;;;; This software is part of the SBCL system. See the README file for ;;;; more information. ;;;; This software is derived from software originally released by Xerox ;;;; Corporation. Copyright and release statements follow. Later modifications ;;;; to the software are in the public domain and are provided with ;;;; absolutely no warranty. See the COPYING and CREDITS files for more ;;;; information. ;;;; copyright information from original PCL sources: ;;;; ;;;; Copyright (c) 1985, 1986, 1987, 1988, 1989, 1990 Xerox Corporation. ;;;; All rights reserved. ;;;; ;;;; Use and copying of this software and preparation of derivative works based ;;;; upon this software are permitted. Any distribution of this software or ;;;; derivative works must comply with all applicable United States export ;;;; control laws. ;;;; ;;;; This software is made available AS IS, and Xerox Corporation makes no ;;;; warranty about the software, its performance or its conformity to any ;;;; specification. (in-package "SB-PCL") (defmacro define-method-combination (&whole form &rest args) (declare (ignore args)) `(progn (with-single-package-locked-error (:symbol ',(second form) "defining ~A as a method combination")) ,(if (and (cddr form) (listp (caddr form))) (expand-long-defcombin form) (expand-short-defcombin form)))) ;;;; standard method combination ;;; The STANDARD method combination type is implemented directly by ;;; the class STANDARD-METHOD-COMBINATION. The method on ;;; COMPUTE-EFFECTIVE-METHOD does standard method combination directly ;;; and is defined by hand in the file combin.lisp. The method for ;;; FIND-METHOD-COMBINATION must appear in this file for bootstrapping ;;; reasons. (defmethod find-method-combination ((generic-function generic-function) (type (eql 'standard)) options) (when options (method-combination-error "The method combination type STANDARD accepts no options.")) *standard-method-combination*) ;;;; short method combinations ;;;; ;;;; Short method combinations all follow the same rule for computing the ;;;; effective method. So, we just implement that rule once. Each short ;;;; method combination object just reads the parameters out of the object ;;;; and runs the same rule. (defun expand-short-defcombin (whole) (let* ((type (cadr whole)) (documentation (getf (cddr whole) :documentation)) (identity-with-one-arg (getf (cddr whole) :identity-with-one-argument nil)) (operator (getf (cddr whole) :operator type))) `(load-short-defcombin ',type ',operator ',identity-with-one-arg ',documentation (sb-c:source-location)))) (defun load-short-defcombin (type operator ioa doc source-location) (let* ((specializers (list (find-class 'generic-function) (intern-eql-specializer type) *the-class-t*)) (old-method (get-method #'find-method-combination () specializers nil)) (new-method nil)) (setq new-method (make-instance 'standard-method :qualifiers () :specializers specializers :lambda-list '(generic-function type options) :function (lambda (args nms &rest cm-args) (declare (ignore nms cm-args)) (apply (lambda (gf type options) (declare (ignore gf)) (short-combine-methods type options operator ioa new-method doc)) args)) :definition-source source-location)) (when old-method (remove-method #'find-method-combination old-method)) (add-method #'find-method-combination new-method) (setf (random-documentation type 'method-combination) doc) type)) (defun short-combine-methods (type options operator ioa method doc) (cond ((null options) (setq options '(:most-specific-first))) ((equal options '(:most-specific-first))) ((equal options '(:most-specific-last))) (t (method-combination-error "Illegal options to a short method combination type.~%~ The method combination type ~S accepts one option which~%~ must be either :MOST-SPECIFIC-FIRST or :MOST-SPECIFIC-LAST." type))) (make-instance 'short-method-combination :type type :options options :operator operator :identity-with-one-argument ioa :definition-source method :documentation doc)) (defmethod compute-effective-method ((generic-function generic-function) (combin short-method-combination) applicable-methods) (let ((type (method-combination-type combin)) (operator (short-combination-operator combin)) (ioa (short-combination-identity-with-one-argument combin)) (order (car (method-combination-options combin))) (around ()) (primary ())) (flet ((invalid (gf combin m) (return-from compute-effective-method `(%invalid-qualifiers ',gf ',combin ',m)))) (dolist (m applicable-methods) (let ((qualifiers (method-qualifiers m))) (cond ((null qualifiers) (invalid generic-function combin m)) ((cdr qualifiers) (invalid generic-function combin m)) ((eq (car