0.7.5.15:
[sbcl.git] / src / code / parse-defmacro.lisp
1 ;;;; the PARSE-DEFMACRO function and related code
2
3 ;;;; This software is part of the SBCL system. See the README file for
4 ;;;; more information.
5 ;;;;
6 ;;;; This software is derived from the CMU CL system, which was
7 ;;;; written at Carnegie Mellon University and released into the
8 ;;;; public domain. The software is in the public domain and is
9 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
10 ;;;; files for more information.
11
12 (in-package "SB!KERNEL")
13
14 ;;; variables for accumulating the results of parsing a DEFMACRO. (Declarations
15 ;;; in DEFMACRO are the reason this isn't as easy as it sounds.)
16 (defvar *arg-tests* nil) ; tests that do argument counting at expansion time
17 (declaim (type list *arg-tests*))
18 (defvar *system-lets* nil) ; LET bindings done to allow lambda-list parsing
19 (declaim (type list *system-lets*))
20 (defvar *user-lets* nil) ; LET bindings that the user has explicitly supplied
21 (declaim (type list *user-lets*))
22
23 ;; the default default for unsupplied &OPTIONAL and &KEY args
24 (defvar *default-default* nil)
25
26 ;;; temps that we introduce and might not reference
27 (defvar *ignorable-vars*)
28 (declaim (type list *ignorable-vars*))
29
30 ;;; Return, as multiple values, a body, possibly a declare form to put
31 ;;; where this code is inserted, the documentation for the parsed
32 ;;; body, and bounds on the number of arguments.
33 (defun parse-defmacro (lambda-list arg-list-name body name error-kind
34                                    &key
35                                    (anonymousp nil)
36                                    (doc-string-allowed t)
37                                    ((:environment env-arg-name))
38                                    ((:default-default *default-default*))
39                                    (error-fun 'error))
40   (multiple-value-bind (forms declarations documentation)
41       (parse-body body doc-string-allowed)
42     (let ((*arg-tests* ())
43           (*user-lets* ())
44           (*system-lets* ())
45           (*ignorable-vars* ()))
46       (multiple-value-bind (env-arg-used minimum maximum)
47           (parse-defmacro-lambda-list lambda-list arg-list-name name
48                                       error-kind error-fun (not anonymousp)
49                                       nil env-arg-name)
50         (values `(let* ,(nreverse *system-lets*)
51                    ,@(when *ignorable-vars*
52                        `((declare (ignorable ,@*ignorable-vars*))))
53                    ,@*arg-tests*
54                    (let* ,(nreverse *user-lets*)
55                      ,@declarations
56                      ,@forms))
57                 `(,@(when (and env-arg-name (not env-arg-used))
58                       `((declare (ignore ,env-arg-name)))))
59                 documentation
60                 minimum
61                 maximum)))))
62
63 ;;; partial reverse-engineered documentation:
64 ;;;   TOPLEVEL is true for calls through PARSE-DEFMACRO from DEFSETF and
65 ;;;     DESTRUCTURING-BIND, false otherwise.
66 ;;; -- WHN 19990620
67 (defun parse-defmacro-lambda-list (possibly-dotted-lambda-list
68                                    arg-list-name
69                                    name
70                                    error-kind
71                                    error-fun
72                                    &optional
73                                    toplevel
74                                    env-illegal
75                                    env-arg-name)
76   (let* (;; PATH is a sort of pointer into the part of the lambda list we're
77          ;; considering at this point in the code. PATH-0 is the root of the
78          ;; lambda list, which is the initial value of PATH.
79          (path-0 (if toplevel
80                    `(cdr ,arg-list-name)
81                    arg-list-name))
82          (path path-0) ; (will change below)
83          (now-processing :required)
84          (maximum 0)
85          (minimum 0)
86          (keys ())
87          ;; ANSI specifies that dotted lists are "treated exactly as if the
88          ;; parameter name that ends the list had appeared preceded by &rest."
89          ;; We force this behavior by transforming dotted lists into ordinary
90          ;; lists with explicit &REST elements.
91          (lambda-list (do ((in-pdll possibly-dotted-lambda-list (cdr in-pdll))
92                            (reversed-result nil))
93                           ((atom in-pdll)
94                            (nreverse (if in-pdll
95                                        (list* in-pdll '&rest reversed-result)
96                                        reversed-result)))
97                         (push (car in-pdll) reversed-result)))
98          rest-name restp allow-other-keys-p env-arg-used)
99     (when (member '&whole (rest lambda-list))
100       (error "&WHOLE may only appear first in ~S lambda-list." error-kind))
101     (do ((rest-of-args lambda-list (cdr rest-of-args)))
102         ((null rest-of-args))
103       (let ((var (car rest-of-args)))
104         (cond ((eq var '&whole)
105                (cond ((and (cdr rest-of-args) (symbolp (cadr rest-of-args)))
106                       (setq rest-of-args (cdr rest-of-args))
107                       (push-let-binding (car rest-of-args) arg-list-name nil))
108                      (t
109                       (defmacro-error "&WHOLE" error-kind name))))
110               ((eq var '&environment)
111                (cond (env-illegal
112                       (error "&ENVIRONMENT is not valid with ~S." error-kind))
113                      ((not toplevel)
114                       (error "&ENVIRONMENT is only valid at top level of ~
115                               lambda-list.")))
