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12 ;;;; Copyright (c) 1985, 1986, 1987, 1988, 1989, 1990 Xerox Corporation.
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16 ;;;; upon this software are permitted. Any distribution of this software or
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26 (defmacro define-method-combination (&whole form &rest args)
27 (declare (ignore args))
30 (expand-long-defcombin form)
31 (expand-short-defcombin form)))
33 ;;;; standard method combination
35 ;;; The STANDARD method combination type is implemented directly by
36 ;;; the class STANDARD-METHOD-COMBINATION. The method on
37 ;;; COMPUTE-EFFECTIVE-METHOD does standard method combination directly
38 ;;; and is defined by hand in the file combin.lisp. The method for
39 ;;; FIND-METHOD-COMBINATION must appear in this file for bootstrapping
41 (defmethod find-method-combination ((generic-function generic-function)
42 (type (eql 'standard))
45 (method-combination-error
46 "The method combination type STANDARD accepts no options."))
47 *standard-method-combination*)
49 ;;;; short method combinations
51 ;;;; Short method combinations all follow the same rule for computing the
52 ;;;; effective method. So, we just implement that rule once. Each short
53 ;;;; method combination object just reads the parameters out of the object
54 ;;;; and runs the same rule.
56 (defclass short-method-combination (standard-method-combination)
58 :reader short-combination-operator
60 (identity-with-one-argument
61 :reader short-combination-identity-with-one-argument
62 :initarg :identity-with-one-argument))
63 (:predicate-name short-method-combination-p))
65 (defun expand-short-defcombin (whole)
66 (let* ((type (cadr whole))
68 (getf (cddr whole) :documentation ""))
69 (identity-with-one-arg
70 (getf (cddr whole) :identity-with-one-argument nil))
72 (getf (cddr whole) :operator type)))
73 `(load-short-defcombin
74 ',type ',operator ',identity-with-one-arg ',documentation)))
76 (defun load-short-defcombin (type operator ioa doc)
77 (let* ((pathname *load-pathname*)
79 (list (find-class 'generic-function)
80 (intern-eql-specializer type)
83 (get-method #'find-method-combination () specializers nil))
86 (make-instance 'standard-method
88 :specializers specializers
89 :lambda-list '(generic-function type options)
90 :function (lambda (args nms &rest cm-args)
91 (declare (ignore nms cm-args))
93 (lambda (gf type options)
95 (short-combine-methods
96 type options operator ioa new-method doc))
98 :definition-source `((define-method-combination ,type) ,pathname)))
100 (remove-method #'find-method-combination old-method))
101 (add-method #'find-method-combination new-method)
104 (defun short-combine-methods (type options operator ioa method doc)
105 (cond ((null options) (setq options '(:most-specific-first)))
106 ((equal options '(:most-specific-first)))
107 ((equal options '(:most-specific-last)))
109 (method-combination-error
110 "Illegal options to a short method combination type.~%~
111 The method combination type ~S accepts one option which~%~
112 must be either :MOST-SPECIFIC-FIRST or :MOST-SPECIFIC-LAST."
114 (make-instance 'short-method-combination
118 :identity-with-one-argument ioa
119 :definition-source method
122 (defmethod compute-effective-method ((generic-function generic-function)
123 (combin short-method-combination)
125 (let ((type (method-combination-type combin))
126 (operator (short-combination-operator combin))
127 (ioa (short-combination-identity-with-one-argument combin))
128 (order (car (method-combination-options combin)))
131 (flet ((invalid (gf combin m)
132 (if *in-precompute-effective-methods-p*
133 (return-from compute-effective-method
134 `(%invalid-qualifiers ',gf ',combin ',m))
135 (invalid-qualifiers gf combin m))))
136 (dolist (m applicable-methods)
137 (let ((qualifiers (method-qualifiers m)))
138 (cond ((null qualifiers) (invalid generic-function combin m))
139 ((cdr qualifiers) (invalid generic-function combin m))
140 ((eq (car qualifiers) :around)
142 ((eq (car qualifiers) type)
144 (t (invalid generic-function combin m))))))
145 (setq around (nreverse around))
147 (:most-specific-last) ; nothing to be done, already in correct order
148 (:most-specific-first
149 (setq primary (nreverse primary))))
151 (if (and (null (cdr primary))
153 `(call-method ,(car primary) ())
154 `(,operator ,@(mapcar (lambda (m) `(call-method ,m ()))
156 (cond ((null primary)
157 ;; As of sbcl-0.8.0.80 we don't seem to need to need
158 ;; to do anything messy like
159 ;; `(APPLY (FUNCTION (IF AROUND
160 ;; 'NO-PRIMARY-METHOD
161 ;; 'NO-APPLICABLE-METHOD)
162 ;; ',GENERIC-FUNCTION
164 ;; here because (for reasons I don't understand at the
165 ;; moment -- WHN) control will never reach here if there
166 ;; are no applicable methods, but instead end up
167 ;; in NO-APPLICABLE-METHODS first.
