/*

  * Copyright 1999-2001,2004 The Apache Software Foundation.

  * 

  * Licensed 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.

  */ 

 package org.apache.commons.workflow.core;

 import org.apache.commons.workflow.Context;

 import org.apache.commons.workflow.Descriptor;

 import org.apache.commons.workflow.StepException;

 import org.apache.commons.workflow.base.DescriptorStep;

 /**

  * <p>For each associated <code>Descriptor</code>, make a copy of the

  * specified Java object and push it on to the evaluation stack, in the

  * order that descriptors are listed.</p>

  *

  * @version $Revision: 155475 $ $Date: 2005-02-26 13:31:11 +0000 (Sat, 26 Feb 2005) $

  * @author Craig R. McClanahan

  */

 public class GetStep extends DescriptorStep {

     // ----------------------------------------------------------= Constructors

     /**

      * Construct a default instance of this Step.

      */

     public GetStep() {

         super();

     }

     /**

      * Construct an instance of this Step with the specified identifier.

      *

      * @param id Step identifier

      */

     public GetStep(String id) {

         super();

         setId(id);

     }

     /**

      * Construct an instance of this Step with the specified identifier

      * and associated Descriptor.

      *

      * @param id Step identifier

      * @param descriptor Initial descriptor

      */

     public GetStep(String id, Descriptor descriptor) {

         super();

         setId(id);

         addDescriptor(descriptor);

     }

     // --------------------------------------------------------- Public Methods

     /**

      * Perform the executable actions related to this Step, in the context of

      * the specified Context.

      *

      * @param context The Context that is tracking our execution state

      *

      * @exception StepException if a processing error has occurred

      */

     public void execute(Context context) throws StepException {

         // Process all associated descriptors

         Descriptor descriptors[] = findDescriptors();

         for (int i = 0; i < descriptors.length; i++) {

             Object value = descriptors[i].get(context);

             if (value == null)

                 throw new StepException

                     ("Cannot retrieve object for " + descriptors[i], this);

             context.push(value);

         }

     }

 }