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6 ;;;; to the software are in the public domain and are provided with
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10 ;;;; copyright information from original PCL sources:
12 ;;;; Copyright (c) 1985, 1986, 1987, 1988, 1989, 1990 Xerox Corporation.
13 ;;;; All rights reserved.
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
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20 ;;;; This software is made available AS IS, and Xerox Corporation makes no
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26 (defmacro define-method-combination (&whole form &rest args)
27 (declare (ignore args))
29 (with-single-package-locked-error
30 (:symbol ',(second form) "defining ~A as a method combination"))
33 (expand-long-defcombin form)
34 (expand-short-defcombin form))))
36 ;;;; standard method combination
38 ;;; The STANDARD method combination type is implemented directly by
39 ;;; the class STANDARD-METHOD-COMBINATION. The method on
40 ;;; COMPUTE-EFFECTIVE-METHOD does standard method combination directly
41 ;;; and is defined by hand in the file combin.lisp. The method for
42 ;;; FIND-METHOD-COMBINATION must appear in this file for bootstrapping
44 (defmethod find-method-combination ((generic-function generic-function)
45 (type (eql 'standard))
48 (method-combination-error
49 "The method combination type STANDARD accepts no options."))
50 *standard-method-combination*)
52 ;;;; short method combinations
54 ;;;; Short method combinations all follow the same rule for computing the
55 ;;;; effective method. So, we just implement that rule once. Each short
56 ;;;; method combination object just reads the parameters out of the object
57 ;;;; and runs the same rule.
59 (defclass short-method-combination (standard-method-combination)
61 :reader short-combination-operator
63 (identity-with-one-argument
64 :reader short-combination-identity-with-one-argument
65 :initarg :identity-with-one-argument))
66 (:predicate-name short-method-combination-p))
68 (defun expand-short-defcombin (whole)
69 (let* ((type (cadr whole))
71 (getf (cddr whole) :documentation ""))
72 (identity-with-one-arg
73 (getf (cddr whole) :identity-with-one-argument nil))
75 (getf (cddr whole) :operator type)))
76 `(load-short-defcombin
77 ',type ',operator ',identity-with-one-arg ',documentation
78 (sb-c:source-location))))
80 (defun load-short-defcombin (type operator ioa doc source-location)
82 (list (find-class 'generic-function)
83 (intern-eql-specializer type)
86 (get-method #'find-method-combination () specializers nil))
89 (make-instance 'standard-method
91 :specializers specializers
92 :lambda-list '(generic-function type options)
93 :function (lambda (args nms &rest cm-args)
94 (declare (ignore nms cm-args))
96 (lambda (gf type options)
98 (short-combine-methods
99 type options operator ioa new-method doc))
101 :definition-source source-location))
103 (remove-method #'find-method-combination old-method))
104 (add-method #'find-method-combination new-method)
105 (setf (random-documentation type 'method-combination) doc)
108 (defun short-combine-methods (type options operator ioa method doc)
109 (cond ((null options) (setq options '(:most-specific-first)))
110 ((equal options '(:most-specific-first)))
111 ((equal options '(:most-specific-last)))
113 (method-combination-error
114 "Illegal options to a short method combination type.~%~
115 The method combination type ~S accepts one option which~%~
116 must be either :MOST-SPECIFIC-FIRST or :MOST-SPECIFIC-LAST."
118 (make-instance 'short-method-combination
122 :identity-with-one-argument ioa
123 :definition-source method
126 (defmethod compute-effective-method ((generic-function generic-function)
127 (combin short-method-combination)
129 (let ((type (method-combination-type combin))
130 (operator (short-combination-operator combin))
131 (ioa (short-combination-identity-with-one-argument combin))
132 (order (car (method-combination-options combin)))
135 (flet ((invalid (gf combin m)
136 (return-from compute-effective-method
137 `(%invalid-qualifiers ',gf ',combin ',m))))
138 (dolist (m applicable-methods)
139 (let ((qualifiers (method-qualifiers m)))
140 (cond ((null qualifiers) (invalid generic-function combin m))
141 ((cdr qualifiers) (invalid generic-function combin m))
142 ((eq (car qualifiers) :around)
144 ((eq (car qualifiers) type)
146 (t (invalid generic-function combin m))))))
147 (setq around (nreverse around))
149 (:most-specific-last) ; nothing to be done, already in correct order
150 (:most-specific-first
151 (setq primary (nreverse primary))))
153 (if (and (null (cdr primary))
155 `(call-method ,(car primary) ())
156 `(,operator ,@(mapcar (lambda (m) `(call-method ,m ()))
158 (cond ((null primary)
159 ;; As of sbcl-0.8.0.80 we don't seem to need to need
160 ;; to do anything messy like
161 ;; `(APPLY (FUNCTION (IF AROUND
162 ;; 'NO-PRIMARY-METHOD
163 ;; 'NO-APPLICABLE-METHOD)
164 ;; ',GENERIC-FUNCTION
166 ;; here because (for reasons I don't understand at the
167 ;; moment -- WHN) control will never reach here if there
168 ;; are no applicable methods, but instead end up
169 ;; in NO-APPLICABLE-METHODS first.
