src/pcl/slots.lisp

   1 ;;;; This software is part of the SBCL system. See the README file for
   2 ;;;; more information.
   3
   4 ;;;; This software is derived from software originally released by Xerox
   5 ;;;; Corporation. Copyright and release statements follow. Later modifications
   6 ;;;; to the software are in the public domain and are provided with
   7 ;;;; absolutely no warranty. See the COPYING and CREDITS files for more
   8 ;;;; information.
   9
  10 ;;;; copyright information from original PCL sources:
  11 ;;;;
  12 ;;;; Copyright (c) 1985, 1986, 1987, 1988, 1989, 1990 Xerox Corporation.
  13 ;;;; All rights reserved.
  14 ;;;;
  15 ;;;; Use and copying of this software and preparation of derivative works based
  16 ;;;; upon this software are permitted. Any distribution of this software or
  17 ;;;; derivative works must comply with all applicable United States export
  18 ;;;; control laws.
  19 ;;;;
  20 ;;;; This software is made available AS IS, and Xerox Corporation makes no
  21 ;;;; warranty about the software, its performance or its conformity to any
  22 ;;;; specification.
  23
  24 (in-package "SB-PCL")
  25 \f
  26 ;;;; ANSI CL condition for unbound slots
  27
  28 (define-condition unbound-slot (cell-error)
  29   ((instance :reader unbound-slot-instance :initarg :instance))
  30   (:report (lambda (condition stream)
  31              (format stream "The slot ~S is unbound in the object ~S."
  32                      (cell-error-name condition)
  33                      (unbound-slot-instance condition)))))
  34
  35 (defmethod wrapper-fetcher ((class standard-class))
  36   'std-instance-wrapper)
  37
  38 (defmethod slots-fetcher ((class standard-class))
  39   'std-instance-slots)
  40
  41 (defmethod raw-instance-allocator ((class standard-class))
  42   'allocate-standard-instance)
  43
  44 ;;; These four functions work on std-instances and fsc-instances. These are
  45 ;;; instances for which it is possible to change the wrapper and the slots.
  46 ;;;
  47 ;;; For these kinds of instances, most specified methods from the instance
  48 ;;; structure protocol are promoted to the implementation-specific class
  49 ;;; std-class. Many of these methods call these four functions.
  50
  51 (defun set-wrapper (inst new)
  52   (cond ((std-instance-p inst)
  53          (setf (std-instance-wrapper inst) new))
  54         ((fsc-instance-p inst)
  55          (setf (fsc-instance-wrapper inst) new))
  56         (t
  57          (error "unrecognized instance type"))))
  58
  59 (defun swap-wrappers-and-slots (i1 i2)
  60   (with-pcl-lock                        ;FIXME is this sufficient?
  61    (cond ((std-instance-p i1)
  62           (let ((w1 (std-instance-wrapper i1))
  63                 (s1 (std-instance-slots i1)))
  64             (setf (std-instance-wrapper i1) (std-instance-wrapper i2))
  65             (setf (std-instance-slots i1) (std-instance-slots i2))
  66             (setf (std-instance-wrapper i2) w1)
  67             (setf (std-instance-slots i2) s1)))
  68          ((fsc-instance-p i1)
  69           (let ((w1 (fsc-instance-wrapper i1))
  70                 (s1 (fsc-instance-slots i1)))
  71             (setf (fsc-instance-wrapper i1) (fsc-instance-wrapper i2))
  72             (setf (fsc-instance-slots i1) (fsc-instance-slots i2))
  73             (setf (fsc-instance-wrapper i2) w1)
  74             (setf (fsc-instance-slots i2) s1)))
  75          (t
  76           (error "unrecognized instance type")))))
  77 \f
  78 ;;;; STANDARD-INSTANCE-ACCESS
  79
  80 (declaim (inline standard-instance-access (setf standard-instance-access)
  81                  funcallable-standard-instance-access
  82                  (setf funcallable-standard-instance-access)))
  83
  84 (defun standard-instance-access (instance location)
  85   (clos-slots-ref (std-instance-slots instance) location))
  86
  87 (defun (setf standard-instance-access) (new-value instance location)
  88   (setf (clos-slots-ref (std-instance-slots instance) location) new-value))
