1 ;;;; various user-level definitions which need to be done particularly
4 ;;;; This software is part of the SBCL system. See the README file for
7 ;;;; This software is derived from the CMU CL system, which was
8 ;;;; written at Carnegie Mellon University and released into the
9 ;;;; public domain. The software is in the public domain and is
10 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
11 ;;;; files for more information.
13 (in-package "SB!IMPL")
15 ;;;; target constants which need to appear as early as possible
17 ;;; an internal tag for marking empty slots, which needs to be defined
18 ;;; as early as possible because it appears in macroexpansions for
19 ;;; iteration over hash tables
21 ;;; CMU CL 18b used :EMPTY for this purpose, which was somewhat nasty
22 ;;; since it's easily accessible to the user, so that e.g.
23 ;;; (DEFVAR *HT* (MAKE-HASH-TABLE))
24 ;;; (SETF (GETHASH :EMPTY *HT*) :EMPTY)
25 ;;; (MAPHASH (LAMBDA (K V) (FORMAT T "~&~S ~S~%" K V)))
26 ;;; gives no output -- oops!
28 ;;; FIXME: It'd probably be good to use the unbound marker for this.
29 ;;; However, there might be some gotchas involving assumptions by
30 ;;; e.g. AREF that they're not going to return the unbound marker,
31 ;;; and there's also the noted-below problem that the C-level code
32 ;;; contains implicit assumptions about this marker.
34 ;;; KLUDGE: Note that as of version 0.pre7 there's a dependence in the
35 ;;; gencgc.c code on this value being a symbol. (This is only one of
36 ;;; several nasty dependencies between that code and this, alas.)
38 (eval-when (:compile-toplevel
:load-toplevel
:execute
)
39 (def!constant
+empty-ht-slot
+ '%empty-ht-slot%
))
40 ;;; We shouldn't need this mess now that EVAL-WHEN works.
42 ;;; KLUDGE: Using a private symbol still leaves us vulnerable to users
43 ;;; getting nonconforming behavior by messing around with
44 ;;; DO-ALL-SYMBOLS. That seems like a fairly obscure problem, so for
45 ;;; now we just don't worry about it. If for some reason it becomes
46 ;;; worrisome and the magic value needs replacement:
47 ;;; * The replacement value needs to be LOADable with EQL preserved,
48 ;;; so that the macroexpansion for WITH-HASH-TABLE-ITERATOR will
49 ;;; work when compiled into a file and loaded back into SBCL.
50 ;;; (Thus, just uninterning %EMPTY-HT-SLOT% doesn't work.)
51 ;;; * The replacement value needs to be acceptable to the
52 ;;; low-level gencgc.lisp hash table scavenging code.
53 ;;; * The change will break binary compatibility, since comparisons
54 ;;; against the value used at the time of compilation are wired
58 ;;;; DO-related stuff which needs to be visible on the cross-compilation host
60 (eval-when (#-sb-xc
:compile-toplevel
:load-toplevel
:execute
)
61 (defun frob-do-body (varlist endlist decls-and-code bind step name block
)
62 (let* ((r-inits nil
) ; accumulator for reversed list
63 (r-steps nil
) ; accumulator for reversed list
66 ;; Check for illegal old-style DO.
67 (when (or (not (listp varlist
)) (atom endlist
))
68 (error "ill-formed ~S -- possibly illegal old style DO?" name
))
69 ;; Parse VARLIST to get R-INITS and R-STEPS.
71 (flet (;; (We avoid using CL:PUSH here so that CL:PUSH can be
72 ;; defined in terms of CL:SETF, and CL:SETF can be
73 ;; defined in terms of CL:DO, and CL:DO can be defined
74 ;; in terms of the current function.)
