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)
24 (defun fdefn-name (fdefn)
25 (declare (type fdefn fdefn))
28 (defun fdefn-fun (fdefn)
29 (declare (type fdefn fdefn)
30 (values (or function null)))
33 (defun (setf fdefn-fun) (fun fdefn)
34 (declare (type function fun)
37 (setf (fdefn-fun fdefn) fun))
39 (defun fdefn-makunbound (fdefn)
40 (declare (type fdefn fdefn))
41 (fdefn-makunbound fdefn))
43 ;;; This function is called by !COLD-INIT after the globaldb has been
44 ;;; initialized, but before anything else. We need to install these
45 ;;; fdefn objects into the globaldb before any top level forms run, or
46 ;;; we will end up with two different fdefn objects being used for the
47 ;;; same function name. *!INITIAL-FDEFN-OBJECTS* is set up by GENESIS.
48 (defvar *!initial-fdefn-objects*)
49 (defun !fdefn-cold-init ()
50 (dolist (fdefn *!initial-fdefn-objects*)
51 (setf (info :function :definition (fdefn-name fdefn)) fdefn)))
53 ;;; Return the fdefn object for NAME. If it doesn't already exist and
54 ;;; CREATE is non-NIL, create a new (unbound) one.
55 (defun fdefinition-object (name create)
56 (declare (values (or fdefn null)))
57 (legal-fun-name-or-type-error name)
58 (let ((fdefn (info :function :definition name)))
59 (if (and (null fdefn) create)
60 (setf (info :function :definition name) (make-fdefn name))
63 ;;; Return the fdefinition of NAME, including any encapsulations.
64 ;;; The compiler emits calls to this when someone tries to FUNCALL
65 ;;; something. SETFable.
66 #!-sb-fluid (declaim (inline %coerce-name-to-fun))
67 (defun %coerce-name-to-fun (name)
68 (let ((fdefn (fdefinition-object name nil)))
69 (or (and fdefn (fdefn-fun fdefn))
70 (error 'undefined-function :name name))))
71 (defun (setf %coerce-name-to-fun) (function name)
72 (let ((fdefn (fdefinition-object name t)))
73 (setf (fdefn-fun fdefn) function)))
75 (defun %coerce-callable-to-fun (callable)
76 (if (functionp callable)
78 (%coerce-name-to-fun callable)))
80 ;;;; definition encapsulation
82 (defstruct (encapsulation-info (:constructor make-encapsulation-info
85 ;; This is definition's encapsulation type. The encapsulated
86 ;; definition is in the previous encapsulation-info element or
87 ;; installed as the global definition of some function name.
89 ;; the previous, encapsulated definition. This used to be installed
90 ;; as a global definition for some function name, but it was
91 ;; replaced by an encapsulation of type TYPE.
92 (definition nil :type function))
94 ;;; Replace the definition of NAME with a function that binds NAME's
95 ;;; arguments to a variable named ARG-LIST, binds name's definition
96 ;;; to a variable named BASIC-DEFINITION, and evaluates BODY in that
97 ;;; context. TYPE is whatever you would like to associate with this
98 ;;; encapsulation for identification in case you need multiple
99 ;;; encapsulations of the same name.
100 (defun encapsulate (name type body)
101 (let ((fdefn (fdefinition-object name nil)))
102 (unless (and fdefn (fdefn-fun fdefn))
103 (error 'undefined-function :name name))
104 ;; We must bind and close over INFO. Consider the case where we
105 ;; encapsulate (the second) an encapsulated (the first)
106 ;; definition, and later someone unencapsulates the encapsulated
107 ;; (first) definition. We don't want our encapsulation (second) to
108 ;; bind basic-definition to the encapsulated (first) definition
109 ;; when it no longer exists. When unencapsulating, we make sure to
110 ;; clobber the appropriate INFO structure to allow
111 ;; basic-definition to be bound to the next definition instead of
112 ;; an encapsulation that no longer exists.
113 (let ((info (make-encapsulation-info type (fdefn-fun fdefn))))
114 (setf (fdefn-fun fdefn)
115 (lambda (&rest arg-list)
116 (declare (special arg-list))
117 (let ((basic-definition (encapsulation-info-definition info)))
118 (declare (special basic-definition))
121 ;;; This is like FIND-IF, except that we do it on a compiled closure's
123 (defun find-if-in-closure (test fun)
124 (dotimes (index (1- (get-closure-length fun)))
125 (let ((elt (%closure-index-ref fun index)))
126 (when (funcall test elt)
129 ;;; Find the encapsulation info that has been closed over.
130 (defun encapsulation-info (fun)
132 (= (widetag-of fun) sb!vm:closure-header-widetag)
133 (find-if-in-closure #'encapsulation-info-p fun)))
135 ;;; When removing an encapsulation, we must remember that
136 ;;; encapsulating definitions close over a reference to the
137 ;;; encapsulation-info that describes the encapsulating definition.
