    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.classfile;
    019
    020import java.io.DataInput;
    021import java.io.DataOutputStream;
    022import java.io.IOException;
    023
    024import org.apache.bcel.Const;
    025import org.apache.bcel.Constants;
    026
    027/**
    028 * This class represents an entry in the exception table of the <em>Code</em> attribute and is used only there. It
    029 * contains a range in which a particular exception handler is active.
    030 *
    031 * @see Code
    032 */
    033public final class CodeException implements Cloneable, Node, Constants {
    034
    035    /**
    036     * Empty array.
    037     */
    038    static final CodeException[] EMPTY_CODE_EXCEPTION_ARRAY = {};
    039    private int startPc; // Range in the code the exception handler is
    040    private int endPc; // active. startPc is inclusive, endPc exclusive
    041    private int handlerPc; /*
    042                            * Starting address of exception handler, i.e., an offset from start of code.
    043                            */
    044
    045    private int catchType; /*
    046                            * If this is zero the handler catches any exception, otherwise it points to the exception class which is to be caught.
    047                            */
    048
    049    /**
    050     * Initialize from another object.
    051     */
    052    public CodeException(final CodeException c) {
    053        this(c.getStartPC(), c.getEndPC(), c.getHandlerPC(), c.getCatchType());
    054    }
    055
    056    /**
    057     * Construct object from file stream.
    058     *
    059     * @param file Input stream
    060     * @throws IOException if an I/O error occurs.
    061     */
    062    CodeException(final DataInput file) throws IOException {
    063        this(file.readUnsignedShort(), file.readUnsignedShort(), file.readUnsignedShort(), file.readUnsignedShort());
    064    }
    065
    066    /**
    067     * @param startPc Range in the code the exception handler is active, startPc is inclusive while
    068     * @param endPc is exclusive
    069     * @param handlerPc Starting address of exception handler, i.e., an offset from start of code.
    070     * @param catchType If zero the handler catches any exception, otherwise it points to the exception class which is to be
    071     *        caught.
    072     */
    073    public CodeException(final int startPc, final int endPc, final int handlerPc, final int catchType) {
    074        this.startPc = startPc;
    075        this.endPc = endPc;
    076        this.handlerPc = handlerPc;
    077        this.catchType = catchType;
    078    }
    079
    080    /**
    081     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
    082     * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
    083     *
    084     * @param v Visitor object
    085     */
    086    @Override
    087    public void accept(final Visitor v) {
    088        v.visitCodeException(this);
    089    }
    090
    091    /**
    092     * @return deep copy of this object
    093     */
    094    public CodeException copy() {
    095        try {
    096            return (CodeException) clone();
    097        } catch (final CloneNotSupportedException e) {
    098            // TODO should this throw?
    099        }
    100        return null;
    101    }
    102
    103    /**
    104     * Dump code exception to file stream in binary format.
    105     *
    106     * @param file Output file stream
    107     * @throws IOException if an I/O error occurs.
    108     */
    109    public void dump(final DataOutputStream file) throws IOException {
    110        file.writeShort(startPc);
    111        file.writeShort(endPc);
    112        file.writeShort(handlerPc);
    113        file.writeShort(catchType);
    114    }
    115
    116    /**
    117     * @return 0, if the handler catches any exception, otherwise it points to the exception class which is to be caught.
    118     */
    119    public int getCatchType() {
    120        return catchType;
    121    }
    122
    123    /**
    124     * @return Exclusive end index of the region where the handler is active.
    125     */
    126    public int getEndPC() {
    127        return endPc;
    128    }
    129
    130    /**
    131     * @return Starting address of exception handler, relative to the code.
    132     */
    133    public int getHandlerPC() {
    134        return handlerPc;
    135    }
    136
    137    /**
    138     * @return Inclusive start index of the region where the handler is active.
    139     */
    140    public int getStartPC() {
    141        return startPc;
    142    }
    143
    144    /**
    145     * @param catchType the type of exception that is caught
    146     */
    147    public void setCatchType(final int catchType) {
    148        this.catchType = catchType;
    149    }
    150
    151    /**
    152     * @param endPc end of handled block
    153     */
    154    public void setEndPC(final int endPc) {
    155        this.endPc = endPc;
    156    }
    157
    158    /**
    159     * @param handlerPc where the actual code is
    160     */
    161    public void setHandlerPC(final int handlerPc) { // TODO unused
    162        this.handlerPc = handlerPc;
    163    }
    164
    165    /**
    166     * @param startPc start of handled block
    167     */
    168    public void setStartPC(final int startPc) { // TODO unused
    169        this.startPc = startPc;
    170    }
    171
    172    /**
    173     * @return String representation.
    174     */
    175    @Override
    176    public String toString() {
    177        return "CodeException(startPc = " + startPc + ", endPc = " + endPc + ", handlerPc = " + handlerPc + ", catchType = " + catchType + ")";
    178    }
    179
    180    public String toString(final ConstantPool cp) {
    181        return toString(cp, true);
    182    }
    183
    184    /**
    185     * @return String representation.
    186     */
    187    public String toString(final ConstantPool cp, final boolean verbose) {
    188        String str;
    189        if (catchType == 0) {
    190            str = "<Any exception>(0)";
    191        } else {
    192            str = Utility.compactClassName(cp.getConstantString(catchType, Const.CONSTANT_Class), false) + (verbose ? "(" + catchType + ")" : "");
    193        }
    194        return startPc + "\t" + endPc + "\t" + handlerPc + "\t" + str;
    195    }
    196}