lsobjects.lsp

   1 ;;; -*- mode: lisp -*-
   2 ;;; Copyright (c) 2005--2007, by A.J. Rossini <blindglobe@gmail.com>
   3 ;;; See COPYRIGHT file for any additional restrictions (BSD license).
   4 ;;; Since 1991, ANSI was finally finished.  Edited for ANSI Common Lisp.
   5
   6 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   7 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   8 ;;;;
   9 ;;;;                    LISP-STAT Object System
  10 ;;;;
  11 ;;;;
  12 ;;;; Simple CL implementation of the object system for Lisp-Stat (LSOS)
  13 ;;;; as described in Tierney (1990).
  14 ;;;;
  15 ;;;; Copyright (c) 1991, by Luke Tierney. Permission is granted for
  16 ;;;; unrestricted use.
  17 ;;;;
  18 ;;;;
  19 ;;;; NOTES:
  20 ;;;;
  21 ;;;;    If your CL's handling of packages is compliant with CLtL, 2nd
  22 ;;;;    Edition (like Macintosh CL version 2), add the feature :CLtL2
  23 ;;;;    before loading or compiling this code.
  24 ;;;;
  25 ;;;;    This implementation does not make use of CLOS. It can coexist
  26 ;;;;    with CLOS, but there are two name conflicts: slot-value and
  27 ;;;;    call-next-method. These two symbols are shadowed in the LSOS
  28 ;;;;    package and must be shadowed in any package that uses LSOS.
  29 ;;;;    Evaluating the function (lsos::use-lsos) from a package after
  30 ;;;;    loading this code shadows these two symbols and does a
  31 ;;;;    use-package for LSOS.
  32 ;;;;
  33 ;;;;    The :compile-method method uses function-lambda-expression
  34 ;;;;    defined in CLtL, 2nd Edition. (This method is only needed if
  35 ;;;;    you want to force compilation of an interpreted method. It is
  36 ;;;;    not used by the compiler.)
  37 ;;;;
  38 ;;;;    The efficiency of this code could be improved by low level
  39 ;;;;    coding of the dispatching functions send, call-method and
  40 ;;;;    call-next-method to avoid creating an argument list. Other
  41 ;;;;    efficiency improvements are possible as well, in particular
  42 ;;;;    by good use of declarations. It may also be possible to build
  43 ;;;;    a more efficient implementation using the CLOS metaclass
  44 ;;;;    protocol.
  45 ;;;;
  46 ;;;;    There are a few minimal tools for experimenting with constraints
  47 ;;;;    in the code; they are marked by #+:constrainthooks. Sometime
  48 ;;;;    soon I hope to augment or replace these hooks with a CORAL-like
  49 ;;;;    constraint system (as used in GARNET).
  50 ;;;;
  51 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  52 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  53
  54
  55 ;;; AJR sez: above is generally true, except that the proto system
  56 ;;; would be built using the MOP (metaobject protocol), not CLOS.
  57 ;;; We use CLOS for a few things, but
  58
  59 ;;; Package Setup
  60
  61 (in-package :cl-user)
  62
  63 (defpackage :lisp-stat-object-system
  64  (:nicknames :ls-objects :lsos :proto-objects)
  65  (:use :common-lisp)
  66  (:export proto-object proto-object-p *proto-object*
  67           kind-of-p make-proto-object *message-hook*
  68           *set-slot-hook* proto-slot-value self send
  69           call-next-proto-method call-proto-method
  70           defmeth defproto defproto2
  71           instance-slots proto-name))
  72
  73 (in-package :lisp-stat-object-system)
  74
  75 ;;; Structure Implementation of Lisp-Stat Object System
  76 ;;; (prototype object system).
  77
  78 (defvar *proto-object-serial* 0)
  79
  80 ;; (defstruct (proto-object
  81 ;;           (:constructor make-proto-object-structure)
  82 ;;           (:print-function print-proto-object-structure)
  83 ;;           (:predicate proto-object-p)
  84 ;;           )
  85 ;;   slots
  86 ;;   methods
  87 ;;   parents
  88 ;;   preclist precedence list
  89 ;;   (serial (incf *proto-object-serial*)))
  90
  91 (defclass proto-slots ()
  92   ((contents)  ;; list of data slots
  93    (name)
  94    (documentation)))
  95 (defclass proto-methods () ;; list of functions that can be called
  96   ((contents)  ;; list of data slots
  97    (name)
  98    (documentation)))
  99 (defclass proto-object-list ()
 100   ((contents)  ;; list of data slots
 101    (name)
 102    (documentation)))
 103 (defclass preclist (proto-object-list) ())
 104 (defclass parent-list (proto-object-list) ())
 105
 106 (defgeneric add-object (proto-struct slot &optional init) ;; location)
 107   (:documentation "proto-struct is the prototype structure that we are
 108   working with, while slot means either slot or method, and value is
 109   the data or the method that we want to add with the name given in
 110   slot.  What the heck was implied by the location arg?"))
 111
 112 (defgeneric delete-object (obj proto-struct)
 113   (:documentation "remove the symbol from the proto object slot or
 114   method list."))
