src/pcl/defclass.lisp

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   2 ;;;; more information.
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  10 ;;;; copyright information from original PCL sources:
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  21 ;;;; warranty about the software, its performance or its conformity to any
  22 ;;;; specification.
  23
  24 (in-package "SB-PCL")
  25 \f
  26 ;;;; DEFCLASS macro and close personal friends
  27
  28 ;;; state for the current DEFCLASS expansion
  29 (defvar *initfunctions-for-this-defclass*)
  30 (defvar *readers-for-this-defclass*)
  31 (defvar *writers-for-this-defclass*)
  32 (defvar *slot-names-for-this-defclass*)
  33
  34 ;;; Like the DEFMETHOD macro, the expansion of the DEFCLASS macro is
  35 ;;; fixed. DEFCLASS always expands into a call to LOAD-DEFCLASS. Until
  36 ;;; the meta-braid is set up, LOAD-DEFCLASS has a special definition
  37 ;;; which simply collects all class definitions up, when the metabraid
  38 ;;; is initialized it is done from those class definitions.
  39 ;;;
  40 ;;; After the metabraid has been setup, and the protocol for defining
  41 ;;; classes has been defined, the real definition of LOAD-DEFCLASS is
  42 ;;; installed by the file std-class.lisp
  43 (defmacro defclass (&environment env name direct-superclasses direct-slots &rest options)
  44   (let (*initfunctions-for-this-defclass*
  45         *readers-for-this-defclass* ;Truly a crock, but we got
  46         *writers-for-this-defclass* ;to have it to live nicely.
  47         *slot-names-for-this-defclass*)
  48     ;; FIXME: It would be nice to collect all errors from the
  49     ;; expansion of a defclass and signal them in a single go.
  50     (multiple-value-bind (metaclass canonical-options)
  51         (canonize-defclass-options name options)
  52     (let ((canonical-slots (canonize-defclass-slots name direct-slots env))
  53           ;; DEFSTRUCT-P should be true if the class is defined
  54           ;; with a metaclass STRUCTURE-CLASS, so that a DEFSTRUCT
  55           ;; is compiled for the class.
  56           (defstruct-p (and (eq **boot-state** 'complete)
  57                             (let ((mclass (find-class metaclass nil)))
  58                               (and mclass
  59                                    (*subtypep
  60                                     mclass
  61                                     *the-class-structure-class*))))))
  62       (let* ((defclass-form
  63               `(let ,(mapcar #'cdr *initfunctions-for-this-defclass*)
  64                  (load-defclass ',name
  65                                 ',metaclass
  66                                 ',direct-superclasses
  67                                 (list ,@canonical-slots)
  68                                 (list ,@(apply #'append
  69                                                (when defstruct-p
  70                                                  '(:from-defclass-p t))
  71                                                 canonical-options))
  72                                 ',*readers-for-this-defclass*
  73                                 ',*writers-for-this-defclass*
  74                                 ',*slot-names-for-this-defclass*
  75                                 (sb-c:source-location)
  76                                 ,@(and (safe-code-p env)
  77                                        '(t))))))
  78         (if defstruct-p
  79             (progn
  80               ;; FIXME: (YUK!) Why do we do this? Because in order
  81               ;; to make the defstruct form, we need to know what
  82               ;; the accessors for the slots are, so we need already
  83               ;; to have hooked into the CLOS machinery.
  84               ;;
  85               ;; There may be a better way to do this: it would
  86               ;; involve knowing enough about PCL to ask "what will
  87               ;; my slot names and accessors be"; failing this, we
  88               ;; currently just evaluate the whole kaboodle, and
  89               ;; then use CLASS-DIRECT-SLOTS. -- CSR, 2002-06-07
  90               (eval defclass-form)
  91               (let* ((include (or (and direct-superclasses
  92                                        (find-class (car direct-superclasses) nil))
  93                                   (and (not (eq name 'structure-object))
  94                                        *the-class-structure-object*)))
  95                      (defstruct-form (make-structure-class-defstruct-form
  96                                       name (class-direct-slots (find-class name))
  97                                       include)))
  98                 `(progn
  99                    (eval-when (:compile-toplevel :load-toplevel :execute)
 100                      ,defstruct-form) ; really compile the defstruct-form
 101                    (eval-when (:compile-toplevel :load-toplevel :execute)
 102                      ,defclass-form))))
 103             `(progn
 104                ;; By telling the type system at compile time about
 105                ;; the existence of a class named NAME, we can avoid
 106                ;; various bogus warnings about "type isn't defined yet"
 107                ;; for code elsewhere in the same file which uses
 108                ;; the name of the type.
