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 (defvar *env-var* nil) ; &ENVIRONMENT variable name
  23
  24 ;; the default default for unsupplied &OPTIONAL and &KEY args
  25 (defvar *default-default* nil)
  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 arg-list-name body name error-kind
  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   (multiple-value-bind (forms declarations documentation)
  42       (parse-body body doc-string-allowed)
  43     (let ((*arg-tests* ())
  44           (*user-lets* ())
  45           (*system-lets* ())
  46           (*ignorable-vars* ())
  47           (*env-var* nil))
  48       (multiple-value-bind (env-arg-used minimum maximum)
  49           (parse-defmacro-lambda-list lambda-list arg-list-name name
  50                                       error-kind error-fun (not anonymousp)
  51                                       nil)
  52         (values `(let* (,@(when env-arg-used
  53                             `((,*env-var* ,env-arg-name)))
  54                         ,@(nreverse *system-lets*))
  55                    ,@(when *ignorable-vars*
  56                        `((declare (ignorable ,@*ignorable-vars*))))
  57                    ,@*arg-tests*
  58                    (let* ,(nreverse *user-lets*)
  59                      ,@declarations
  60                      ,@forms))
  61                 `(,@(when (and env-arg-name (not env-arg-used))
  62                       `((declare (ignore ,env-arg-name)))))
  63                 documentation
  64                 minimum
  65                 maximum)))))
  66
  67 ;;; partial reverse-engineered documentation:
  68 ;;;   TOPLEVEL is true for calls through PARSE-DEFMACRO from DEFSETF and
  69 ;;;     DESTRUCTURING-BIND, false otherwise.
  70 ;;; -- WHN 19990620
  71 (defun parse-defmacro-lambda-list (possibly-dotted-lambda-list
  72                                    arg-list-name
  73                                    name
  74                                    error-kind
  75                                    error-fun
  76                                    &optional
  77                                    toplevel
  78                                    env-illegal)
  79   (let* (;; PATH is a sort of pointer into the part of the lambda list we're
  80          ;; considering at this point in the code. PATH-0 is the root of the
  81          ;; lambda list, which is the initial value of PATH.
  82          (path-0 (if toplevel
  83                      `(cdr ,arg-list-name)
  84                      arg-list-name))
  85          (path path-0) ; (will change below)
  86          (now-processing :required)
  87          (maximum 0)
  88          (minimum 0)
  89          (keys ())
  90          (key-seen nil)
  91          ;; ANSI specifies that dotted lists are "treated exactly as if the
  92          ;; parameter name that ends the list had appeared preceded by &rest."
  93          ;; We force this behavior by transforming dotted lists into ordinary
  94          ;; lists with explicit &REST elements.
  95          (lambda-list (do ((in-pdll possibly-dotted-lambda-list (cdr in-pdll))
  96                            (reversed-result nil))
  97                           ((atom in-pdll)
  98                            (nreverse (if in-pdll
  99                                          (list* in-pdll '&rest reversed-result)
 100                                          reversed-result)))
 101                         (push (car in-pdll) reversed-result)))
 102          rest-name restp allow-other-keys-p env-arg-used)
 103     (when (member '&whole (rest lambda-list))
 104       (error "&WHOLE may only appear first in ~S lambda-list." error-kind))
 105     (do ((rest-of-args lambda-list (cdr rest-of-args)))
 106         ((null rest-of-args))
 107       (macrolet ((process-sublist (var sublist-name path)
 108                    (once-only ((var var))
 109                      `(if (consp ,var)
 110                           (let ((sub-list-name (gensym ,sublist-name)))
 111                             (push-sub-list-binding sub-list-name ,path ,var
 112                                                    name error-kind error-fun)
 113                             (parse-defmacro-lambda-list ,var sub-list-name name
 114                                                         error-kind error-fun))
 115                           (push-let-binding ,var ,path nil)))))
 116         (let ((var (car rest-of-args)))
 117           (typecase var
 118             (list
 119              (case now-processing
 120                ((:required)
 121                 (when restp
 122                   (defmacro-error "required argument after &REST/&BODY"
 123                       error-kind name))
 124                 (process-sublist var "SUBLIST-" `(car ,path))
 125                 (setq path `(cdr ,path)
 126                       minimum (1+ minimum)
 127                       maximum (1+ maximum)))
 128                ((:optionals)
 129                 (destructuring-bind (varname &optional initform supplied-p)
 130                     var
 131                   (push-optional-binding varname initform supplied-p
 132                                          `(not (null ,path)) `(car ,path)
 133                                          name error-kind error-fun))
 134                 (setq path `(cdr ,path)
 135                       maximum (1+ maximum)))
 136                ((:keywords)
 137                 (let* ((keyword-given (consp (car var)))
 138                        (variable (if keyword-given
 139                                      (cadar var)
 140                                      (car var)))
 141                        (keyword (if keyword-given
 142                                     (caar var)
 143                                     (keywordicate variable)))
 144                        (supplied-p (caddr var)))
 145                   (push-optional-binding variable (cadr var) supplied-p
 146                                          `(keyword-supplied-p ',keyword
 147                                                               ,rest-name)
 148                                          `(lookup-keyword ',keyword
 149                                                           ,rest-name)
 150                                          name error-kind error-fun)
 151                   (push keyword keys)))
 152                ((:auxs)
 153                 (push-let-binding (car var) (cadr var) nil))))
 154             ((and symbol (not (eql nil)))
 155              (case var
 156                (&whole
 157                 (cond ((cdr rest-of-args)
 158                        (setq rest-of-args (cdr rest-of-args))
 159                        (process-sublist (car rest-of-args)
 160                                         "WHOLE-LIST-" arg-list-name))
 161                       (t
 162                        (defmacro-error "&WHOLE" error-kind name))))
 163                (&environment
 164                 (cond (env-illegal
 165                        (error "&ENVIRONMENT is not valid with ~S." error-kind))
 166                       ((not toplevel)
 167                        (error "&ENVIRONMENT is only valid at top level of ~
 168                              lambda-list."))