  89
  90 (defun funcallable-standard-instance-access (instance location)
  91   (clos-slots-ref (fsc-instance-slots instance) location))
  92
  93 (defun (setf funcallable-standard-instance-access) (new-value instance location)
  94   (setf (clos-slots-ref (fsc-instance-slots instance) location) new-value))
  95 \f
  96 ;;;; SLOT-VALUE, (SETF SLOT-VALUE), SLOT-BOUNDP, SLOT-MAKUNBOUND
  97
  98 (declaim (ftype (sfunction (t symbol) t) slot-value))
  99 (defun slot-value (object slot-name)
 100   (let* ((wrapper (valid-wrapper-of object))
 101          (cell (find-slot-cell wrapper slot-name))
 102          (location (car cell))
 103          (value
 104           (cond ((fixnump location)
 105                  (if (std-instance-p object)
 106                      (standard-instance-access object location)
 107                      (funcallable-standard-instance-access object location)))
 108                 ((consp location)
 109                  (cdr location))
 110                 ((not cell)
 111                  (return-from slot-value
 112                    (values (slot-missing (wrapper-class* wrapper) object slot-name
 113                                          'slot-value))))
 114                 ((not location)
 115                  (return-from slot-value
 116                    (slot-value-using-class (wrapper-class* wrapper) object (cddr cell))))
 117                 (t
 118                  (bug "Bogus slot cell in SLOT-VALUE: ~S" cell)))))
 119     (if (eq +slot-unbound+ value)
 120         (slot-unbound (wrapper-class* wrapper) object slot-name)
 121         value)))
 122
 123 (define-compiler-macro slot-value (&whole form object slot-name
 124                                    &environment env)
 125   (if (and (constantp slot-name env)
 126            (interned-symbol-p (constant-form-value slot-name env)))
 127       `(accessor-slot-value ,object ,slot-name)
 128       form))
 129
 130 (defun set-slot-value (object slot-name new-value)
 131   (let* ((wrapper (valid-wrapper-of object))
 132          (cell (find-slot-cell wrapper slot-name))
 133          (location (car cell))
 134          (type-check-function (cadr cell)))
 135     (when type-check-function
 136       (funcall (the function type-check-function) new-value))
 137     (cond ((fixnump location)
 138            (if (std-instance-p object)
 139                (setf (standard-instance-access object location) new-value)
 140                (setf (funcallable-standard-instance-access object location)
 141                      new-value)))
 142           ((consp location)
 143            (setf (cdr location) new-value))
 144           ((not cell)
 145            (slot-missing (wrapper-class* wrapper) object slot-name 'setf new-value))
 146           ((not location)
 147            (setf (slot-value-using-class (wrapper-class* wrapper) object (cddr cell))
 148                  new-value))
 149           (t
 150            (bug "Bogus slot-cell in SET-SLOT-VALUE: ~S" cell))))
 151   new-value)
 152
 153 ;;; A version of SET-SLOT-VALUE for use in safe code, where we want to
 154 ;;; check types when writing to slots:
 155 ;;;   * Doesn't have an optimizing compiler-macro
 156 ;;;   * Isn't special-cased in WALK-METHOD-LAMBDA
 157 (defun safe-set-slot-value (object slot-name new-value)
 158   (set-slot-value object slot-name new-value))
 159
 160 (define-compiler-macro set-slot-value (&whole form object slot-name new-value
 161                                       &environment env)
 162   (if (and (constantp slot-name env)
 163            (interned-symbol-p (constant-form-value slot-name env))
 164            ;; We can't use the ACCESSOR-SET-SLOT-VALUE path in safe
 165            ;; code, since it'll use the global automatically generated
 166            ;; accessor, which won't do typechecking. (SLOT-OBJECT
 167            ;; won't have been compiled with SAFETY 3, so SAFE-P will
 168            ;; be NIL in MAKE-STD-WRITER-METHOD-FUNCTION).