 115
 116 (defgeneric objects (proto-struct)
 117   (:documentation "return list of object symbols, perhaps slots,
 118   methods, parents, objects in precedence, as suggested by the arg."))
 119
 120 (defgeneric get-object (objSym proto-struct)
 121   (:documentation "accessor for the value of the symbol in the
 122   particular instance of the prototyping object."))
 123
 124
 125
 126 (defclass proto-object ()
 127     ((slots
 128       :initform (list)
 129       :type proto-slots
 130       :accessor proto-object-slots )
 131      (methods
 132       :initform (list)
 133       :type proto-methods
 134       :accessor proto-object-methods )
 135      (parents
 136       :initform (make-instance 'parent-list)
 137       :type parent-list
 138       :accessor proto-object-parents )
 139      (preclist ;; precedence list
 140       :initform (make-instance 'preclist)
 141       :type preclist
 142       :accessor proto-object-preclist
 143       :documentation "precedence list." )
 144      (serial
 145       :initform (incf *proto-object-serial*)
 146       :type integer
 147       :accessor proto-object-serial
 148       :documentation "Similar idea to serial number." )
 149      (self2
 150       :initform nil
 151       :type integer
 152       :accessor proto-self
 153       :documentation "can we embed the global within the class structure?" )))
 154
 155 ;; We denote default-ish proto-object variable names by po or po?.
 156
 157 (defvar *proto-object* (make-instance 'proto-object)
 158   "*proto-object* is the global root object.")
 159
 160 (defun proto-object-p (x)
 161       "Args: (x)
 162 Returns T if X is an object, NIL otherwise.  Do we really need this?"
 163   (typep x 'proto-object))
 164
 165 (defun print-proto-object-structure (po stream depth)
 166   (declare (ignore depth))
 167   (send po :print stream))
 168
 169 ;;; AJR:FIXME:Is this going to cause issues with concurrency/threading?
 170 ;;; (need to appropriately handle interrupts).
 171 (defvar *proto-self* nil
 172   "special variable to hold current value of SELF.
 173 Assign to current object that we are working with.  Local to proto package.
 174 Currently working to embed within the object structure rather than a global.")
 175
 176 ;; The way that self works is that we try to make sure that we set
 177 ;; *self* upon message entry and unset at message exit.  This is a
 178 ;; good strategy provided that concurrency is not in play.
 179
 180 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 181 ;;;
 182 ;;;               Predicates for Consistency Checking
 183 ;;;
 184 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 185
 186 (defun non-nil-symbol-p (x)
 187   (unless (and x (symbolp x)) (error "bad symbol - ~s" x)))
 188
 189 (defun check-object (po)
 190   "Returns self if true, throws an error otherwise."
 191   (if (proto-object-p po) po (error "bad object - ~s" po)))
 192
 193 (defun kind-of-p (pox poy)
 194 "Args: (x y)
 195 Returns T if X and Y are objects and X inherits from Y, NIL otherwise."
 196   (if (and (proto-object-p pox) (proto-object-p poy))
 197       (if (member poy (proto-object-preclist pox)) t nil)
 198       nil))
 199
 200 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 201 ;;;
 202 ;;;                     Precedence List Functions
 203 ;;;
 204 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 205
 206 (defgeneric find-SC (po)
 207   (:documentation "Return a copy of the complete precedence list for po."))
 208
 209 (defmethod find-SC ((po proto-object))
 210   (copy-list (proto-object-preclist po)))
 211
 212
 213 (defgeneric find-S (po)
 214   (:documentation "return a reverse-sorted, duplicate-free list of
 215   parent objects."))
 216
 217 (defmethod find-S ((po proto-object))
 218   (do ((result nil)
 219        (parents (proto-object-parents po) (rest parents)))
 220       ((not (consp parents))
 221        (delete-duplicates (cons po result)))
 222     (setf result (nconc (find-SC (first parents)) result))))
 223
 224
 225 (defgeneric find-RC (po)
 226   (:documentation "find local precedence ordering."))
 227
 228 (defmethod find-RC (po)
 229   (let ((list (copy-list (proto-object-parents po))))
 230     (do ((next list (rest next)))
 231         ((not (consp next)) list)
 232       (setf (first  next) (cons po (first next)))
 233       (setf po (rest (first next))))))
 234
 235
 236 (defgeneric find-R (S)
 237   (:documentation "find partial precedence ordering."))
 238
 239 (defmethod find-R ((S proto-object))
 240   (do ((result nil)
 241        (S S (rest S)))
 242       ((not (consp S))
 243        (delete-duplicates result))
 244     (setf result (nconc result (find-RC (first S))))))
 245
 246
 247 (defun has-predecessor (x R)
 248   "check if x has a predecessor according to R."
 249   (dolist (cell R nil)
 250     (if (and (consp cell) (eq x (rest cell))) (return t))))
 251
 252 (defun find-no-predecessor-list (S R)
 253   "find list of objects in S without predecessors, by R."
 254   (let ((result nil))
 255     (dolist (x S result)
 256       (unless (has-predecessor x R) (setf result (cons x result))))))
 257
 258 (defun child-position (x P)
 259 "find the position of child, if any, of x in P, the list found so
 260 far."
