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 * @see     Attribute
036 */
037public final class Synthetic extends Attribute {
038
039    private byte[] bytes;
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 Synthetic(final Synthetic c) {
047        this(c.getNameIndex(), c.getLength(), c.getBytes(), c.getConstantPool());
048    }
049
050
051    /**
052     * @param name_index Index in constant pool to CONSTANT_Utf8, which
053     * should represent the string "Synthetic".
054     * @param length Content length in bytes - should be zero.
055     * @param bytes Attribute contents
056     * @param constant_pool The constant pool this attribute is associated
057     * with.
058     */
059    public Synthetic(final int name_index, final int length, final byte[] bytes, final ConstantPool constant_pool) {
060        super(Const.ATTR_SYNTHETIC, name_index, length, constant_pool);
061        this.bytes = bytes;
062    }
063
064
065    /**
066     * Construct object from input stream.
067     *
068     * @param name_index Index in constant pool to CONSTANT_Utf8
069     * @param length Content length in bytes
070     * @param input Input stream
071     * @param constant_pool Array of constants
072     * @throws IOException
073     */
074    Synthetic(final int name_index, final int length, final DataInput input, final ConstantPool constant_pool)
075            throws IOException {
076        this(name_index, length, (byte[]) null, constant_pool);
077        if (length > 0) {
078            bytes = new byte[length];
079            input.readFully(bytes);
080            println("Synthetic attribute with length > 0");
081        }
082    }
083
084
085    /**
086     * Called by objects that are traversing the nodes of the tree implicitely
087     * defined by the contents of a Java class. I.e., the hierarchy of methods,
088     * fields, attributes, etc. spawns a tree of objects.
089     *
090     * @param v Visitor object
091     */
092    @Override
093    public void accept( final Visitor v ) {
094        v.visitSynthetic(this);
095    }
096
097
098    /**
099     * Dump source file attribute to file stream in binary format.
100     *
101     * @param file Output file stream
102     * @throws IOException
103     */
104    @Override
105    public void dump( final DataOutputStream file ) throws IOException {
106        super.dump(file);
107        if (super.getLength() > 0) {
108            file.write(bytes, 0, super.getLength());
109        }
110    }
111
112
113    /**
114     * @return data bytes.
115     */
116    public byte[] getBytes() {
117        return bytes;
118    }
119
120
121    /**
122     * @param bytes
123     */
124    public void setBytes( final byte[] bytes ) {
125        this.bytes = bytes;
126    }
127
128
129    /**
130     * @return String representation.
131     */
132    @Override
133    public String toString() {
134        final StringBuilder buf = new StringBuilder("Synthetic");
135        if (super.getLength() > 0) {
136            buf.append(" ").append(Utility.toHexString(bytes));
137        }
138        return buf.toString();
139    }
140
141
142    /**
143     * @return deep copy of this attribute
144     */
145    @Override
146    public Attribute copy( final ConstantPool _constant_pool ) {
147        final Synthetic c = (Synthetic) clone();
148        if (bytes != null) {
149            c.bytes = new byte[bytes.length];
150            System.arraycopy(bytes, 0, c.bytes, 0, bytes.length);
151        }
152        c.setConstantPool(_constant_pool);
153        return c;
154    }
155}