 169            (not (safe-code-p env)))
 170       `(accessor-set-slot-value ,object ,slot-name ,new-value)
 171       form))
 172
 173 (defun slot-boundp (object slot-name)
 174   (let* ((wrapper (valid-wrapper-of object))
 175          (cell (find-slot-cell wrapper slot-name))
 176          (location (car cell))
 177          (value
 178           (cond ((fixnump location)
 179                  (if (std-instance-p object)
 180                      (standard-instance-access object location)
 181                      (funcallable-standard-instance-access object location)))
 182                 ((consp location)
 183                  (cdr location))
 184                 ((not cell)
 185                  (return-from slot-boundp
 186                    (and (slot-missing (wrapper-class* wrapper) object slot-name
 187                                       'slot-boundp)
 188                         t)))
 189                 ((not location)
 190                  (return-from slot-boundp
 191                    (slot-boundp-using-class (wrapper-class* wrapper) object (cddr cell))))
 192                 (t
 193                  (bug "Bogus slot cell in SLOT-VALUE: ~S" cell)))))
 194     (not (eq +slot-unbound+ value))))
 195
 196 (define-compiler-macro slot-boundp (&whole form object slot-name
 197                                     &environment env)
 198   (if (and (constantp slot-name env)
 199            (interned-symbol-p (constant-form-value slot-name env)))
 200       `(accessor-slot-boundp ,object ,slot-name)
 201       form))
 202
 203 (defun slot-makunbound (object slot-name)
 204   (let* ((wrapper (valid-wrapper-of object))
 205          (cell (find-slot-cell wrapper slot-name))
 206          (location (car cell)))
 207     (cond ((fixnump location)
 208            (if (std-instance-p object)
 209                (setf (standard-instance-access object location) +slot-unbound+)
 210                (setf (funcallable-standard-instance-access object location)
 211                      +slot-unbound+)))
 212           ((consp location)
 213            (setf (cdr location) +slot-unbound+))
 214           ((not cell)
 215            (slot-missing (wrapper-class* wrapper) object slot-name 'slot-makunbound))
 216           ((not location)
 217            (slot-makunbound-using-class (wrapper-class* wrapper) object (cddr cell)))
 218           (t
 219            (bug "Bogus slot-cell in SLOT-MAKUNBOUND: ~S" cell))))
 220   object)
 221
 222 (defun slot-exists-p (object slot-name)
 223   (let ((class (class-of object)))
 224     (not (null (find-slot-definition class slot-name)))))
 225
 226 (defvar *unbound-slot-value-marker* (make-unprintable-object "unbound slot"))
 227
 228 ;;; This isn't documented, but is used within PCL in a number of print
 229 ;;; object methods. (See NAMED-OBJECT-PRINT-FUNCTION.)
 230 (defun slot-value-or-default (object slot-name &optional
 231                               (default *unbound-slot-value-marker*))
 232   (if (slot-boundp object slot-name)
 233       (slot-value object slot-name)
 234       default))
 235
 236 (defmethod slot-value-using-class ((class std-class)
 237                                    (object standard-object)
 238                                    (slotd standard-effective-slot-definition))
 239   ;; FIXME: Do we need this? SLOT-VALUE checks for obsolete
 240   ;; instances. Are users allowed to call this directly?
 241   (check-obsolete-instance object)
 242   (let* ((location (slot-definition-location slotd))
 243          (value
 244           (typecase location
 245             (fixnum
 246              (cond ((std-instance-p object)
 247                     (clos-slots-ref (std-instance-slots object)
 248                                     location))
 249                    ((fsc-instance-p object)
 250                     (clos-slots-ref (fsc-instance-slots object)
 251                                     location))
 252                    (t (bug "unrecognized instance type in ~S"
 253                            'slot-value-using-class))))
 254             (cons
 255              (cdr location))
 256             (t
 257              (instance-structure-protocol-error slotd
 258                                                 'slot-value-using-class)))))
 259     (if (eq value +slot-unbound+)
 260         (values (slot-unbound class object (slot-definition-name slotd)))
 261         value)))
 262
 263 (defmethod (setf slot-value-using-class)
 264            (new-value (class std-class)
 265                       (object standard-object)
 266                       (slotd standard-effective-slot-definition))
 267   ;; FIXME: Do we need this? SET-SLOT-VALUE checks for obsolete
 268   ;; instances. Are users allowed to call this directly?
