ParameterMatcher


1   /*
2    * Copyright 1999-2004 The Apache Software Foundation.
3    * 
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    * 
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    * 
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  package org.apache.cocoon.matching;
17  
18  import org.apache.avalon.framework.parameters.Parameters;
19  import org.apache.avalon.framework.thread.ThreadSafe;
20  
21  import java.util.HashMap  ;
22  import java.util.Map  ;
23  
24  /**
25   * This class allows for matching based on a parameter provided from the sitemap.
26   * If the specified sitemap parameter exists, its value is retrieved for later
27   * sitemap substitution.
28   *
29   * <p><b>Example:</b></p>
30   * <pre>
31   * &lt;map:match type="parameter" pattern="dest"&gt;
32   *     &lt;map:redirect-to uri="{1}"/&gt;
33   * &lt;/map:match&gt;
34   * </pre>
35   *
36   * @author <a HREF="mailto:vgritsenko@apache.org">Vadim Gritsenko</a>
37   * @version CVS $Id: ParameterMatcher.java 30932 2004-07-29 17:35:38Z vgritsenko $
38   */
39  public class ParameterMatcher implements Matcher, ThreadSafe
40  {
41      /**
42       * Match method to see if the sitemap parameter exists. If it does
43       * have a value the parameter added to the array list for later
44       * sitemap substitution.
45       *
46       * @param pattern name of sitemap parameter to find
47       * @param objectModel environment passed through via cocoon
48       * @return null or map containing value of sitemap parameter 'pattern'
49       */
50      public Map   match(String   pattern, Map   objectModel, Parameters parameters) {
51  
52          String   parameter = parameters.getParameter(pattern, null);
53          if (parameter == null) {
54              return null; // no parameter defined
55          } else {
56              Map   map = new HashMap  ();
57              map.put("1", parameter);
58              return map; // parameter defined, return map
59          }
60      }
61  }
62
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