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 (defun find-slot-definition (class slot-name)
  79   (dolist (slot (class-slots class) nil)
  80     (when (eql slot-name (slot-definition-name slot))
  81       (return slot))))
  82
  83 (declaim (ftype (sfunction (t symbol) t) slot-value))
  84 (defun slot-value (object slot-name)
  85   (let* ((class (class-of object))
  86          (slot-definition (find-slot-definition class slot-name)))
  87     (if (null slot-definition)
  88         (values (slot-missing class object slot-name 'slot-value))
  89         (slot-value-using-class class object slot-definition))))
  90
  91 (define-compiler-macro slot-value (&whole form object slot-name)
  92   (if (and (constantp slot-name)
  93            (interned-symbol-p (eval slot-name)))
  94       `(accessor-slot-value ,object ,slot-name)
  95       form))
  96
  97 (defun set-slot-value (object slot-name new-value)
  98   (let* ((class (class-of object))
  99          (slot-definition (find-slot-definition class slot-name)))
 100     (if (null slot-definition)
 101         (progn (slot-missing class object slot-name 'setf new-value)
 102                new-value)
 103         (setf (slot-value-using-class class object slot-definition)
 104               new-value))))
 105
 106 (define-compiler-macro set-slot-value (&whole form object slot-name new-value)
 107   (if (and (constantp slot-name)
 108            (interned-symbol-p (eval slot-name)))
 109       `(accessor-set-slot-value ,object ,slot-name ,new-value)
 110       form))
 111
 112 (defun slot-boundp (object slot-name)
 113   (let* ((class (class-of object))
 114          (slot-definition (find-slot-definition class slot-name)))
 115     (if (null slot-definition)
 116         (not (not (slot-missing class object slot-name 'slot-boundp)))
 117         (slot-boundp-using-class class object slot-definition))))
 118
 119 (setf (gdefinition 'slot-boundp-normal) #'slot-boundp)
 120
 121 (define-compiler-macro slot-boundp (&whole form object slot-name)
 122   (if (and (constantp slot-name)
 123            (interned-symbol-p (eval slot-name)))
 124       `(accessor-slot-boundp ,object ,slot-name)
 125       form))
 126
 127 (defun slot-makunbound (object slot-name)
 128   (let* ((class (class-of object))
 129          (slot-definition (find-slot-definition class slot-name)))
 130     (if (null slot-definition)
 131         (slot-missing class object slot-name 'slot-makunbound)
 132         (slot-makunbound-using-class class object slot-definition))
 133     object))
 134
 135 (defun slot-exists-p (object slot-name)
 136   (let ((class (class-of object)))
 137     (not (null (find-slot-definition class slot-name)))))
 138
 139 ;;; This isn't documented, but is used within PCL in a number of print
 140 ;;; object methods. (See NAMED-OBJECT-PRINT-FUNCTION.)
 141 (defun slot-value-or-default (object slot-name &optional (default "unbound"))
 142   (if (slot-boundp object slot-name)
 143       (slot-value object slot-name)
 144       default))
 145 \f
 146 (defun standard-instance-access (instance location)
 147   (clos-slots-ref (std-instance-slots instance) location))
 148
 149 (defun funcallable-standard-instance-access (instance location)
 150   (clos-slots-ref (fsc-instance-slots instance) location))
 151
 152 (defmethod slot-value-using-class ((class std-class)
 153                                    (object std-object)
 154                                    (slotd standard-effective-slot-definition))
 155   (check-obsolete-instance object)
 156   (let* ((location (slot-definition-location slotd))
 157          (value (typecase location
 158                   (fixnum
 159                    (cond ((std-instance-p object)
 160                           (clos-slots-ref (std-instance-slots object)
 161                                           location))
 162                          ((fsc-instance-p object)
 163                           (clos-slots-ref (fsc-instance-slots object)
 164                                           location))
 165                          (t (error "unrecognized instance type"))))
 166                   (cons
 167                    (cdr location))
 168                   (t
 169                    (error "~@<The slot ~S has neither :INSTANCE nor :CLASS ~
 170                            allocation, so it can't be read by the default ~
 171                            ~S method.~@:>"
 172                           slotd 'slot-value-using-class)))))
 173     (if (eq value +slot-unbound+)
 174         (values (slot-unbound class object (slot-definition-name slotd)))
 175         value)))
 176
 177 (defmethod (setf slot-value-using-class)
 178            (new-value (class std-class)
 179                       (object std-object)
 180                       (slotd standard-effective-slot-definition))
 181   (check-obsolete-instance object)
 182   (let ((location (slot-definition-location slotd)))
 183     (typecase location
 184       (fixnum
 185        (cond ((std-instance-p object)
 186               (setf (clos-slots-ref (std-instance-slots object) location)
 187                     new-value))
 188              ((fsc-instance-p object)
 189               (setf (clos-slots-ref (fsc-instance-slots object) location)
 190                     new-value))
 191              (t (error "unrecognized instance type"))))
 192       (cons
 193        (setf (cdr location) new-value))
 194       (t
 195        (error "~@<The slot ~S has neither :INSTANCE nor :CLASS allocation, ~
 196                    so it can't be written by the default ~S method.~:@>"
 197               slotd '(setf slot-value-using-class))))))
 198
 199 (defmethod slot-boundp-using-class
 200            ((class std-class)
 201             (object std-object)
 202             (slotd standard-effective-slot-definition))
 203   (check-obsolete-instance object)
 204   (let* ((location (slot-definition-location slotd))
 205          (value (typecase location
 206                   (fixnum
 207                    (cond ((std-instance-p object)
