private Object continuation;

   public boolean executeWithContinuations()
   {
      try
      {
         this.enterContext();

         if (this.continuation == null)
         {
            Context c = this.fetchRhinoContext();
            Scriptable s = this.fetchRhinoScope();
            c.executeScriptWithContinuations(this.rhinoScript, s);
         }
         else
         {
            this.resume();
         }

         // done
         return false;
      }
      catch (ContinuationPending pending)
      {
         this.continuation = pending.getContinuation();

         // continue later
         return true;
      }
      finally
      {
         this.exitContext();
      }
   }

   public void yield()
   {
      if (this.continuation != null)
      {
         throw new IllegalStateException();
      }

      try
      {
         this.enterContext();

         throw this.fetchRhinoContext().captureContinuation();
      }
      finally
      {
         this.exitContext();
      }
   }

   private void resume()
   {
      if (this.continuation == null)
      {
         throw new IllegalStateException();
      }

      final Object cont = this.continuation;

      this.continuation = null;

      try
      {
         this.enterContext();

         Context c = this.fetchRhinoContext();
         Scriptable s = this.fetchRhinoScope();
         c.resumeContinuation(cont, s, null);
      }
      finally
      {
         this.exitContext();
      }
   }