138 ;;; When you find an info with the target type, the previous info in
139 ;;; the chain has the ensulating definition of that type. We take the
140 ;;; encapsulated definition from the info with the target type, and we
141 ;;; store it in the previous info structure whose encapsulating
142 ;;; definition it describes looks to this previous info structure for
143 ;;; a definition to bind (see ENCAPSULATE). When removing the first
144 ;;; info structure, we do something conceptually equal, but
145 ;;; mechanically it is different.
146 (defun unencapsulate (name type)
148 "Removes NAME's most recent encapsulation of the specified TYPE."
149 (let* ((fdefn (fdefinition-object name nil))
150 (encap-info (encapsulation-info (fdefn-fun fdefn))))
151 (declare (type (or encapsulation-info null) encap-info))
152 (cond ((not encap-info)
153 ;; It disappeared on us, so don't worry about it.
155 ((eq (encapsulation-info-type encap-info) type)
156 ;; It's the first one, so change the fdefn object.
157 (setf (fdefn-fun fdefn)
158 (encapsulation-info-definition encap-info)))
160 ;; It must be an interior one, so find it.
162 (let ((next-info (encapsulation-info
163 (encapsulation-info-definition encap-info))))
165 ;; Not there, so don't worry about it.
167 (when (eq (encapsulation-info-type next-info) type)
168 ;; This is it, so unlink us.
169 (setf (encapsulation-info-definition encap-info)
170 (encapsulation-info-definition next-info))
172 (setf encap-info next-info))))))
175 ;;; Does NAME have an encapsulation of the given TYPE?
176 (defun encapsulated-p (name type)
177 (let ((fdefn (fdefinition-object name nil)))
178 (do ((encap-info (encapsulation-info (fdefn-fun fdefn))
180 (encapsulation-info-definition encap-info))))
181 ((null encap-info) nil)
182 (declare (type (or encapsulation-info null) encap-info))
183 (when (eq (encapsulation-info-type encap-info) type)
188 ;;; KLUDGE: Er, it looks as though this means that
189 ;;; (FUNCALL (FDEFINITION 'FOO))
190 ;;; doesn't do the same thing as
192 ;;; and (SYMBOL-FUNCTION 'FOO) isn't in general the same thing
193 ;;; as (FDEFINITION 'FOO). That doesn't look like ANSI behavior to me.
194 ;;; Look e.g. at the ANSI definition of TRACE: "Whenever a traced
195 ;;; function is invoked, information about the call, ..". Try this:
196 ;;; (DEFUN FOO () (PRINT "foo"))
199 ;;; (FUNCALL (FDEFINITION 'FOO))
200 ;;; What to do? ANSI says TRACE "Might change the definitions of the
201 ;;; functions named by function-names." Might it be OK to just get
202 ;;; punt all this encapsulation stuff and go back to a simple but
203 ;;; correct implementation of TRACE? We'd lose the ability to redefine
204 ;;; a TRACEd function and keep the trace in place, but that seems
205 ;;; tolerable to me. (Is the wrapper stuff needed for anything else
208 ;;; The only problem I can see with not having a wrapper: If tracing
209 ;;; EQ, EQL, EQUAL, or EQUALP causes its function address to change,
210 ;;; it will mess up the MAKE-HASH-TABLE logic which uses EQ tests
211 ;;; on those function values. But given the ANSI statement about
212 ;;; TRACE causing things to change, that doesn't seem too unreasonable;
213 ;;; and we might even be able to forbid tracing these functions.
214 ;;; -- WHN 2001-11-02
215 (defun fdefinition (name)
217 "Return name's global function definition taking care to respect any
218 encapsulations and to return the innermost encapsulated definition.
220 (let ((fun (%coerce-name-to-fun name)))
222 (let ((encap-info (encapsulation-info fun)))
224 (setf fun (encapsulation-info-definition encap-info))
227 (defvar *setf-fdefinition-hook* nil
229 "This holds functions that (SETF FDEFINITION) invokes before storing the
230 new value. These functions take the function name and the new value.")
232 (defun %set-fdefinition (name new-value)
234 "Set NAME's global function definition."
235 (declare (type function new-value) (optimize (safety 1)))
236 (let ((fdefn (fdefinition-object name t)))
237 ;; *SETF-FDEFINITION-HOOK* won't be bound when initially running
238 ;; top level forms in the kernel core startup.
239 (when (boundp '*setf-fdefinition-hook*)
240 (dolist (f *setf-fdefinition-hook*)
241 (funcall f name new-value)))
243 (let ((encap-info (encapsulation-info (fdefn-fun fdefn))))
248 (encapsulation-info-definition encap-info))))
250 (setf encap-info more-info)
252 (setf (encapsulation-info-definition encap-info)
255 (setf (fdefn-fun fdefn) new-value))))))
257 ;;;; FBOUNDP and FMAKUNBOUND
259 (defun fboundp (name)
261 "Return true if name has a global function definition."
262 (let ((fdefn (fdefinition-object name nil)))
263 (and fdefn (fdefn-fun fdefn) t)))
265 (defun fmakunbound (name)
267 "Make NAME have no global function definition."
268 (let ((fdefn (fdefinition-object name nil)))
270 (fdefn-makunbound fdefn)))
271 (sb!kernel:undefine-fun-name name)