 269   (check-obsolete-instance object)
 270   (let ((location (slot-definition-location slotd))
 271         (type-check-function
 272          (when (safe-p class)
 273            (slot-definition-type-check-function slotd))))
 274     (flet ((check (new-value)
 275              (when type-check-function
 276                (funcall (the function type-check-function) new-value))
 277              new-value))
 278       (typecase location
 279         (fixnum
 280          (cond ((std-instance-p object)
 281                 (setf (clos-slots-ref (std-instance-slots object) location)
 282                       (check new-value)))
 283                ((fsc-instance-p object)
 284                 (setf (clos-slots-ref (fsc-instance-slots object) location)
 285                       (check new-value)))
 286                 (t (bug "unrecognized instance type in ~S"
 287                         '(setf slot-value-using-class)))))
 288         (cons
 289          (setf (cdr location) (check new-value)))
 290         (t
 291          (instance-structure-protocol-error
 292           slotd '(setf slot-value-using-class)))))))
 293
 294 (defmethod slot-boundp-using-class
 295            ((class std-class)
 296             (object standard-object)
 297             (slotd standard-effective-slot-definition))
 298   ;; FIXME: Do we need this? SLOT-BOUNDP checks for obsolete
 299   ;; instances. Are users allowed to call this directly?
 300   (check-obsolete-instance object)
 301   (let* ((location (slot-definition-location slotd))
 302          (value
 303           (typecase location
 304             (fixnum
 305              (cond ((std-instance-p object)
 306                           (clos-slots-ref (std-instance-slots object)
 307                                           location))
 308                    ((fsc-instance-p object)
 309                     (clos-slots-ref (fsc-instance-slots object)
 310                                     location))
 311                    (t (bug "unrecognized instance type in ~S"
 312                            'slot-boundp-using-class))))
 313             (cons
 314              (cdr location))
 315             (t
 316              (instance-structure-protocol-error slotd
 317                                                 'slot-boundp-using-class)))))
 318     (not (eq value +slot-unbound+))))
 319
 320 (defmethod slot-makunbound-using-class
 321            ((class std-class)
 322             (object standard-object)
 323             (slotd standard-effective-slot-definition))
 324   (check-obsolete-instance object)
 325   (let ((location (slot-definition-location slotd)))
 326     (typecase location
 327       (fixnum
 328        (cond ((std-instance-p object)
 329               (setf (clos-slots-ref (std-instance-slots object) location)
 330                     +slot-unbound+))
 331              ((fsc-instance-p object)
 332               (setf (clos-slots-ref (fsc-instance-slots object) location)
 333                     +slot-unbound+))
 334              (t (bug "unrecognized instance type in ~S"
 335                      'slot-makunbound-using-class))))
 336       (cons
 337        (setf (cdr location) +slot-unbound+))
 338       (t
 339        (instance-structure-protocol-error slotd
 340                                           'slot-makunbound-using-class))))
 341   object)
 342
 343 (defmethod slot-value-using-class
 344     ((class condition-class)
 345      (object condition)
 346      (slotd condition-effective-slot-definition))
 347   (let ((fun (slot-definition-reader-function slotd)))
 348     (declare (type function fun))
 349     (funcall fun object)))
 350
 351 (defmethod (setf slot-value-using-class)
 352     (new-value
 353      (class condition-class)
 354      (object condition)
 355      (slotd condition-effective-slot-definition))
 356   (let ((fun (slot-definition-writer-function slotd)))
 357     (declare (type function fun))
 358     (funcall fun new-value object)))
 359
 360 (defmethod slot-boundp-using-class
 361     ((class condition-class)
 362      (object condition)
 363      (slotd condition-effective-slot-definition))
 364   (let ((fun (slot-definition-boundp-function slotd)))
 365     (declare (type function fun))
 366     (funcall fun object)))
 367
 368 (defmethod slot-makunbound-using-class ((class condition-class) object slot)
 369   (error "attempt to unbind slot ~S in condition object ~S."
