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*) ; tests that do argument counting at expansion time
  17 (declaim (type list *arg-tests*))
  18 (defvar *system-lets*) ; LET bindings done to allow lambda-list parsing
  19 (declaim (type list *system-lets*))
  20 (defvar *user-lets*) ; LET bindings that the user has explicitly supplied
  21 (declaim (type list *user-lets*))
  22 (defvar *env-var*) ; &ENVIRONMENT variable name
  23
  24 ;; the default default for unsupplied &OPTIONAL and &KEY args
  25 (defvar *default-default*)
  26
  27 ;;; temps that we introduce and might not reference
  28 (defvar *ignorable-vars*)
  29 (declaim (type list *ignorable-vars*))
  30
  31 ;;; Return, as multiple values, a body, possibly a DECLARE form to put
  32 ;;; where this code is inserted, the documentation for the parsed
  33 ;;; body, and bounds on the number of arguments.
  34 (defun parse-defmacro (lambda-list whole-var body name context
  35                        &key
  36                        (anonymousp nil)
  37                        (doc-string-allowed t)
  38                        ((:environment env-arg-name))
  39                        ((:default-default *default-default*))
  40                        (error-fun 'error)
  41                        (wrap-block t))
  42   (multiple-value-bind (forms declarations documentation)
  43       (parse-body body :doc-string-allowed doc-string-allowed)
  44     (let ((*arg-tests* ())
  45           (*user-lets* ())
  46           (*system-lets* ())
  47           (*ignorable-vars* ())
  48           (*env-var* nil))
  49       (multiple-value-bind (env-arg-used minimum maximum)
  50           (parse-defmacro-lambda-list lambda-list whole-var name context
  51                                       :error-fun error-fun
  52                                       :anonymousp anonymousp)
  53         (values `(let* (,@(nreverse *system-lets*))
  54                    ,@(when *ignorable-vars*
  55                        `((declare (ignorable ,@*ignorable-vars*))))
  56                    ,@*arg-tests*
  57                    (let* (,@(when env-arg-used
  58                             `((,*env-var* ,env-arg-name)))
  59                           ,@(nreverse *user-lets*))
  60                      ,@declarations
  61                      ,@(if wrap-block
  62                            `((block ,(fun-name-block-name name)
  63                                ,@forms))
  64                            forms)))
  65                 `(,@(when (and env-arg-name (not env-arg-used))
  66                       `((declare (ignore ,env-arg-name)))))
  67                 documentation
  68                 minimum
  69                 maximum)))))
  70
  71 (defun parse-defmacro-lambda-list (possibly-dotted-lambda-list
  72                                    whole-var
  73                                    name
  74                                    context
  75                                    &key
  76                                    error-fun
  77                                    anonymousp
  78                                    env-illegal
  79                                    sublist)
  80   (let* (;; PATH is a sort of pointer into the part of the lambda list we're
  81          ;; considering at this point in the code. PATH-0 is the root of the
  82          ;; lambda list, which is the initial value of PATH.
  83          (path-0 (if (or anonymousp sublist) whole-var `(cdr ,whole-var)))
  84          (path path-0) ; will change below
  85          (compiler-macro-whole (gensym "CMACRO-&WHOLE"))
  86          (now-processing :required)
  87          (maximum 0)
  88          (minimum 0)
  89          (keys ())
  90          (key-seen nil)
  91          (aux-seen nil)
  92          (optional-seen nil)
  93          ;; ANSI specifies that dotted lists are "treated exactly as if the
  94          ;; parameter name that ends the list had appeared preceded by &rest."
  95          ;; We force this behavior by transforming dotted lists into ordinary
  96          ;; lists with explicit &REST elements.
  97          (lambda-list (do ((in-pdll possibly-dotted-lambda-list (cdr in-pdll))
  98                            (reversed-result nil))
  99                           ((atom in-pdll)
 100                            (nreverse (if in-pdll
 101                                          (list* in-pdll '&rest reversed-result)
 102                                          reversed-result)))
 103                         (push (car in-pdll) reversed-result)))
 104          rest-name restp allow-other-keys-p env-arg-used)
 105     (when (member '&whole (rest lambda-list))
 106       (error "&WHOLE may only appear first in ~S lambda-list." context))
 107     ;; Special case compiler-macros: if car of the form is FUNCALL,
 108     ;; skip over it for destructuring, pretending cdr of the form is
 109     ;; the actual form. Save original for &whole
 110     (when (eq context 'define-compiler-macro)
 111       (push-let-binding compiler-macro-whole whole-var :system t)
 112       (push compiler-macro-whole *ignorable-vars*)
 113       (push-let-binding whole-var whole-var
 114                         :system t
 115                         :when `(not (eq 'funcall (car ,whole-var)))
 116                         ;; do we need to SETF too?
