removes once hasNext() has *  been called... will add if necessary. */public abstract class WrapperIterator implements Iterator{    protected final static Object SKIP_TOKEN = new Object();    final static boolean DEBUG = true;    Iterator inner;    boolean  supports_remove;    Object   lastOut = null;    Object   nextOut = SKIP_TOKEN;        public WrapperIterator(Iterator inner, boolean supports_remove)    { 	this.inner = inner; 	this.supports_remove = supports_remove;    }    public WrapperIterator(Iterator inner)    { this( inner, false ); }    public boolean hasNext()    {	findNext();	return nextOut != SKIP_TOKEN;     }    private void findNext()    {	if (nextOut == SKIP_TOKEN)	    {		while (inner.hasNext() && nextOut == SKIP_TOKEN)		    this.nextOut = transformObject( inner.next() );	    }    }    public Object next()    {	findNext();	if (nextOut != SKIP_TOKEN)	    {		lastOut = nextOut;		nextOut = SKIP_TOKEN;	    }	else	    throw new NoSuchElementException();	//postcondition	if (DEBUG)	    DebugUtils.myAssert( nextOut == SKIP_TOKEN && lastOut != SKIP_TOKEN );	return lastOut;    }        public void remove()    { 	if (supports_remove)	    {		if (nextOut != SKIP_TOKEN)		    throw new UnsupportedOperationException(this.getClass().getName() +							    " cannot support remove after" +							    " hasNext() has been called!");		if (lastOut != SKIP_TOKEN)		    inner.remove();		else		    throw new NoSuchElementException();	    }	else	    throw new UnsupportedOperationException();     }    /**     * return SKIP_TOKEN to indicate an object should be     * skipped, i.e., not exposed as part of the iterator.     * (we don't use null, because we want to support iterators     * over null-accepting Collections.)     */    protected abstract Object transformObject(Object o);}