116                (cond ((and (cdr rest-of-args) (symbolp (cadr rest-of-args)))
117                       (setq rest-of-args (cdr rest-of-args))
118                       (push-let-binding (car rest-of-args) env-arg-name nil)
119                       (setq env-arg-used t))
120                      (t
121                       (defmacro-error "&ENVIRONMENT" error-kind name))))
122               ((or (eq var '&rest)
123                    (eq var '&body))
124                (cond ((and (cdr rest-of-args) (symbolp (cadr rest-of-args)))
125                       (setq rest-of-args (cdr rest-of-args))
126                       (setq restp t)
127                       (push-let-binding (car rest-of-args) path nil))
128                      (t
129                       (defmacro-error (symbol-name var) error-kind name))))
130               ((eq var '&optional)
131                (setq now-processing :optionals))
132               ((eq var '&key)
133                (setq now-processing :keywords)
134                (setq rest-name (gensym "KEYWORDS-"))
135                (push rest-name *ignorable-vars*)
136                (setq restp t)
137                (push-let-binding rest-name path t))
138               ((eq var '&allow-other-keys)
139                (setq allow-other-keys-p t))
140               ((eq var '&aux)
141                (setq now-processing :auxs))
142               ((listp var)
143                (cond ; (since it's too early to use CASE)
144                  ((eq now-processing :required)
145                   (let ((sub-list-name (gensym "SUBLIST-")))
146                     (push-sub-list-binding sub-list-name `(car ,path) var
147                                            name error-kind error-fun)
148                     (parse-defmacro-lambda-list var sub-list-name name
149                                                 error-kind error-fun))
150                   (setq path `(cdr ,path)
151                         minimum (1+ minimum)
152                         maximum (1+ maximum)))
153                  ((eq now-processing :optionals)
154                   (destructuring-bind (varname &optional initform supplied-p)
155                       var
156                     (push-optional-binding varname initform supplied-p
157                                            `(not (null ,path)) `(car ,path)
158                                            name error-kind error-fun))
159                   (setq path `(cdr ,path)
160                         maximum (1+ maximum)))
161                  ((eq now-processing :keywords)
162                   (let* ((keyword-given (consp (car var)))
163                          (variable (if keyword-given
164                                        (cadar var)
165                                        (car var)))
166                          (keyword (if keyword-given
167                                       (caar var)
168                                       (keywordicate variable)))
169                          (supplied-p (caddr var)))
170                     (push-optional-binding variable (cadr var) supplied-p
171                                            `(keyword-supplied-p ',keyword
172                                                                 ,rest-name)
173                                            `(lookup-keyword ',keyword
174                                                             ,rest-name)
175                                            name error-kind error-fun)
176                     (push keyword keys)))
177                  ((eq now-processing :auxs)
178                   (push-let-binding (car var) (cadr var) nil))))
179               ((symbolp var)
180                (cond ; (too early in bootstrapping to use CASE)
181                 ;; FIXME: ^ This "too early in bootstrapping" is no
182                 ;; longer an issue in current SBCL bootstrapping.
183                  ((eq now-processing :required)
184                   (push-let-binding var `(car ,path) nil)
185                   (setq minimum (1+ minimum)
186                         maximum (1+ maximum)
187                         path `(cdr ,path)))
188                  ((eq now-processing :optionals)
189                   (push-let-binding var `(car ,path) nil `(not (null ,path)))
190                   (setq path `(cdr ,path)
191                         maximum (1+ maximum)))
192                  ((eq now-processing :keywords)
193                   (let ((key (keywordicate var)))
194                     (push-let-binding var
195                                       `(lookup-keyword ,key ,rest-name)
196                                       nil)
197                     (push key keys)))
198                  ((eq now-processing :auxs)
199                   (push-let-binding var nil nil))))
200               (t
201                (error "non-symbol in lambda-list: ~S" var)))))
202     (let (;; common subexpression, suitable for passing to functions
203           ;; which expect a MAXIMUM argument regardless of whether
204           ;; there actually is a maximum number of arguments
205           ;; (expecting MAXIMUM=NIL when there is no maximum)
206           (explicit-maximum (and (not restp) maximum)))
207       (push `(unless ,(if restp
208                           ;; (If RESTP, then the argument list might be
209                           ;; dotted, in which case ordinary LENGTH won't
210                           ;; work.)