 261   (let ((count 0))
 262     (declare (fixnum count))
 263     (dolist (next P -1)
 264       (if (member x (proto-object-parents next)) (return count))
 265       (incf count))))
 266
 267 (defun next-object (no-preds P)
 268 "find the next object in the precedence list from objects with no
 269 predecessor and current list."
 270   (cond
 271    ((not (consp no-preds)) nil)
 272    ((not (consp (rest no-preds))) (first no-preds))
 273    (t
 274     (let ((count -1)
 275           (result nil))
 276       (declare (fixnum count))
 277       (dolist (x no-preds result)
 278         (let ((tcount (child-position x P)))
 279           (declare (fixnum tcount))
 280           (when (> tcount count)
 281             (setf result x)
 282             (setf count tcount))))))))
 283
 284 (defun trim-S (x S)
 285   "Remove object x from S."
 286   (delete x S))
 287
 288 (defun trim-R (x R)
 289   "Remove all pairs containing x from R. x is assumed to have no
 290 predecessors, so only the first position is checked."
 291   (delete x R :key #'first))
 292
 293 (defun precedence-list (object)
 294   "Calculate the object's precedence list."
 295   (do* ((S (find-S object))
 296         (R (find-R S))
 297         (P nil)
 298         (no-preds nil)
 299         (next nil))
 300        ((not (consp S)) P)
 301     (setf no-preds (find-no-predecessor-list S R))
 302     (setf next (next-object no-preds P))
 303     (if (null next) (error "inconsistent precedence order"))
 304     (setf P (nconc P (list next)))
 305     (setf S (trim-S next S))
 306     (setf R (trim-R next R))))
 307
 308 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 309 ;;;
 310 ;;;                 Object Construction Functions
 311 ;;;
 312 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 313
 314 (defun calculate-preclist (object)
 315   "Return the precedence list for the object."
 316   (let ((parents (proto-object-parents (check-object object))))
 317     (if (not (consp parents)) (error "bad parent list - ~s" parents))
 318     (if (consp (rest parents))
 319         (precedence-list object)
 320         (let ((parent (check-object (first parents))))
 321           (cons object (proto-object-preclist parent))))))
 322
 323 (defun has-duplicates (list)
 324   "predicate: takes a list, and returns true if duplicates.
 325 This should be simpler, right?  Used in next function only?"
 326   (do ((next list (rest next)))
 327       ((not (consp next)) nil)
 328     (if (member (first next) (rest next)) (return t))))
 329
 330 (defun check-parents (parents)
 331   "Ensure valid parents: They must be null, object, or consp without duplicates."
 332   (cond
 333    ((or (null parents) (proto-object-p parents)) parents)
 334    ((consp parents)
 335     (dolist (parent parents) (check-object parent))
 336     (if (has-duplicates parents)
 337         (error "parents may not contain duplicates")))
 338    (t (error "bad parents - ~s" parents))))
 339
 340 (defun make-basic-object (parents object)
 341   "Creates a basic object for the prototype system by ensuring that it
 342 can be placed into the storage heirarchy.
 343 If object is not initialized, instantiate the structure.
 344 Place into parental structure.
 345 If parents is null, use root *object*,
 346 if parents is a single object, use it (encapsulate as list)
 347 otherwise, use parents"
 348
 349   (check-parents parents)
 350   (if (not (proto-object-p object))
 351       (setf object (make-instance
 352                     'proto-object
 353                     :preclist (proto-object-preclist *proto-object*)
 354                     :parents
 355         (cond ((null parents) (list *proto-object*))
 356               ((proto-object-p parents) (list parents))
 357               (t parents)))))
 358   (setf (proto-object-preclist object) (calculate-preclist object))
 359   object)
 360
 361 (defun make-object (&rest parents)
 362   "Args: (&rest parents)
 363 Returns a new object with parents PARENTS. If PARENTS is NIL,
 364 (list *PROTO-OBJECT*) is used."
 365   (make-basic-object parents NIL))
 366
 367 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 368 ;;;;
 369 ;;;;                   Constraint Hook Functions
 370 ;;;;
 371 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 372
 373 (pushnew :constrainthooks *features*)
 374
 375 #+:constrainthooks
 376 (progn
 377   (defvar *message-hook* nil)
 378   (defvar *set-slot-hook* nil)
 379
 380   (defun check-constraint-hooks (object sym slot)
 381     (let ((hook (if slot *set-slot-hook* *message-hook*)))
 382       (if hook
 383           (if slot
 384               (let ((*set-slot-hook* nil))
 385                 (funcall hook object sym))
 386               (let ((*message-hook* nil))
 387                 (funcall hook object sym)))))))
 388
 389 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 390 ;;;
 391 ;;;                     Slot Access Functions
 392 ;;;
 393 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 394
 395 ;;; AJR: should specialize appropriately, the following:
 396 (defun make-slot-entry (x y) (cons x y))
 397 (defun slot-entry-p (x) (consp x))
 398 (defun slot-entry-key (x) (first x))
 399 (defun slot-entry-value (x) (rest x))
 400 (defun set-slot-entry-value (x v) (setf (rest x) v))
 401 (defsetf slot-entry-value set-slot-entry-value)
 402
 403 (defun find-own-slot (x slot)
 404   (if (proto-object-p x) (assoc slot (proto-object-slots x))))
 405
 406 (defun find-slot (x slot)
 407   (if (proto-object-p x)
 408     (let ((preclist (proto-object-preclist x)))
 409       (dolist (object preclist)
 410         (let ((slot-entry (find-own-slot object slot)))
 411           (if slot-entry (return slot-entry)))))))
 412
 413 ;; To remove.
