/*

  * Copyright (C) 1998-2000 Semiotek Inc.  All Rights Reserved.

  *

  * Redistribution and use in source and binary forms, with or without

  * modification, are permitted under the terms of either of the following

  * Open Source licenses:

  *

  * The GNU General Public License, version 2, or any later version, as

  * published by the Free Software Foundation

  * (http://www.fsf.org/copyleft/gpl.html);

  *

  *  or

  *

  * The Semiotek Public License (http://webmacro.org/LICENSE.)

  *

  * This software is provided "as is", with NO WARRANTY, not even the

  * implied warranties of fitness to purpose, or merchantability. You

  * assume all risks and liabilities associated with its use.

  *

  * See www.webmacro.org for more information on the WebMacro project.

  */

 package org.webmacro.directive;

 import org.webmacro.Context;

 import org.webmacro.FastWriter;

 import org.webmacro.PropertyException;

 import org.webmacro.engine.BuildContext;

 import org.webmacro.engine.BuildException;

 import org.webmacro.engine.Variable;

 import java.io.IOException;

 /**

  * The #attribute directive allows you to set a template attribute such

  * that it is accessible from the servlet.

  */

 public class AttributeDirective extends Directive

 {

     private static final int ATTRIBUTE_TARGET = 1;

     private static final int ATTRIBUTE_RESULT = 2;

     private static final ArgDescriptor[]

             myArgs = new ArgDescriptor[]{

                 new LValueArg(ATTRIBUTE_TARGET),

                 new AssignmentArg(),

                 new RValueArg(ATTRIBUTE_RESULT)

             };

     private static final DirectiveDescriptor

             myDescr = new DirectiveDescriptor(null, null, myArgs, null);

     public static DirectiveDescriptor getDescriptor ()

     {

         return myDescr;

     }

     public Object build (DirectiveBuilder builder,

                          BuildContext bc)

             throws BuildException

     {

         Variable target = null;

         Object result = null;

         try { 

             target = (Variable) builder.getArg(ATTRIBUTE_TARGET, bc);

             result = builder.getArg(ATTRIBUTE_RESULT, bc);

         }

         catch (ClassCastException e)

         {

             throw new NotVariableBuildException(myDescr.name, e);

         }

         if (!target.isSimpleName())

             throw new NotSimpleVariableBuildException(myDescr.name);

         try

         {

             target.setValue(bc, result);

         }

         catch (PropertyException e)

         {

             throw new BuildException("#attribute: Exception setting variable "

                     + target.toString(), e);

         }

         return null;

     }

     public void write (FastWriter out, Context context)

             throws PropertyException, IOException

     {

     }

 }