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