// BreakpointManager.java - A convenience class for dealing with breakpoints

/* Copyright (C) 2006  Free Software Foundation

   This file is part of libgcj.

This software is copyrighted work licensed under the terms of the
Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
details.  */

package gnu.gcj.jvmti;

import java.util.Hashtable;

/**
 * A class which manages breakpoints in the VM interpreter engine.
 *
 * BreakpointManager is a location manager that the interpreter
 * uses to lookup the original instruction for any given installed
 * breakpoint. JVMTI does not allow multiple breakpoints to be set
 * at any given location.
 *
 * @author Keith Seitz (keiths@redhat.com)
 */
public class BreakpointManager
{
  private static BreakpointManager _instance = new BreakpointManager ();

  // List of breakpoints indexed by Location
  private Hashtable _breakpoints;

  private BreakpointManager ()
  {
    _breakpoints = new Hashtable ();
  }

  /**
   * Creates a new breakpoint. SetBreakpoint will verify the validity
   * of the arguments.
   *
   * @param method  method in which to set breakpoint (a jmethodID)
   * @param location index where the breakpoint is to be set (a jlocation)
   */
  public static Breakpoint newBreakpoint (long method, long location)
  {
    Breakpoint bp = new Breakpoint (method, location);
    Location loc = new Location (method, location);
    _instance._breakpoints.put (loc, bp);
    return bp;
  }

  /**
   * Deletes the breakpoint at the given Location
   *
   * @param method method in which to clear breakpoint
   * @param location index of breakpoint in method
   */
  public static void deleteBreakpoint (long method, long location)
  {
    Location loc = new Location (method, location);
    _instance._breakpoints.remove (loc);
  }

  /**
   * Returns the breakpoint at the given location or null if none installed
   * at location
   *
   * @param method the jmethodID of the breakpoint location
   * @param location the index in the method
   */
  public static Breakpoint getBreakpoint (long method, long location)
  {
    Location loc = new Location (method, location);
    return (Breakpoint) _instance._breakpoints.get (loc);
  }
}