    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 *
    046 * @see Code
    047 */
    048public final class ExceptionTable extends Attribute {
    049
    050    private int[] exceptionIndexTable; // constant pool
    051
    052    /**
    053     * Initialize from another object. Note that both objects use the same references (shallow copy). Use copy() for a
    054     * physical copy.
    055     *
    056     * @param c Source to copy.
    057     */
    058    public ExceptionTable(final ExceptionTable c) {
    059        this(c.getNameIndex(), c.getLength(), c.getExceptionIndexTable(), c.getConstantPool());
    060    }
    061
    062    /**
    063     * Constructs object from input stream.
    064     *
    065     * @param nameIndex Index in constant pool.
    066     * @param length Content length in bytes.
    067     * @param input Input stream.
    068     * @param constantPool Array of constants.
    069     * @throws IOException if an I/O error occurs.
    070     */
    071    ExceptionTable(final int nameIndex, final int length, final DataInput input, final ConstantPool constantPool) throws IOException {
    072        this(nameIndex, length, (int[]) null, constantPool);
    073        exceptionIndexTable = ClassParser.readU2U2Table(input);
    074    }
    075
    076    /**
    077     * Constructs an ExceptionTable.
    078     *
    079     * @param nameIndex Index in constant pool.
    080     * @param length Content length in bytes.
    081     * @param exceptionIndexTable Table of indices in constant pool.
    082     * @param constantPool Array of constants.
    083     */
    084    public ExceptionTable(final int nameIndex, final int length, final int[] exceptionIndexTable, final ConstantPool constantPool) {
    085        super(Const.ATTR_EXCEPTIONS, nameIndex, length, constantPool);
    086        this.exceptionIndexTable = ArrayUtils.nullToEmpty(exceptionIndexTable);
    087        Args.requireU2(this.exceptionIndexTable.length, "exceptionIndexTable.length");
    088    }
    089
    090    /**
    091     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
    092     * That is, the hierarchy of methods, fields, attributes, and so on spawns a tree of objects.
    093     *
    094     * @param v Visitor object.
    095     */
    096    @Override
    097    public void accept(final Visitor v) {
    098        v.visitExceptionTable(this);
    099    }
    100
    101    /**
    102     * Creates a deep copy of this attribute.
    103     *
    104     * @return deep copy of this attribute.
    105     */
    106    @Override
    107    public Attribute copy(final ConstantPool constantPool) {
    108        final ExceptionTable c = (ExceptionTable) clone();
    109        if (exceptionIndexTable != null) {
    110            c.exceptionIndexTable = exceptionIndexTable.clone();
    111        }
    112        c.setConstantPool(constantPool);
    113        return c;
    114    }
    115
    116    /**
    117     * Dumps exceptions attribute to file stream in binary format.
    118     *
    119     * @param file Output file stream.
    120     * @throws IOException if an I/O error occurs.
    121     */
    122    @Override
    123    public void dump(final DataOutputStream file) throws IOException {
    124        super.dump(file);
    125        file.writeShort(exceptionIndexTable.length);
    126        for (final int index : exceptionIndexTable) {
    127            file.writeShort(index);
    128        }
    129    }
    130
    131    /**
    132     * Gets the array of indices into constant pool of thrown exceptions.
    133     *
    134     * @return Array of indices into constant pool of thrown exceptions.
    135     */
    136    public int[] getExceptionIndexTable() {
    137        return exceptionIndexTable;
    138    }
    139
    140    /**
    141     * Gets the class names of thrown exceptions.
    142     *
    143     * @return class names of thrown exceptions.
    144     */
    145    public String[] getExceptionNames() {
    146        final String[] names = new String[exceptionIndexTable.length];
    147        Arrays.setAll(names, i -> Utility.pathToPackage(super.getConstantPool().getConstantString(exceptionIndexTable[i], Const.CONSTANT_Class)));
    148        return names;
    149    }
    150
    151    /**
    152     * Gets the length of exception table.
    153     *
    154     * @return Length of exception table.
    155     */
    156    public int getNumberOfExceptions() {
    157        return exceptionIndexTable == null ? 0 : exceptionIndexTable.length;
    158    }
    159
    160    /**
    161     * Sets the exception index table.
    162     *
    163     * @param exceptionIndexTable the list of exception indexes Also redefines number_of_exceptions according to table
    164     *        length.
    165     */
    166    public void setExceptionIndexTable(final int[] exceptionIndexTable) {
    167        this.exceptionIndexTable = ArrayUtils.nullToEmpty(exceptionIndexTable);
    168    }
    169
    170    /**
    171     * @return String representation, that is, a list of thrown exceptions.
    172     */
    173    @Override
    174    public String toString() {
    175        final StringBuilder buf = new StringBuilder();
    176        String str;
    177        buf.append("Exceptions: ");
    178        for (int i = 0; i < exceptionIndexTable.length; i++) {
    179            str = super.getConstantPool().getConstantString(exceptionIndexTable[i], Const.CONSTANT_Class);
    180            buf.append(Utility.compactClassName(str, false));
    181            if (i < exceptionIndexTable.length - 1) {
    182                buf.append(", ");
    183            }
    184        }
    185        return buf.toString();
    186    }
    187}