| /* |
| * 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. |
| */ |
| |
| 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. |
| */ |
| 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>{@code SKIP_BODY} 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>{@code EVALUATE_BODY} 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>{@code END_EVALUATION} if the transformation should be ended.</li> |
| * <li>{@code REPEAT_EVALUATION} 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; |
| } |