 109                ;;
 110                ;; We only need to do this at compile time, because
 111                ;; at load and execute time we write the actual
 112                ;; full-blown class, so the "a class of this name is
 113                ;; coming" note we write here would be irrelevant.
 114                (eval-when (:compile-toplevel)
 115                  (%compiler-defclass ',name
 116                                      ',*readers-for-this-defclass*
 117                                      ',*writers-for-this-defclass*
 118                                      ',*slot-names-for-this-defclass*))
 119                ,defclass-form)))))))
 120
 121 (defun canonize-defclass-options (class-name options)
 122   (maplist (lambda (sublist)
 123              (let ((option-name (first (pop sublist))))
 124                (when (member option-name sublist :key #'first :test #'eq)
 125                  (error 'simple-program-error
 126                         :format-control "Multiple ~S options in DEFCLASS ~S."
 127                         :format-arguments (list option-name class-name)))))
 128            options)
 129   (let (metaclass
 130         default-initargs
 131         documentation
 132         canonized-options)
 133       (dolist (option options)
 134         (unless (listp option)
 135           (error "~S is not a legal defclass option." option))
 136         (case (first option)
 137           (:metaclass
 138            (let ((maybe-metaclass (second option)))
 139              (unless (and maybe-metaclass (legal-class-name-p maybe-metaclass))
 140                (error 'simple-program-error
 141                       :format-control "~@<The value of the :metaclass option (~S) ~
 142                          is not a legal class name.~:@>"
 143                       :format-arguments (list maybe-metaclass)))
 144              (setf metaclass maybe-metaclass)))
 145           (:default-initargs
 146            (let (initargs arg-names)
 147              (doplist (key val) (cdr option)
 148                (when (member key arg-names :test #'eq)
 149                  (error 'simple-program-error
 150                         :format-control "~@<Duplicate initialization argument ~
 151                                            name ~S in :DEFAULT-INITARGS of ~
 152                                            DEFCLASS ~S.~:>"
 153                         :format-arguments (list key class-name)))
 154                (push key arg-names)
 155                (push ``(,',key ,',val ,,(make-initfunction val)) initargs))
 156              (setf default-initargs t)
 157              (push `(:direct-default-initargs (list ,@(nreverse initargs)))
 158                    canonized-options)))
 159           (:documentation
 160            (unless (stringp (second option))
 161              (error "~S is not a legal :documentation value" (second option)))
 162            (setf documentation t)
 163            (push `(:documentation ,(second option)) canonized-options))
 164           (otherwise
 165            (push `(',(car option) ',(cdr option)) canonized-options))))
 166       (unless default-initargs
 167         (push '(:direct-default-initargs nil) canonized-options))
 168       (values (or metaclass 'standard-class) (nreverse canonized-options))))
 169
 170 (defun canonize-defclass-slots (class-name slots env)
 171   (let (canonized-specs)
 172     (dolist (spec slots)
 173       (when (atom spec)
 174         (setf spec (list spec)))
 175       (when (and (cdr spec) (null (cddr spec)))
 176         (error 'simple-program-error
 177                :format-control "~@<in DEFCLASS ~S, the slot specification ~S ~
 178                                 is invalid; the probable intended meaning may ~
 179                                 be achieved by specifiying ~S instead.~:>"
 180                :format-arguments (list class-name spec
 181                                        `(,(car spec) :initform ,(cadr spec)))))
 182       (let* ((name (car spec))
 183              (plist (cdr spec))
 184              (readers ())
 185              (writers ())
 186              (initargs ())
 187              (others ())
 188              (unsupplied (list nil))
 189              (type t)
 190              (initform unsupplied))
 191         (check-slot-name-for-defclass name class-name env)
 192         (push name *slot-names-for-this-defclass*)
 193         (flet ((note-reader (x)
 194                  (unless (symbolp x)
 195                    (error 'simple-program-error
 196                           :format-control "Slot reader name ~S for slot ~S in ~
 197                                            DEFCLASS ~S is not a symbol."
 198                           :format-arguments (list x name class-name)))
 199                  (push x readers)
 200                  (push x *readers-for-this-defclass*))
 201                (note-writer (x)
 202                  (push x writers)
 203                  (push x *writers-for-this-defclass*)))
 204           (doplist (key val) plist
 205             (case key
 206               (:accessor (note-reader val) (note-writer `(setf ,val)))
 207               (:reader   (note-reader val))
 208               (:writer   (note-writer val))
 209               (:initarg
 210                (unless (symbolp val)
 211                  (error 'simple-program-error
 212                         :format-control "Slot initarg name ~S for slot ~S in ~