171 ;; FIXME: The way that we arrange for .ARGS. to be bound
172 ;; here seems weird. We rely on EXPAND-EFFECTIVE-METHOD-FUNCTION
173 ;; recognizing any form whose operator is %NO-PRIMARY-METHOD
174 ;; as magical, and carefully surrounding it with a
175 ;; LAMBDA form which binds .ARGS. But...
176 ;; 1. That seems fragile, because the magicalness of
177 ;; %NO-PRIMARY-METHOD forms is scattered around
178 ;; the system. So it could easily be broken by
179 ;; locally-plausible maintenance changes like,
180 ;; e.g., using the APPLY expression above.
181 ;; 2. That seems buggy w.r.t. to MOPpish tricks in
183 ;; (DEFMETHOD COMPUTE-EFFECTIVE-METHOD :AROUND (...)
184 ;; `(PROGN ,(CALL-NEXT-METHOD) (INCF *MY-CTR*)))
185 `(%no-primary-method ',generic-function .args.))
186 ((null around) main-method)
188 `(call-method ,(car around)
189 (,@(cdr around) (make-method ,main-method))))))))
191 (defmethod invalid-qualifiers ((gf generic-function)
192 (combin short-method-combination)
194 (let ((qualifiers (method-qualifiers method))
195 (type (method-combination-type combin)))
197 ((null qualifiers) "has no qualifiers")
198 ((cdr qualifiers) "has too many qualifiers")
199 (t (aver (and (neq (car qualifiers) type)
200 (neq (car qualifiers) :around)))
201 "has an invalid qualifier"))))
202 (invalid-method-error
204 "The method ~S on ~S ~A.~%~
205 The method combination type ~S was defined with the~%~
206 short form of DEFINE-METHOD-COMBINATION and so requires~%~
207 all methods have either the single qualifier ~S or the~%~
208 single qualifier :AROUND."
209 method gf why type type))))
211 ;;;; long method combinations
213 (defun expand-long-defcombin (form)
214 (let ((type (cadr form))
215 (lambda-list (caddr form))
216 (method-group-specifiers (cadddr form))
220 (when (and (consp (car body)) (eq (caar body) :arguments))
221 (setq args-option (cdr (pop body))))
222 (when (and (consp (car body)) (eq (caar body) :generic-function))
223 (setq gf-var (cadr (pop body))))
224 (multiple-value-bind (documentation function)
225 (make-long-method-combination-function
226 type lambda-list method-group-specifiers args-option gf-var
228 `(load-long-defcombin ',type ',documentation #',function
229 ',args-option (sb-c:source-location)))))
231 (defvar *long-method-combination-functions* (make-hash-table :test 'eq))
233 (defun load-long-defcombin (type doc function args-lambda-list source-location)
235 (list (find-class 'generic-function)
236 (intern-eql-specializer type)
239 (get-method #'find-method-combination () specializers nil))
241 (make-instance 'standard-method
243 :specializers specializers
244 :lambda-list '(generic-function type options)
245 :function (lambda (args nms &rest cm-args)
246 (declare (ignore nms cm-args))
248 (lambda (generic-function type options)
249 (declare (ignore generic-function))
250 (make-instance 'long-method-combination
253 :args-lambda-list args-lambda-list
256 :definition-source source-location)))
257 (setf (gethash type *long-method-combination-functions*) function)
258 (when old-method (remove-method #'find-method-combination old-method))
259 (add-method #'find-method-combination new-method)
260 (setf (random-documentation type 'method-combination) doc)
263 (defmethod compute-effective-method ((generic-function generic-function)
264 (combin long-method-combination)
266 (funcall (gethash (method-combination-type combin)
267 *long-method-combination-functions*)
272 (defun make-long-method-combination-function
273 (type ll method-group-specifiers args-option gf-var body)
274 (declare (ignore type))
275 (multiple-value-bind (real-body declarations documentation)
278 (wrap-method-group-specifier-bindings method-group-specifiers
282 (push `(,gf-var .generic-function.) (cadr wrapped-body)))
285 (setq wrapped-body (deal-with-args-option wrapped-body args-option)))
289 `(apply #'(lambda ,ll ,wrapped-body)
290 (method-combination-options .method-combination.))))
294 `(lambda (.generic-function. .method-combination. .applicable-methods.)
