package org.apache.commons.workflow.core;

 import org.apache.commons.workflow.Context;

 import org.apache.commons.workflow.Descriptor;

 import org.apache.commons.workflow.Step;

 import org.apache.commons.workflow.StepException;

 /**

  * <p>Evaluate properties specified by the associated Descriptors, and

  * transfer control to the specified step if ANY of them are

  * <code>false</code> (if boolean) or null (if Object).

  *

  * <b>This is the exact opposite of OrStep</b>

  *

  * To avoid non-deterministic evaluation stack behavior, all of the

  * specified Descriptors are always evaluated.</p>

  *

  * <p>Supported Attributes:</p>

  * <ul>

  * <li><strong>step</strong> - Identifier of the Step to which control

  *     should be transferred if the condition is met.</li>

  * </ul>

  *

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

  * @author Preston Sheldon

  */

 public class NotOrStep extends GotoStep {

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

     /**

      * Construct a default instance of this Step.

      */

     public NotOrStep() {

         super();

     }

     /**

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

      *

      * @param id Step identifier

      */

     public NotOrStep(String id) {

         this(id, null, null);

     }

     /**

      * Construct a fully configured instance of this Step.

      *

      * @param id Step identifier of this step

      * @param step Step identifier to which control should be redirected

      */

     public NotOrStep(String id, String step) {

         this(id, step, null);

     }

     /**

      * Construct a fully configured instance of this Step.

      *

      * @param id Step identifier of this step

      * @param step Step identifier to which control should be redirected

      * @param descriptor Initial descriptor to be added

      */

     public NotOrStep(String id, String step, Descriptor descriptor) {

         super();

         setId(id);

         setStep(step);

         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

         boolean condition = false;

         Descriptor descriptors[] = findDescriptors();

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

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

             if (value != null) {

                 if (value instanceof Boolean) {

                     if (((Boolean) value).booleanValue())

                         condition = true;

                 } else {

                     condition = true;

                 }

             }

         }

         // Conditionally forward control to the specified step

         if (!condition) {

             Step next = getOwner().findStep(this.step);

             if (next == null)

                 throw new StepException("Cannot find step '" + step + "'",

                                         this);

             context.setNextStep(next);

         }

     }

 }