1 ;;;; This file contains functions that hack on the global function
2 ;;;; namespace (primarily concerned with SETF functions here). Also,
3 ;;;; function encapsulation and routines that set and return
4 ;;;; definitions disregarding whether they might be encapsulated.
6 ;;;; This software is part of the SBCL system. See the README file for
9 ;;;; This software is derived from the CMU CL system, which was
10 ;;;; written at Carnegie Mellon University and released into the
11 ;;;; public domain. The software is in the public domain and is
12 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
13 ;;;; files for more information.
15 (in-package "SB!IMPL")
17 (sb!int
::/show0
"fdefinition.lisp 22")
19 ;;;; fdefinition (fdefn) objects
21 (defun make-fdefn (name)
22 #!-immobile-space
(make-fdefn name
)
23 ;; This is %primitive because it needs pseudo-atomic,
24 ;; otherwise it would just be an alien-funcall.
26 (let ((fdefn (truly-the (values fdefn
)
27 (%primitive sb
!vm
::alloc-immobile-fdefn name
))))
28 (%primitive fdefn-makunbound fdefn
)
31 (defun fdefn-name (fdefn)
32 (declare (type fdefn fdefn
))
35 (defun fdefn-fun (fdefn)
36 (declare (type fdefn fdefn
)
37 (values (or function null
)))
40 (defun (setf fdefn-fun
) (fun fdefn
)
41 (declare (type function fun
)
44 #!+immobile-code
(sb!vm
::%set-fdefn-fun fdefn fun
)
45 #!-immobile-code
(setf (fdefn-fun fdefn
) fun
))
47 (defun fdefn-makunbound (fdefn)
48 (declare (type fdefn fdefn
))
49 (fdefn-makunbound fdefn
))
51 #!-sb-fluid
(declaim (inline symbol-fdefn
))
52 ;; Return SYMBOL's fdefinition, if any, or NIL. SYMBOL must already
53 ;; have been verified to be a symbol by the caller.
54 (defun symbol-fdefn (symbol)
55 (declare (optimize (safety 0)))
56 (info-vector-fdefn (symbol-info-vector symbol
)))
58 ;; Return the fdefn object for NAME, or NIL if there is no fdefn.
59 ;; Signal an error if name isn't valid.
60 ;; Assume that exists-p implies LEGAL-FUN-NAME-P.
62 (declaim (ftype (sfunction ((or symbol list
)) (or fdefn null
)) find-fdefn
))
63 (defun find-fdefn (name)
64 (declare (explicit-check))
65 (when (symbolp name
) ; Don't need LEGAL-FUN-NAME-P check
66 (return-from find-fdefn
(symbol-fdefn name
)))
67 ;; Technically the ALLOW-ATOM argument of NIL isn't needed, but
68 ;; the compiler isn't figuring out not to test SYMBOLP twice in a row.
69 (with-globaldb-name (key1 key2 nil
) name
71 ;; INFO-GETHASH returns NIL or a vector. INFO-VECTOR-FDEFN accepts
72 ;; either. If fdefn isn't found, fall through to the legality test.
73 (awhen (info-vector-fdefn (info-gethash name
*info-environment
*))
74 (return-from find-fdefn it
))
77 (awhen (symbol-info-vector key1
)
78 (multiple-value-bind (data-idx descriptor-idx field-idx
)
79 (info-find-aux-key/packed it key2
)
80 (declare (type index descriptor-idx
)
81 (type (integer 0 #.
+infos-per-word
+) field-idx
))
82 ;; Secondary names must have at least one info, so if a descriptor
83 ;; exists, there's no need to extract the n-infos field.
85 (when (eql (incf field-idx
) +infos-per-word
+)
86 (setq field-idx
0 descriptor-idx
(1+ descriptor-idx
)))
87 (when (eql (packed-info-field it descriptor-idx field-idx
)
89 (return-from find-fdefn
90 (aref it
(1- (the index data-idx
))))))))
91 (when (eq key1
'setf
) ; bypass the legality test
92 (return-from find-fdefn nil
))))
93 (legal-fun-name-or-type-error name
))
95 (declaim (ftype (sfunction (t) fdefn
) find-or-create-fdefn
))
96 (defun find-or-create-fdefn (name)
98 ;; We won't reach here if the name was not legal
99 (let ((fdefn (get-info-value-initializing :function
:definition name
101 (when (typep name
'(cons (eql sb
!pcl
::slot-accessor
)))
102 (sb!pcl
::ensure-accessor name
))
105 ;;; Remove NAME's FTYPE information unless it was explicitly PROCLAIMED.
106 ;;; The NEW-FUNCTION argument is presently unused, but could be used
107 ;;; for checking compatibility of the NEW-FUNCTION against a proclamation.
