#| -*-Scheme-*-

$Id: clscon.scm,v 1.16 2007/01/05 21:19:23 cph Exp $

Copyright (C) 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
    1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
    2006, 2007 Massachusetts Institute of Technology

This file is part of MIT/GNU Scheme.

MIT/GNU Scheme 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.

MIT/GNU Scheme 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 MIT/GNU Scheme; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301,
USA.

|#

;;;; Class/Object System: Class Constructor

(declare (usual-integrations))

;;; ******************************************************************
;;; This software is intended for use in the Edwin window system only.
;;; Don't think about using it for anything else, since it is not, and
;;; likely will not ever, be supported as a part of the Scheme system.
;;; ******************************************************************

(define (make-class name superclass variables)
  (let ((entry (assq name class-descriptors))
	(object-size
	 (+ (length variables)
	    (if superclass (class-object-size superclass) 1)))
	(transforms (make-instance-transforms superclass variables)))
    (let ((make-class
	   (lambda ()
	     (let ((class
		    (%make-class name
				 superclass
				 object-size
				 transforms
				 (cons '()
				       (and superclass
					    (class-methods superclass))))))
	       (named-structure/set-tag-description! class
		 (make-define-structure-type
		  'VECTOR
		  name
		  (list->vector (map car transforms))
		  (list->vector (map cdr transforms))
		  (make-vector (length transforms) (lambda () #f))
		  (standard-unparser-method name #f)
		  class
		  object-size))
	       class))))
      (if (not entry)
	  (let ((class (make-class)))
	    (set! class-descriptors (cons (cons name class) class-descriptors))
	    class)
	  (let ((class (cdr entry)))
	    (cond ((not (eq? (class-superclass class) superclass))
		   (let ((class (make-class)))
		     (set-cdr! entry class)
		     class))
		  ((and (= object-size (class-object-size class))
			(equal? transforms (class-instance-transforms class)))
		   class)
		  (else
		   (warn "Redefining class:" name)
		   (set-class-object-size! class object-size)
		   (set-class-instance-transforms! class transforms)
		   class)))))))

(define (make-instance-transforms superclass variables)
  (define (generate variables n)
    (if (pair? variables)
	(cons (cons (car variables) n)
	      (generate (cdr variables) (+ n 1)))
	'()))
  (if superclass
      (append (class-instance-transforms superclass)
	      (generate variables (class-object-size superclass)))
      (generate variables 1)))

(define (name->class name)
  (let ((entry (assq name class-descriptors)))
    (if (not entry)
	(error "Unknown class name:" name))
    (cdr entry)))

(define class-descriptors
  '())