295 (declare (ignorable .generic-function.
296 .method-combination. .applicable-methods.))
297 (block .long-method-combination-function. ,wrapped-body))))))
299 (define-condition long-method-combination-error
300 (reference-condition simple-error)
303 :references (list '(:ansi-cl :macro define-method-combination))))
307 ;;; The semantics of long form method combination in the presence of
308 ;;; multiple methods with the same specializers in the same method
309 ;;; group are unclear by the spec: a portion of the standard implies
310 ;;; that an error should be signalled, and another is more lenient.
312 ;;; It is reasonable to allow a single method group of * to bypass all
313 ;;; rules, as this is explicitly stated in the standard.
315 (defun group-cond-clause (name tests specializer-cache star-only)
316 (let ((maybe-error-clause
318 `(setq ,specializer-cache .specializers.)
319 `(if (and (equal ,specializer-cache .specializers.)
320 (not (null .specializers.)))
321 (return-from .long-method-combination-function.
322 '(error 'long-method-combination-error
323 :format-control "More than one method of type ~S ~
324 with the same specializers."
325 :format-arguments (list ',name)))
326 (setq ,specializer-cache .specializers.)))))
329 (push .method. ,name))))
331 (defun wrap-method-group-specifier-bindings
332 (method-group-specifiers declarations real-body)
333 (let (names specializer-caches cond-clauses required-checks order-cleanups)
334 (let ((nspecifiers (length method-group-specifiers)))
335 (dolist (method-group-specifier method-group-specifiers)
336 (multiple-value-bind (name tests description order required)
337 (parse-method-group-specifier method-group-specifier)
338 (declare (ignore description))
339 (let ((specializer-cache (gensym)))
341 (push specializer-cache specializer-caches)
342 (push (group-cond-clause name tests specializer-cache
343 (and (eq (cadr method-group-specifier) '*)
347 (push `(when (null ,name)
348 (return-from .long-method-combination-function.
349 '(error 'long-method-combination-error
350 :format-control "No ~S methods."
351 :format-arguments (list ',name))))
353 (loop (unless (and (constantp order)
354 (neq order (setq order (eval order))))
356 (push (cond ((eq order :most-specific-first)
357 `(setq ,name (nreverse ,name)))
358 ((eq order :most-specific-last) ())
361 (:most-specific-first
362 (setq ,name (nreverse ,name)))
363 (:most-specific-last))))
365 `(let (,@(nreverse names) ,@(nreverse specializer-caches))
367 (dolist (.method. .applicable-methods.)
368 (let ((.qualifiers. (method-qualifiers .method.))
369 (.specializers. (method-specializers .method.)))
370 (declare (ignorable .qualifiers. .specializers.))
371 (cond ,@(nreverse cond-clauses))))
372 ,@(nreverse required-checks)
373 ,@(nreverse order-cleanups)
376 (defun parse-method-group-specifier (method-group-specifier)
377 ;;(declare (values name tests description order required))
378 (let* ((name (pop method-group-specifier))
384 (if (or (null method-group-specifier)
385 (memq (car method-group-specifier)
386 '(:description :order :required)))
387 (return-from collect-tests t)
388 (let ((pattern (pop method-group-specifier)))
389 (push pattern patterns)
390 (push (parse-qualifier-pattern name pattern)
392 (nreverse collect))))
395 (getf method-group-specifier :description
396 (make-default-method-group-description patterns))
397 (getf method-group-specifier :order :most-specific-first)
398 (getf method-group-specifier :required nil))))
400 (defun parse-qualifier-pattern (name pattern)
401 (cond ((eq pattern '()) `(null .qualifiers.))
403 ((symbolp pattern) `(,pattern .qualifiers.))
404 ((listp pattern) `(qualifier-check-runtime ',pattern .qualifiers.))
405 (t (error "In the method group specifier ~S,~%~
406 ~S isn't a valid qualifier pattern."
409 (defun qualifier-check-runtime (pattern qualifiers)
410 (loop (cond ((and (null pattern) (null qualifiers))
412 ((eq pattern '*) (return t))
413 ((and pattern qualifiers (eq (car pattern) (car qualifiers)))
418 (defun make-default-method-group-description (patterns)
421 "methods matching one of the patterns: ~{~S, ~} ~S"
422 (butlast patterns) (car (last patterns)))
424 "methods matching the pattern: ~S"
427 ;;; This baby is a complete mess. I can't believe we put it in this
428 ;;; way. No doubt this is a large part of what drives MLY crazy.
430 ;;; At runtime (when the effective-method is run), we bind an intercept
431 ;;; lambda-list to the arguments to the generic function.
433 ;;; At compute-effective-method time, the symbols in the :arguments
434 ;;; option are bound to the symbols in the intercept lambda list.