108 ;;; (We could issue a warning and/or remove the type if incompatible.)
109 (defun maybe-clobber-ftype (name new-function
)
110 (declare (ignore new-function
))
111 (unless (eq :declared
(info :function
:where-from name
))
112 (clear-info :function
:type name
)))
114 ;;; Return the fdefn-fun of NAME's fdefinition including any encapsulations.
115 ;;; LOOKUP-FN, defaulting to FIND-FDEFN, specifies how to lookup the fdefn.
116 ;;; As a special case it can be given as SYMBOL-FDEFN which is slightly quicker.
117 ;;; This is the core of the implementation of the standard FDEFINITION function,
118 ;;; but as we've defined FDEFINITION, that strips encapsulations.
119 (defmacro %coerce-name-to-fun
(name &optional
(lookup-fn 'find-fdefn
)
124 (let ((fdefn (,lookup-fn name
)))
126 (let ((f (fdefn-fun (truly-the fdefn fdefn
))))
127 ;; If STRICTLY-FUNCTIONP is true, we make sure not to return an error
128 ;; trampoline. This extra check ensures that full calls such as
129 ;; (MAPCAR 'OR '()) signal an error that OR isn't a function.
130 ;; This accords with the non-requirement that macros store strictly
131 ;; a function in the symbol that names them. In many implementations,
132 ;; (FUNCTIONP (SYMBOL-FUNCTION 'OR)) => NIL. We want to pretend that.
134 (,@(if strictly-functionp
135 '(unless (macro/special-guard-fun-p f
))
138 (restart-case (error 'undefined-function
:name name
)
140 :report
(lambda (stream)
141 (format stream
"Retry using ~s." name
)))
143 :report
(lambda (stream)
144 (format stream
"Use specified function"))
145 :interactive read-evaluated-form
146 (when (functionp value
)
148 (setf name
(the ,(if (eq lookup-fn
'symbol-fdefn
)
154 ;; Return T if FUNCTION is the error-signaling trampoline
155 ;; for a macro or a special operator. Test for this by seeing
156 ;; whether FUNCTION is the same closure as for a known macro.
157 ;; For cold-init to work, this must pick any macro defined before
158 ;; this function is. A safe choice is a macro from this same file.
159 (declaim (inline macro
/special-guard-fun-p
))
160 (defun macro/special-guard-fun-p
(function)
161 ;; When inlined, this is a few instructions shorter than CLOSUREP
162 ;; if we already know that FUNCTION is a function.
163 ;; It will signal a type error if not, which is the right thing to do anyway.
164 ;; (this isn't quite a true predicate)
165 (and (= (fun-subtype function
) sb
!vm
:closure-header-widetag
)
166 ;; Prior to cold-init fixing up the load-time-value, this compares
167 ;; %closure-fun to 0, which is ok - it returns NIL.
168 (eq (load-time-value (%closure-fun
(symbol-function '%coerce-name-to-fun
))
170 (%closure-fun function
))))
172 ;; Coerce CALLABLE (a function-designator) to a FUNCTION.
173 ;; The compiler emits this when someone tries to FUNCALL something.
174 ;; Extended-function-designators are not accepted,
175 ;; This function declares EXPLICIT-CHECK, and we avoid calling
176 ;; SYMBOL-FUNCTION because that would do another check.
177 ;; It would be great if this could change its error message
178 ;; depending on the input to either:
179 ;; "foo is not a function designator" if not a CALLABLE
180 ;; "foo does not designate a currently defined function"
181 ;; if a symbol does not satisfy FBOUNDP.
182 (defun %coerce-callable-to-fun
(callable)
183 (declare (explicit-check))
186 (symbol (%coerce-name-to-fun callable symbol-fdefn t
))))
189 ;;;; definition encapsulation
191 (defstruct (encapsulation-info (:constructor make-encapsulation-info
194 ;; This is definition's encapsulation type. The encapsulated
195 ;; definition is in the previous ENCAPSULATION-INFO element or
196 ;; installed as the global definition of some function name.
198 ;; the previous, encapsulated definition. This used to be installed
199 ;; as a global definition for some function name, but it was
200 ;; replaced by an encapsulation of type TYPE.
201 (definition nil
:type function
))
203 ;;; Replace the definition of NAME with a function that calls FUNCTION
204 ;;; with the original function and its arguments.
205 ;;; TYPE is whatever you would like to associate with this
206 ;;; encapsulation for identification in case you need multiple
207 ;;; encapsulations of the same name.
