    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;
    025
    026/**
    027 * This class represents the table of exceptions that are thrown by a
    028 * method. This attribute may be used once per method.  The name of
    029 * this class is <em>ExceptionTable</em> for historical reasons; The
    030 * Java Virtual Machine Specification, Second Edition defines this
    031 * attribute using the name <em>Exceptions</em> (which is inconsistent
    032 * with the other classes).
    033 *
    034 * @version $Id$
    035 * @see     Code
    036 */
    037public final class ExceptionTable extends Attribute {
    038
    039    private int[] exception_index_table; // constant pool
    040
    041
    042    /**
    043     * Initialize from another object. Note that both objects use the same
    044     * references (shallow copy). Use copy() for a physical copy.
    045     */
    046    public ExceptionTable(final ExceptionTable c) {
    047        this(c.getNameIndex(), c.getLength(), c.getExceptionIndexTable(), c.getConstantPool());
    048    }
    049
    050
    051    /**
    052     * @param name_index Index in constant pool
    053     * @param length Content length in bytes
    054     * @param exception_index_table Table of indices in constant pool
    055     * @param constant_pool Array of constants
    056     */
    057    public ExceptionTable(final int name_index, final int length, final int[] exception_index_table,
    058            final ConstantPool constant_pool) {
    059        super(Const.ATTR_EXCEPTIONS, name_index, length, constant_pool);
    060        this.exception_index_table = exception_index_table != null ? exception_index_table : new int[0];
    061    }
    062
    063
    064    /**
    065     * Construct object from input stream.
    066     * @param name_index Index in constant pool
    067     * @param length Content length in bytes
    068     * @param input Input stream
    069     * @param constant_pool Array of constants
    070     * @throws IOException
    071     */
    072    ExceptionTable(final int name_index, final int length, final DataInput input, final ConstantPool constant_pool) throws IOException {
    073        this(name_index, length, (int[]) null, constant_pool);
    074        final int number_of_exceptions = input.readUnsignedShort();
    075        exception_index_table = new int[number_of_exceptions];
    076        for (int i = 0; i < number_of_exceptions; i++) {
    077            exception_index_table[i] = input.readUnsignedShort();
    078        }
    079    }
    080
    081
    082    /**
    083     * Called by objects that are traversing the nodes of the tree implicitely
    084     * defined by the contents of a Java class. I.e., the hierarchy of methods,
    085     * fields, attributes, etc. spawns a tree of objects.
    086     *
    087     * @param v Visitor object
    088     */
    089    @Override
    090    public void accept( final Visitor v ) {
    091        v.visitExceptionTable(this);
    092    }
    093
    094
    095    /**
    096     * Dump exceptions attribute to file stream in binary format.
    097     *
    098     * @param file Output file stream
    099     * @throws IOException
    100     */
    101    @Override
    102    public final void dump( final DataOutputStream file ) throws IOException {
    103        super.dump(file);
    104        file.writeShort(exception_index_table.length);
    105        for (final int index : exception_index_table) {
    106            file.writeShort(index);
    107        }
    108    }
    109
    110
    111    /**
    112     * @return Array of indices into constant pool of thrown exceptions.
    113     */
    114    public final int[] getExceptionIndexTable() {
    115        return exception_index_table;
    116    }
    117
    118
    119    /**
    120     * @return Length of exception table.
    121     */
    122    public final int getNumberOfExceptions() {
    123        return exception_index_table == null ? 0 : exception_index_table.length;
    124    }
    125
    126
    127    /**
    128     * @return class names of thrown exceptions
    129     */
    130    public final String[] getExceptionNames() {
    131        final String[] names = new String[exception_index_table.length];
    132        for (int i = 0; i < exception_index_table.length; i++) {
    133            names[i] = super.getConstantPool().getConstantString(exception_index_table[i],
    134                    Const.CONSTANT_Class).replace('/', '.');
    135        }
    136        return names;
    137    }
    138
    139
    140    /**
    141     * @param exception_index_table the list of exception indexes
    142     * Also redefines number_of_exceptions according to table length.
    143     */
    144    public final void setExceptionIndexTable( final int[] exception_index_table ) {
    145        this.exception_index_table = exception_index_table != null ? exception_index_table : new int[0];
    146    }
    147
    148
    149    /**
    150     * @return String representation, i.e., a list of thrown exceptions.
    151     */
    152    @Override
    153    public final String toString() {
    154        final StringBuilder buf = new StringBuilder();
    155        String str;
    156        buf.append("Exceptions: ");
    157        for (int i = 0; i < exception_index_table.length; i++) {
    158            str = super.getConstantPool().getConstantString(exception_index_table[i], Const.CONSTANT_Class);
    159            buf.append(Utility.compactClassName(str, false));
    160            if (i < exception_index_table.length - 1) {
    161                buf.append(", ");
    162            }
    163        }
    164        return buf.toString();
    165    }
    166
    167
    168    /**
    169     * @return deep copy of this attribute
    170     */
    171    @Override
    172    public Attribute copy( final ConstantPool _constant_pool ) {
    173        final ExceptionTable c = (ExceptionTable) clone();
    174        if (exception_index_table != null) {
    175            c.exception_index_table = new int[exception_index_table.length];
    176            System.arraycopy(exception_index_table, 0, c.exception_index_table, 0,
    177                    exception_index_table.length);
    178        }
    179        c.setConstantPool(_constant_pool);
    180        return c;
    181    }
    182}