;;; -*-lisp-*-
;;;
;;; Output driver for SOD translator
;;;
;;; (c) 2009 Straylight/Edgeware
;;;

;;;----- Licensing notice ---------------------------------------------------
;;;
;;; This file is part of the Simple Object Definition system.
;;;
;;; SOD is free software; you can redistribute it and/or modify
;;; it under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 2 of the License, or
;;; (at your option) any later version.
;;;
;;; SOD is distributed in the hope that it will be useful,
;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with SOD; if not, write to the Free Software Foundation,
;;; Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

(cl:in-package #:sod)

;;;--------------------------------------------------------------------------
;;; Sequencing machinery.

(defclass sequencer-item ()
  ((name :initarg :name :reader sequencer-item-name)
   (functions :initarg :functions :initform nil
	      :type list :accessor sequencer-item-functions))
  (:documentation
   "Represents a distinct item to be sequenced by a SEQUENCER.

   A SEQUENCER-ITEM maintains a list of FUNCTIONS which are invoked when the
   sequencer is invoked.  This class is not intended to be subclassed."))

;;;--------------------------------------------------------------------------
;;; Output preparation.

(defvar *seen-announcement*)		;Keep me unbound!
#+hmm
(defmethod add-output-hooks :around (object reason sequencer &rest stuff)
  "Arrange not to invoke any object more than once during a particular
   announcement."
  (declare (ignore stuff))
  (cond ((not (boundp '*seen-announcement*))
	 (let ((*seen-announcement* (make-hash-table)))
	   (setf (gethash object *seen-announcement*) t)
	   (call-next-method)))
	((gethash object *seen-announcement*)
	 nil)
	(t
	 (setf (gethash object *seen-announcement*) t)
	 (call-next-method))))

;;;--------------------------------------------------------------------------
;;; Utility macro.

;;;----- That's all, folks --------------------------------------------------