 414 (defun add-slot (x slot value)
 415   "Remove when completely replaced by add-object methods."
 416   (add-object x slot value))
 417
 418 (defmethod add-object ((x (type proto-object)
 419                        (slot symbol)
 420                        &optional
 421                        init)) ;; location))
 422   ;; (check-object x)
 423   ;; (non-nil-symbol-p slot)
 424 ;  #+nil(if (nilp slot)
 425 ;      ;; This is wrong but has the right flavor of what should be
 426 ;      ;; happening.
 427 ;      (setf slot (gensym)))
 428   (let ((slot-entry (find-own-slot x slot)))
 429     (if slot-entry
 430       (setf (slot-entry-value slot-entry) init)
 431       (setf (proto-object-slots x)
 432             (cons (make-slot-entry slot init) (proto-object-slots x)))))
 433   nil) ;; I think we want to return something, but what?
 434
 435 ;; This might be more appropriate as a "setter" dispatching on a
 436 ;;   (proto-object slot)
 437 ;; argument.
 438
 439 ;; REMOVE ME when obsolete
 440 (defun delete-slot (x slot)
 441   (delete-object x slot))
 442
 443 (defmethod delete-object ((x proto-object)
 444                           (slot symbol))
 445   ;; (check-object x)
 446   (setf (proto-object-slots x)
 447         (delete slot (proto-object-slots x) :key #'slot-entry-key)))
 448
 449 (defun get-slot-value (x slot &optional no-err)
 450   (check-object x)
 451   (let ((slot-entry (find-slot x slot)))
 452     (if (slot-entry-p slot-entry)
 453       (slot-entry-value slot-entry)
 454       (unless no-err (error "no slot named ~s in this object" slot)))))
 455
 456 (defun set-slot-value (x slot value)
 457   (check-object x)
 458   (let ((slot-entry (find-own-slot x slot)))
 459     (cond
 460      ((slot-entry-p slot-entry)
 461       (set-slot-entry-value slot-entry value)
 462       #+:constrainthooks (check-constraint-hooks x slot t))
 463      (t
 464       (if (find-slot x slot)
 465         (error "object does not own slot ~s" slot)
 466         (error "no slot named ~s in this object" slot))))))
 467
 468 (defun get-self ()
 469   "Return current proto-object being manipulated.  We are going to die
 470   in a multithreaded environment."
 471   (if (not (proto-object-p *proto-self*))
 472       (error "not in a method"))
 473   *proto-self*)
 474
 475 (defun proto-slot-value (slot)
 476 "Args: (slot)
 477 Must be used in a method. Returns the value of current objects slot
 478 named SLOT."
 479   (get-slot-value (get-self) slot))
 480
 481 (defun proto-slot-value-setf (slot value)
 482   (set-slot-value (get-self) slot value))
 483
 484 (defsetf proto-slot-value proto-slot-value-setf)
 485
 486 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 487 ;;;;
 488 ;;;;                   Method Access Functions;
 489 ;;;;
 490 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 491
 492 (defun make-method-entry (x y) (cons x y))
 493 (defun method-entry-p (x) (consp x))
 494 (defun method-entry-key (x) (first x))
 495 (defun method-entry-method (x) (rest x))
 496 (defun set-method-entry-method (x v) (setf (rest x) v))
 497 (defsetf method-entry-method set-method-entry-method)
 498
 499 (defun find-own-method (x selector)
 500   (if (proto-object-p x) (assoc selector (proto-object-methods x))))
 501
 502 (defun find-lsos-method (x selector)
 503   (if (proto-object-p x)
 504     (let ((preclist (proto-object-preclist x)))
 505       (dolist (object preclist)
 506         (let ((method-entry (find-own-method object selector)))
 507           (if method-entry (return method-entry)))))))
 508
 509 (defun add-lsos-method (x selector value)
 510   "x = object; selector = name of method; value = form computing the method."