76 (setq r-inits
(cons x r-inits
)))
77 ;; common error-handling
79 (error "~S is an illegal form for a ~S varlist." v name
)))
80 (cond ((symbolp v
) (push-on-r-inits v
))
82 (unless (symbolp (first v
))
83 (error "~S step variable is not a symbol: ~S"
86 (let ((lv (length v
)))
87 ;; (We avoid using CL:CASE here so that CL:CASE can
88 ;; be defined in terms of CL:SETF, and CL:SETF can
89 ;; be defined in terms of CL:DO, and CL:DO can be
90 ;; defined in terms of the current function.)
92 (push-on-r-inits (first v
)))
96 (push-on-r-inits (list (first v
) (second v
)))
97 (setq r-steps
(list* (third v
) (first v
) r-steps
)))
98 (t (illegal-varlist)))))
99 (t (illegal-varlist)))))
100 ;; Construct the new form.
101 (multiple-value-bind (code decls
)
102 (parse-body decls-and-code
:doc-string-allowed nil
)
104 (,bind
,(nreverse r-inits
)
110 (,step
,@(nreverse r-steps
))
112 (unless ,(first endlist
) (go ,label-1
))
113 (return-from ,block
(progn ,@(rest endlist
))))))))))
115 ;; Define "exchanged subtract" So that DECF on a symbol requires no LET binding:
116 ;; (DECF I (EXPR)) -> (SETQ I (XSUBTRACT (EXPR) I))
117 ;; which meets the CLHS 5.1.3 requirement to eval (EXPR) prior to reading
118 ;; the old value of I. Formerly in 'setf' but too late to avoid full calls.
119 (declaim (inline xsubtract
))
120 (defun xsubtract (a b
) (- b a
))
124 ;;; Automate an idiom often found in macros:
125 ;;; (LET ((FOO (GENSYM "FOO"))
126 ;;; (MAX-INDEX (GENSYM "MAX-INDEX-")))
129 ;;; "Good notation eliminates thought." -- Eric Siggia
131 ;;; Incidentally, this is essentially the same operator which
132 ;;; _On Lisp_ calls WITH-GENSYMS.
133 (defmacro with-unique-names
(symbols &body body
)
134 `(let ,(mapcar (lambda (symbol)
135 (let* ((symbol-name (symbol-name symbol
))
136 (stem (if (every #'alpha-char-p symbol-name
)
138 (concatenate 'string symbol-name
"-"))))
139 `(,symbol
(sb!xc
:gensym
,stem
))))
143 ;;; Return a list of N gensyms. (This is a common suboperation in
144 ;;; macros and other code-manipulating code.)
145 (declaim (ftype (function (unsigned-byte &optional t
) (values list
&optional
))
147 (defun make-gensym-list (n &optional name
)
148 (let ((arg (if name
(string name
) "G")))
149 (loop repeat n collect
(sb!xc
:gensym arg
))))
153 ;;; Lots of code wants to get to the KEYWORD package or the
154 ;;; COMMON-LISP package without a lot of fuss, so we cache them in
155 ;;; variables on the host, or use L-T-V forms on the target.
156 (macrolet ((def-it (sym expr
)
158 `(progn (declaim (type package
,sym
))
159 (defglobal ,sym
,expr
))
161 ;; We don't need to declaim the type. FIND-PACKAGE
162 ;; returns a package, and L-T-V propagates types.
163 ;; It's ugly how it achieves that, but it's a separate concern.
164 `(define-symbol-macro ,sym
(load-time-value ,expr t
))))
165 (def-it *cl-package
* (find-package "COMMON-LISP"))
166 (def-it *keyword-package
* (find-package "KEYWORD")))
168 ;;; Concatenate together the names of some strings and symbols,
169 ;;; producing a symbol in the current package.
170 (eval-when (#-sb-xc
:compile-toplevel
:load-toplevel
:execute
)
171 (defun symbolicate (&rest things
)
172 (declare (dynamic-extent things
))
175 (if (singleton-p things
)
176 (string (first things
))
177 (let* ((length (reduce #'+ things
178 :key
(lambda (x) (length (string x
)))))
179 (name (make-array length
:element-type
'character
))
181 (dolist (thing things name
)
182 (let ((x (string thing
)))
183 (replace name x
:start1 index
)
184 (incf index
(length x
))))))))))
188 (sb!xc
:gensym
(symbol-name x
))
191 ;;; like SYMBOLICATE, but producing keywords
192 (defun keywordicate (&rest things
)
193 (let ((*package
* *keyword-package
*))
194 (apply #'symbolicate things
)))
196 ;;; Access *PACKAGE* in a way which lets us recover when someone has
197 ;;; done something silly like (SETF *PACKAGE* :CL-USER) in unsafe code.