169 ;; FIXME: The way that we arrange for .ARGS. to be bound
170 ;; here seems weird. We rely on EXPAND-EFFECTIVE-METHOD-FUNCTION
171 ;; recognizing any form whose operator is %NO-PRIMARY-METHOD
172 ;; as magical, and carefully surrounding it with a
173 ;; LAMBDA form which binds .ARGS. But...
174 ;; 1. That seems fragile, because the magicalness of
175 ;; %NO-PRIMARY-METHOD forms is scattered around
176 ;; the system. So it could easily be broken by
177 ;; locally-plausible maintenance changes like,
178 ;; e.g., using the APPLY expression above.
179 ;; 2. That seems buggy w.r.t. to MOPpish tricks in
181 ;; (DEFMETHOD COMPUTE-EFFECTIVE-METHOD :AROUND (...)
182 ;; `(PROGN ,(CALL-NEXT-METHOD) (INCF *MY-CTR*)))
183 `(%no-primary-method ',generic-function .args.))
184 ((null around) main-method)
186 `(call-method ,(car around)
187 (,@(cdr around) (make-method ,main-method))))))))
189 (defmethod invalid-qualifiers ((gf generic-function)
190 (combin short-method-combination)
192 (let ((qualifiers (method-qualifiers method))
193 (type (method-combination-type combin)))
195 ((null qualifiers) "has no qualifiers")
196 ((cdr qualifiers) "has too many qualifiers")
197 (t (aver (and (neq (car qualifiers) type)
198 (neq (car qualifiers) :around)))
199 "has an invalid qualifier"))))
200 (invalid-method-error
202 "The method ~S on ~S ~A.~%~
203 The method combination type ~S was defined with the~%~
204 short form of DEFINE-METHOD-COMBINATION and so requires~%~
205 all methods have either the single qualifier ~S or the~%~
206 single qualifier :AROUND."
207 method gf why type type))))
209 ;;;; long method combinations
211 (defun expand-long-defcombin (form)
212 (let ((type (cadr form))
213 (lambda-list (caddr form))
214 (method-group-specifiers (cadddr form))
218 (when (and (consp (car body)) (eq (caar body) :arguments))
219 (setq args-option (cdr (pop body))))
220 (when (and (consp (car body)) (eq (caar body) :generic-function))
221 (setq gf-var (cadr (pop body))))
222 (multiple-value-bind (documentation function)
223 (make-long-method-combination-function
224 type lambda-list method-group-specifiers args-option gf-var
226 `(load-long-defcombin ',type ',documentation #',function
229 (defvar *long-method-combination-functions* (make-hash-table :test 'eq))
231 (defun load-long-defcombin (type doc function args-lambda-list)
233 (list (find-class 'generic-function)
234 (intern-eql-specializer type)
237 (get-method #'find-method-combination () specializers nil))
239 (make-instance 'standard-method
241 :specializers specializers
242 :lambda-list '(generic-function type options)
243 :function (lambda (args nms &rest cm-args)
244 (declare (ignore nms cm-args))
246 (lambda (generic-function type options)
247 (declare (ignore generic-function))
248 (make-instance 'long-method-combination
251 :args-lambda-list args-lambda-list
254 :definition-source `((define-method-combination ,type)
256 (setf (gethash type *long-method-combination-functions*) function)
257 (when old-method (remove-method #'find-method-combination old-method))
258 (add-method #'find-method-combination new-method)
261 (defmethod compute-effective-method ((generic-function generic-function)
262 (combin long-method-combination)
264 (funcall (gethash (method-combination-type combin)
265 *long-method-combination-functions*)
270 (defun make-long-method-combination-function
271 (type ll method-group-specifiers args-option gf-var body)
272 (declare (ignore type))
273 (multiple-value-bind (real-body declarations documentation)
276 (wrap-method-group-specifier-bindings method-group-specifiers
280 (push `(,gf-var .generic-function.) (cadr wrapped-body)))
283 (setq wrapped-body (deal-with-args-option wrapped-body args-option)))
287 `(apply #'(lambda ,ll ,wrapped-body)
288 (method-combination-options .method-combination.))))