 169                       (env-arg-used
 170                        (error "Repeated &ENVIRONMENT.")))
 171                 (cond ((and (cdr rest-of-args) (symbolp (cadr rest-of-args)))
 172                        (setq rest-of-args (cdr rest-of-args))
 173                        (check-defmacro-arg (car rest-of-args))
 174                        (setq *env-var* (car rest-of-args))
 175                        (setq env-arg-used t))
 176                       (t
 177                        (defmacro-error "&ENVIRONMENT" error-kind name))))
 178                ((&rest &body)
 179                 (cond ((and (not restp) (cdr rest-of-args))
 180                        (setq rest-of-args (cdr rest-of-args))
 181                        (setq restp t)
 182                        (process-sublist (car rest-of-args) "REST-LIST-" path))
 183                       (t
 184                        (defmacro-error (symbol-name var) error-kind name))))
 185                (&optional
 186                 (setq now-processing :optionals))
 187                (&key
 188                 (setq now-processing :keywords)
 189                 (setq rest-name (gensym "KEYWORDS-"))
 190                 (push rest-name *ignorable-vars*)
 191                 (setq restp t)
 192                 (setq key-seen t)
 193                 (push-let-binding rest-name path t))
 194                (&allow-other-keys
 195                 (setq allow-other-keys-p t))
 196                (&aux
 197                 (setq now-processing :auxs))
 198                ;; FIXME: Other lambda list keywords.
 199                (t
 200                 (case now-processing
 201                   ((:required)
 202                    (when restp
 203                      (defmacro-error "required argument after &REST/&BODY"
 204                          error-kind name))
 205                    (push-let-binding var `(car ,path) nil)
 206                    (setq minimum (1+ minimum)
 207                          maximum (1+ maximum)
 208                          path `(cdr ,path)))
 209                   ((:optionals)
 210                    (push-let-binding var `(car ,path) nil `(not (null ,path)))
 211                    (setq path `(cdr ,path)
 212                          maximum (1+ maximum)))
 213                   ((:keywords)
 214                    (let ((key (keywordicate var)))
 215                      (push-let-binding var
 216                                        `(lookup-keyword ,key ,rest-name)
 217                                        nil)
 218                      (push key keys)))
 219                   ((:auxs)
 220                    (push-let-binding var nil nil))))))
 221             (t
 222              (error "non-symbol in lambda-list: ~S" var))))))
 223     (let (;; common subexpression, suitable for passing to functions
 224           ;; which expect a MAXIMUM argument regardless of whether
 225           ;; there actually is a maximum number of arguments
 226           ;; (expecting MAXIMUM=NIL when there is no maximum)
 227           (explicit-maximum (and (not restp) maximum)))
 228       (unless (and restp (zerop minimum))
 229         (push `(unless ,(if restp
 230                             ;; (If RESTP, then the argument list might be
 231                             ;; dotted, in which case ordinary LENGTH won't
 232                             ;; work.)
 233                             `(list-of-length-at-least-p ,path-0 ,minimum)
 234                             `(proper-list-of-length-p ,path-0 ,minimum ,maximum))
 235                  ,(if (eq error-fun 'error)
 236                       `(arg-count-error ',error-kind ',name ,path-0
 237                                         ',lambda-list ,minimum
 238                                         ,explicit-maximum)
 239                       `(,error-fun 'arg-count-error
 240                                    :kind ',error-kind
 241                                    ,@(when name `(:name ',name))
 242                                    :args ,path-0
 243                                    :lambda-list ',lambda-list
 244                                    :minimum ,minimum
 245                                    :maximum ,explicit-maximum)))
 246               *arg-tests*))
 247       (when key-seen
 248         (let ((problem (gensym "KEY-PROBLEM-"))
 249               (info (gensym "INFO-")))
 250           (push `(multiple-value-bind (,problem ,info)
 251                      (verify-keywords ,rest-name
 252                                       ',keys
 253                                       ',allow-other-keys-p)
 254                    (when ,problem
 255                      (,error-fun
 256                       'defmacro-lambda-list-broken-key-list-error
 257                       :kind ',error-kind
 258                       ,@(when name `(:name ',name))
 259                       :problem ,problem
 260                       :info ,info)))
 261                 *arg-tests*)))
 262       (values env-arg-used minimum explicit-maximum))))
 263
 264 ;;; We save space in macro definitions by calling this function.