436 ;;; FIXME: in here we have not one but two mini-copies of a weird
437 ;;; hybrid of PARSE-LAMBDA-LIST and PARSE-DEFMACRO-LAMBDA-LIST.
438 (defun deal-with-args-option (wrapped-body args-lambda-list)
439 (let ((intercept-rebindings
441 (dolist (arg args-lambda-list (nreverse rebindings))
442 (unless (member arg lambda-list-keywords)
444 (symbol (push `(,arg ',arg) rebindings))
446 (unless (symbolp (car arg))
447 (error "invalid lambda-list specifier: ~S." arg))
448 (push `(,(car arg) ',(car arg)) rebindings))
449 (t (error "invalid lambda-list-specifier: ~S." arg)))))))
453 ;; Count the number of required and optional parameters in
454 ;; ARGS-LAMBDA-LIST into NREQ and NOPT, and set WHOLE to the
455 ;; name of a &WHOLE parameter, if any.
456 (when (member '&whole (rest args-lambda-list))
457 (error 'simple-program-error
458 :format-control "~@<The value of the :ARGUMENTS option of ~
459 DEFINE-METHOD-COMBINATION is~2I~_~S,~I~_but &WHOLE may ~
460 only appear first in the lambda list.~:>"
461 :format-arguments (list args-lambda-list)))
462 (loop with state = 'required
463 for arg in args-lambda-list do
464 (if (memq arg lambda-list-keywords)
467 (required (incf nreq))
468 (&optional (incf nopt))
469 (&whole (setq whole arg state 'required)))))
470 ;; This assumes that the head of WRAPPED-BODY is a let, and it
471 ;; injects let-bindings of the form (ARG 'SYM) for all variables
472 ;; of the argument-lambda-list; SYM is a gensym.
473 (aver (memq (first wrapped-body) '(let let*)))
474 (setf (second wrapped-body)
475 (append intercept-rebindings (second wrapped-body)))
476 ;; Be sure to fill out the args lambda list so that it can be too
477 ;; short if it wants to.
478 (unless (or (memq '&rest args-lambda-list)
479 (memq '&allow-other-keys args-lambda-list))
480 (let ((aux (memq '&aux args-lambda-list)))
481 (setq args-lambda-list
482 (append (ldiff args-lambda-list aux)
483 (if (memq '&key args-lambda-list)
487 ;; .GENERIC-FUNCTION. is bound to the generic function in the
488 ;; method combination function, and .GF-ARGS* is bound to the
489 ;; generic function arguments in effective method functions
490 ;; created for generic functions having a method combination that
493 ;; The DESTRUCTURING-BIND binds the parameters of the
494 ;; ARGS-LAMBDA-LIST to actual generic function arguments. Because
495 ;; ARGS-LAMBDA-LIST may be shorter or longer than the generic
496 ;; function's lambda list, which is only known at run time, this
497 ;; destructuring has to be done on a slighly modified list of
498 ;; actual arguments, from which values might be stripped or added.
500 ;; Using one of the variable names in the body inserts a symbol
501 ;; into the effective method, and running the effective method
502 ;; produces the value of actual argument that is bound to the
504 `(let ((inner-result. ,wrapped-body)
505 (gf-lambda-list (generic-function-lambda-list .generic-function.)))
506 `(destructuring-bind ,',args-lambda-list
507 (frob-combined-method-args
508 .gf-args. ',gf-lambda-list
510 ,,(when (memq '.ignore. args-lambda-list)
511 ''(declare (ignore .ignore.)))
512 ;; If there is a &WHOLE in the args-lambda-list, let
513 ;; it result in the actual arguments of the generic-function
514 ;; not the frobbed list.
516 ``(setq ,',whole .gf-args.))
519 ;;; Partition VALUES into three sections: required, optional, and the
520 ;;; rest, according to required, optional, and other parameters in
521 ;;; LAMBDA-LIST. Make the required and optional sections NREQ and
522 ;;; NOPT elements long by discarding values or adding NILs. Value is
523 ;;; the concatenated list of required and optional sections, and what
524 ;;; is left as rest from VALUES.
525 (defun frob-combined-method-args (values lambda-list nreq nopt)
526 (loop with section = 'required
527 for arg in lambda-list
528 if (memq arg lambda-list-keywords) do
530 (unless (eq section '&optional)
532 else if (eq section 'required)
534 and collect (pop values) into required
535 else if (eq section '&optional)
537 and collect (pop values) into optional
539 (flet ((frob (list n m)
540 (cond ((> n m) (butlast list (- n m)))
541 ((< n m) (nconc list (make-list (- m n))))
543 (return (nconc (frob required nr nreq)
544 (frob optional no nopt)