 117                         :else `(setf ,whole-var (cdr ,whole-var))))
 118     (do ((rest-of-lambda-list lambda-list (cdr rest-of-lambda-list)))
 119         ((null rest-of-lambda-list))
 120       (macrolet ((process-sublist (var kind path)
 121                    (once-only ((var var))
 122                      `(if (listp ,var)
 123                           (let ((sublist-name (gensym ,kind)))
 124                             (push-sublist-binding sublist-name ,path ,var
 125                                                   name context error-fun)
 126                             (parse-defmacro-lambda-list ,var sublist-name name
 127                                                         context
 128                                                         :error-fun error-fun
 129                                                         :sublist t))
 130                           (push-let-binding ,var ,path))))
 131                  (normalize-singleton (var)
 132                    `(when (null (cdr ,var))
 133                      (setf (cdr ,var) (list *default-default*)))))
 134         (let ((var (car rest-of-lambda-list)))
 135           (typecase var
 136             (list
 137              (case now-processing
 138                ((:required)
 139                 (when restp
 140                   (defmacro-error (format nil "required argument after ~A"
 141                                           restp)
 142                       context name))
 143                 (when (process-sublist var "REQUIRED-" `(car ,path))
 144                   ;; Note &ENVIRONMENT from DEFSETF sublist
 145                   (aver (eq context 'defsetf))
 146                   (setf env-arg-used t))
 147                 (setq path `(cdr ,path)
 148                       minimum (1+ minimum)
 149                       maximum (1+ maximum)))
 150                ((:optionals)
 151                 (normalize-singleton var)
 152                 (destructuring-bind
 153                       (varname &optional default-form suppliedp-name)
 154                     var
 155                   (push-optional-binding varname default-form suppliedp-name
 156                                          :is-supplied-p `(not (null ,path))
 157                                          :path `(car ,path)
 158                                          :name name
 159                                          :context context
 160                                          :error-fun error-fun))
 161                 (setq path `(cdr ,path)
 162                       maximum (1+ maximum)))
 163                ((:keywords)
 164                 (normalize-singleton var)
 165                 (let* ((keyword-given (consp (car var)))
 166                        (variable (if keyword-given
 167                                      (cadar var)
 168                                      (car var)))
 169                        (keyword (if keyword-given
 170                                     (caar var)
 171                                     (keywordicate variable)))
 172                        (default-form (cadr var))
 173                        (suppliedp-name (caddr var)))
 174                   (push-optional-binding variable default-form suppliedp-name
 175                                          :is-supplied-p
 176                                          `(keyword-supplied-p ',keyword
 177                                                               ,rest-name)
 178                                          :path
 179                                          `(lookup-keyword ',keyword ,rest-name)
 180                                          :name name
 181                                          :context context
 182                                          :error-fun error-fun)
 183                   (push keyword keys)))
 184                ((:auxs)
 185                 (push-let-binding (car var) (cadr var)))))
 186             ((and symbol (not (eql nil)))
 187              (case var
 188                (&whole
 189                 (cond ((cdr rest-of-lambda-list)
 190                        (pop rest-of-lambda-list)
 191                        (process-sublist (car rest-of-lambda-list)
 192                                         "WHOLE-LIST-"
 193                                         (if (eq 'define-compiler-macro context)
 194                                             compiler-macro-whole
 195                                             whole-var)))
 196                       (t
 197                        (defmacro-error "&WHOLE" context name))))
 198                (&environment
 199                 (cond (env-illegal
 200                        (error "&ENVIRONMENT is not valid with ~S." context))
 201                       ;; DEFSETF explicitly allows &ENVIRONMENT, and we get
 202                       ;; it here in a sublist.
 203                       ((and sublist (neq context 'defsetf))
 204                        (error "&ENVIRONMENT is only valid at top level of ~
 205                              lambda-list."))
 206                       (env-arg-used
 207                        (error "Repeated &ENVIRONMENT.")))
 208                 (cond ((and (cdr rest-of-lambda-list)
 209                             (symbolp (cadr rest-of-lambda-list)))
 210                        (setq rest-of-lambda-list (cdr rest-of-lambda-list))
 211                        (check-defmacro-arg (car rest-of-lambda-list))
 212                        (setq *env-var* (car rest-of-lambda-list)
 213                              env-arg-used t))
 214                       (t
 215                        (defmacro-error "&ENVIRONMENT" context name))))
 216                ((&rest &body)
 217                 (cond ((or key-seen aux-seen)
 218                        (error "~A after ~A in ~A"
 219                               var (or key-seen aux-seen) context))
 220                       ((and (not restp) (cdr rest-of-lambda-list))
 221                        (setq rest-of-lambda-list (cdr rest-of-lambda-list)
 222                              restp var)
 223                        (process-sublist (car rest-of-lambda-list)
 224                                         "REST-LIST-" path))
 225                       (t
 226                        (defmacro-error (symbol-name var) context name))))
 227                (&optional
 228                 (when (or key-seen aux-seen restp)
 229                   (error "~A after ~A in ~A lambda-list."
