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    }