qualifiers) :around) (push m around)) ((eq (car qualifiers) type) (push m primary)) (t (invalid generic-function combin m)))))) (setq around (nreverse around)) (ecase order (:most-specific-last) ; nothing to be done, already in correct order (:most-specific-first (setq primary (nreverse primary)))) (let ((main-method (if (and (null (cdr primary)) (not (null ioa))) `(call-method ,(car primary) ()) `(,operator ,@(mapcar (lambda (m) `(call-method ,m ())) primary))))) (cond ((null primary) ;; As of sbcl-0.8.0.80 we don't seem to need to need ;; to do anything messy like ;; `(APPLY (FUNCTION (IF AROUND ;; 'NO-PRIMARY-METHOD ;; 'NO-APPLICABLE-METHOD) ;; ',GENERIC-FUNCTION ;; .ARGS.) ;; here because (for reasons I don't understand at the ;; moment -- WHN) control will never reach here if there ;; are no applicable methods, but instead end up ;; in NO-APPLICABLE-METHODS first. ;; ;; FIXME: The way that we arrange for .ARGS. to be bound ;; here seems weird. We rely on EXPAND-EFFECTIVE-METHOD-FUNCTION ;; recognizing any form whose operator is %NO-PRIMARY-METHOD ;; as magical, and carefully surrounding it with a ;; LAMBDA form which binds .ARGS. But... ;; 1. That seems fragile, because the magicalness of ;; %NO-PRIMARY-METHOD forms is scattered around ;; the system. So it could easily be broken by ;; locally-plausible maintenance changes like, ;; e.g., using the APPLY expression above. ;; 2. That seems buggy w.r.t. to MOPpish tricks in ;; user code, e.g. ;; (DEFMETHOD COMPUTE-EFFECTIVE-METHOD :AROUND (...) ;; `(PROGN ,(CALL-NEXT-METHOD) (INCF *MY-CTR*))) `(%no-primary-method ',generic-function .args.)) ((null around) main-method) (t `(call-method ,(car around) (,@(cdr around) (make-method ,main-method)))))))) (defmethod invalid-qualifiers ((gf generic-function) (combin short-method-combination) method) (let ((qualifiers (method-qualifiers method)) (type (method-combination-type combin))) (let ((why (cond ((null qualifiers) "has no qualifiers") ((cdr qualifiers) "has too many qualifiers") (t (aver (and (neq (car qualifiers) type) (neq (car qualifiers) :around))) "has an invalid qualifier")))) (invalid-method-error method "The method ~S on ~S ~A.~%~ The method combination type ~S was defined with the~%~ short form of DEFINE-METHOD-COMBINATION and so requires~%~ all methods have either the single qualifier ~S or the~%~ single qualifier :AROUND." method gf why type type)))) ;;;; long method combinations (defun expand-long-defcombin (form) (let ((type (cadr form)) (lambda-list (caddr form)) (method-group-specifiers (cadddr form)) (body (cddddr form)) (args-option ()) (gf-var nil)) (when (and (consp (car body)) (eq (caar body) :arguments)) (setq args-option (cdr (pop body)))) (when (and (consp (car body)) (eq (caar body) :generic-function)) (setq gf-var (cadr (pop body)))) (multiple-value-bind (documentation function) (make-long-method-combination-function type lambda-list method-group-specifiers args-option gf-var body) `(load-long-defcombin ',type ',documentation #',function ',args-option (sb-c:source-location))))) (defvar *long-method-combination-functions* (make-hash-table :test 'eq)) (defun load-long-defcombin (type doc function args-lambda-list source-location) (let* ((specializers (list (find-class 'generic-function) (intern-eql-specializer type) *the-class-t*)) (old-method (get-method #'find-method-combination () specializers nil)) (new-method (make-instance 'standard-method :qualifiers () :specializers specializers :lambda-list '(generic-function type options) :function (lambda (args nms &rest cm-args) (declare (ignore nms cm-args)) (apply (lambda (generic-function type options) (declare (ignore generic-function)) (make-instance 'long-method-combination :type type :options options :args-lambda-list args-lambda-list :documentation doc)) args)) :definition-source source-location))) (setf (gethash type *long-method-combination-functions*) function) (when old-method (remove-method #'find-method-combination old-method)) (add-method #'find-method-combination new-method) (setf (random-documentation type 'method-combination) doc) type)) (defmethod compute-effective-method ((generic-function generic-function) (combin long-method-combination) applicable-methods) (funcall (gethash (method-combination-type combin) *long-method-combination-functions*) generic-function combin applicable-methods)) (defun make-long-method-combination-function (type ll method-group-specifiers args-option gf-var body) (declare (ignore type)) (multiple-value-bind (real-body declarations documentation) (parse-body body) (let ((wrapped-body (wrap-method-group-specifier-bindings method-group-specifiers