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 */
017package org.apache.bcel.verifier.structurals;
018
019import java.util.HashMap;
020import java.util.HashSet;
021import java.util.Map;
022import java.util.Set;
023
024import org.apache.bcel.generic.CodeExceptionGen;
025import org.apache.bcel.generic.InstructionHandle;
026import org.apache.bcel.generic.MethodGen;
027
028/**
029 * This class allows easy access to ExceptionHandler objects.
030 */
031public class ExceptionHandlers {
032
033    /**
034     * Empty array.
035     */
036    private static final ExceptionHandler[] EMPTY_ARRAY = {};
037
038    /**
039     * The ExceptionHandler instances. Key: InstructionHandle objects, Values: HashSet<ExceptionHandler> instances.
040     */
041    private final Map<InstructionHandle, Set<ExceptionHandler>> exceptionHandlers;
042
043    /**
044     * Constructs a new ExceptionHandlers instance.
045     */
046    public ExceptionHandlers(final MethodGen mg) {
047        exceptionHandlers = new HashMap<>();
048        final CodeExceptionGen[] cegs = mg.getExceptionHandlers();
049        for (final CodeExceptionGen ceg : cegs) {
050            final ExceptionHandler eh = new ExceptionHandler(ceg.getCatchType(), ceg.getHandlerPC());
051            for (InstructionHandle ih = ceg.getStartPC(); ih != ceg.getEndPC().getNext(); ih = ih.getNext()) {
052                exceptionHandlers.computeIfAbsent(ih, k -> new HashSet<>()).add(eh);
053            }
054        }
055    }
056
057    /**
058     * Returns all the ExceptionHandler instances representing exception handlers that protect the instruction ih.
059     */
060    public ExceptionHandler[] getExceptionHandlers(final InstructionHandle ih) {
061        final Set<ExceptionHandler> hsSet = exceptionHandlers.get(ih);
062        if (hsSet == null) {
063            return EMPTY_ARRAY;
064        }
065        return hsSet.toArray(ExceptionHandler.EMPTY_ARRAY);
066    }
067
068}