asn1/src/main/java/org/apache/directory/shared/asn1/Asn1Object.java

/*
 *   Copyright 2005 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.directory.shared.asn1;


import java.nio.ByteBuffer;

import org.apache.directory.shared.asn1.codec.DecoderException;
import org.apache.directory.shared.asn1.codec.EncoderException;


/**
 * An abstract class which implements basic TLV operations.
 * 
 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
 */
public abstract class Asn1Object
{
    // ~ Instance fields
    // ----------------------------------------------------------------------------

    /** The object's current length. It is used while decoding PDUs */
    private transient int currentLength;

    /** The object's expected length. It is used while decoding PDUs */
    private transient int expectedLength;

    /** The encapsulating Object */
    protected transient Asn1Object parent;


    // ~ Methods
    // ------------------------------------------------------------------------------------

    /**
     * Get the current object length, which is the sum of all inner length
     * already decoded.
     * 
     * @return The current object's length
     */
    public int getCurrentLength()
    {
        return currentLength;
    }


    /**
     * Compute the object length, which is the sum of all inner length.
     * 
     * @return The object's computed length
     */
    public abstract int computeLength();


    /**
     * Encode the object to a PDU.
     * 
     * @param buffer
     *            The buffer where to put the PDU
     * @return The PDU.
     */
    public ByteBuffer encode( ByteBuffer buffer ) throws EncoderException
    {
        return null;
    }


    /**
     * Get the expected object length.
     * 
     * @return The expected object's length
     */
    public int getExpectedLength()
    {
        return expectedLength;
    }


    /**
     * Add a length to the object
     * 
     * @param length
     *            The length to add.
     * @throws DecoderException
     *             Thrown if the current length exceed the expected length
     */
    public void addLength( int length ) throws DecoderException
    {
        currentLength += length;

        if ( currentLength > expectedLength )
        {
            throw new DecoderException( "Current Length is above expected Length" );
        }
    }


    /**
     * Set the expected length
     * 
     * @param expectedLength
     *            The expectedLength to set.
     */
    public void setExpectedLength( int expectedLength )
    {
        this.expectedLength = expectedLength;
    }


    /**
     * Set the current length
     * 
     * @param currentLength
     *            The currentLength to set.
     */
    public void setCurrentLength( int currentLength )
    {
        this.currentLength = currentLength;
    }


    /**
     * Get the parent
     * 
     * @return Returns the parent.
     */
    public Asn1Object getParent()
    {
        return parent;
    }


    /**
     * Set the parent
     * 
     * @param parent
     *            The parent to set.
     */
    public void setParent( Asn1Object parent )
    {
        this.parent = parent;
    }
}