    001    // Copyright 2011 The Apache Software Foundation
    002    //
    003    // Licensed under the Apache License, Version 2.0 (the "License");
    004    // you may not use this file except in compliance with the License.
    005    // You may obtain a copy of the License at
    006    //
    007    // http://www.apache.org/licenses/LICENSE-2.0
    008    //
    009    // Unless required by applicable law or agreed to in writing, software
    010    // distributed under the License is distributed on an "AS IS" BASIS,
    011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    012    // See the License for the specific language governing permissions and
    013    // limitations under the License.
    014
    015    package org.apache.tapestry5.plastic;
    016
    017    /**
    018     * Allows a portion of a method to be marked so that exception and finally handlers can be provided.
    019     *
    020     * @see InstructionBuilder#startTryCatch(TryCatchCallback)
    021     */
    022    public interface TryCatchBlock
    023    {
    024        /**
    025         * Invoked first, to generate the code in which exceptions may be caught.
    026         */
    027        void addTry(InstructionBuilderCallback callback);
    028
    029        /**
    030         * Ends the block (if not already ended) and inserts a catch block for the named exception.
    031         * The InstructionBuilder is returned so that the code for handling the exception can be added. The exception object
    032         * will be on top of the stack. This should be called after {@link #addTry(InstructionBuilderCallback)}.
    033         * <p>
    034         * Note: no attempt is made currently to sort the handlers; for example adding a catch for java.lang.Exception first
    035         * will mean that more specific exception handlers added later will never be invoked.
    036         *
    037         * @param exceptionClassName
    038         *            caught exception class
    039         * @param callback
    040         *            that implements the logic of the catch block
    041         */
    042        @Opcodes("TRYCATCHBLOCK")
    043        void addCatch(String exceptionClassName, InstructionBuilderCallback callback);
    044
    045        /**
    046         * As with {@link #addCatch(String, InstructionBuilderCallback)}, but the exception caught is
    047         * null, which acts as a finally block in the Java language. This must be called last (after
    048         * {@link #addTry(InstructionBuilderCallback)} and any calls to
    049         * {@link #addCatch(String, InstructionBuilderCallback)}.
    050         *
    051         * @param callback
    052         *            implements the logic of the finally block
    053         */
    054        @Opcodes("TRYCATCHBLOCK")
    055        void addFinally(InstructionBuilderCallback callback);
    056    }