 230                          var (or key-seen aux-seen restp) context))
 231                 (when optional-seen
 232                   (error "Multiple ~A in ~A lambda list." var context))
 233                 (setq now-processing :optionals
 234                       optional-seen var))
 235                (&key
 236                 (when aux-seen
 237                   (error "~A after ~A in ~A lambda-list." '&key '&aux context))
 238                 (when key-seen
 239                   (error "Multiple ~A in ~A lambda-list." '&key context))
 240                 (setf now-processing :keywords
 241                       rest-name (gensym "KEYWORDS-")
 242                       restp var
 243                       key-seen var)
 244                 (push rest-name *ignorable-vars*)
 245                 (push-let-binding rest-name path :system t))
 246                (&allow-other-keys
 247                 (unless (eq now-processing :keywords)
 248                   (error "~A outside ~A section of lambda-list in ~A."
 249                          var '&key context))
 250                 (when allow-other-keys-p
 251                   (error "Multiple ~A in ~A lambda-list." var context))
 252                 (setq allow-other-keys-p t))
 253                (&aux
 254                 (when (eq context 'defsetf)
 255                   (error "~A not allowed in a ~A lambda-list." var context))
 256                 (when aux-seen
 257                   (error "Multiple ~A in ~A lambda-list." '&aux context))
 258                 (setq now-processing :auxs
 259                       aux-seen var))
 260                ;; FIXME: Other lambda list keywords.
 261                (t
 262                 (case now-processing
 263                   ((:required)
 264                    (when restp
 265                      (defmacro-error (format nil "required argument after ~A"
 266                                              restp)
 267                          context name))
 268                    (push-let-binding var `(car ,path))
 269                    (setq minimum (1+ minimum)
 270                          maximum (1+ maximum)
 271                          path `(cdr ,path)))
 272                   ((:optionals)
 273                    (push-let-binding var `(car ,path)
 274                                      :when `(not (null ,path)))
 275                    (setq path `(cdr ,path)
 276                          maximum (1+ maximum)))
 277                   ((:keywords)
 278                    (let ((key (keywordicate var)))
 279                      (push-let-binding
 280                       var
 281                       `(lookup-keyword ,key ,rest-name)
 282                       :when `(keyword-supplied-p ,key ,rest-name))
 283                      (push key keys)))
 284                   ((:auxs)
 285                    (push-let-binding var nil))))))
 286             (t
 287              (error "non-symbol in lambda-list: ~S" var))))))
 288     (let (;; common subexpression, suitable for passing to functions
 289           ;; which expect a MAXIMUM argument regardless of whether
 290           ;; there actually is a maximum number of arguments
 291           ;; (expecting MAXIMUM=NIL when there is no maximum)
 292           (explicit-maximum (and (not restp) maximum)))
 293       (unless (and restp (zerop minimum))
 294         (push (let ((args-form (if (eq 'define-compiler-macro context)
 295                                    `(if (eq 'funcall (car ,whole-var))
 296                                         (cdr ,path-0)
 297                                         ,path-0)
 298                                    path-0)))
 299                 (with-unique-names (args)
 300                   `(let ((,args ,args-form))
 301                      (unless ,(if restp
 302                                   ;; (If RESTP, then the argument list
 303                                   ;; might be dotted, in which case
 304                                   ;; ordinary LENGTH won't work.)
 305                                   `(list-of-length-at-least-p ,args ,minimum)
 306                                   `(proper-list-of-length-p ,args
 307                                                             ,minimum
 308                                                             ,maximum))
 309                        ,(if (eq error-fun 'error)
 310                             `(arg-count-error ',context ',name ,args
 311                                               ',lambda-list ,minimum
 312                                               ,explicit-maximum)
 313                             `(,error-fun 'arg-count-error
 314                                          :kind ',context
 315                                          ,@(when name `(:name ',name))
 316                                          :args ,args
 317                                          :lambda-list ',lambda-list
 318                                          :minimum ,minimum
 319                                          :maximum ,explicit-maximum))))))
 320               *arg-tests*))
 321       (when key-seen
 322         (let ((problem (gensym "KEY-PROBLEM-"))
 323               (info (gensym "INFO-")))
 324           (push `(multiple-value-bind (,problem ,info)
 325                      (verify-keywords ,rest-name
 326                                       ',keys
 327                                       ',allow-other-keys-p)
 328                    (when ,problem
 329                      (,error-fun
 330                       'defmacro-lambda-list-broken-key-list-error
 331                       :kind ',context
 332                       ,@(when name `(:name ',name))
 333                       :problem ,problem
 334                       :info ,info)))
 335                 *arg-tests*)))
 336       (values env-arg-used minimum explicit-maximum))))
 337
 338 ;;; We save space in macro definitions by calling this function.
