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
015package 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 */
022public 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}