 511   (check-object x)
 512   (non-nil-symbol-p selector)
 513   (let ((method-entry (find-own-method x selector)))
 514     (if method-entry
 515       (setf (method-entry-method method-entry) value)
 516       (setf (proto-object-methods x)
 517             (cons (make-method-entry selector value) (proto-object-methods x)))))
 518   nil)
 519
 520 (defun delete-method (x selector)
 521   (check-object x)
 522   (setf (proto-object-methods x)
 523         (delete selector (proto-object-methods x) :key #'method-entry-key)))
 524
 525 (defun get-message-method (x selector &optional no-err)
 526   (check-object x)
 527   (let ((method-entry (find-lsos-method x selector)))
 528     (if (method-entry-p method-entry)
 529       (method-entry-method method-entry)
 530       (unless no-err (error "no method for selector ~s" selector)))))
 531
 532 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 533 ;;;
 534 ;;;                   Message Sending Functions
 535 ;;;
 536 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 537
 538 (defvar *current-preclist* nil)
 539 (defvar *current-selector* nil)
 540
 541 (defun sendmsg (object selector preclist args)
 542   (let ((method-entry nil)
 543         (method nil))
 544
 545     ;; look for the message in the precedence list
 546     (loop
 547       (setf method-entry (find-own-method (first preclist) selector))
 548       (if (or method-entry (not (consp preclist))) (return))
 549       (setf preclist (rest preclist)))
 550     (cond
 551      ((null method-entry) (error "no method for selector ~s" selector))
 552      ((not (method-entry-p method-entry)) (error "bad method entry"))
 553      (t (setf method (method-entry-method method-entry))))
 554
 555     ;; invoke the method
 556     (let ((*current-preclist* preclist)
 557           (*current-selector* selector)
 558           (*proto-self* object))
 559       (multiple-value-prog1
 560         (apply method object args)
 561         #+:constrainthooks (check-constraint-hooks object selector nil)))))
 562
 563 ;;;; built-in send function
 564 (defun send (object selector &rest args)
 565 "Args: (object selector &rest args)
 566 Applies first method for SELECTOR found in OBJECT's precedence list to
 567 OBJECT and ARGS."
 568   (sendmsg object selector (proto-object-preclist object) args))
 569
 570 ;;;; call-next-proto-method - call inherited version of current method
 571 (defun call-next-proto-method (&rest args)
 572 "Args (&rest args)
 573 Funcalls next method for current selector and precedence list. Can only be
 574 used in a method."
 575   (sendmsg *proto-self* *current-selector* (rest *current-preclist*) args))
 576
 577 (defun call-proto-method (object selector &rest args)
 578 "Args (object selector &rest args)
 579 Funcalls method for SELECTOR found in OBJECT to SELF. Can only be used in
 580 a method.
 581 Call method belonging to another object on current object."
 582   (sendmsg *proto-self* selector (proto-object-preclist object) args))
 583
 584 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 585 ;;;
 586 ;;;                  Object Documentation
 587 ;;;
 588 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 589
 590 (defun find-documentation (x sym add)
 591   (if (proto-object-p x)
 592     (let ((doc (find-own-slot x 'documentation)))
 593       (if (and (null doc) add) (add-slot x 'documentation nil))
 594       (if (slot-entry-p doc) (assoc sym (slot-entry-value doc))))))
 595
 596 (defun add-documentation (x sym value)
 597   (check-object x)
 598   (non-nil-symbol-p sym)
 599   (let ((doc-entry (find-documentation x sym t)))
 600     (cond
 601      ((not (null doc-entry))
 602       (setf (rest doc-entry) value))
 603      (t
 604       (set-slot-value x
 605                       'documentation
 606                       (cons (cons sym value)
 607                             (get-slot-value x 'documentation))))))
 608   nil)
 609
 610 (defun get-documentation (x sym)
 611   (check-object x)
 612   (dolist (object (proto-object-preclist x))
 613     (let ((doc-entry (find-documentation object sym nil))) ;; FIXME: verify
 614       (if doc-entry (return (rest doc-entry))))))
 615
 616 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 617 ;;;;
 618 ;;;;                         DEFMETH Macro
 619 ;;;;
 620 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 621
 622 (defmacro defmeth (object name arglist first &rest body)
 623   "Syntax: (defmeth object method-name lambda-list [doc] {form}*)
 624 OBJECT must evaluate to an existing object. Installs a method for NAME in
 625 the value of OBJECT and installs DOC in OBJECTS's documentation.
 626 RETURNS: method-name."
 627   (declare (ignorable self))  ;; hints for the compiler that sometimes it isn't used
 628   (if (and body (stringp first))
 629     `(progn ;; first=docstring + body
 630        (add-lsos-method ,object ,name
 631                  #'(lambda (self ,@arglist) (block ,name ,@body)))
 632        (add-documentation ,object ,name ,first)
 633        ,name)
 634     `(progn ;; first=code + body
 635        (add-lsos-method ,object ,name
 636                    #'(lambda (self ,@arglist) (block ,name ,first ,@body)))
 637        ,name)))
 638
 639 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 640 ;;;
 641 ;;;             Prototype Construction
 642 ;;;
 643 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 644
 645 (defun find-instance-slots (x slots)
 646   (let ((result (nreverse (delete-duplicates (copy-list slots)))))
 647     (dolist (parent (proto-object-parents x) (nreverse result))
 648       (dolist (slot (get-slot-value parent 'instance-slots))
 649         (pushnew slot result)))))
 650
 651 (defun get-initial-slot-value (object slot)
 652   (let ((entry (find-slot object slot)))
 653     (if (slot-entry-p entry) (slot-entry-value entry))))
 654
 655 (defun make-prototype (object name ivars cvars doc set)
 656   (setf ivars (find-instance-slots object ivars))
 657   (add-slot object 'instance-slots ivars)
 658   (add-slot object 'proto-name name)
 659   (dolist (slot ivars)
 660     (add-slot object slot (get-initial-slot-value object slot)))
 661   (dolist (slot cvars)
 662     (add-slot object slot nil))
 663
 664   (if (and doc (stringp doc))
 665     (add-documentation object 'proto doc))
 666   (if set (setf (symbol-value name) object)))
 667
 668
 669 (defmacro defproto (name &optional ivars cvars parents doc)
 670 "Syntax (defproto name &optional ivars cvars (parent *proto-object*) doc)
 671 Makes a new object prototype with instance variables IVARS, 'class'
 672 variables CVARS and parents PARENT. PARENT can be a single object or
 673 a list of objects. IVARS and CVARS must be lists."
