001    /**
002     * JDBM LICENSE v1.00
003     *
004     * Redistribution and use of this software and associated documentation
005     * ("Software"), with or without modification, are permitted provided
006     * that the following conditions are met:
007     *
008     * 1. Redistributions of source code must retain copyright
009     *    statements and notices.  Redistributions must also contain a
010     *    copy of this document.
011     *
012     * 2. Redistributions in binary form must reproduce the
013     *    above copyright notice, this list of conditions and the
014     *    following disclaimer in the documentation and/or other
015     *    materials provided with the distribution.
016     *
017     * 3. The name "JDBM" must not be used to endorse or promote
018     *    products derived from this Software without prior written
019     *    permission of Cees de Groot.  For written permission,
020     *    please contact cg@cdegroot.com.
021     *
022     * 4. Products derived from this Software may not be called "JDBM"
023     *    nor may "JDBM" appear in their names without prior written
024     *    permission of Cees de Groot.
025     *
026     * 5. Due credit should be given to the JDBM Project
027     *    (http://jdbm.sourceforge.net/).
028     *
029     * THIS SOFTWARE IS PROVIDED BY THE JDBM PROJECT AND CONTRIBUTORS
030     * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
031     * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
032     * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
033     * CEES DE GROOT OR ANY CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
034     * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
035     * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
036     * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
037     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
038     * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
039     * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
040     * OF THE POSSIBILITY OF SUCH DAMAGE.
041     *
042     * Copyright 2001 (C) Alex Boisvert. All Rights Reserved.
043     * Contributions are Copyright (C) 2001 by their associated contributors.
044     *
045     */
046    
047    package jdbm.helper;
048    
049    import java.io.IOException;
050    
051    /**
052     * Browser to traverse a collection of tuples.  The browser allows for
053     * forward and reverse order traversal.
054     *
055     * @author <a href="mailto:boisvert@intalio.com">Alex Boisvert</a>
056     * @version $Id: TupleBrowser.java,v 1.2 2001/05/19 14:02:00 boisvert Exp $
057     */
058    public abstract class TupleBrowser {
059    
060        /**
061         * Get the next tuple.
062         *
063         * @param tuple Tuple into which values are copied.
064         * @return True if values have been copied in tuple, or false if there is
065         *         no next tuple.
066         */
067        public abstract boolean getNext( Tuple tuple )
068            throws IOException;
069    
070    
071        /**
072         * Get the previous tuple.
073         *
074         * @param tuple Tuple into which values are copied.
075         * @return True if values have been copied in tuple, or false if there is
076         *         no previous tuple.
077         */
078        public abstract boolean getPrevious( Tuple tuple )
079            throws IOException;
080    
081    }