/* IdManager.java -- "Interface" for JDWP ID management
   Copyright (C) 2005 Free Software Foundation

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Classpath is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

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along with GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
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or based on this library.  If you modify this library, you may extend
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package gnu.classpath.jdwp.vm;

import gnu.classpath.jdwp.exception.InvalidClassException;
import gnu.classpath.jdwp.exception.InvalidObjectException;
import gnu.classpath.jdwp.id.ObjectId;
import gnu.classpath.jdwp.id.ReferenceTypeId;

import java.io.IOException;
import java.nio.ByteBuffer;

/**
 * This abstract class describes an ID management interface. Every VM must
 * provide a way to assign and query JDWP object and reference type IDs.
 *
 * Please note that the back-end assumes all IDs are eight bytes.
 * 
 * @author Keith Seitz (address@hidden)
 */
public abstract class IdManager
{
  /**
   * Returns an id for the given object. This method must return a valid
   * <code>ObjectId</code>.
   *
   * @param theObject  the object to get an ID
   * @returns  the ID of the object
   */
  public abstract ObjectId getObjectId (Object theObject);

  /**
   * Returns the <code>ObjectId</code> for a given ID. Unlike
   * <code>getObjectId</code>, it throws an exception if the ID is not
   * known.
   *
   * @param id  the numerical ID of the desired <code>JdwpId</code>
   * @throws InvalidObjectException if the ID is not found
   */
  public abstract ObjectId get (long id)
    throws InvalidObjectException;

  /**
   * Gets the reference type id for the given class. This method must return
   * a valid ID.
   *
   * @param clazz  the class for which to get an ID
   * @returns  the ID of the class
   */
  public abstract ReferenceTypeId getReferenceTypeId (Class clazz);

  /**
   * Returns the <code>ReferenceTypeId</code> for a given ID. Unlike
   * <code>getReferenceTypeId</code>, it throws an exception if the ID is not
   * known.
   *
   * @param id  the numerical ID of the desired reference type
   * @throws InvalidClassException if the ID is not found
   */
  public abstract ReferenceTypeId getReferenceType (long id)
    throws InvalidClassException;

  /**
   * Reads a numerical ID from the stream, returning
   * the actual ID associated with it.
   * 
   * IDs are assumed to be eight bytes.
   *
   * @param bb  the buffer from which to read the ID 
   * @returns the object id
   * @throws IOException for any errors reading from the stream
   * @throws InvaildObjectException if ID is not found
   */
  public ObjectId readId (ByteBuffer bb)
    throws IOException, InvalidObjectException
  {
    long id = bb.getLong ();
    return get (id);
  }

  /**
   * Reads a numerical ID from the stream, returning
   * the actual reference type ID associated with it.
   *
   * IDs are assumed to be eight bytes.
   *
   * @param bb  the buffer from which to read the ID 
   * @returns the JdwpId
   * @throws IOException for any errors reading from the stream
   * @throws InvaildObjectException if ID is not found
   */
  public ReferenceTypeId readReferenceTypeId (ByteBuffer bb)
    throws IOException, InvalidClassException
  {
    long id = bb.getLong ();
    return getReferenceType (id);
  }
}