gistfile1.cpp

  /**
   *  This method always executes on the separate stack created for the context.
   *
   *  Fortunately for us, Message always has an Array of arguments.
   *
   *    Arity -3:   VALUE func(VALUE argument_array);
   *    Arity -2:   VALUE func(VALUE receiver, VALUE argument_array);
   *    Arity -1:   VALUE func(int argument_count, VALUE*, VALUE receiver);
   *    Otherwise:  VALUE func(VALUE receiver, VALUE arg1[, VALUE arg2, ...]);    // Currently max 10 args
   *
   *  TODO:   Argument count check?
   *  TODO:   Check for inefficiencies.
   */
  void VMNativeMethod::perform_call()
  {
    NativeMethodContext* context = NativeMethodContext::current();
    NativeMethod::PointerTo c_method = context->method->actual_function_object();

    Message* message = context->message;

    HandleTo receiver(context->handles, message->recv);

    switch (context->method->arity()->to_int()) {
      case ARGS_IN_RUBY_ARRAY: {                    /* Braces required to create objects in a switch */

        HandleTo args(context->handles, message->arguments);
        context->return_value = c_method(args);

        break;
      }

      case RECEIVER_PLUS_ARGS_IN_RUBY_ARRAY: {

        HandleTo args(context->handles, message->arguments);
        context->return_value = c_method(receiver, args);

        break;
      }
//
//      case ARG_COUNT_ARGS_IN_C_ARRAY_PLUS_RECEIVER: {
//
//        for (std::size_t i = 0; i < message->total_args; ++i) {
//          HandleTo(context->handles, message->arguments->get(context->state, i));
//        }
//
//        context->return_value = c_method( message->total_args
//                                        , &context->handles[1]    /* Guaranteed to produce an array-like pointer. 1 leaves out receiver. */
//                                        , receiver);
//
//        break;
//      }

      default:
        sassert(false && "Not a valid arity, wth?");
    }

    context->action = NativeMethodContext::RETURN_FROM_C;

    jump_to_execution_point_in(context->dispatch_point);
    /* Never actually returns, control never reaches here. */
  }