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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 1709648 2015-10-20 17:08:10Z 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       * @exception 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       * @exception 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       * @exception 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 }