/*
 * 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 org.apache.bcel.generic;

/**
 * Thrown by InstructionList.remove() when one or multiple disposed instructions
 * are still being referenced by an InstructionTargeter object. I.e. the
 * InstructionTargeter has to be notified that (one of) the InstructionHandle it
 * is referencing is being removed from the InstructionList and thus not valid anymore.
 *
 * <p>Making this an exception instead of a return value forces the user to handle
 * these case explicitely in a try { ... } catch. The following code illustrates
 * how this may be done:</p>
 *
 * <PRE>
 *     ...
 *     try {
 *         il.delete(start_ih, end_ih);
 *     } catch(TargetLostException e) {
 *         for (InstructionHandle target : e.getTargets()) {
 *             for (InstructionTargeter targeter : target.getTargeters()) {
 *                 targeter.updateTarget(target, new_target);
 *             }
 *         }
 *     }
 * </PRE>
 *
 * @see InstructionHandle
 * @see InstructionList
 * @see InstructionTargeter
 * @version $Id$
 */
public final class TargetLostException extends Exception {

    private static final long serialVersionUID = -6857272667645328384L;
    private final InstructionHandle[] targets;


    TargetLostException(final InstructionHandle[] t, final String mesg) {
        super(mesg);
        targets = t;
    }


    /**
     * @return list of instructions still being targeted.
     */
    public InstructionHandle[] getTargets() {
        return targets;
    }
}
