package org.apache.turbine.pipeline;

 /*

  * Licensed to the Apache Software Foundation (ASF) under one

  * or more contributor license agreements.  See the NOTICE file

  * distributed with this work for additional information

  * regarding copyright ownership.  The ASF licenses this file

  * to you under the Apache License, Version 2.0 (the

  * "License"); you may not use this file except in compliance

  * with the License.  You may obtain a copy of the License at

  *

  *   http://www.apache.org/licenses/LICENSE-2.0

  *

  * Unless required by applicable law or agreed to in writing,

  * software distributed under the License is distributed on an

  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

  * KIND, either express or implied.  See the License for the

  * specific language governing permissions and limitations

  * under the License.

  */

 import java.io.IOException;

 import org.apache.turbine.util.RunData;

 import org.apache.turbine.util.TurbineException;

 /**

  * Valve that can be used as the basis of Valve implementations.

  *

  * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a>

  * @author <a href="mailto:peter@courcoux.biz">Peter Courcoux</a>

  * @version $Id: AbstractValve.java 1773378 2016-12-09 13:19:59Z tv $

  */

 public abstract class AbstractValve

     implements Valve

 {

     /**

      * Initialize this valve for use in a pipeline.

      *

      * @throws Exception if initialization fails

      */

     @Override

     public void initialize()

         throws Exception

     {

         // empty

     }

     /**

      * @see org.apache.turbine.pipeline.Valve#invoke(PipelineData, ValveContext)

      */

     @Override

     public abstract void invoke(PipelineData data, ValveContext context)

         throws IOException, TurbineException;

     /**

      * Utility for getting RunData out of the pipelineData object.

      *

      * @param pipelineData Turbine request data

      * @return the RunData object extracted from pipelineData

      */

     public final RunData getRunData(PipelineData pipelineData)

     {

         if(!(pipelineData instanceof RunData))

         {

             throw new RuntimeException("Can't cast pipelineData to rundata");

         }

         return (RunData)pipelineData;

     }

 }