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    1   /*
    2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/util/StackedIterator.java,v 1.11 2005/06/28 13:44:44 elharo Exp $
    3    * $Revision: 1.11 $
    4    * $Date: 2005/06/28 13:44:44 $
    5    *
    6    * ====================================================================
    7    *
    8    * Copyright (C) 2000-2002 bob mcwhirter & James Strachan.
    9    * All rights reserved.
    10   *
    11   * Redistribution and use in source and binary forms, with or without
    12   * modification, are permitted provided that the following conditions
    13   * are met:
    14   *
    15   * 1. Redistributions of source code must retain the above copyright
    16   *    notice, this list of conditions, and the following disclaimer.
    17   *
    18   * 2. Redistributions in binary form must reproduce the above copyright
    19   *    notice, this list of conditions, and the disclaimer that follows
    20   *    these conditions in the documentation and/or other materials
    21   *    provided with the distribution.
    22   *
    23   * 3. The name "Jaxen" must not be used to endorse or promote products
    24   *    derived from this software without prior written permission.  For
    25   *    written permission, please contact license@jaxen.org.
    26   *
    27   * 4. Products derived from this software may not be called "Jaxen", nor
    28   *    may "Jaxen" appear in their name, without prior written permission
    29   *    from the Jaxen Project Management (pm@jaxen.org).
    30   *
    31   * In addition, we request (but do not require) that you include in the
    32   * end-user documentation provided with the redistribution and/or in the
    33   * software itself an acknowledgement equivalent to the following:
    34   *     "This product includes software developed by the
    35   *      Jaxen Project <http://www.jaxen.org/>."
    36   * Alternatively, the acknowledgment may be graphical using the logos
    37   * available at http://www.jaxen.org/
    38   *
    39   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
    40   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
    41   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
    42   * DISCLAIMED.  IN NO EVENT SHALL THE Jaxen AUTHORS OR THE PROJECT
    43   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
    44   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
    45   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
    46   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
    47   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
    48   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
    49   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
    50   * SUCH DAMAGE.
    51   *
    52   * ====================================================================
    53   * This software consists of voluntary contributions made by many
    54   * individuals on behalf of the Jaxen Project and was originally
    55   * created by bob mcwhirter <bob@werken.com> and
    56   * James Strachan <jstrachan@apache.org>.  For more information on the
    57   * Jaxen Project, please see <http://www.jaxen.org/>.
    58   *
    59   * $Id: StackedIterator.java,v 1.11 2005/06/28 13:44:44 elharo Exp $
    60   */
    61
    62
    63
    64  package org.jaxen.util;
    65
    66  import java.util.HashSet;
    67  import java.util.Iterator;
    68  import java.util.LinkedList;
    69  import java.util.NoSuchElementException;
    70  import java.util.Set;
    71
    72  import org.jaxen.Navigator;
    73
    74  /***
    75   * @deprecated this iterator is no longer used to implement any of the Jaxen axes. If you have implemented
    76   * a navigator-specific axis based on this class, take a look at the DescendantAxisIterator for ideas
    77   * on how to remove that dependency.
    78   */
    79  public abstract class StackedIterator implements Iterator
    80  {
    81
    82      private LinkedList iteratorStack;
    83      private Navigator  navigator;
    84
    85      private Set        created;
    86
    87      public StackedIterator(Object contextNode,
    88                             Navigator navigator)
    89      {
    90          this.iteratorStack = new LinkedList();
    91          this.created       = new HashSet();
    92
    93          init( contextNode,
    94                navigator );
    95      }
    96
    97      protected StackedIterator()
    98      {
    99          this.iteratorStack = new LinkedList();
    100         this.created       = new HashSet();
    101     }
    102
    103     protected void init(Object contextNode,
    104                         Navigator navigator)
    105     {
    106         this.navigator     = navigator;
    107
    108         //pushIterator( internalCreateIterator( contextNode ) );
    109     }
    110
    111     protected Iterator internalCreateIterator(Object contextNode)
    112     {
    113         if ( this.created.contains( contextNode ) )
    114         {
    115             return null;
    116         }
    117
    118         this.created.add( contextNode );
    119
    120         return createIterator( contextNode );
    121     }
    122
    123     public boolean hasNext()
    124     {
    125         Iterator curIter = currentIterator();
    126
    127         if ( curIter == null )
    128         {
    129             return false;
    130         }
    131
    132         return curIter.hasNext();
    133     }
    134
    135     public Object next() throws NoSuchElementException
    136     {
    137         if ( ! hasNext() )
    138         {
    139             throw new NoSuchElementException();
    140         }
    141
    142         Iterator curIter = currentIterator();
    143         Object   object  = curIter.next();
    144
    145         pushIterator( internalCreateIterator( object ) );
    146
    147         return object;
    148     }
    149
    150     public void remove() throws UnsupportedOperationException
    151     {
    152         throw new UnsupportedOperationException();
    153     }
    154
    155     abstract protected Iterator createIterator(Object contextNode);
    156
    157     protected void pushIterator(Iterator iter)
    158     {
    159         if ( iter != null )
    160         {
    161             this.iteratorStack.addFirst(iter); //addLast( iter );
    162         }
    163     }
    164
    165     private Iterator currentIterator()
    166     {
    167         while ( iteratorStack.size() > 0 )
    168         {
    169             Iterator curIter = (Iterator) iteratorStack.getFirst();
    170
    171             if ( curIter.hasNext() )
    172             {
    173                 return curIter;
    174             }
    175
    176             iteratorStack.removeFirst();
    177         }
    178
    179         return null;
    180     }
    181
    182     protected Navigator getNavigator()
    183     {
    184         return this.navigator;
    185     }
    186 }