    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 is derived from <em>Attribute</em> and declares this class as
    028 * `synthetic', i.e., it needs special handling.  The JVM specification
    029 * states "A class member that does not appear in the source code must be
    030 * marked using a Synthetic attribute."  It may appear in the ClassFile
    031 * attribute table, a field_info table or a method_info table.  This class
    032 * is intended to be instantiated from the
    033 * <em>Attribute.readAttribute()</em> method.
    034 *
    035 * @version $Id$
    036 * @see     Attribute
    037 */
    038public final class Synthetic extends Attribute {
    039
    040    private byte[] bytes;
    041
    042
    043    /**
    044     * Initialize from another object. Note that both objects use the same
    045     * references (shallow copy). Use copy() for a physical copy.
    046     */
    047    public Synthetic(final Synthetic c) {
    048        this(c.getNameIndex(), c.getLength(), c.getBytes(), c.getConstantPool());
    049    }
    050
    051
    052    /**
    053     * @param name_index Index in constant pool to CONSTANT_Utf8, which
    054     * should represent the string "Synthetic".
    055     * @param length Content length in bytes - should be zero.
    056     * @param bytes Attribute contents
    057     * @param constant_pool The constant pool this attribute is associated
    058     * with.
    059     */
    060    public Synthetic(final int name_index, final int length, final byte[] bytes, final ConstantPool constant_pool) {
    061        super(Const.ATTR_SYNTHETIC, name_index, length, constant_pool);
    062        this.bytes = bytes;
    063    }
    064
    065
    066    /**
    067     * Construct object from input stream.
    068     *
    069     * @param name_index Index in constant pool to CONSTANT_Utf8
    070     * @param length Content length in bytes
    071     * @param input Input stream
    072     * @param constant_pool Array of constants
    073     * @throws IOException
    074     */
    075    Synthetic(final int name_index, final int length, final DataInput input, final ConstantPool constant_pool)
    076            throws IOException {
    077        this(name_index, length, (byte[]) null, constant_pool);
    078        if (length > 0) {
    079            bytes = new byte[length];
    080            input.readFully(bytes);
    081            System.err.println("Synthetic attribute with length > 0");
    082        }
    083    }
    084
    085
    086    /**
    087     * Called by objects that are traversing the nodes of the tree implicitely
    088     * defined by the contents of a Java class. I.e., the hierarchy of methods,
    089     * fields, attributes, etc. spawns a tree of objects.
    090     *
    091     * @param v Visitor object
    092     */
    093    @Override
    094    public void accept( final Visitor v ) {
    095        v.visitSynthetic(this);
    096    }
    097
    098
    099    /**
    100     * Dump source file attribute to file stream in binary format.
    101     *
    102     * @param file Output file stream
    103     * @throws IOException
    104     */
    105    @Override
    106    public final void dump( final DataOutputStream file ) throws IOException {
    107        super.dump(file);
    108        if (super.getLength() > 0) {
    109            file.write(bytes, 0, super.getLength());
    110        }
    111    }
    112
    113
    114    /**
    115     * @return data bytes.
    116     */
    117    public final byte[] getBytes() {
    118        return bytes;
    119    }
    120
    121
    122    /**
    123     * @param bytes
    124     */
    125    public final void setBytes( final byte[] bytes ) {
    126        this.bytes = bytes;
    127    }
    128
    129
    130    /**
    131     * @return String representation.
    132     */
    133    @Override
    134    public final String toString() {
    135        final StringBuilder buf = new StringBuilder("Synthetic");
    136        if (super.getLength() > 0) {
    137            buf.append(" ").append(Utility.toHexString(bytes));
    138        }
    139        return buf.toString();
    140    }
    141
    142
    143    /**
    144     * @return deep copy of this attribute
    145     */
    146    @Override
    147    public Attribute copy( final ConstantPool _constant_pool ) {
    148        final Synthetic c = (Synthetic) clone();
    149        if (bytes != null) {
    150            c.bytes = new byte[bytes.length];
    151            System.arraycopy(bytes, 0, c.bytes, 0, bytes.length);
    152        }
    153        c.setConstantPool(_constant_pool);
    154        return c;
    155    }
    156}