cvs commit: jakarta-commons/collections/src/java/org/apache/commons/collections ListIteratorWrapper.java

[mo...@apache.org]

morgand     02/04/09 09:40:44

  Added:       collections/src/java/org/apache/commons/collections
                        ListIteratorWrapper.java
  Log:
  ListIteratorWrapper allows Iterators to simulate ListIterator behaviour
  
  Revision  Changes    Path
  1.1                  jakarta-commons/collections/src/java/org/apache/commons/collections/ListIteratorWrapper.java
  
  Index: ListIteratorWrapper.java
  ===================================================================
  /*
   * $Header: /home/cvs/jakarta-commons/collections/src/java/org/apache/commons/collections/ListIteratorWrapper.java,v 1.1 2002/04/09 16:40:43 morgand Exp $
   * $Revision: 1.1 $
   * $Date: 2002/04/09 16:40:43 $
   *
   * ====================================================================
   *
   * The Apache Software License, Version 1.1
   *
   * Copyright (c) 1999-2002 The Apache Software Foundation.  All rights
   * reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   *
   * 3. The end-user documentation included with the redistribution, if
   *    any, must include the following acknowlegement:
   *       "This product includes software developed by the
   *        Apache Software Foundation (http://www.apache.org/)."
   *    Alternately, this acknowlegement may appear in the software itself,
   *    if and wherever such third-party acknowlegements normally appear.
   *
   * 4. The names "The Jakarta Project", "Commons", and "Apache Software
   *    Foundation" must not be used to endorse or promote products derived
   *    from this software without prior written permission. For written
   *    permission, please contact apache@apache.org.
   *
   * 5. Products derived from this software may not be called "Apache"
   *    nor may "Apache" appear in their names without prior written
   *    permission of the Apache Group.
   *
   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   *
   */
  package org.apache.commons.collections;
  
  import java.util.Iterator;
  import java.util.LinkedList;
  import java.util.ListIterator;
  import java.util.NoSuchElementException;
  
  /**
   * As the wrapped Iterator is traversed, ListIteratorWrapper
   * builds a LinkedList of its values, permitting all required
   * operations of ListIterator.
   * 
   * @author Morgan Delagrange
   * @version $Revision: 1.1 $ $Date: 2002/04/09 16:40:43 $
   */
  public class ListIteratorWrapper implements ListIterator {
  
      // Constructor
      //-------------------------------------------------------------------------
  
      public ListIteratorWrapper(Iterator iterator) {
          this.iterator = iterator;
      }
  
      // ListIterator interface
      //-------------------------------------------------------------------------
  
      public void add(Object o) throws UnsupportedOperationException {
          throw new UnsupportedOperationException(UNSUPPORTED_OPERATION_MESSAGE);
      }
  
      public boolean hasNext() {
          if (currentIndex == wrappedIteratorIndex) {
              return iterator.hasNext();
          }
  
          return true;
      }
  
      public boolean hasPrevious() {
          if (currentIndex == 0) {
              return false;
          }
  
          return true;
      }
  
      public Object next() throws NoSuchElementException {
          if (currentIndex < wrappedIteratorIndex) {
              ++currentIndex;
              return list.get(currentIndex - 1);
          }
  
          Object retval = iterator.next();
          list.add(retval);
          ++currentIndex;
          ++wrappedIteratorIndex;
          return retval;
      }
  
      public int nextIndex() {
          return currentIndex;
      }
  
      public Object previous() throws NoSuchElementException {
          if (currentIndex == 0) {
              throw new NoSuchElementException();
          }
  
          --currentIndex;
          return list.get(currentIndex);    
      }
  
      public int previousIndex() {
          return currentIndex - 1;
      }
  
      public void remove() throws UnsupportedOperationException {
          throw new UnsupportedOperationException(UNSUPPORTED_OPERATION_MESSAGE);
      }
  
      public void set(Object o) throws UnsupportedOperationException {
          throw new UnsupportedOperationException(UNSUPPORTED_OPERATION_MESSAGE);
      }
  
      // Attributes
      //-------------------------------------------------------------------------
  
      /** Holds value of property "iterator". */
      private Iterator iterator = null;
      private LinkedList list = new LinkedList();
      
      // position of this iterator
      private int currentIndex = 0;
      // position of the wrapped iterator
      // this Iterator should only be used to populate the list
      private int wrappedIteratorIndex = 0;
  
      private static final String UNSUPPORTED_OPERATION_MESSAGE =
          "ListIteratorWrapper does not support optional operations of ListIterator.";
  
  }
  
  
  
  

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