;;;; -*- Mode: Lisp; Syntax: ANSI-Common-Lisp; Base: 10 -*-
;;;; *************************************************************************
;;;; FILE IDENTIFICATION
;;;;
;;;; Name:          rules.lisp
;;;; Purpose:       Slot and Class rules
;;;; Programmer:    Kevin M. Rosenberg
;;;; Date Started:  Apr 2000
;;;;
;;;; $Id: rules.lisp,v 1.34 2003/04/25 03:35:58 kevin Exp $
;;;;
;;;; This file is Copyright (c) 2000-2002 by Kevin M. Rosenberg
;;;;
;;;; *************************************************************************
 
(in-package :hyperobject)

(eval-when (:compile-toplevel :execute)
  (declaim (optimize (speed 2) (safety 2) (compilation-speed 0) (debug 2))))

;;; Slot accessor and class rules

(defclass rule ()
  ((name :initarg :name :initform nil :accessor name)
   (dependants :initarg :dependants :initform nil :accessor dependants)
   (volatile :initarg :volatile :initform nil :accessor volatile)
   (access-slots :initarg :access-slots :initform nil :accessor access-slots)
   (source-code :initarg :source-code :initform nil :accessor source-code)
   (func :initform nil :initarg :func :accessor func)))

(defun compile-rule (source-code dependants volatile cl)
  (let ((access (appendnew dependants volatile)))
    (compile nil
	     (eval
	      `(lambda (obj)
		 (when (every #'(lambda (x) (slot-boundp obj x))
			      (quote ,dependants))
		   (with-slots ,access obj
		     ,@source-code)))))))
  
(defun finalize-rules (cl)
  (let* ((direct-rules (direct-rules cl))
	 (rules '()))
    (dolist (rule direct-rules)
      (destructuring-bind (name (&key dependants volatile) &rest source-code)
	  rule
	(setf dependants (mklist dependants)
	      volatile (mklist volatile))
	(push
	 (make-instance 'rule :name name :dependants dependants
			:volatile volatile :source-code source-code
			:access-slots (appendnew dependants volatile)
			:func (compile-rule
			       source-code dependants volatile cl))
	 rules)))
    (setf (rules cl) (nreverse rules))))


(defun fire-class-rules (cl obj slot)
  "Fire all class rules. Called after a slot is modified."
  (let ((name (slot-definition-name slot)))
    (dolist (rule (rules cl))
      (when (find name (dependants rule))
	(cmsg-c :debug "firing rule: ~W" (source-code rule))
	(funcall (func rule) obj)))))


#+ignore
(defmethod (setf slot-value-using-class) :around
    (new-value (cl hyperobject-class) obj (slot hyperobject-esd))
  ;; this does not work on gerd-pcl in cmu 18e+
  (esd-value-constraint slot)
  (call-next-method))

;; required for cmucl18e+ work-around
(defmethod (setf slot-value-using-class) :around
    (new-value (cl hyperobject-class) obj (slot hyperobject-esd))

  #+ignore
  (cmsg-c :verbose "Setf slot value: class: ~s, obj: ~s, slot: ~s, value: ~s" cl (class-of obj) slot new-value)
  
  (let ((func (when (slot-boundp slot 'value-constraint)
		(esd-value-constraint slot))))
    (cond
      ((and func (not (funcall func new-value)))
       (warn "Rejected change to value of slot ~a of object ~a"
	     (slot-definition-name slot) obj)
       (slot-value obj (slot-definition-name slot)))
      (t
       (prog1
	   (call-next-method)
	 (when (direct-rules cl)
	   (fire-class-rules cl obj slot)))))))


#+ignore
(defmethod (setf slot-value-using-class) :around
    (new-value (cl hyperobject-class) obj (slot hyperobject-esd))
  (let ((value (call-next-method)))
    (cmsg-c :verbose "slot value: class: ~s, obj: ~s, slot: ~s" cl (class-of obj) slot)
    value))