292 `(lambda (.generic-function. .method-combination. .applicable-methods.)
293 (declare (ignorable .generic-function.
294 .method-combination. .applicable-methods.))
295 (block .long-method-combination-function. ,wrapped-body))))))
297 ;; parse-method-group-specifiers parse the method-group-specifiers
299 (defun wrap-method-group-specifier-bindings
300 (method-group-specifiers declarations real-body)
306 (dolist (method-group-specifier method-group-specifiers)
307 (multiple-value-bind (name tests description order required)
308 (parse-method-group-specifier method-group-specifier)
309 (declare (ignore description))
310 (let ((specializer-cache (gensym)))
312 (push specializer-cache specializer-caches)
314 (if (and (equal ,specializer-cache .specializers.)
315 (not (null .specializers.)))
316 (return-from .long-method-combination-function.
317 '(error "More than one method of type ~S ~
318 with the same specializers."
320 (setq ,specializer-cache .specializers.))
321 (push .method. ,name))
324 (push `(when (null ,name)
325 (return-from .long-method-combination-function.
326 '(error "No ~S methods." ',name)))
328 (loop (unless (and (constantp order)
329 (neq order (setq order (eval order))))
331 (push (cond ((eq order :most-specific-first)
332 `(setq ,name (nreverse ,name)))
333 ((eq order :most-specific-last) ())
336 (:most-specific-first
337 (setq ,name (nreverse ,name)))
338 (:most-specific-last))))
340 `(let (,@(nreverse names) ,@(nreverse specializer-caches))
342 (dolist (.method. .applicable-methods.)
343 (let ((.qualifiers. (method-qualifiers .method.))
344 (.specializers. (method-specializers .method.)))
345 (declare (ignorable .qualifiers. .specializers.))
346 (cond ,@(nreverse cond-clauses))))
347 ,@(nreverse required-checks)
348 ,@(nreverse order-cleanups)
351 (defun parse-method-group-specifier (method-group-specifier)
352 ;;(declare (values name tests description order required))
353 (let* ((name (pop method-group-specifier))
359 (if (or (null method-group-specifier)
360 (memq (car method-group-specifier)
361 '(:description :order :required)))
362 (return-from collect-tests t)
363 (let ((pattern (pop method-group-specifier)))
364 (push pattern patterns)
365 (push (parse-qualifier-pattern name pattern)
367 (nreverse collect))))
370 (getf method-group-specifier :description
371 (make-default-method-group-description patterns))
372 (getf method-group-specifier :order :most-specific-first)
373 (getf method-group-specifier :required nil))))
375 (defun parse-qualifier-pattern (name pattern)
376 (cond ((eq pattern '()) `(null .qualifiers.))
378 ((symbolp pattern) `(,pattern .qualifiers.))
379 ((listp pattern) `(qualifier-check-runtime ',pattern .qualifiers.))
380 (t (error "In the method group specifier ~S,~%~
381 ~S isn't a valid qualifier pattern."
384 (defun qualifier-check-runtime (pattern qualifiers)
385 (loop (cond ((and (null pattern) (null qualifiers))
387 ((eq pattern '*) (return t))
388 ((and pattern qualifiers (eq (car pattern) (car qualifiers)))
393 (defun make-default-method-group-description (patterns)
396 "methods matching one of the patterns: ~{~S, ~} ~S"
397 (butlast patterns) (car (last patterns)))
399 "methods matching the pattern: ~S"
402 ;;; This baby is a complete mess. I can't believe we put it in this
403 ;;; way. No doubt this is a large part of what drives MLY crazy.
405 ;;; At runtime (when the effective-method is run), we bind an intercept
406 ;;; lambda-list to the arguments to the generic function.
408 ;;; At compute-effective-method time, the symbols in the :arguments
409 ;;; option are bound to the symbols in the intercept lambda list.