 208                           (clos-slots-ref (std-instance-slots object)
 209                                           location))
 210                          ((fsc-instance-p object)
 211                           (clos-slots-ref (fsc-instance-slots object)
 212                                           location))
 213                          (t (error "unrecognized instance type"))))
 214                   (cons
 215                    (cdr location))
 216                   (t
 217                    (error "~@<The slot ~S has neither :INSTANCE nor :CLASS ~
 218                            allocation, so it can't be read by the default ~S ~
 219                            method.~@:>"
 220                           slotd 'slot-boundp-using-class)))))
 221     (not (eq value +slot-unbound+))))
 222
 223 (defmethod slot-makunbound-using-class
 224            ((class std-class)
 225             (object std-object)
 226             (slotd standard-effective-slot-definition))
 227   (check-obsolete-instance object)
 228   (let ((location (slot-definition-location slotd)))
 229     (typecase location
 230       (fixnum
 231        (cond ((std-instance-p object)
 232               (setf (clos-slots-ref (std-instance-slots object) location)
 233                     +slot-unbound+))
 234              ((fsc-instance-p object)
 235               (setf (clos-slots-ref (fsc-instance-slots object) location)
 236                     +slot-unbound+))
 237              (t (error "unrecognized instance type"))))
 238       (cons
 239        (setf (cdr location) +slot-unbound+))
 240       (t
 241        (error "~@<The slot ~S has neither :INSTANCE nor :CLASS allocation, ~
 242                so it can't be written by the default ~S method.~@:>"
 243               slotd 'slot-makunbound-using-class))))
 244   object)
 245
 246 (defmethod slot-value-using-class
 247     ((class condition-class)
 248      (object condition)
 249      (slotd condition-effective-slot-definition))
 250   (let ((fun (slot-definition-reader-function slotd)))
 251     (declare (type function fun))
 252     (funcall fun object)))
 253
 254 (defmethod (setf slot-value-using-class)
 255     (new-value
 256      (class condition-class)
 257      (object condition)
 258      (slotd condition-effective-slot-definition))
 259   (let ((fun (slot-definition-writer-function slotd)))
 260     (declare (type function fun))
 261     (funcall fun new-value object)))
 262
 263 (defmethod slot-boundp-using-class
 264     ((class condition-class)
 265      (object condition)
 266      (slotd condition-effective-slot-definition))
 267   (let ((fun (slot-definition-boundp-function slotd)))
 268     (declare (type function fun))
 269     (funcall fun object)))
 270
 271 (defmethod slot-makunbound-using-class ((class condition-class) object slot)
 272   (error "attempt to unbind slot ~S in condition object ~S."
 273          slot object))
 274
 275 (defmethod slot-value-using-class
 276     ((class structure-class)
 277      (object structure-object)
 278      (slotd structure-effective-slot-definition))
 279   (let* ((function (slot-definition-internal-reader-function slotd))
 280          (value (funcall function object)))
 281     (declare (type function function))
 282     (if (eq value +slot-unbound+)
 283         (values (slot-unbound class object (slot-definition-name slotd)))
 284         value)))
 285
 286 (defmethod (setf slot-value-using-class)
 287     (new-value (class structure-class)
 288                (object structure-object)
 289                (slotd structure-effective-slot-definition))
 290   (let ((function (slot-definition-internal-writer-function slotd)))
 291     (declare (type function function))
 292     (funcall function new-value object)))
 293
 294 (defmethod slot-boundp-using-class
 295            ((class structure-class)
 296             (object structure-object)
 297             (slotd structure-effective-slot-definition))
 298   t)
 299
 300 (defmethod slot-makunbound-using-class
 301            ((class structure-class)
 302             (object structure-object)
 303             (slotd structure-effective-slot-definition))
 304   (error "Structure slots can't be unbound."))
 305 \f
 306 (defmethod slot-missing
 307            ((class t) instance slot-name operation &optional new-value)
 308   (error "~@<When attempting to ~A, the slot ~S is missing from the ~
 309           object ~S.~@:>"
 310          (ecase operation
 311            (slot-value "read the slot's value (slot-value)")
 312            (setf (format nil
 313                          "set the slot's value to ~S (SETF of SLOT-VALUE)"
 314                          new-value))
 315            (slot-boundp "test to see whether slot is bound (SLOT-BOUNDP)")
 316            (slot-makunbound "make the slot unbound (SLOT-MAKUNBOUND)"))
 317          slot-name
 318          instance))
 319
 320 (defmethod slot-unbound ((class t) instance slot-name)
 321   (error 'unbound-slot :name slot-name :instance instance))
 322
 323 (defun slot-unbound-internal (instance position)
 324   (values
 325    (slot-unbound
 326     (class-of instance)
 327     instance
 328     (etypecase position
 329       (fixnum
 330        (nth position (wrapper-instance-slots-layout (wrapper-of instance))))
 331       (cons
 332        (car position))))))
 333 \f
 334 (defmethod allocate-instance ((class standard-class) &rest initargs)
 335   (declare (ignore initargs))
 336   (unless (class-finalized-p class) (finalize-inheritance class))
 337   (allocate-standard-instance (class-wrapper class)))
 338
 339 (defmethod allocate-instance ((class structure-class) &rest initargs)
 340   (declare (ignore initargs))
 341   (let ((constructor (class-defstruct-constructor class)))
 342     (if constructor
 343         (funcall constructor)
 344         (error "can't allocate an instance of class ~S" (class-name class)))))
 345
 346 (defmethod allocate-instance ((class condition-class) &rest initargs)
 347   (declare (ignore initargs))
 348   (make-condition (class-name class)))