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