FilterIterator xref

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    1   /*
    2    * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
    3    *
    4    * This software is open source.
    5    * See the bottom of this file for the licence.
    6    */
    7
    8   package org.dom4j.tree;
    9
    10  import java.util.Iterator;
    11  import java.util.NoSuchElementException;
    12
    13  /***
    14   * <p>
    15   * <code>FilterIterator</code> is an abstract base class which is useful for
    16   * implementors of {@link Iterator}which filter an existing iterator.
    17   * </p>
    18   *
    19   * @author <a href="mailto:james.strachan@metastuff.com">James Strachan </a>
    20   * @version $Revision: 1.10 $
    21   *
    22   * @deprecated THIS CLASS WILL BE REMOVED IN dom4j-1.6 !!
    23   */
    24  public abstract class FilterIterator implements Iterator {
    25      protected Iterator proxy;
    26
    27      private Object next;
    28
    29      private boolean first = true;
    30
    31      public FilterIterator(Iterator proxy) {
    32          this.proxy = proxy;
    33      }
    34
    35      public boolean hasNext() {
    36          if (first) {
    37              next = findNext();
    38              first = false;
    39          }
    40
    41          return next != null;
    42      }
    43
    44      public Object next() throws NoSuchElementException {
    45          if (!hasNext()) {
    46              throw new NoSuchElementException();
    47          }
    48
    49          Object answer = this.next;
    50          this.next = findNext();
    51
    52          return answer;
    53      }
    54
    55      /***
    56       * Always throws UnsupportedOperationException as this class does look-ahead
    57       * with its internal iterator.
    58       *
    59       * @throws UnsupportedOperationException
    60       *             always
    61       */
    62      public void remove() {
    63          throw new UnsupportedOperationException();
    64      }
    65
    66      /***
    67       * Filter method to perform some matching on the given element.
    68       *
    69       * @param element
    70       *            DOCUMENT ME!
    71       *
    72       * @return true if the given element matches the filter and should be appear
    73       *         in the iteration
    74       */
    75      protected abstract boolean matches(Object element);
    76
    77      protected Object findNext() {
    78          if (proxy != null) {
    79              while (proxy.hasNext()) {
    80                  Object nextObject = proxy.next();
    81
    82                  if ((nextObject != null) && matches(nextObject)) {
    83                      return nextObject;
    84                  }
    85              }
    86
    87              proxy = null;
    88          }
    89
    90          return null;
    91      }
    92  }
    93
    94  /*
    95   * Redistribution and use of this software and associated documentation
    96   * ("Software"), with or without modification, are permitted provided that the
    97   * following conditions are met:
    98   *
    99   * 1. Redistributions of source code must retain copyright statements and
    100  * notices. Redistributions must also contain a copy of this document.
    101  *
    102  * 2. Redistributions in binary form must reproduce the above copyright notice,
    103  * this list of conditions and the following disclaimer in the documentation
    104  * and/or other materials provided with the distribution.
    105  *
    106  * 3. The name "DOM4J" must not be used to endorse or promote products derived
    107  * from this Software without prior written permission of MetaStuff, Ltd. For
    108  * written permission, please contact dom4j-info@metastuff.com.
    109  *
    110  * 4. Products derived from this Software may not be called "DOM4J" nor may
    111  * "DOM4J" appear in their names without prior written permission of MetaStuff,
    112  * Ltd. DOM4J is a registered trademark of MetaStuff, Ltd.
    113  *
    114  * 5. Due credit should be given to the DOM4J Project - http://www.dom4j.org
    115  *
    116  * THIS SOFTWARE IS PROVIDED BY METASTUFF, LTD. AND CONTRIBUTORS ``AS IS'' AND
    117  * ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
    118  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
    119  * ARE DISCLAIMED. IN NO EVENT SHALL METASTUFF, LTD. OR ITS CONTRIBUTORS BE
    120  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
    121  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
    122  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
    123  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
    124  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
    125  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
    126  * POSSIBILITY OF SUCH DAMAGE.
    127  *
    128  * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
    129  */