410 (defun deal-with-args-option (wrapped-body args-lambda-list)
411 (let ((intercept-rebindings
413 (dolist (arg args-lambda-list (nreverse rebindings))
414 (unless (member arg lambda-list-keywords)
415 (push `(,arg ',arg) rebindings)))))
419 ;; Count the number of required and optional parameters in
420 ;; ARGS-LAMBDA-LIST into NREQ and NOPT, and set WHOLE to the
421 ;; name of a &WHOLE parameter, if any.
422 (when (member '&whole (rest args-lambda-list))
423 (error 'simple-program-error
424 :format-control "~@<The value of the :ARGUMENTS option of ~
425 DEFINE-METHOD-COMBINATION is~2I~_~S,~I~_but &WHOLE may ~
426 only appear first in the lambda list.~:>"
427 :format-arguments (list args-lambda-list)))
428 (loop with state = 'required
429 for arg in args-lambda-list do
430 (if (memq arg lambda-list-keywords)
433 (required (incf nreq))
434 (&optional (incf nopt))
435 (&whole (setq whole arg state 'required)))))
436 ;; This assumes that the head of WRAPPED-BODY is a let, and it
437 ;; injects let-bindings of the form (ARG 'SYM) for all variables
438 ;; of the argument-lambda-list; SYM is a gensym.
439 (aver (memq (first wrapped-body) '(let let*)))
440 (setf (second wrapped-body)
441 (append intercept-rebindings (second wrapped-body)))
442 ;; Be sure to fill out the args lambda list so that it can be too
443 ;; short if it wants to.
444 (unless (or (memq '&rest args-lambda-list)
445 (memq '&allow-other-keys args-lambda-list))
446 (let ((aux (memq '&aux args-lambda-list)))
447 (setq args-lambda-list
448 (append (ldiff args-lambda-list aux)
449 (if (memq '&key args-lambda-list)
453 ;; .GENERIC-FUNCTION. is bound to the generic function in the
454 ;; method combination function, and .GF-ARGS* is bound to the
455 ;; generic function arguments in effective method functions
456 ;; created for generic functions having a method combination that
459 ;; The DESTRUCTURING-BIND binds the parameters of the
460 ;; ARGS-LAMBDA-LIST to actual generic function arguments. Because
461 ;; ARGS-LAMBDA-LIST may be shorter or longer than the generic
462 ;; function's lambda list, which is only known at run time, this
463 ;; destructuring has to be done on a slighly modified list of
464 ;; actual arguments, from which values might be stripped or added.
466 ;; Using one of the variable names in the body inserts a symbol
467 ;; into the effective method, and running the effective method
468 ;; produces the value of actual argument that is bound to the
470 `(let ((inner-result. ,wrapped-body)
471 (gf-lambda-list (generic-function-lambda-list .generic-function.)))
472 `(destructuring-bind ,',args-lambda-list
473 (frob-combined-method-args
474 .gf-args. ',gf-lambda-list
476 ,,(when (memq '.ignore. args-lambda-list)
477 ''(declare (ignore .ignore.)))
478 ;; If there is a &WHOLE in the args-lambda-list, let
479 ;; it result in the actual arguments of the generic-function
480 ;; not the frobbed list.
482 ``(setq ,',whole .gf-args.))
485 ;;; Partition VALUES into three sections: required, optional, and the
486 ;;; rest, according to required, optional, and other parameters in
487 ;;; LAMBDA-LIST. Make the required and optional sections NREQ and
488 ;;; NOPT elements long by discarding values or adding NILs. Value is
489 ;;; the concatenated list of required and optional sections, and what
490 ;;; is left as rest from VALUES.
491 (defun frob-combined-method-args (values lambda-list nreq nopt)
492 (loop with section = 'required
493 for arg in lambda-list
494 if (memq arg lambda-list-keywords) do
496 (unless (eq section '&optional)
498 else if (eq section 'required)
500 and collect (pop values) into required
501 else if (eq section '&optional)
503 and collect (pop values) into optional
505 (flet ((frob (list n m)
506 (cond ((> n m) (butlast list (- n m)))
507 ((< n m) (nconc list (make-list (- m n))))
509 (return (nconc (frob required nr nreq)
510 (frob optional no nopt)