;;;; -*- Mode: Lisp; Syntax: ANSI-Common-Lisp; Base: 10 -*-
;;;; *************************************************************************
;;;; FILE IDENTIFICATION
;;;;
;;;; Name:          attrib-class.lisp
;;;; Purpose:       Defines metaclass allowing use of attributes on slots
;;;; Programmer:    Kevin M. Rosenberg
;;;; Date Started:  Apr 2000
;;;;
;;;; $Id: attrib-class.lisp,v 1.4 2002/10/10 16:23:48 kevin Exp $
;;;;
;;;; This file, part of KMRCL, is Copyright (c) 2002 by Kevin M. Rosenberg
;;;;
;;;; KMRCL users are granted the rights to distribute and use this software
;;;; as governed by the terms of the Lisp Lesser GNU Public License
;;;; (http://opensource.franz.com/preamble.html), also known as the LLGPL.
;;;; *************************************************************************

;;;; Defines a metaclass that allows the use of attributes (or subslots)
;;;; on slots. Based on example in AMOP, but modified to use ACL's MOP.

(in-package :kmrcl)

(defclass attributes-dsd (mop::standard-direct-slot-definition)
  ((attributes :initarg :attributes :initform nil 
	       :accessor attributes)))

(defclass attributes-esd (mop::standard-effective-slot-definition)
  ((attributes :initarg :attributes :initform nil 
	       :accessor slot-definition-attributes)))


(defclass attributes-class (mop::standard-class)
  ()
  )

(defmethod mop::direct-slot-definition-class ((cl attributes-class) 
					      &rest iargs &key attributes)
  (declare (ignorable attributes))
;;  (format t "attributes:~s iargs:~s~%" attributes iargs)
  (find-class 'attributes-dsd))


(defmethod mop::compute-effective-slot-definition :around
	   ((cl attributes-class) slot dsds)
  (declare (ignorable slot))
  (apply
   #'make-instance 'attributes-esd 
   :attributes (remove-duplicates (mapappend #'attributes dsds))
   (excl::compute-effective-slot-definition-initargs cl dsds))
  )


#+ignore
(defmethod mop::compute-effective-slot-definition ((cl attributes-class) slot dsds)
  (declare (ignorable slot))
  (let ((normal-slot (call-next-method)))
    (setf (slot-definition-attributes normal-slot)
      (remove-duplicates
       (mapappend #'slot-definition-attributes dsds)))
    normal-slot))


(defmethod mop::compute-slots ((class attributes-class))
  (let* ((normal-slots (call-next-method))
	 (alist
	  (mapcar
	   #'(lambda (slot)
	       (let ((attr-list (mapcar #'(lambda (attr) (cons attr nil))
					(slot-definition-attributes slot))))
		 (when attr-list
		   (cons (mop::slot-definition-name slot) attr-list))))
	   normal-slots)))
    (setq alist (delete nil alist))
    (cons (mop::make-instance 'mop::standard-effective-slot-definition
	    :name 'all-attributes
	    :initform `',alist
	    :initfunction #'(lambda () alist))
	  normal-slots)))
  
(defun slot-attribute (instance slot-name attribute)
  (cdr (slot-attribute-bucket instance slot-name attribute)))

(defun (setf slot-attribute) (new-value instance slot-name attribute)
  (setf (cdr (slot-attribute-bucket instance slot-name attribute))
    new-value))

(defun slot-attribute-bucket (instance slot-name attribute)
  (let* ((all-buckets (slot-value instance 'all-attributes))
	 (slot-bucket (assoc slot-name all-buckets)))
    (unless slot-bucket
      (error "The slot named ~S of ~S has no attributes."
	     slot-name instance))
    (let ((attr-bucket (assoc attribute (cdr slot-bucket))))
      (unless attr-bucket
	(error "The slot named ~S of ~S has no attributes named ~S."
	       slot-name instance attribute))
      attr-bucket)))


#||
(in-package :kmrcl)

(defclass credit-rating ()
  ((level :attributes (date-set time-set))
   (id :attributes (person-setting)))
  (:metaclass kmrcl:attributes-class))
(defparameter cr (make-instance 'credit-rating))

(format t "~&date-set: ~a" (slot-attribute cr 'level 'date-set))
(setf (slot-attribute cr 'level 'date-set) "12/15/1990")
(format t "~&date-set: ~a" (slot-attribute cr 'level 'date-set))
  
(defclass monitored-credit-rating (credit-rating)
  ((level :attributes (last-checked interval date-set))
   (cc :initarg :cc)
   (id :attributes (verified))
   )
  (:metaclass attributes-class))
(defparameter mcr (make-instance 'monitored-credit-rating))

(setf (slot-attribute mcr 'level 'date-set) "01/05/2002")
(format t "~&date-set for mcr: ~a" (slot-attribute mcr 'level 'date-set))

||#