package jde.debugger.command;

import com.sun.jdi.IncompatibleThreadStateException;
import com.sun.jdi.ObjectCollectedException;
import com.sun.jdi.StackFrame;
import com.sun.jdi.ThreadReference;
import com.sun.jdi.Value;
import jde.debugger.Etc;
import jde.debugger.JDEException;
import jde.debugger.Rep;

/**
 * 'evaluate' command.
 * <p>
 *
 * <b>Syntax:</b>
 * <pre>
 * evaluate threadID stackFrameIndex "expression"
 * </pre>
 *
 * <b>Returns:</b>
 * <pre>
 * (jde-dbo-command-result cmd_id {@link Rep#getValueRep(Value) value})
 * </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. Note that many evaluations
 *  might not be possible depending on the state of the thread
 * </ul>
 *
 * Copyright (c) 2000, 2001, 2003    Paul Kinnucan
 *
 * @author Paul Kinnucan
 * @version $Revision: 1.3 $
 * 
 */
public class EvaluateExpression extends DebugProcessCommand {
    
  /**
   *
   * @exception jde.debugger.JDEException <description>
   */
  public void doCommand() throws JDEException {

    // we'll suspend the thread later on, but wanna resume it later
    // so keep track.
    boolean weSuspendedThread = false;

    if (m_args.size() < 3) 
      throw new JDEException("Insufficient arguments");

    ThreadReference tRef = null;

    try {
	    
      // need a valid thread to work in...
      Long   uniqueID   = Etc.safeGetLong(m_args.remove(0), "thread ID");
      int    frameIndex = Etc.safeGetint(m_args.remove(0), "frame index");
      Object oRef       = m_debugger.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;
	    
      // suspend it on our own so that nothing funny happens during
      // the time we're trying to do expression evaluation
      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");
      }

      String expr = m_args.remove(0).toString();
      Value  val  = Etc.evaluate(expr, frame);
	    
      m_debugger.signalCommandResult(m_cmdID, Rep.getValueRep(val), CMD_OK, NOQUOTE);
	    
    } finally {
      if (weSuspendedThread && (tRef != null)) tRef.resume();
    }
 
  }

  public Object clone() {return new EvaluateExpression();}
  
} // GetLocals

/*
 * $Log: EvaluateExpression.java,v $
 * Revision 1.3  2003/01/15 05:56:26  paulk
 * Add Petter Mahlen's changes.
 *
 * Revision 1.2  2001/03/24 05:42:36  paulk
 * Updated to reflect reorganization of debugger code.
 *
 * Revision 1.1  2000/08/14 02:37:40  paulk
 * Initial revision.
 *
 * Revision 1.1  2000/04/10 05:33:28  paulk
 * Initial revision.
 *
 *
 */

// End of EvaluateExpression.java