 339 (defun arg-count-error (context name args lambda-list minimum maximum)
 340   (let (#-sb-xc-host
 341         (sb!debug:*stack-top-hint* (nth-value 1 (find-caller-name-and-frame))))
 342     (error 'arg-count-error
 343            :kind context
 344            :name name
 345            :args args
 346            :lambda-list lambda-list
 347            :minimum minimum
 348            :maximum maximum)))
 349
 350 (defun push-sublist-binding (variable path object name context error-fun)
 351   (check-defmacro-arg variable)
 352   (let ((var (gensym "TEMP-")))
 353     (push `(,variable
 354             (let ((,var ,path))
 355               (if (listp ,var)
 356                 ,var
 357                 (,error-fun 'defmacro-bogus-sublist-error
 358                             :kind ',context
 359                             ,@(when name `(:name ',name))
 360                             :object ,var
 361                             :lambda-list ',object))))
 362           *system-lets*)))
 363
 364 (defun push-let-binding (variable form
 365                          &key system when (else *default-default*))
 366   (check-defmacro-arg variable)
 367   (let ((let-form (if when
 368                       `(,variable (if ,when ,form ,else))
 369                       `(,variable ,form))))
 370     (if system
 371         (push let-form *system-lets*)
 372         (push let-form *user-lets*))))
 373
 374 (defun push-optional-binding (value-var init-form suppliedp-name
 375                               &key is-supplied-p path name context error-fun)
 376   (unless suppliedp-name
 377     (setq suppliedp-name (gensym "SUPPLIEDP-")))
 378   (push-let-binding suppliedp-name is-supplied-p :system t)
 379   (cond ((consp value-var)
 380          (let ((whole-thing (gensym "OPTIONAL-SUBLIST-")))
 381            (push-sublist-binding whole-thing
 382                                  `(if ,suppliedp-name ,path ,init-form)
 383                                  value-var name context error-fun)
 384            (parse-defmacro-lambda-list value-var whole-thing name
 385                                        context
 386                                        :error-fun error-fun
 387                                        :sublist t)))
 388         ((symbolp value-var)
 389          (push-let-binding value-var path :when suppliedp-name :else init-form))
 390         (t
 391          (error "illegal optional variable name: ~S" value-var))))
 392
 393 (defun defmacro-error (problem context name)
 394   (error "illegal or ill-formed ~A argument in ~A~@[ ~S~]"
 395          problem context name))
 396
 397 (defun check-defmacro-arg (arg)
 398   (when (or (and *env-var* (eq arg *env-var*))
 399             (member arg *system-lets* :key #'car)
 400             (member arg *user-lets* :key #'car))
 401     (error "variable ~S occurs more than once" arg)))
 402
 403 ;;; Determine whether KEY-LIST is a valid list of keyword/value pairs.
 404 ;;; Do not signal the error directly, 'cause we don't know how it
 405 ;;; should be signaled.
 406 (defun verify-keywords (key-list valid-keys allow-other-keys)
 407   (do ((already-processed nil)
 408        (unknown-keyword nil)
 409        (remaining key-list (cddr remaining)))
 410       ((null remaining)
 411        (if (and unknown-keyword
 412                 (not allow-other-keys)
 413                 (not (lookup-keyword :allow-other-keys key-list)))
 414            (values :unknown-keyword (list unknown-keyword valid-keys))
 415            (values nil nil)))
 416     (cond ((not (and (consp remaining) (listp (cdr remaining))))
 417            (return (values :dotted-list key-list)))
 418           ((null (cdr remaining))
 419            (return (values :odd-length key-list)))
 420           ((or (eq (car remaining) :allow-other-keys)
 421                (member (car remaining) valid-keys))
 422            (push (car remaining) already-processed))
 423           (t
 424            (setq unknown-keyword (car remaining))))))
 425
 426 (defun lookup-keyword (keyword key-list)
 427   (do ((remaining key-list (cddr remaining)))
 428       ((endp remaining))
 429     (when (eq keyword (car remaining))
 430       (return (cadr remaining)))))
 431
 432 (defun keyword-supplied-p (keyword key-list)
 433   (do ((remaining key-list (cddr remaining)))
 434       ((endp remaining))
 435     (when (eq keyword (car remaining))
 436       (return t))))