211                           `(list-of-length-at-least-p ,path-0 ,minimum)
212                           `(proper-list-of-length-p ,path-0 ,minimum ,maximum))
213                ,(if (eq error-fun 'error)
214                     `(arg-count-error ',error-kind ',name ,path-0
215                                       ',lambda-list ,minimum
216                                       ,explicit-maximum)
217                     `(,error-fun 'arg-count-error
218                                  :kind ',error-kind
219                                  ,@(when name `(:name ',name))
220                                  :args ,path-0
221                                  :lambda-list ',lambda-list
222                                  :minimum ,minimum
223                                  :maximum ,explicit-maximum)))
224             *arg-tests*)
225       (when keys
226         (let ((problem (gensym "KEY-PROBLEM-"))
227               (info (gensym "INFO-")))
228           (push `(multiple-value-bind (,problem ,info)
229                      (verify-keywords ,rest-name
230                                       ',keys
231                                       ',allow-other-keys-p)
232                    (when ,problem
233                      (,error-fun
234                       'defmacro-lambda-list-broken-key-list-error
235                       :kind ',error-kind
236                       ,@(when name `(:name ',name))
237                       :problem ,problem
238                       :info ,info)))
239                 *arg-tests*)))
240       (values env-arg-used minimum explicit-maximum))))
241
242 ;;; We save space in macro definitions by calling this function.
243 (defun arg-count-error (error-kind name args lambda-list minimum maximum)
244   (let (#-sb-xc-host
245         (sb!debug:*stack-top-hint* (nth-value 1 (find-caller-name-and-frame))))
246     (error 'arg-count-error
247            :kind error-kind
248            :name name
249            :args args
250            :lambda-list lambda-list
251            :minimum minimum
252            :maximum maximum)))
253
254 (defun push-sub-list-binding (variable path object name error-kind error-fun)
255   (let ((var (gensym "TEMP-")))
256     (push `(,variable
257             (let ((,var ,path))
258               (if (listp ,var)
259                 ,var
260                 (,error-fun 'defmacro-bogus-sublist-error
261                             :kind ',error-kind
262                             ,@(when name `(:name ',name))
263                             :object ,var
264                             :lambda-list ',object))))
265           *system-lets*)))
266
267 (defun push-let-binding (variable path systemp &optional condition
268                                   (init-form *default-default*))
269   (let ((let-form (if condition
270                       `(,variable (if ,condition ,path ,init-form))
271                       `(,variable ,path))))
272     (if systemp
273       (push let-form *system-lets*)
274       (push let-form *user-lets*))))
275
276 (defun push-optional-binding (value-var init-form supplied-var condition path
277                                         name error-kind error-fun)
278   (unless supplied-var
279     (setq supplied-var (gensym "SUPPLIEDP-")))
280   (push-let-binding supplied-var condition t)
281   (cond ((consp value-var)
282          (let ((whole-thing (gensym "OPTIONAL-SUBLIST-")))
283            (push-sub-list-binding whole-thing
284                                   `(if ,supplied-var ,path ,init-form)
285                                   value-var name error-kind error-fun)
286            (parse-defmacro-lambda-list value-var whole-thing name
287                                        error-kind error-fun)))
288         ((symbolp value-var)
289          (push-let-binding value-var path nil supplied-var init-form))
290         (t
291          (error "illegal optional variable name: ~S" value-var))))
292
293 (defun defmacro-error (problem kind name)
294   (error "illegal or ill-formed ~A argument in ~A~@[ ~S~]"
295          problem kind name))
296
297 ;;; Determine whether KEY-LIST is a valid list of keyword/value pairs.
298 ;;; Do not signal the error directly, 'cause we don't know how it
299 ;;; should be signaled.
300 (defun verify-keywords (key-list valid-keys allow-other-keys)
301   (do ((already-processed nil)
302        (unknown-keyword nil)
303        (remaining key-list (cddr remaining)))
304       ((null remaining)
305        (if (and unknown-keyword
306                 (not allow-other-keys)
307                 (not (lookup-keyword :allow-other-keys key-list)))
308            (values :unknown-keyword (list unknown-keyword valid-keys))
309            (values nil nil)))
310     (cond ((not (and (consp remaining) (listp (cdr remaining))))
311            (return (values :dotted-list key-list)))
312           ((null (cdr remaining))
313            (return (values :odd-length key-list)))
314           ((or (eq (car remaining) :allow-other-keys)
315                (member (car remaining) valid-keys))
316            (push (car remaining) already-processed))
317           (t
318            (setq unknown-keyword (car remaining))))))
319
320 (defun lookup-keyword (keyword key-list)
321   (do ((remaining key-list (cddr remaining)))
322       ((endp remaining))
323     (when (eq keyword (car remaining))
324       (return (cadr remaining)))))
325
326 (defun keyword-supplied-p (keyword key-list)
327   (do ((remaining key-list (cddr remaining)))
328       ((endp remaining))
329     (when (eq keyword (car remaining))
330       (return t))))