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    1   /*
    2    * $Id: AppendIteratorFilter.java 471756 2006-11-06 15:01:43Z husted $
    3    *
    4    * Licensed to the Apache Software Foundation (ASF) under one
    5    * or more contributor license agreements.  See the NOTICE file
    6    * distributed with this work for additional information
    7    * regarding copyright ownership.  The ASF licenses this file
    8    * to you under the Apache License, Version 2.0 (the
    9    * "License"); you may not use this file except in compliance
    10   * with the License.  You may obtain a copy of the License at
    11   *
    12   *  http://www.apache.org/licenses/LICENSE-2.0
    13   *
    14   * Unless required by applicable law or agreed to in writing,
    15   * software distributed under the License is distributed on an
    16   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    17   * KIND, either express or implied.  See the License for the
    18   * specific language governing permissions and limitations
    19   * under the License.
    20   */
    21  package org.apache.struts2.util;
    22
    23  import java.util.ArrayList;
    24  import java.util.Iterator;
    25  import java.util.List;
    26
    27  import com.opensymphony.xwork2.Action;
    28
    29
    30  /***
    31   * A bean that takes several iterators and outputs them in sequence
    32   *
    33   * @see org.apache.struts2.components.AppendIterator
    34   * @see org.apache.struts2.views.jsp.iterator.AppendIteratorTag
    35   */
    36  public class AppendIteratorFilter extends IteratorFilterSupport implements Iterator, Action {
    37
    38      List iterators = new ArrayList();
    39
    40      // Attributes ----------------------------------------------------
    41      List sources = new ArrayList();
    42
    43
    44      // Public --------------------------------------------------------
    45      public void setSource(Object anIterator) {
    46          sources.add(anIterator);
    47      }
    48
    49      // Action implementation -----------------------------------------
    50      public String execute() {
    51          // Make source transformations
    52          for (int i = 0; i < sources.size(); i++) {
    53              Object source = sources.get(i);
    54              iterators.add(getIterator(source));
    55          }
    56
    57          return SUCCESS;
    58      }
    59
    60      // Iterator implementation ---------------------------------------
    61      public boolean hasNext() {
    62          if (iterators.size() > 0) {
    63              return (((Iterator) iterators.get(0)).hasNext());
    64          } else {
    65              return false;
    66          }
    67      }
    68
    69      public Object next() {
    70          try {
    71              return ((Iterator) iterators.get(0)).next();
    72          } finally {
    73              if (iterators.size() > 0) {
    74                  if (!((Iterator) iterators.get(0)).hasNext()) {
    75                      iterators.remove(0);
    76                  }
    77              }
    78          }
    79      }
    80
    81      public void remove() {
    82          throw new UnsupportedOperationException();
    83      }
    84  }