    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.classfile;
    018
    019import java.io.DataInput;
    020import java.io.DataOutputStream;
    021import java.io.IOException;
    022
    023import org.apache.bcel.Const;
    024import org.apache.bcel.Constants;
    025
    026/**
    027 * This class represents an entry in the exception table of the <em>Code</em> attribute and is used only there. It
    028 * contains a range in which a particular exception handler is active.
    029 *
    030 * @see Code
    031 */
    032public final class CodeException implements Cloneable, Node, Constants {
    033
    034    /**
    035     * Empty array.
    036     */
    037    static final CodeException[] EMPTY_CODE_EXCEPTION_ARRAY = {};
    038    private int startPc; // Range in the code the exception handler is
    039    private int endPc; // active. startPc is inclusive, endPc exclusive
    040    private int handlerPc; /*
    041                            * Starting address of exception handler, i.e., an offset from start of code.
    042                            */
    043
    044    private int catchType; /*
    045                            * If this is zero the handler catches any exception, otherwise it points to the exception class which is to be caught.
    046                            */
    047
    048    /**
    049     * Initialize from another object.
    050     */
    051    public CodeException(final CodeException c) {
    052        this(c.getStartPC(), c.getEndPC(), c.getHandlerPC(), c.getCatchType());
    053    }
    054
    055    /**
    056     * Construct object from file stream.
    057     *
    058     * @param file Input stream
    059     * @throws IOException if an I/O error occurs.
    060     */
    061    CodeException(final DataInput file) throws IOException {
    062        this(file.readUnsignedShort(), file.readUnsignedShort(), file.readUnsignedShort(), file.readUnsignedShort());
    063    }
    064
    065    /**
    066     * @param startPc Range in the code the exception handler is active, startPc is inclusive while
    067     * @param endPc is exclusive
    068     * @param handlerPc Starting address of exception handler, i.e., an offset from start of code.
    069     * @param catchType If zero the handler catches any exception, otherwise it points to the exception class which is to be
    070     *        caught.
    071     */
    072    public CodeException(final int startPc, final int endPc, final int handlerPc, final int catchType) {
    073        this.startPc = startPc;
    074        this.endPc = endPc;
    075        this.handlerPc = handlerPc;
    076        this.catchType = catchType;
    077    }
    078
    079    /**
    080     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
    081     * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
    082     *
    083     * @param v Visitor object
    084     */
    085    @Override
    086    public void accept(final Visitor v) {
    087        v.visitCodeException(this);
    088    }
    089
    090    /**
    091     * @return deep copy of this object
    092     */
    093    public CodeException copy() {
    094        try {
    095            return (CodeException) clone();
    096        } catch (final CloneNotSupportedException e) {
    097            // TODO should this throw?
    098        }
    099        return null;
    100    }
    101
    102    /**
    103     * Dump code exception to file stream in binary format.
    104     *
    105     * @param file Output file stream
    106     * @throws IOException if an I/O error occurs.
    107     */
    108    public void dump(final DataOutputStream file) throws IOException {
    109        file.writeShort(startPc);
    110        file.writeShort(endPc);
    111        file.writeShort(handlerPc);
    112        file.writeShort(catchType);
    113    }
    114
    115    /**
    116     * @return 0, if the handler catches any exception, otherwise it points to the exception class which is to be caught.
    117     */
    118    public int getCatchType() {
    119        return catchType;
    120    }
    121
    122    /**
    123     * @return Exclusive end index of the region where the handler is active.
    124     */
    125    public int getEndPC() {
    126        return endPc;
    127    }
    128
    129    /**
    130     * @return Starting address of exception handler, relative to the code.
    131     */
    132    public int getHandlerPC() {
    133        return handlerPc;
    134    }
    135
    136    /**
    137     * @return Inclusive start index of the region where the handler is active.
    138     */
    139    public int getStartPC() {
    140        return startPc;
    141    }
    142
    143    /**
    144     * @param catchType the type of exception that is caught
    145     */
    146    public void setCatchType(final int catchType) {
    147        this.catchType = catchType;
    148    }
    149
    150    /**
    151     * @param endPc end of handled block
    152     */
    153    public void setEndPC(final int endPc) {
    154        this.endPc = endPc;
    155    }
    156
    157    /**
    158     * @param handlerPc where the actual code is
    159     */
    160    public void setHandlerPC(final int handlerPc) { // TODO unused
    161        this.handlerPc = handlerPc;
    162    }
    163
    164    /**
    165     * @param startPc start of handled block
    166     */
    167    public void setStartPC(final int startPc) { // TODO unused
    168        this.startPc = startPc;
    169    }
    170
    171    /**
    172     * @return String representation.
    173     */
    174    @Override
    175    public String toString() {
    176        return "CodeException(startPc = " + startPc + ", endPc = " + endPc + ", handlerPc = " + handlerPc + ", catchType = " + catchType + ")";
    177    }
    178
    179    public String toString(final ConstantPool cp) {
    180        return toString(cp, true);
    181    }
    182
    183    /**
    184     * @return String representation.
    185     */
    186    public String toString(final ConstantPool cp, final boolean verbose) {
    187        String str;
    188        if (catchType == 0) {
    189            str = "<Any exception>(0)";
    190        } else {
    191            str = Utility.compactClassName(cp.getConstantString(catchType, Const.CONSTANT_Class), false) + (verbose ? "(" + catchType + ")" : "");
    192        }
    193        return startPc + "\t" + endPc + "\t" + handlerPc + "\t" + str;
    194    }
    195}