    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one
    003 * or more contributor license agreements.  See the NOTICE file
    004 * distributed with this work for additional information
    005 * regarding copyright ownership.  The ASF licenses this file
    006 * to you under the Apache License, Version 2.0 (the
    007 * "License"); you may not use this file except in compliance
    008 * with the License.  You may obtain a copy of the License at
    009 *
    010 *   https://www.apache.org/licenses/LICENSE-2.0
    011 *
    012 * Unless required by applicable law or agreed to in writing,
    013 * software distributed under the License is distributed on an
    014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    015 * KIND, either express or implied.  See the License for the
    016 * specific language governing permissions and limitations
    017 * under the License.
    018 */
    019package org.apache.bcel.verifier.structurals;
    020
    021import java.util.HashMap;
    022import java.util.HashSet;
    023import java.util.Map;
    024import java.util.Set;
    025
    026import org.apache.bcel.generic.CodeExceptionGen;
    027import org.apache.bcel.generic.InstructionHandle;
    028import org.apache.bcel.generic.MethodGen;
    029
    030/**
    031 * This class allows easy access to ExceptionHandler objects.
    032 */
    033public class ExceptionHandlers {
    034
    035    /**
    036     * Empty array.
    037     */
    038    private static final ExceptionHandler[] EMPTY_ARRAY = {};
    039
    040    /**
    041     * The ExceptionHandler instances. Key: InstructionHandle objects, Values: HashSet<ExceptionHandler> instances.
    042     */
    043    private final Map<InstructionHandle, Set<ExceptionHandler>> exceptionHandlers;
    044
    045    /**
    046     * Constructs a new ExceptionHandlers instance.
    047     *
    048     * @param mg the method generator.
    049     */
    050    public ExceptionHandlers(final MethodGen mg) {
    051        exceptionHandlers = new HashMap<>();
    052        final CodeExceptionGen[] cegs = mg.getExceptionHandlers();
    053        for (final CodeExceptionGen ceg : cegs) {
    054            final ExceptionHandler eh = new ExceptionHandler(ceg.getCatchType(), ceg.getHandlerPC());
    055            for (InstructionHandle ih = ceg.getStartPC(); ih != ceg.getEndPC().getNext(); ih = ih.getNext()) {
    056                exceptionHandlers.computeIfAbsent(ih, k -> new HashSet<>()).add(eh);
    057            }
    058        }
    059    }
    060
    061    /**
    062     * Returns all the ExceptionHandler instances representing exception handlers that protect the instruction ih.
    063     *
    064     * @param ih the instruction handle.
    065     * @return array of exception handlers.
    066     */
    067    public ExceptionHandler[] getExceptionHandlers(final InstructionHandle ih) {
    068        final Set<ExceptionHandler> hsSet = exceptionHandlers.get(ih);
    069        if (hsSet == null) {
    070            return EMPTY_ARRAY;
    071        }
    072        return hsSet.toArray(ExceptionHandler.EMPTY_ARRAY);
    073    }
    074
    075}