 370          slot object))
 371
 372 (defmethod slot-value-using-class
 373     ((class structure-class)
 374      (object structure-object)
 375      (slotd structure-effective-slot-definition))
 376   (let* ((function (slot-definition-internal-reader-function slotd))
 377          (value (funcall function object)))
 378     (declare (type function function))
 379     ;; FIXME: Is this really necessary? Structure slots should surely
 380     ;; never be unbound!
 381     (if (eq value +slot-unbound+)
 382         (values (slot-unbound class object (slot-definition-name slotd)))
 383         value)))
 384
 385 (defmethod (setf slot-value-using-class)
 386     (new-value (class structure-class)
 387                (object structure-object)
 388                (slotd structure-effective-slot-definition))
 389   (let ((function (slot-definition-internal-writer-function slotd)))
 390     (declare (type function function))
 391     (funcall function new-value object)))
 392
 393 (defmethod slot-boundp-using-class
 394            ((class structure-class)
 395             (object structure-object)
 396             (slotd structure-effective-slot-definition))
 397   t)
 398
 399 (defmethod slot-makunbound-using-class
 400            ((class structure-class)
 401             (object structure-object)
 402             (slotd structure-effective-slot-definition))
 403   (error "Structure slots can't be unbound."))
 404 \f
 405 (defmethod slot-missing
 406            ((class t) instance slot-name operation &optional new-value)
 407   (error "~@<When attempting to ~A, the slot ~S is missing from the ~
 408           object ~S.~@:>"
 409          (ecase operation
 410            (slot-value "read the slot's value (slot-value)")
 411            (setf (format nil
 412                          "set the slot's value to ~S (SETF of SLOT-VALUE)"
 413                          new-value))
 414            (slot-boundp "test to see whether slot is bound (SLOT-BOUNDP)")
 415            (slot-makunbound "make the slot unbound (SLOT-MAKUNBOUND)"))
 416          slot-name
 417          instance))
 418
 419 (defmethod slot-unbound ((class t) instance slot-name)
 420   (restart-case
 421       (error 'unbound-slot :name slot-name :instance instance)
 422     (use-value (v)
 423       :report "Return a value as the slot-value."
 424       :interactive read-evaluated-form
 425       v)
 426     (store-value (v)
 427       :report "Store and return a value as the slot-value."
 428       :interactive read-evaluated-form
 429       (setf (slot-value instance slot-name) v))))
 430
 431 (defun slot-unbound-internal (instance position)
 432   (values
 433    (slot-unbound
 434     (class-of instance)
 435     instance
 436     (etypecase position
 437       (fixnum
 438        (nth position (wrapper-instance-slots-layout (wrapper-of instance))))
 439       (cons
 440        (car position))))))
 441 \f
 442 ;;; FIXME: AMOP says that allocate-instance imples finalize-inheritance
 443 ;;; if the class is not yet finalized, but we don't seem to be taking
 444 ;;; care of this for non-standard-classes.x
 445 (defmethod allocate-instance ((class standard-class) &rest initargs)
 446   (declare (ignore initargs))
 447   (unless (class-finalized-p class)
 448     (finalize-inheritance class))
 449   (allocate-standard-instance (class-wrapper class)))
 450
 451 (defmethod allocate-instance ((class structure-class) &rest initargs)
 452   (declare (ignore initargs))
 453   (let ((constructor (class-defstruct-constructor class)))
 454     (if constructor
 455         (funcall constructor)
 456         (allocate-standard-instance (class-wrapper class)))))
 457
 458 ;;; FIXME: It would be nicer to have allocate-instance return
 459 ;;; uninitialized objects for conditions as well.
 460 (defmethod allocate-instance ((class condition-class) &rest initargs)
 461   (declare (ignore initargs))
 462   (make-condition (class-name class)))
 463
 464 (defmethod allocate-instance ((class built-in-class) &rest initargs)
 465   (declare (ignore initargs))
 466   (error "Cannot allocate an instance of ~S." class)) ; So sayeth AMOP
 467