Synthetic.java

/*
 * Copyright  2000-2004 The Apache Software Foundation
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); 
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License. 
 *
 */
package org.apache.bcel5_2_0.classfile;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;

import org.apache.bcel5_2_0.Constants;

/**
 * This class is derived from <em>Attribute</em> and declares this class as
 * `synthetic', i.e., it needs special handling.  The JVM specification
 * states "A class member that does not appear in the source code must be
 * marked using a Synthetic attribute."  It may appear in the ClassFile
 * attribute table, a field_info table or a method_info table.  This class
 * is intended to be instantiated from the
 * <em>Attribute.readAttribute()</em> method.
 *
 * @version $Id: Synthetic.java 386056 2006-03-15 11:31:56Z tcurdt $
 * @author  <A HREF="mailto:m.dahm@gmx.de">M. Dahm</A>
 * @see     Attribute
 */
public final class Synthetic extends Attribute {

    private byte[] bytes;


    /**
     * Initialize from another object. Note that both objects use the same
     * references (shallow copy). Use copy() for a physical copy.
     */
    public Synthetic(Synthetic c) {
        this(c.getNameIndex(), c.getLength(), c.getBytes(), c.getConstantPool());
    }


    /**
     * @param name_index Index in constant pool to CONSTANT_Utf8, which
     * should represent the string "Synthetic".
     * @param length Content length in bytes - should be zero.
     * @param bytes Attribute contents
     * @param constant_pool The constant pool this attribute is associated
     * with.
     */
    public Synthetic(int name_index, int length, byte[] bytes, ConstantPool constant_pool) {
        super(Constants.ATTR_SYNTHETIC, name_index, length, constant_pool);
        this.bytes = bytes;
    }


    /**
     * Construct object from file stream.
     * @param name_index Index in constant pool to CONSTANT_Utf8
     * @param length Content length in bytes
     * @param file Input stream
     * @param constant_pool Array of constants
     * @throws IOException
     */
    Synthetic(int name_index, int length, DataInputStream file, ConstantPool constant_pool)
            throws IOException {
        this(name_index, length, (byte[]) null, constant_pool);
        if (length > 0) {
            bytes = new byte[length];
            file.readFully(bytes);
            System.err.println("Synthetic attribute with length > 0");
        }
    }


    /**
     * Called by objects that are traversing the nodes of the tree implicitely
     * defined by the contents of a Java class. I.e., the hierarchy of methods,
     * fields, attributes, etc. spawns a tree of objects.
     *
     * @param v Visitor object
     */
    public void accept( Visitor v ) {
        v.visitSynthetic(this);
    }


    /**
     * Dump source file attribute to file stream in binary format.
     *
     * @param file Output file stream
     * @throws IOException
     */
    public final void dump( DataOutputStream file ) throws IOException {
        super.dump(file);
        if (length > 0) {
            file.write(bytes, 0, length);
        }
    }


    /**
     * @return data bytes.
     */
    public final byte[] getBytes() {
        return bytes;
    }


    /**
     * @param bytes
     */
    public final void setBytes( byte[] bytes ) {
        this.bytes = bytes;
    }


    /**
     * @return String representation.
     */
    public final String toString() {
    	StringBuilder buf = new StringBuilder("Synthetic");
        if (length > 0) {
            buf.append(" ").append(Utility.toHexString(bytes));
        }
        return buf.toString();
    }


    /**
     * @return deep copy of this attribute
     */
    public Attribute copy( ConstantPool _constant_pool ) {
        Synthetic c = (Synthetic) clone();
        if (bytes != null) {
            c.bytes = new byte[bytes.length];
            System.arraycopy(bytes, 0, c.bytes, 0, bytes.length);
        }
        c.constant_pool = _constant_pool;
        return c;
    }
}