 213                                          DEFCLASS ~S is not a symbol."
 214                         :format-arguments (list val name class-name)))
 215                (push val initargs))
 216               (otherwise
 217                (when (member key '(:initform :allocation :type :documentation))
 218                  (when (eq key :initform)
 219                    (setf initform val))
 220                  (when (eq key :type)
 221                    (setf type val))
 222                  (when (get-properties others (list key))
 223                    (error 'simple-program-error
 224                           :format-control "Duplicate slot option ~S for slot ~
 225                                            ~S in DEFCLASS ~S."
 226                           :format-arguments (list key name class-name))))
 227                ;; For non-standard options multiple entries go in a list
 228                (push val (getf others key))))))
 229         ;; Unwrap singleton lists (AMOP 5.4.2)
 230         (do ((head others (cddr head)))
 231             ((null head))
 232           (unless (cdr (second head))
 233             (setf (second head) (car (second head)))))
 234         (let ((canon `(:name ',name :readers ',readers :writers ',writers
 235                              :initargs ',initargs ',others)))
 236           (push (if (eq initform unsupplied)
 237                     `(list* ,@canon)
 238                     `(list* :initfunction ,(make-initfunction initform)
 239                             ,@canon))
 240                 canonized-specs))))
 241     (nreverse canonized-specs)))
 242
 243
 244 (defun check-slot-name-for-defclass (name class-name env)
 245   (flet ((slot-name-illegal (reason)
 246            (error 'simple-program-error
 247                   :format-control
 248                   (format nil "~~@<In DEFCLASS ~~S, the slot name ~~S ~
 249                                is ~A.~~@:>" reason)
 250                   :format-arguments (list class-name name))))
 251     (cond ((not (symbolp name))
 252            (slot-name-illegal "not a symbol"))
 253           ((keywordp name)
 254            (slot-name-illegal "a keyword"))
 255           ((constantp name env)
 256            (slot-name-illegal "a constant"))
 257           ((member name *slot-names-for-this-defclass* :test #'eq)
 258            (error 'simple-program-error
 259                   :format-control "Multiple slots named ~S in DEFCLASS ~S."
 260                   :format-arguments (list name class-name))))))
 261
 262 (defun make-initfunction (initform)
 263   (cond ((or (eq initform t)
 264              (equal initform ''t))
 265          '(function constantly-t))
 266         ((or (eq initform nil)
 267              (equal initform ''nil))
 268          '(function constantly-nil))
 269         ((or (eql initform 0)
 270              (equal initform ''0))
 271          '(function constantly-0))
 272         (t
 273          (let ((entry (assoc initform *initfunctions-for-this-defclass*
 274                              :test #'equal)))
 275            (unless entry
 276              (setq entry (list initform
 277                                (gensym)
 278                                `(function (lambda ()
 279                                   (declare (optimize
 280                                             (sb-c:store-coverage-data 0)))
 281                                   ,initform))))
 282              (push entry *initfunctions-for-this-defclass*))
 283            (cadr entry)))))
 284
 285 (defun %compiler-defclass (name readers writers slots)
 286   ;; ANSI says (Macro DEFCLASS, section 7.7) that DEFCLASS, if it
 287   ;; "appears as a top level form, the compiler must make the class
 288   ;; name be recognized as a valid type name in subsequent
 289   ;; declarations (as for deftype) and be recognized as a valid class
 290   ;; name for defmethod parameter specializers and for use as the
 291   ;; :metaclass option of a subsequent defclass."
 292   (preinform-compiler-about-class-type name)
 293   (preinform-compiler-about-accessors readers writers slots))
 294
 295 (defun preinform-compiler-about-class-type (name)
 296   ;; Unless the type system already has an actual type attached to
 297   ;; NAME (in which case (1) writing a placeholder value over that
 298   ;; actual type as a compile-time side-effect would probably be a bad
 299   ;; idea and (2) anyway we don't need to modify it in order to make
 300   ;; NAME be recognized as a valid type name)
 301   (with-single-package-locked-error (:symbol name "proclaiming ~S as a class"))
 302   (unless (info :type :kind name)
 303     ;; Tell the compiler to expect a class with the given NAME, by
 304     ;; writing a kind of minimal placeholder type information. This
 305     ;; placeholder will be overwritten later when the class is defined.