declarations real-body))) (when gf-var (push `(,gf-var .generic-function.) (cadr wrapped-body))) (when args-option (setq wrapped-body (deal-with-args-option wrapped-body args-option))) (when ll (setq wrapped-body `(apply #'(lambda ,ll ,wrapped-body) (method-combination-options .method-combination.)))) (values documentation `(lambda (.generic-function. .method-combination. .applicable-methods.) (declare (ignorable .generic-function. .method-combination. .applicable-methods.)) (block .long-method-combination-function. ,wrapped-body)))))) (define-condition long-method-combination-error (reference-condition simple-error) () (:default-initargs :references (list '(:ansi-cl :macro define-method-combination)))) ;;; NOTE: ;;; ;;; The semantics of long form method combination in the presence of ;;; multiple methods with the same specializers in the same method ;;; group are unclear by the spec: a portion of the standard implies ;;; that an error should be signalled, and another is more lenient. ;;; ;;; It is reasonable to allow a single method group of * to bypass all ;;; rules, as this is explicitly stated in the standard. (defun group-cond-clause (name tests specializer-cache star-only) (let ((maybe-error-clause (if star-only `(setq ,specializer-cache .specializers.) `(if (and (equal ,specializer-cache .specializers.) (not (null .specializers.))) (return-from .long-method-combination-function. '(error 'long-method-combination-error :format-control "More than one method of type ~S ~ with the same specializers." :format-arguments (list ',name))) (setq ,specializer-cache .specializers.))))) `((or ,@tests) ,maybe-error-clause (push .method. ,name)))) (defun wrap-method-group-specifier-bindings (method-group-specifiers declarations real-body) (let (names specializer-caches cond-clauses required-checks order-cleanups) (let ((nspecifiers (length method-group-specifiers))) (dolist (method-group-specifier method-group-specifiers) (multiple-value-bind (name tests description order required) (parse-method-group-specifier method-group-specifier) (declare (ignore description)) (let ((specializer-cache (gensym))) (push name names) (push specializer-cache specializer-caches) (push (group-cond-clause name tests specializer-cache (and (eq (cadr method-group-specifier) '*) (= nspecifiers 1))) cond-clauses) (when required (push `(when (null ,name) (return-from .long-method-combination-function. '(error 'long-method-combination-error :format-control "No ~S methods." :format-arguments (list ',name)))) required-checks)) (loop (unless (and (constantp order) (neq order (setq order (eval order)))) (return t))) (push (cond ((eq order :most-specific-first) `(setq ,name (nreverse ,name))) ((eq order :most-specific-last) ()) (t `(ecase ,order (:most-specific-first (setq ,name (nreverse ,name))) (:most-specific-last)))) order-cleanups)))) `(let (,@(nreverse names) ,@(nreverse specializer-caches)) ,@declarations (dolist (.method. .applicable-methods.) (let ((.qualifiers. (method-qualifiers .method.)) (.specializers. (method-specializers .method.))) (declare (ignorable .qualifiers. .specializers.)) (cond ,@(nreverse cond-clauses)))) ,@(nreverse required-checks) ,@(nreverse order-cleanups) ,@real-body)))) (defun parse-method-group-specifier (method-group-specifier) ;;(declare (values name tests description order required)) (let* ((name (pop method-group-specifier)) (patterns ()) (tests (let (collect) (block collect-tests (loop (if (or (null method-group-specifier) (memq (car method-group-specifier) '(:description :order :required))) (return-from collect-tests t) (let ((pattern (pop method-group-specifier))) (push pattern patterns) (push (parse-qualifier-pattern name pattern) collect))))) (nreverse collect)))) (values name tests (getf method-group-specifier :description (make-default-method-group-description patterns)) (getf method-group-specifier :order :most-specific-first) (getf method-group-specifier :required nil)))) (defun parse-qualifier-pattern (name pattern) (cond ((eq pattern '()) `(null .qualifiers.)) ((eq pattern '*) t) ((symbolp pattern) `(,pattern .qualifiers.)) ((listp pattern) `(qualifier-check-runtime ',pattern .qualifiers.)) (t (error "In the method group specifier ~S,~%~ ~S isn't a valid qualifier pattern." name pattern)))) (defun qualifier-check-runtime (pattern qualifiers) (loop (cond ((and (null pattern) (null qualifiers)) (return t)) ((eq pattern '*) (return t)) ((and pattern qualifiers (eq (car pattern) (car qualifiers))) (pop pattern) (pop qualifiers)) (t (return nil))))) (defun make-default-method-group-description (patterns) (if (cdr patterns) (format nil "methods matching one of