/*
 * Copyright (c) 2000, 2001    Paul Kinnucan
 *
 * $Revision: 1.3 $
 */

package jde.debugger.command;
import jde.debugger.JDEException;
import jde.debugger.Etc;
import com.sun.jdi.ObjectReference;
import jde.debugger.Rep;
import com.sun.jdi.ThreadReference;
import com.sun.jdi.StackFrame;
import com.sun.jdi.IncompatibleThreadStateException;
import com.sun.jdi.ObjectCollectedException;
import jde.debugger.LispForm;
import com.sun.jdi.AbsentInformationException;
import com.sun.jdi.NativeMethodException;
import com.sun.jdi.InvalidStackFrameException;



/**
 * Gets the "this" object of a specified stack frame.
 * <p>
 *
 * <b>Syntax:</b>
 * <pre>
 * get_this threadID stackFrameIndex
 * </pre>
 *
 * <b>Returns:</b>
 * <pre>
 *  (jde-dbo-command-result cmd_id {@link Rep#getObjectRep(ObjectReference, ObjectStore) detailed-object-info})
 * </pre>
 *
 * <b>Comments:</b>
 * <ul>
 * <li> Note that stackFrameIndex = 0 corresponds to the
 * current stackframe.
 * <li> The threadID and stackFrameIndex can be got from the
 *	'get_threads' command.
 * </ul>
 *
 * @author Paul Kinnucan
 * @version $Revision: 1.3 $
 */
 public class GetThis extends DebugProcessCommand {
  
  /**
   *
   * @exception jde.debugger.JDEException <description>
   */
   public void doCommand() throws JDEException {

     boolean weSuspendedThread = false;
     ThreadReference tRef = null;

     if (args.size() != 2) 
       throw new JDEException("Insufficient arguments");

     try {

       Long uniqueID = Etc.safeGetLong(args.remove(0), "thread ID");
       int frameIndex = Etc.safeGetint(args.remove(0), "frame index");
	    
       Object oRef = proc.getStore().get(uniqueID);
       if (oRef == null) {
	 throw new JDEException("No such thread exists");
       } else if (!(oRef instanceof ThreadReference)) {
	 throw new JDEException("Object is not a thread");
       }
	    
       tRef = (ThreadReference)oRef;

       if (!tRef.isSuspended()) {
	 tRef.suspend();
	 weSuspendedThread = true;
       } 
       

       StackFrame frame = null;
       try {
	 frame = tRef.frame(frameIndex);
       } catch (IncompatibleThreadStateException ex) {
	 throw new JDEException("Thread is not suspended");
       } catch (IndexOutOfBoundsException ex) {
	 throw new JDEException("Invalid frame");
       } catch (ObjectCollectedException ex) {
	 throw new JDEException("The frame has already been garbage collected");
       }

       if (frame == null) {
	 throw new JDEException("Error ascertaining frame");
       }

       ObjectReference thisObj = null;
       try {
	 thisObj = frame.thisObject();
       } catch (InvalidStackFrameException ex) {
	 throw new JDEException("Invalid stack frame.");
       } 

       jde.signalCommandResult(procID, cmdID, Rep.getObjectRep(thisObj, proc.getStore(), true));
				    
     } finally {
       if (weSuspendedThread && (tRef != null)) tRef.resume();
     }
 
   }

  public Object clone() {return new GetThis();}
  
} // GetThis

/*
 * $Log: GetThis.java,v $
 * Revision 1.3  2001/03/24 05:42:36  paulk
 * Updated to reflect reorganization of debugger code.
 *
 * Revision 1.2  2000/08/14 02:42:16  paulk
 * DebugCommandFactory.java
 *
 * Revision 1.1  2000/04/10 05:35:23  paulk
 * Initial revision.
 *
 *
 */

// End of GetTbis.java