 306     (setf (info :type :kind name) :forthcoming-defclass-type))
 307   (values))
 308
 309 (defun preinform-compiler-about-accessors (readers writers slots)
 310   (flet ((inform (names type &key key)
 311            (mapc (lambda (name)
 312                    (let ((name (if key (funcall key name) name)))
 313                      (when (eq (info :function :where-from name) :assumed)
 314                        (sb-c:proclaim-ftype name type :defined))))
 315                  names)))
 316     (let ((rtype (specifier-type '(function (t) t)))
 317           (wtype (specifier-type '(function (t t) t))))
 318       (inform readers rtype)
 319       (inform writers wtype)
 320       (inform slots rtype :key #'slot-reader-name)
 321       (inform slots rtype :key #'slot-boundp-name)
 322       (inform slots wtype :key #'slot-writer-name))))
 323 \f
 324 ;;; This is the early definition of LOAD-DEFCLASS. It just collects up
 325 ;;; all the class definitions in a list. Later, in braid1.lisp, these
 326 ;;; are actually defined.
 327
 328 ;;; Each entry in *EARLY-CLASS-DEFINITIONS* is an EARLY-CLASS-DEFINITION.
 329 (defparameter *early-class-definitions* ())
 330
 331 (defun early-class-definition (class-name)
 332   (or (find class-name *early-class-definitions* :key #'ecd-class-name)
 333       (error "~S is not a class in *early-class-definitions*." class-name)))
 334
 335 (defun make-early-class-definition
 336        (name source-location metaclass
 337         superclass-names canonical-slots other-initargs)
 338   (list 'early-class-definition
 339         name source-location metaclass
 340         superclass-names canonical-slots other-initargs))
 341
 342 (defun ecd-class-name        (ecd) (nth 1 ecd))
 343 (defun ecd-source-location   (ecd) (nth 2 ecd))
 344 (defun ecd-metaclass         (ecd) (nth 3 ecd))
 345 (defun ecd-superclass-names  (ecd) (nth 4 ecd))
 346 (defun ecd-canonical-slots   (ecd) (nth 5 ecd))
 347 (defun ecd-other-initargs    (ecd) (nth 6 ecd))
 348
 349 (defvar *early-class-slots* nil)
 350
 351 (defun canonical-slot-name (canonical-slot)
 352   (getf canonical-slot :name))
 353
 354 (defun early-class-slots (class-name)
 355   (cdr (or (assoc class-name *early-class-slots*)
 356            (let ((a (cons class-name
 357                           (mapcar #'canonical-slot-name
 358                                   (early-collect-inheritance class-name)))))
 359              (push a *early-class-slots*)
 360              a))))
 361
 362 (defun early-class-size (class-name)
 363   (length (early-class-slots class-name)))
 364
 365 (defun early-collect-inheritance (class-name)
 366   ;;(declare (values slots cpl default-initargs direct-subclasses))
 367   (let ((cpl (early-collect-cpl class-name)))
 368     (values (early-collect-slots cpl)
 369             cpl
 370             (early-collect-default-initargs cpl)
 371             (let (collect)
 372               (dolist (definition *early-class-definitions*)
 373                 (when (memq class-name (ecd-superclass-names definition))
 374                   (push (ecd-class-name definition) collect)))
 375               (nreverse collect)))))
 376
 377 (defun early-collect-slots (cpl)
 378   (let* ((definitions (mapcar #'early-class-definition cpl))
 379          (super-slots (mapcar #'ecd-canonical-slots definitions))
 380          (slots (apply #'append (reverse super-slots))))
 381     (dolist (s1 slots)
 382       (let ((name1 (canonical-slot-name s1)))
 383         (dolist (s2 (cdr (memq s1 slots)))
 384           (when (eq name1 (canonical-slot-name s2))
 385             (error "More than one early class defines a slot with the~%~
 386                     name ~S. This can't work because the bootstrap~%~
 387                     object system doesn't know how to compute effective~%~
 388                     slots."