198 ;;; (Such an assignment is undefined behavior, so it's sort of reasonable for
199 ;;; it to cause the system to go totally insane afterwards, but it's a
200 ;;; fairly easy mistake to make, so let's try to recover gracefully instead.)
201 ;;; This function is called while compiling this file because DO-ANONYMOUS
202 ;;; is a delayed-def!macro, the constructor for which calls SANE-PACKAGE.
203 (eval-when (:load-toplevel
:execute
#+sb-xc-host
:compile-toplevel
)
204 (defun sane-package ()
205 ;; Perhaps it's possible for *PACKAGE* to be set to a non-package in some
206 ;; host Lisp, but in SBCL it isn't, and the PACKAGEP test below would be
207 ;; elided unless forced to be NOTINLINE.
208 (declare (notinline packagep
))
209 (let* ((maybe-package *package
*)
210 (packagep (packagep maybe-package
)))
211 ;; And if we don't also always check for deleted packages - as was true
212 ;; when the "#+sb-xc-host" reader condition was absent - then half of the
213 ;; COND becomes unreachable, making this function merely return *PACKAGE*
214 ;; in the cross-compiler, producing a code deletion note.
216 ;; For good measure, we also catch the problem of
217 ;; *PACKAGE* being bound to a deleted package.
218 ;; Technically, this is not undefined behavior in itself,
219 ;; but it will immediately lead to undefined to behavior,
220 ;; since almost any operation on a deleted package is
222 ;; The "%" accessor avoids calling %FIND-PACKAGE-OR-LOSE,
223 ;; though it probably does not make much difference, if any.
224 (#+sb-xc-host package-name
#-sb-xc-host package-%name
228 ;; We're in the undefined behavior zone. First, munge the
229 ;; system back into a defined state.
230 (let ((really-package
231 (load-time-value (find-package :cl-user
) t
)))
232 (setf *package
* really-package
)
234 (error 'simple-type-error
236 :expected-type
'(and package
(satisfies package-name
))
238 "~@<~S can't be a ~A: ~2I~_It has been reset to ~S.~:>"
239 :format-arguments
(list '*package
*
242 (type-of maybe-package
))
243 really-package
))))))))
245 ;;; Access *DEFAULT-PATHNAME-DEFAULTS*, issuing a warning if its value
246 ;;; is silly. (Unlike the vaguely-analogous SANE-PACKAGE, we don't
247 ;;; actually need to reset the variable when it's silly, since even
248 ;;; crazy values of *DEFAULT-PATHNAME-DEFAULTS* don't leave the system
249 ;;; in a state where it's hard to recover interactively.)
250 (defun sane-default-pathname-defaults ()
251 (let* ((dfd *default-pathname-defaults
*)
252 (dfd-dir (pathname-directory dfd
)))
253 ;; It's generally not good to use a relative pathname for
254 ;; *DEFAULT-PATHNAME-DEFAULTS*, since relative pathnames
255 ;; are defined by merging into a default pathname (which is,
256 ;; by default, *DEFAULT-PATHNAME-DEFAULTS*).
257 (when (and (consp dfd-dir
)
258 (eql (first dfd-dir
) :relative
))
260 "~@<~S is a relative pathname. (But we'll try using it anyway.)~@:>"
261 '*default-pathname-defaults
*))
264 ;;; Compile a version of BODY for all TYPES, and dispatch to the
265 ;;; correct one based on the value of VAR. This was originally used
266 ;;; only for strings, hence the name. Renaming it to something more
267 ;;; generic might not be a bad idea.
