    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 */
    019
    020package org.apache.bcel.classfile;
    021
    022import java.io.DataInput;
    023import java.io.DataOutputStream;
    024import java.io.IOException;
    025import java.util.Arrays;
    026
    027import org.apache.bcel.Const;
    028import org.apache.bcel.util.Args;
    029import org.apache.commons.lang3.ArrayUtils;
    030
    031/**
    032 * This class represents the table of exceptions that are thrown by a method. This attribute may be used once per
    033 * method. The name of this class is <em>ExceptionTable</em> for historical reasons; The Java Virtual Machine
    034 * Specification, Second Edition defines this attribute using the name <em>Exceptions</em> (which is inconsistent with
    035 * the other classes).
    036 *
    037 * <pre>
    038 * Exceptions_attribute {
    039 *   u2 attribute_name_index;
    040 *   u4 attribute_length;
    041 *   u2 number_of_exceptions;
    042 *   u2 exception_index_table[number_of_exceptions];
    043 * }
    044 * </pre>
    045 * @see Code
    046 */
    047public final class ExceptionTable extends Attribute {
    048
    049    private int[] exceptionIndexTable; // constant pool
    050
    051    /**
    052     * Initialize from another object. Note that both objects use the same references (shallow copy). Use copy() for a
    053     * physical copy.
    054     *
    055     * @param c Source to copy.
    056     */
    057    public ExceptionTable(final ExceptionTable c) {
    058        this(c.getNameIndex(), c.getLength(), c.getExceptionIndexTable(), c.getConstantPool());
    059    }
    060
    061    /**
    062     * Constructs object from input stream.
    063     *
    064     * @param nameIndex Index in constant pool
    065     * @param length Content length in bytes
    066     * @param input Input stream
    067     * @param constantPool Array of constants
    068     * @throws IOException if an I/O error occurs.
    069     */
    070    ExceptionTable(final int nameIndex, final int length, final DataInput input, final ConstantPool constantPool) throws IOException {
    071        this(nameIndex, length, (int[]) null, constantPool);
    072        final int exceptionCount = input.readUnsignedShort();
    073        exceptionIndexTable = new int[exceptionCount];
    074        for (int i = 0; i < exceptionCount; i++) {
    075            exceptionIndexTable[i] = input.readUnsignedShort();
    076        }
    077    }
    078
    079    /**
    080     * @param nameIndex Index in constant pool
    081     * @param length Content length in bytes
    082     * @param exceptionIndexTable Table of indices in constant pool
    083     * @param constantPool Array of constants
    084     */
    085    public ExceptionTable(final int nameIndex, final int length, final int[] exceptionIndexTable, final ConstantPool constantPool) {
    086        super(Const.ATTR_EXCEPTIONS, nameIndex, length, constantPool);
    087        this.exceptionIndexTable = ArrayUtils.nullToEmpty(exceptionIndexTable);
    088        Args.requireU2(this.exceptionIndexTable.length, "exceptionIndexTable.length");
    089    }
    090
    091    /**
    092     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
    093     * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
    094     *
    095     * @param v Visitor object
    096     */
    097    @Override
    098    public void accept(final Visitor v) {
    099        v.visitExceptionTable(this);
    100    }
    101
    102    /**
    103     * @return deep copy of this attribute
    104     */
    105    @Override
    106    public Attribute copy(final ConstantPool constantPool) {
    107        final ExceptionTable c = (ExceptionTable) clone();
    108        if (exceptionIndexTable != null) {
    109            c.exceptionIndexTable = exceptionIndexTable.clone();
    110        }
    111        c.setConstantPool(constantPool);
    112        return c;
    113    }
    114
    115    /**
    116     * Dump exceptions attribute to file stream in binary format.
    117     *
    118     * @param file Output file stream
    119     * @throws IOException if an I/O error occurs.
    120     */
    121    @Override
    122    public void dump(final DataOutputStream file) throws IOException {
    123        super.dump(file);
    124        file.writeShort(exceptionIndexTable.length);
    125        for (final int index : exceptionIndexTable) {
    126            file.writeShort(index);
    127        }
    128    }
    129
    130    /**
    131     * @return Array of indices into constant pool of thrown exceptions.
    132     */
    133    public int[] getExceptionIndexTable() {
    134        return exceptionIndexTable;
    135    }
    136
    137    /**
    138     * @return class names of thrown exceptions
    139     */
    140    public String[] getExceptionNames() {
    141        final String[] names = new String[exceptionIndexTable.length];
    142        Arrays.setAll(names, i -> Utility.pathToPackage(super.getConstantPool().getConstantString(exceptionIndexTable[i], Const.CONSTANT_Class)));
    143        return names;
    144    }
    145
    146    /**
    147     * @return Length of exception table.
    148     */
    149    public int getNumberOfExceptions() {
    150        return exceptionIndexTable == null ? 0 : exceptionIndexTable.length;
    151    }
    152
    153    /**
    154     * @param exceptionIndexTable the list of exception indexes Also redefines number_of_exceptions according to table
    155     *        length.
    156     */
    157    public void setExceptionIndexTable(final int[] exceptionIndexTable) {
    158        this.exceptionIndexTable = ArrayUtils.nullToEmpty(exceptionIndexTable);
    159    }
    160
    161    /**
    162     * @return String representation, i.e., a list of thrown exceptions.
    163     */
    164    @Override
    165    public String toString() {
    166        final StringBuilder buf = new StringBuilder();
    167        String str;
    168        buf.append("Exceptions: ");
    169        for (int i = 0; i < exceptionIndexTable.length; i++) {
    170            str = super.getConstantPool().getConstantString(exceptionIndexTable[i], Const.CONSTANT_Class);
    171            buf.append(Utility.compactClassName(str, false));
    172            if (i < exceptionIndexTable.length - 1) {
    173                buf.append(", ");
    174            }
    175        }
    176        return buf.toString();
    177    }
    178}