 389                    name1)))))
 390     slots))
 391
 392 (defun early-collect-cpl (class-name)
 393   (labels ((walk (c)
 394              (let* ((definition (early-class-definition c))
 395                     (supers (ecd-superclass-names definition)))
 396                (cons c
 397                      (apply #'append (mapcar #'early-collect-cpl supers))))))
 398     (remove-duplicates (walk class-name) :from-end nil :test #'eq)))
 399
 400 (defun early-collect-default-initargs (cpl)
 401   (let ((default-initargs ()))
 402     (dolist (class-name cpl)
 403       (let* ((definition (early-class-definition class-name))
 404              (others (ecd-other-initargs definition)))
 405         (loop (when (null others) (return nil))
 406               (let ((initarg (pop others)))
 407                 (unless (eq initarg :direct-default-initargs)
 408                  (error "~@<The defclass option ~S is not supported by ~
 409                         the bootstrap object system.~:@>"
 410                         initarg)))
 411               (setq default-initargs
 412                     (nconc default-initargs (reverse (pop others)))))))
 413     (reverse default-initargs)))
 414
 415 (defun !bootstrap-slot-index (class-name slot-name)
 416   (or (position slot-name (early-class-slots class-name))
 417       (error "~S not found" slot-name)))
 418
 419 ;;; !BOOTSTRAP-GET-SLOT and !BOOTSTRAP-SET-SLOT are used to access and
 420 ;;; change the values of slots during bootstrapping. During
 421 ;;; bootstrapping, there are only two kinds of objects whose slots we
 422 ;;; need to access, CLASSes and SLOT-DEFINITIONs. The first argument
 423 ;;; to these functions tells whether the object is a CLASS or a
 424 ;;; SLOT-DEFINITION.
 425 ;;;
 426 ;;; Note that the way this works it stores the slot in the same place
 427 ;;; in memory that the full object system will expect to find it
 428 ;;; later. This is critical to the bootstrapping process, the whole
 429 ;;; changeover to the full object system is predicated on this.
 430 ;;;
 431 ;;; One important point is that the layout of standard classes and
 432 ;;; standard slots must be computed the same way in this file as it is
 433 ;;; by the full object system later.
 434 (defmacro !bootstrap-get-slot (type object slot-name)
 435   `(clos-slots-ref (get-slots ,object)
 436                    (!bootstrap-slot-index ,type ,slot-name)))
 437 (defun !bootstrap-set-slot (type object slot-name new-value)
 438   (setf (!bootstrap-get-slot type object slot-name) new-value))
 439
 440 (defun early-class-name (class)
 441   (!bootstrap-get-slot 'class class 'name))
 442
 443 (defun early-class-precedence-list (class)
 444   (!bootstrap-get-slot 'pcl-class class '%class-precedence-list))
 445
 446 (defun early-class-name-of (instance)
 447   (early-class-name (class-of instance)))
 448
 449 (defun early-class-slotds (class)
 450   (!bootstrap-get-slot 'slot-class class 'slots))
 451
 452 (defun early-slot-definition-name (slotd)
 453   (!bootstrap-get-slot 'standard-effective-slot-definition slotd 'name))
 454
 455 (defun early-slot-definition-location (slotd)
 456   (!bootstrap-get-slot 'standard-effective-slot-definition slotd 'location))
 457
 458 (defun early-slot-definition-info (slotd)
 459   (!bootstrap-get-slot 'standard-effective-slot-definition slotd 'info))
 460
 461 (defun early-accessor-method-slot-name (method)
 462   (!bootstrap-get-slot 'standard-accessor-method method 'slot-name))
 463
 464 (unless (fboundp 'class-name-of)
 465   (setf (symbol-function 'class-name-of)
 466         (symbol-function 'early-class-name-of)))
 467 (unintern 'early-class-name-of)
 468
 469 (defun early-class-direct-subclasses (class)
 470   (!bootstrap-get-slot 'class class 'direct-subclasses))
 471
 472 (declaim (notinline load-defclass))
 473 (defun load-defclass (name metaclass supers canonical-slots canonical-options
 474                       readers writers slot-names source-location &optional safe-p)
 475   ;; SAFE-P is used by REAL-LOAD-DEFCLASS, but can be ignored here, since
 476   ;; during the bootstrap we won't have (SAFETY 3).
 477   (declare (ignore safe-p))
 478   (%compiler-defclass name readers writers slot-names)
 479   (setq supers  (copy-tree supers)
 480         canonical-slots   (copy-tree canonical-slots)
 481         canonical-options (copy-tree canonical-options))
 482   (let ((ecd
 483          (make-early-class-definition name
 484                                       source-location
 485                                       metaclass
 486                                       supers
 487                                       canonical-slots
 488                                       canonical-options))
 489         (existing
 490          (find name *early-class-definitions* :key #'ecd-class-name)))
 491     (setq *early-class-definitions*
 492           (cons ecd (remove existing *early-class-definitions*)))
 493     ecd))