the patterns: ~{~S, ~} ~S" (butlast patterns) (car (last patterns))) (format nil "methods matching the pattern: ~S" (car patterns)))) ;;; This baby is a complete mess. I can't believe we put it in this ;;; way. No doubt this is a large part of what drives MLY crazy. ;;; ;;; At runtime (when the effective-method is run), we bind an intercept ;;; lambda-list to the arguments to the generic function. ;;; ;;; At compute-effective-method time, the symbols in the :arguments ;;; option are bound to the symbols in the intercept lambda list. ;;; ;;; FIXME: in here we have not one but two mini-copies of a weird ;;; hybrid of PARSE-LAMBDA-LIST and PARSE-DEFMACRO-LAMBDA-LIST. (defun deal-with-args-option (wrapped-body args-lambda-list) (let ((intercept-rebindings (let (rebindings) (dolist (arg args-lambda-list (nreverse rebindings)) (unless (member arg lambda-list-keywords) (typecase arg (symbol (push `(,arg ',arg) rebindings)) (cons (unless (symbolp (car arg)) (error "invalid lambda-list specifier: ~S." arg)) (push `(,(car arg) ',(car arg)) rebindings)) (t (error "invalid lambda-list-specifier: ~S." arg))))))) (nreq 0) (nopt 0) (whole nil)) ;; Count the number of required and optional parameters in ;; ARGS-LAMBDA-LIST into NREQ and NOPT, and set WHOLE to the ;; name of a &WHOLE parameter, if any. (when (member '&whole (rest args-lambda-list)) (error 'simple-program-error :format-control "~@" :format-arguments (list args-lambda-list))) (loop with state = 'required for arg in args-lambda-list do (if (memq arg lambda-list-keywords) (setq state arg) (case state (required (incf nreq)) (&optional (incf nopt)) (&whole (setq whole arg state 'required))))) ;; This assumes that the head of WRAPPED-BODY is a let, and it ;; injects let-bindings of the form (ARG 'SYM) for all variables ;; of the argument-lambda-list; SYM is a gensym. (aver (memq (first wrapped-body) '(let let*))) (setf (second wrapped-body) (append intercept-rebindings (second wrapped-body))) ;; Be sure to fill out the args lambda list so that it can be too ;; short if it wants to. (unless (or (memq '&rest args-lambda-list) (memq '&allow-other-keys args-lambda-list)) (let ((aux (memq '&aux args-lambda-list))) (setq args-lambda-list (append (ldiff args-lambda-list aux) (if (memq '&key args-lambda-list) '(&allow-other-keys) '(&rest .ignore.)) aux)))) ;; .GENERIC-FUNCTION. is bound to the generic function in the ;; method combination function, and .GF-ARGS* is bound to the ;; generic function arguments in effective method functions ;; created for generic functions having a method combination that ;; uses :ARGUMENTS. ;; ;; The DESTRUCTURING-BIND binds the parameters of the ;; ARGS-LAMBDA-LIST to actual generic function arguments. Because ;; ARGS-LAMBDA-LIST may be shorter or longer than the generic ;; function's lambda list, which is only known at run time, this ;; destructuring has to be done on a slighly modified list of ;; actual arguments, from which values might be stripped or added. ;; ;; Using one of the variable names in the body inserts a symbol ;; into the effective method, and running the effective method ;; produces the value of actual argument that is bound to the ;; symbol. `(let ((inner-result. ,wrapped-body) (gf-lambda-list (generic-function-lambda-list .generic-function.))) `(destructuring-bind ,',args-lambda-list (frob-combined-method-args .gf-args. ',gf-lambda-list ,',nreq ,',nopt) ,,(when (memq '.ignore. args-lambda-list) ''(declare (ignore .ignore.))) ;; If there is a &WHOLE in the args-lambda-list, let ;; it result in the actual arguments of the generic-function ;; not the frobbed list. ,,(when whole ``(setq ,',whole .gf-args.)) ,inner-result.)))) ;;; Partition VALUES into three sections: required, optional, and the ;;; rest, according to required, optional, and other parameters in ;;; LAMBDA-LIST. Make the required and optional sections NREQ and ;;; NOPT elements long by discarding values or adding NILs. Value is ;;; the concatenated list of required and optional sections, and what ;;; is left as rest from VALUES. (defun frob-combined-method-args (values lambda-list nreq nopt) (loop with section = 'required for arg in lambda-list if (memq arg lambda-list-keywords) do (setq section arg) (unless (eq section '&optional) (loop-finish)) else if (eq section 'required) count t into nr and collect (pop values) into required else if (eq section '&optional) count t into no and collect (pop values) into optional finally (flet ((frob (list n m) (cond ((> n m) (butlast list (- n m))) ((< n m) (nconc list (make-list (- m n)))) (t list)))) (return (nconc (frob required nr nreq) (frob optional no nopt) values)))))