208 (defun encapsulate (name type function
)
209 (let* ((fdefn (find-fdefn name
))
210 (underlying-fun (sb!c
:safe-fdefn-fun fdefn
)))
211 (when (typep underlying-fun
'generic-function
)
212 (return-from encapsulate
213 (encapsulate-generic-function underlying-fun type function
)))
214 ;; We must bind and close over INFO. Consider the case where we
215 ;; encapsulate (the second) an encapsulated (the first)
216 ;; definition, and later someone unencapsulates the encapsulated
217 ;; (first) definition. We don't want our encapsulation (second) to
218 ;; bind basic-definition to the encapsulated (first) definition
219 ;; when it no longer exists. When unencapsulating, we make sure to
220 ;; clobber the appropriate INFO structure to allow
221 ;; basic-definition to be bound to the next definition instead of
222 ;; an encapsulation that no longer exists.
223 (let ((info (make-encapsulation-info type underlying-fun
)))
224 (setf (fdefn-fun fdefn
)
225 (named-lambda encapsulation
(&rest args
)
226 (apply function
(encapsulation-info-definition info
)
229 ;;; This is like FIND-IF, except that we do it on a compiled closure's
231 (defun find-if-in-closure (test closure
)
232 (declare (closure closure
))
233 (do-closure-values (value closure
)
234 (when (funcall test value
)
237 ;;; Find the encapsulation info that has been closed over.
238 (defun encapsulation-info (fun)
240 (find-if-in-closure #'encapsulation-info-p fun
)))
242 ;;; When removing an encapsulation, we must remember that
243 ;;; encapsulating definitions close over a reference to the
244 ;;; ENCAPSULATION-INFO that describes the encapsulating definition.
245 ;;; When you find an info with the target type, the previous info in
246 ;;; the chain has the ensulating definition of that type. We take the
247 ;;; encapsulated definition from the info with the target type, and we
248 ;;; store it in the previous info structure whose encapsulating
249 ;;; definition it describes looks to this previous info structure for
250 ;;; a definition to bind (see ENCAPSULATE). When removing the first
251 ;;; info structure, we do something conceptually equal, but
252 ;;; mechanically it is different.
253 (defun unencapsulate (name type
)
254 "Removes NAME's most recent encapsulation of the specified TYPE."
255 (let* ((fdefn (find-fdefn name
))
256 (encap-info (encapsulation-info (fdefn-fun fdefn
))))
257 (declare (type (or encapsulation-info null
) encap-info
))
258 (when (and fdefn
(typep (fdefn-fun fdefn
) 'generic-function
))
259 (return-from unencapsulate
260 (unencapsulate-generic-function (fdefn-fun fdefn
) type
)))
261 (cond ((not encap-info
)
262 ;; It disappeared on us, so don't worry about it.
264 ((eq (encapsulation-info-type encap-info
) type
)
265 ;; It's the first one, so change the fdefn object.
266 (setf (fdefn-fun fdefn
)
267 (encapsulation-info-definition encap-info
)))
269 ;; It must be an interior one, so find it.
271 (let ((next-info (encapsulation-info
272 (encapsulation-info-definition encap-info
))))
274 ;; Not there, so don't worry about it.
276 (when (eq (encapsulation-info-type next-info
) type
)
277 ;; This is it, so unlink us.
278 (setf (encapsulation-info-definition encap-info
)
279 (encapsulation-info-definition next-info
))
281 (setf encap-info next-info
))))))
284 ;;; Does NAME have an encapsulation of the given TYPE?
285 (defun encapsulated-p (name type
)
286 (let ((fdefn (find-fdefn name
)))
287 (when (and fdefn
(typep (fdefn-fun fdefn
) 'generic-function
))
288 (return-from encapsulated-p
289 (encapsulated-generic-function-p (fdefn-fun fdefn
) type
)))
290 (do ((encap-info (encapsulation-info (fdefn-fun fdefn
))
292 (encapsulation-info-definition encap-info
))))
293 ((null encap-info
) nil
)
294 (declare (type (or encapsulation-info null
) encap-info
))
295 (when (eq (encapsulation-info-type encap-info
) type
)
300 ;;; KLUDGE: Er, it looks as though this means that
301 ;;; (FUNCALL (FDEFINITION 'FOO))
302 ;;; doesn't do the same thing as
304 ;;; and (SYMBOL-FUNCTION 'FOO) isn't in general the same thing
305 ;;; as (FDEFINITION 'FOO). That doesn't look like ANSI behavior to me.
