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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.apache.commons.discovery.resource.names;
18  
19  import org.apache.commons.discovery.ResourceNameDiscover;
20  import org.apache.commons.discovery.ResourceNameIterator;
21  
22  
23  /***
24   * Helper class for methods implementing the ResourceNameDiscover interface.
25   * 
26   * @author Richard A. Sitze
27   */
28  public abstract class ResourceNameDiscoverImpl implements ResourceNameDiscover
29  {
30      /***
31       * Locate names of resources that are bound to <code>resourceName</code>.
32       * 
33       * @return ResourceNameIterator
34       */
35      public abstract ResourceNameIterator findResourceNames(String resourceName);
36  
37      /***
38       * Locate names of resources that are bound to <code>resourceName</code>.
39       * 
40       * @return ResourceNameIterator
41       */
42      public ResourceNameIterator findResourceNames(final ResourceNameIterator inputNames) {
43          return new ResourceNameIterator() {
44              private ResourceNameIterator resourceNames = null;
45              private String resourceName = null;
46              
47              public boolean hasNext() {
48                  if (resourceName == null) {
49                      resourceName = getNextResourceName();
50                  }
51                  return resourceName != null;
52              }
53              
54              public String nextResourceName() {
55                  String name = resourceName;
56                  resourceName = null;
57                  return name;
58              }
59              
60              private String getNextResourceName() {
61                  while (inputNames.hasNext() && (resourceNames == null  ||  !resourceNames.hasNext())) {
62                      resourceNames =
63                          findResourceNames(inputNames.nextResourceName());
64                  }
65      
66                  return (resourceNames != null  &&  resourceNames.hasNext())
67                         ? resourceNames.nextResourceName()
68                         : null;
69              }
70          };
71      }
72  }