 674   (let ((obsym (gensym))
 675         (namesym (gensym))
 676         (parsym (gensym)))
 677     `(progn
 678        (let* ((,namesym ',name)
 679               (,parsym ,parents)
 680               (,obsym (make-basic-object (if (listp ,parsym)
 681                                              ,parsym
 682                                              (list ,parsym)) ;; should this be ,@parsym ?
 683                                          nil)))
 684          (make-prototype ,obsym ,namesym ,ivars ,cvars ,doc t)
 685          ,namesym))))
 686
 687
 688 ;; Infrastructure for new defproto from Common-Lisp Cookbook!  Thanks!
 689
 690 ;(defmacro odd-define (name buildargs)
 691 ;   `(progn (defun ,(build-symbol make-a- (:< name))
 692 ;                                 ,buildargs
 693 ;              (vector ,(length buildargs) ',name ,@buildargs))
 694 ;           (defun ,(build-symbol test-whether- (:< name)) (x)
 695 ;              (and (vectorp x) (eq (aref x 1) ',name))
 696 ;           (defun ,(build-symbol (:< name) -copy) (x)
 697 ;              ...)
 698 ;           (defun ,(build-symbol (:< name) -deactivate) (x)
 699 ;              ...))))
 700
 701 ;(defmacro for (listspec exp)
 702 ;   (cond ((and (= (length listspec) 3)
 703 ;               (symbolp (car listspec))
 704 ;               (eq (cadr listspec) ':in))
 705 ;          `(mapcar (lambda (,(car listspec))
 706 ;                      ,exp)
 707 ;                   ,(caddr listspec)))
 708 ;         (t (error "Ill-formed: ~s" `(for ,listspec ,exp)))))
 709
 710 ;(defmacro symstuff (l)
 711 ;   `(concatenate 'string
 712 ;      ,@(for (x :in l)
 713 ;           (cond ((stringp x)
 714 ;                  `',x)
 715 ;                 ((atom x)
 716 ;                  `',(format nil "~a" x))
 717 ;                 ((eq (car x) ':<)
 718 ;                  `(format nil "~a" ,(cadr x)))
 719 ;                 ((eq (car x) ':++)
 720 ;                  `(format nil "~a" (incf ,(cadr x))))
 721 ;                 (t
 722 ;                  `(format nil "~a" ,x))))))
 723
 724 ;(defmacro build-symbol (&rest l)
 725 ;   (let ((p (find-if (lambda (x)
 726 ;                      (and (consp x)
 727 ;                           (eq (car x) ':package)))
 728 ;                     l)))
 729 ;     (cond (p
 730 ;           (setq l (remove p l))))
 731 ;     (let ((pkg (cond ((eq (cadr p) 'nil)
 732 ;                      nil)
 733 ;                     (t `(find-package ',(cadr p))))))
 734 ;       (cond (p
 735 ;             (cond (pkg
 736 ;                    `(values (intern ,(symstuff l) ,pkg)))
 737 ;                   (t
 738 ;                    `(make-symbol ,(symstuff l)))))
 739 ;            (t
 740 ;             `(values (intern ,(symstuff l))))))))
 741
 742 (defmacro defproto2 (name &optional ivars cvars parents doc force)
 743   "Syntax (defproto name &optional ivars cvars (parent *proto-object*) doc)
 744 Makes a new object prototype with instance variables IVARS, 'class'
 745 variables CVARS and parents PARENT. PARENT can be a single object or
 746 a list of objects. IVARS and CVARS must be lists.  DOC should be a
 747 string."
 748   (if (and (boundp name)
 749            (not force))
 750       (error "Force T to rebind a prototype object.")
 751       (let ((obsym (gensym))
 752             (parsym (gensym)))
 753         `(progn
 754           (defvar ,name (list) ,doc)
 755           (let* ((,parsym ,parents)
 756                  (,obsym (make-basic-object
 757                           (if (listp ,parsym)
 758                               ,parsym
 759                               (list ,@parsym)) ;; should this be ,@parsym ?