 265 (defun arg-count-error (error-kind name args lambda-list minimum maximum)
 266   (let (#-sb-xc-host
 267         (sb!debug:*stack-top-hint* (nth-value 1 (find-caller-name-and-frame))))
 268     (error 'arg-count-error
 269            :kind error-kind
 270            :name name
 271            :args args
 272            :lambda-list lambda-list
 273            :minimum minimum
 274            :maximum maximum)))
 275
 276 (defun push-sub-list-binding (variable path object name error-kind error-fun)
 277   (check-defmacro-arg variable)
 278   (let ((var (gensym "TEMP-")))
 279     (push `(,variable
 280             (let ((,var ,path))
 281               (if (listp ,var)
 282                 ,var
 283                 (,error-fun 'defmacro-bogus-sublist-error
 284                             :kind ',error-kind
 285                             ,@(when name `(:name ',name))
 286                             :object ,var
 287                             :lambda-list ',object))))
 288           *system-lets*)))
 289
 290 (defun push-let-binding (variable path systemp &optional condition
 291                                   (init-form *default-default*))
 292   (check-defmacro-arg variable)
 293   (let ((let-form (if condition
 294                       `(,variable (if ,condition ,path ,init-form))
 295                       `(,variable ,path))))
 296     (if systemp
 297       (push let-form *system-lets*)
 298       (push let-form *user-lets*))))
 299
 300 (defun push-optional-binding (value-var init-form supplied-var condition path
 301                                         name error-kind error-fun)
 302   (unless supplied-var
 303     (setq supplied-var (gensym "SUPPLIEDP-")))
 304   (push-let-binding supplied-var condition t)
 305   (cond ((consp value-var)
 306          (let ((whole-thing (gensym "OPTIONAL-SUBLIST-")))
 307            (push-sub-list-binding whole-thing
 308                                   `(if ,supplied-var ,path ,init-form)
 309                                   value-var name error-kind error-fun)
 310            (parse-defmacro-lambda-list value-var whole-thing name
 311                                        error-kind error-fun)))
 312         ((symbolp value-var)
 313          (push-let-binding value-var path nil supplied-var init-form))
 314         (t
 315          (error "illegal optional variable name: ~S" value-var))))
 316
 317 (defun defmacro-error (problem kind name)
 318   (error "illegal or ill-formed ~A argument in ~A~@[ ~S~]"
 319          problem kind name))
 320
 321 (defun check-defmacro-arg (arg)
 322   (when (or (and *env-var* (eq arg *env-var*))
 323             (member arg *system-lets* :key #'car)
 324             (member arg *user-lets* :key #'car))
 325     (error "variable ~S occurs more than once" arg)))
 326
 327 ;;; Determine whether KEY-LIST is a valid list of keyword/value pairs.
 328 ;;; Do not signal the error directly, 'cause we don't know how it
 329 ;;; should be signaled.
 330 (defun verify-keywords (key-list valid-keys allow-other-keys)
 331   (do ((already-processed nil)
 332        (unknown-keyword nil)
 333        (remaining key-list (cddr remaining)))
 334       ((null remaining)
 335        (if (and unknown-keyword
 336                 (not allow-other-keys)
 337                 (not (lookup-keyword :allow-other-keys key-list)))
 338            (values :unknown-keyword (list unknown-keyword valid-keys))
 339            (values nil nil)))
 340     (cond ((not (and (consp remaining) (listp (cdr remaining))))
 341            (return (values :dotted-list key-list)))
 342           ((null (cdr remaining))
 343            (return (values :odd-length key-list)))
 344           ((or (eq (car remaining) :allow-other-keys)
 345                (member (car remaining) valid-keys))
 346            (push (car remaining) already-processed))
 347           (t
 348            (setq unknown-keyword (car remaining))))))
 349
 350 (defun lookup-keyword (keyword key-list)
 351   (do ((remaining key-list (cddr remaining)))
 352       ((endp remaining))
 353     (when (eq keyword (car remaining))
 354       (return (cadr remaining)))))
 355
 356 (defun keyword-supplied-p (keyword key-list)
 357   (do ((remaining key-list (cddr remaining)))
 358       ((endp remaining))
 359     (when (eq keyword (car remaining))
 360       (return t))))