306 ;;; Look e.g. at the ANSI definition of TRACE: "Whenever a traced
307 ;;; function is invoked, information about the call, ..". Try this:
308 ;;; (DEFUN FOO () (PRINT "foo"))
311 ;;; (FUNCALL (FDEFINITION 'FOO))
312 ;;; What to do? ANSI says TRACE "Might change the definitions of the
313 ;;; functions named by function-names." Might it be OK to just get
314 ;;; punt all this encapsulation stuff and go back to a simple but
315 ;;; correct implementation of TRACE? We'd lose the ability to redefine
316 ;;; a TRACEd function and keep the trace in place, but that seems
317 ;;; tolerable to me. (Is the wrapper stuff needed for anything else
320 ;;; The only problem I can see with not having a wrapper: If tracing
321 ;;; EQ, EQL, EQUAL, or EQUALP causes its function address to change,
322 ;;; it will mess up the MAKE-HASH-TABLE logic which uses EQ tests
323 ;;; on those function values. But given the ANSI statement about
324 ;;; TRACE causing things to change, that doesn't seem too unreasonable;
325 ;;; and we might even be able to forbid tracing these functions.
326 ;;; -- WHN 2001-11-02
327 (defun fdefinition (name)
328 "Return name's global function definition taking care to respect any
329 encapsulations and to return the innermost encapsulated definition.
331 (declare (explicit-check))
332 (let ((fun (%coerce-name-to-fun name
)))
334 (let ((encap-info (encapsulation-info fun
)))
336 (setf fun
(encapsulation-info-definition encap-info
))
339 (defvar *setf-fdefinition-hook
* nil
340 "A list of functions that (SETF FDEFINITION) invokes before storing the
341 new value. The functions take the function name and the new value.")
343 ;; Reject any "object of implementation-dependent nature" that
344 ;; so happens to be a function in SBCL, but which must not be
345 ;; bound to a function-name by way of (SETF FEDFINITION).
346 (defun err-if-unacceptable-function (object setter
)
347 (declare (notinline macro
/special-guard-fun-p
)) ; not performance-critical
348 (when (macro/special-guard-fun-p object
)
349 (error 'simple-reference-error
350 :references
(list '(:ansi-cl
:function fdefinition
))
351 :format-control
"~S is not acceptable to ~S."
352 :format-arguments
(list object setter
))))
354 (defun %set-fdefinition
(name new-value
)
355 "Set NAME's global function definition."
356 (declare (type function new-value
) (optimize (safety 1)))
357 (declare (explicit-check))
358 (err-if-unacceptable-function new-value
'(setf fdefinition
))
359 (with-single-package-locked-error (:symbol name
"setting fdefinition of ~A")
360 (maybe-clobber-ftype name new-value
)
362 ;; Check for hash-table stuff. Woe onto him that mixes encapsulation
364 (when (and (symbolp name
) (fboundp name
)
365 (boundp '*user-hash-table-tests
*))
366 (let ((old (symbol-function name
)))
367 (declare (special *user-hash-table-tests
*))
368 (dolist (spec *user-hash-table-tests
*)
369 (cond ((eq old
(second spec
))
371 (setf (second spec
) new-value
))
372 ((eq old
(third spec
))
374 (setf (third spec
) new-value
))))))
376 ;; FIXME: This is a good hook to have, but we should probably
377 ;; reserve it for users.
378 (let ((fdefn (find-or-create-fdefn name
)))
379 ;; *SETF-FDEFINITION-HOOK* won't be bound when initially running
380 ;; top level forms in the kernel core startup.
381 (when (boundp '*setf-fdefinition-hook
*)
382 (dolist (f *setf-fdefinition-hook
*)
383 (declare (type function f
))
384 (funcall f name new-value
)))
386 (let ((encap-info (encapsulation-info (fdefn-fun fdefn
))))
391 (encapsulation-info-definition encap-info
))))
393 (setf encap-info more-info
)
395 (setf (encapsulation-info-definition encap-info
)
398 (setf (fdefn-fun fdefn
) new-value
)))))))
400 ;;;; FBOUNDP and FMAKUNBOUND
402 (defun fboundp (name)
403 "Return true if name has a global function definition."
404 (declare (explicit-check))
405 (let ((fdefn (find-fdefn name
)))
406 (and fdefn
(fdefn-fun fdefn
) t
)))
408 ;; Byte index 2 of the fdefn's header is the statically-linked flag
410 (defmacro sb
!vm
::fdefn-has-static-callers
(fdefn)
411 `(sap-ref-8 (int-sap (get-lisp-obj-address ,fdefn
))
412 (- 2 sb
!vm
::other-pointer-lowtag
)))
414 (defun fmakunbound (name)
415 "Make NAME have no global function definition."
416 (declare (explicit-check))
417 (with-single-package-locked-error
418 (:symbol name
"removing the function or macro definition of ~A")
419 (let ((fdefn (find-fdefn name
)))
422 (unless (eql (sb!vm
::fdefn-has-static-callers fdefn
) 0)
423 (sb!vm
::remove-static-links fdefn
))
424 (fdefn-makunbound fdefn
)))
425 (undefine-fun-name name
)