/*
* Copyright (c) 2003 The Visigoth Software Society. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution, if
* any, must include the following acknowledgement:
* "This product includes software developed by the
* Visigoth Software Society (http://www.visigoths.org/)."
* Alternately, this acknowledgement may appear in the software itself,
* if and wherever such third-party acknowledgements normally appear.
*
* 4. Neither the name "FreeMarker", "Visigoth", nor any of the names of the
* project contributors may be used to endorse or promote products derived
* from this software without prior written permission. For written
* permission, please contact [email protected].
*
* 5. Products derived from this software may not be called "FreeMarker" or "Visigoth"
* nor may "FreeMarker" or "Visigoth" appear in their names
* without prior written permission of the Visigoth Software Society.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE VISIGOTH SOFTWARE SOCIETY OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Visigoth Software Society. For more
* information on the Visigoth Software Society, please see
* http://www.visigoths.org/
*/
package freemarker.template;
import java.io.IOException;
/**
* An interface that can be implemented by writers returned from
* {@link TemplateTransformModel#getWriter(java.io.Writer, java.util.Map)}. The
* methods on this
* interfaces are callbacks that will be called by the template engine and that
* give the writer a chance to better control the evaluation of the transform
* body. The writer can instruct the engine to skip or to repeat body
* evaluation, and gets notified about exceptions that are thrown during the
* body evaluation.
*
* @author Attila Szegedi
* @version $Id: TransformControl.java,v 1.11 2005/06/16 18:13:58 ddekany Exp $
*/
public interface TransformControl
{
/**
* Constant returned from {@link #afterBody()} that tells the
* template engine to repeat transform body evaluation and feed
* it again to the transform.
*/
public static final int REPEAT_EVALUATION = 0;
/**
* Constant returned from {@link #afterBody()} that tells the
* template engine to end the transform and close the writer.
*/
public static final int END_EVALUATION = 1;
/**
* Constant returned from {@link #onStart()} that tells the
* template engine to skip evaluation of the body.
*/
public static final int SKIP_BODY = 0;
/**
* Constant returned from {@link #onStart()} that tells the
* template engine to evaluate the body.
*/
public static final int EVALUATE_BODY = 1;
/**
* Called before the body is evaluated for the first time.
* @return
* <ul>
* <li><tt>SKIP_BODY</tt> if the transform wants to ignore the body. In this
* case, only {@link java.io.Writer#close()} is called next and processing ends.</li>
* <li><tt>EVALUATE_BODY</tt> to normally evaluate the body of the transform
* and feed it to the writer</li>
* </ul>
*/
public int onStart() throws TemplateModelException, IOException;
/**
* Called after the body has been evaluated.
* @return
* <ul>
* <li><tt>END_EVALUATION</tt> if the transformation should be ended.</li>
* <li><tt>REPEAT_EVALUATION</tt> to have the engine re-evaluate the
* transform body and feed it again to the writer.</li>
* </ul>
*/
public int afterBody() throws TemplateModelException, IOException;
/**
* Called if any exception occurs during the transform between the
* {@link TemplateTransformModel#getWriter(java.io.Writer, java.util.Map)} call
* and the {@link java.io.Writer#close()} call.
* @param t the throwable that represents the exception. It can be any
* non-checked throwable, as well as {@link TemplateException} and
* {@link java.io.IOException}.
*
* @throws Throwable is recommended that the methods rethrow the received
* throwable. If the method wants to throw another throwable, it should
* either throw a non-checked throwable, or an instance of
* {@link TemplateException} and {@link java.io.IOException}. Throwing any
* other checked exception will cause the engine to rethrow it as
* a {@link java.lang.reflect.UndeclaredThrowableException}.
*/
public void onError(Throwable t) throws Throwable;
}
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