 760                           nil)))
 761             (make-prototype ,obsym ,name ,ivars ,cvars ,doc t)
 762             ,name)))))
 763
 764 ;; (macro-expand-1 (defproto2 *mytest*))
 765
 766 ;; recall:
 767 ;; , => turn on evaluation again (not macro substitution)
 768 ;; ` => template comes (use , to undo template and restore eval
 769 ;; ' => regular quote (not special in this context), 'ted => (quote ted)
 770
 771
 772 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 773 ;;;
 774 ;;;                   Initialize the Root Object
 775 ;;;
 776 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 777
 778 (setf (proto-object-preclist *proto-object*) (list *proto-object*))
 779 (add-slot *proto-object* 'instance-slots nil)
 780 (add-slot *proto-object* 'proto-name '*proto-object*)
 781 (add-slot *proto-object* 'documentation nil)  ; AJR - for SBCL compiler
 782                                         ; issues about macro with
 783                                         ; unknown slot
 784
 785 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 786 ;;;
 787 ;;;                       *PROTO-OBJECT* Methods
 788 ;;;
 789 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 790
 791 (defmeth *proto-object* :isnew (&rest args)
 792 "Method args: (&rest args)
 793 Checks ARGS for keyword arguments matching slots and uses them to
 794 initialize slots."
 795   (if args
 796     (dolist (slot-entry (proto-object-slots self))
 797       (let* ((slot (slot-entry-key slot-entry))
 798              (key (intern (symbol-name slot) (find-package 'keyword)))
 799              (val (proto-slot-value slot))
 800              (new-val (getf args key val)))
 801         (unless (eq val new-val) (setf (proto-slot-value slot) new-val)))))
 802   self)
 803
 804 (defmeth *proto-object* :has-slot (slot &key own)
 805 "Method args: (slot &optional own)
 806 Returns T if slot SLOT exists, NIL if not. If OWN is not NIL
 807 only checks the object; otherwise check the entire precedence list."
 808   (let ((entry (if own (find-own-slot self slot) (find-slot self slot))))
 809     (if entry t nil)))
 810
 811 (defmeth *proto-object* :add-slot (slot &optional value)
 812 "Method args: (slot &optional value)
 813 Installs slot SLOT in object, if it does not already exist, and
 814 sets its value to VLAUE."
 815   (add-slot self slot value)
 816   value)
 817
 818 (defmeth *proto-object* :delete-slot (slot)
 819 "Method args: (slot)
 820 Deletes slot SLOT from object if it exists."
 821   (delete-slot self slot)
 822   nil)
 823
 824 (defmeth *proto-object* :own-slots ()
 825 "Method args: ()
 826 Returns list of names of slots owned by object."
 827   (mapcar #'slot-entry-key (proto-object-slots self)))
 828
 829 (defmeth *proto-object* :has-method (selector &key own)
 830 "Method args: (selector &optional own)
 831 Returns T if method for SELECTOR exists, NIL if not. If OWN is not NIL
 832 only checks the object; otherwise check the entire precedence list."
 833   (let ((entry (if own
 834                  (find-own-method self selector)
 835                  (find-lsos-method self selector))))
 836     (if entry t nil)))
 837
 838 (defmeth *proto-object* :add-method (selector method)
 839 "Method args: (selector method)
 840 Installs METHOD for SELECTOR in object."
 841   (add-lsos-method self selector method)
 842   nil)
 843
 844 (defmeth *proto-object* :delete-method (selector)
 845 "Method args: (selector)
 846 Deletes method for SELECTOR in object if it exists."
 847   (delete-method self selector)
 848   nil)
 849
 850 (defmeth *proto-object* :get-method (selector)
 851 "Method args: (selector)
 852 Returns method for SELECTOR symbol from object's precedence list."
 853   (get-message-method self selector))
 854
 855 (defmeth *proto-object* :own-methods ()
 856 "Method args ()
 857 Returns copy of selectors for methods owned by object."
 858   (mapcar #'method-entry-key (proto-object-methods self)))
 859
 860 (defmeth *proto-object* :parents ()
 861 "Method args: ()
 862 Returns copy of parents list."
 863   (copy-list (proto-object-parents self)))
 864
 865 (defmeth *proto-object* :precedence-list ()
 866 "Method args: ()
 867 Returns copy of the precedence list."
 868   (copy-list (proto-object-preclist self)))
 869
 870 (defmeth *proto-object* :show (&optional (stream t))
 871 "Method Args: ()
 872 Prints object's internal data."
 873   (format stream "Slots = ~s~%" (proto-object-slots self))
 874   (format stream "Methods = ~s~%" (proto-object-methods self))
 875   (format stream "Parents = ~s~%" (proto-object-parents self))
 876   (format stream "Precedence List  = ~s~%" (proto-object-preclist self))
 877   nil)
 878
 879 (defmeth *proto-object* :reparent (&rest parents)
 880 "Method args: (&rest parents)
 881 Changes precedence list to correspond to PARENTS. Does not change descendants."
 882   (make-basic-object parents self))
 883
 884 (defmeth *proto-object* :make-prototype (name &optional ivars)
 885   (make-prototype self name ivars nil nil nil)
 886   self)
 887
 888 (defmeth *proto-object* :internal-doc (sym &optional new)
 889 "Method args (topic &optional value)
 890 Retrieves or installs documentation for topic."
 891   (if new (add-documentation self sym new))
 892   (get-documentation self sym))
 893
 894 (defmeth *proto-object* :new (&rest args)
 895 "Method args: (&rest args)
 896 Creates new object using self as prototype."
 897   (let* ((object (make-object self)))
 898     (if (proto-slot-value 'instance-slots)
 899         (dolist (s (proto-slot-value 'instance-slots))
 900                 (send object :add-slot s (proto-slot-value s))))
 901     (apply #'send object :isnew args)
 902     object))
 903
 904 (defmeth *proto-object* :retype (proto &rest args)
 905 "Method args: (proto &rest args)
 906 Changes object to inherit directly from prototype PROTO. PROTO
 907 must be a prototype and SELF must not be one."
