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1   package org.apache.turbine.modules;
2   
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  
22  import org.apache.turbine.Turbine;
23  import org.apache.turbine.pipeline.PipelineData;
24  
25  /**
26   * The purpose of this class is to allow one to load and execute
27   * Navigation modules.
28   *
29   * @author <a href="mailto:mbryson@mont.mindspring.com">Dave Bryson</a>
30   * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
31   * @author <a href="mailto:peter@courcoux.biz">Peter Courcoux</a>
32   * @version $Id: NavigationLoader.java 1773378 2016-12-09 13:19:59Z tv $
33   */
34  public class NavigationLoader
35      extends GenericLoader<Navigation>
36      implements Loader<Navigation>
37  {
38      /** The single instance of this class. */
39      private static NavigationLoader instance = new NavigationLoader();
40  
41      /**
42       * These ctor's are private to force clients to use getInstance()
43       * to access this class.
44       */
45      private NavigationLoader()
46      {
47          super();
48      }
49  
50      /**
51       * Attempts to load and execute the external Navigation. This is
52       * used when you want to execute a Navigation which returns its
53       * output via a MultiPartElement instead of out the data.getPage()
54       * value.  This allows you to easily chain the execution of
55       * Navigation modules together.
56       *
57       * @param pipelineData Turbine information.
58       * @param name Name of object that will execute the navigation.
59       * @return the navigation module output
60       * @throws Exception a generic exception.
61       */
62      public String eval(PipelineData pipelineData, String name)
63              throws Exception
64      {
65          // Execute Navigation
66          return getAssembler(name).build(pipelineData);
67      }
68  
69      /**
70       * Attempts to load and execute the external Navigation.
71       *
72       * @param pipelineData Turbine information.
73       * @param name Name of object instance.
74       * @throws Exception a generic exception.
75       */
76      @Override
77      public void exec(PipelineData pipelineData, String name)
78      		throws Exception
79      {
80          this.eval(pipelineData, name);
81      }
82  
83      /**
84       * Pulls out an instance of the object by name.  Name is just the
85       * single name of the object.
86       *
87       * @param name Name of object instance.
88       * @return A Layout with the specified name, or null.
89       * @throws Exception a generic exception.
90       */
91      @Override
92      public Navigation getAssembler(String name)
93          throws Exception
94      {
95          return getAssembler(Navigation.class, name);
96      }
97  
98      /**
99       * @see org.apache.turbine.modules.Loader#getCacheSize()
100      */
101     @Override
102     public int getCacheSize()
103     {
104         return NavigationLoader.getConfiguredCacheSize();
105     }
106 
107     /**
108      * The method through which this class is accessed.
109      *
110      * @return The single instance of this class.
111      */
112     public static NavigationLoader getInstance()
113     {
114         return instance;
115     }
116 
117     /**
118      * Helper method to get the configured cache size for this module
119      *
120      * @return the configure cache size
121      */
122     private static int getConfiguredCacheSize()
123     {
124         return Turbine.getConfiguration().getInt(Navigation.CACHE_SIZE_KEY,
125                 Navigation.CACHE_SIZE_DEFAULT);
126     }
127 }