268 (def!macro string-dispatch
((&rest types
) var
&body body
)
269 (let ((fun (sb!xc
:gensym
"STRING-DISPATCH-FUN")))
272 (declare (inline ,fun
))
274 ,@(loop for type in types
275 ;; TRULY-THE allows transforms to take advantage of the type
276 ;; information without need for constraint propagation.
277 collect
`(,type
(,fun
(truly-the ,type
,var
))))))))
279 ;;; Give names to elements of a numeric sequence.
280 (defmacro defenum
((&key
(start 0) (step 1))
286 (dolist (id identifiers
)
288 (multiple-value-bind (sym docs
)
290 (values (car id
) (cdr id
))
292 (push `(def!constant
,sym
293 ,(+ start
(* step index
))
298 ,@(nreverse results
))))
300 ;;; generalization of DEFCONSTANT to values which are the same not
301 ;;; under EQL but under e.g. EQUAL or EQUALP
303 ;;; DEFCONSTANT-EQX is to be used instead of DEFCONSTANT for values
304 ;;; which are appropriately compared using the function given by the
305 ;;; EQX argument instead of EQL.
307 (defmacro defconstant-eqx
(symbol expr eqx
&optional doc
)
308 `(def!constant
,symbol
309 (%defconstant-eqx-value
',symbol
,expr
,eqx
)
310 ,@(when doc
(list doc
))))
311 (defun %defconstant-eqx-value
(symbol expr eqx
)
312 (declare (type function eqx
))
313 (flet ((bummer (explanation)
314 (error "~@<bad DEFCONSTANT-EQX ~S ~2I~_~S: ~2I~_~A ~S~:>"
318 (symbol-value symbol
))))
319 (cond ((not (boundp symbol
))
321 ((not (constantp symbol
))
322 (bummer "already bound as a non-constant"))
323 ((not (funcall eqx
(symbol-value symbol
) expr
))
324 (bummer "already bound as a different constant value"))
326 (symbol-value symbol
)))))
328 ;;; a helper function for various macros which expect clauses of a
329 ;;; given length, etc.
331 ;;; Return true if X is a proper list whose length is between MIN and
333 (defun proper-list-of-length-p (x min
&optional
(max min
))
334 ;; FIXME: This implementation will hang on circular list
335 ;; structure. Since this is an error-checking utility, i.e. its
336 ;; job is to deal with screwed-up input, it'd be good style to fix
337 ;; it so that it can deal with circular list structure.
338 (cond ((minusp max
) nil
)
339 ((null x
) (zerop min
))
342 (proper-list-of-length-p (cdr x
)
349 (defun proper-list-p (x)
351 (return-from proper-list-p
(null x
)))
352 (let ((rabbit (cdr x
))
354 (flet ((pop-rabbit ()
355 (when (eql rabbit turtle
) ; circular
356 (return-from proper-list-p nil
))
358 (return-from proper-list-p
(null rabbit
)))
364 ;;; Helpers for defining error-signalling NOP's for "not supported
365 ;;; here" operations.
366 (defmacro define-unsupported-fun
(name &optional
367 (doc "Unsupported on this platform.")
369 "~S is unsupported on this platform ~
370 (OS, CPU, whatever)."
373 (declare (ignorable doc
))
374 `(defun ,name
(&rest args
)
377 (declare (ignore args
))
378 (error 'unsupported-operator
379 :format-control
,control
380 :format-arguments
(if ,controlp
',arguments
(list ',name
)))))
382 ;;; This is like DO, except it has no implicit NIL block.
383 (def!macro do-anonymous
(varlist endlist
&rest body
)
384 (frob-do-body varlist endlist body
'let
'psetq
'do-anonymous
(gensym)))
387 (defmacro awhen
(test &body body
)
391 (defmacro acond
(&rest clauses
)
394 (destructuring-bind ((test &body body
) &rest rest
) clauses
395 (let ((it (copy-symbol 'it
)))
398 (let ((it ,it
)) (declare (ignorable it
)) ,@body
)