 908   (if (send self :has-slot 'instance-slots :own t)
 909       (error "can't retype a prototype"))
 910   (if (not (send proto :has-slot 'instance-slots :own t))
 911       (error "not a prototype - ~a" proto))
 912   (send self :reparent proto)
 913   (dolist (s (send proto :slot-value 'instance-slots))
 914     (send self :add-slot s (proto-slot-value s)))
 915   (apply #'send self :isnew args)
 916   self)
 917
 918 (defmeth *proto-object* :print (&optional (stream *standard-output*))
 919 "Method args: (&optional (stream *standard-output*))
 920 Default object printing method."
 921   (cond
 922     ((send self :has-slot 'proto-name)
 923      (format stream
 924              "#<Object: ~D, prototype = ~A>"
 925              (proto-object-serial self)
 926              (proto-slot-value 'proto-name)))
 927     (t (format stream "#<Object: ~D>" (proto-object-serial self)))))
 928
 929 (defmeth *proto-object* :slot-value (sym &optional (val nil set))
 930          "Method args: (sym &optional val)
 931 Sets and retrieves value of slot named SYM. Signals an error if slot
 932 does not exist."
 933     (if set (setf (proto-slot-value sym) val))
 934     (proto-slot-value sym))
 935
 936 (defmeth *proto-object* :slot-names ()
 937 "Method args: ()
 938 Returns list of slots available to the object."
 939   (apply #'append
 940          (mapcar #'(lambda (x) (send x :own-slots))
 941                  (send self :precedence-list))))
 942
 943 (defmeth *proto-object* :method-selectors ()
 944 "Method args: ()
 945 Returns list of method selectors available to object."
 946   (apply #'append
 947          (mapcar #'(lambda (x) (send x :own-methods))
 948                  (send self :precedence-list))))
 949
 950
 951 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 952 ;;;;
 953 ;;;;                      Object Help Methods
 954 ;;;;
 955 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 956
 957 (defmeth *proto-object* :doc-topics ()
 958 "Method args: ()
 959 Returns all topics with documentation for this object."
 960   (remove-duplicates
 961    (mapcar #'car
 962            (apply #'append
 963                   (mapcar
 964                    #'(lambda (x)
 965                        (if (send x :has-slot 'documentation :own t)
 966                            (send x :slot-value (quote documentation))))
 967                    (send self :precedence-list))))))
 968
 969 (defmeth *proto-object* :documentation (topic &optional (val nil set))
 970 "Method args: (topic &optional val)
 971 Retrieves or sets object documentation for topic."
 972   (if set (send self :internal-doc topic val))
 973   (let ((val (dolist (i (send self :precedence-list))
 974                      (let ((val (send i :internal-doc topic)))
 975                        (if val (return val))))))
 976     val))
 977
 978 (defmeth *proto-object* :delete-documentation (topic)
 979 "Method args: (topic)
 980 Deletes object documentation for TOPIC."
 981   (setf (proto-slot-value 'documentation)
 982         ;;(remove :title nil :test #'(lambda (x y) (eql x (first y)))) ;; original
 983         (remove topic (send self :documentation) :test #'(lambda (x y) (eql x (first y))))) ;; AJR:PROBLEM?
 984   nil)
 985
 986 (defmeth *proto-object* :help (&optional topic)
 987 "Method args: (&optional topic)
 988 Prints help message for TOPIC, or genreal help if TOPIC is NIL."
 989   (if topic
 990       (let ((doc (send self :documentation topic)))
 991         (cond
 992           (doc (princ topic) (terpri) (princ doc) (terpri))
 993           (t (format t "Sorry, no help available on ~a~%" topic))))
 994       (let ((topics (stable-sort (copy-seq (send self :doc-topics))
 995                                  #'(lambda (x y)
 996                                      (string-lessp (string x) (string y)))))
 997             (proto-doc (send self :documentation 'proto)))
 998         (if (send self :has-slot 'proto-name)
 999             (format t "~s~%" (proto-slot-value 'proto-name)))
1000         (when proto-doc (princ proto-doc) (terpri))
1001         (format t "Help is available on the following:~%~%")
1002         (dolist (i topics) (format t "~s " i))
1003         (terpri)))
1004   (values))
1005
1006 (defmeth *proto-object* :compile-method (name)
1007 "Method args: (name)
1008 Compiles method NAME unless it is already compiled. The object must
1009 own the method."
1010   (unless (send self :has-method name)
1011           (error "No ~s method in this object" name))
1012   (unless (send self :has-method name :own t)
1013           (error "Object does not own ~s method" name))
1014   (let ((fun (send self :get-method name)))
1015     (unless (compiled-function-p fun)
1016             (multiple-value-bind (form env) (function-lambda-expression fun)
1017                  (if env
1018                      (error
1019                       "method may have been defined in non-null environment"))
1020                  (send self :add-method name (compile nil form))))))