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1 | ;;; -*-lisp-*- |
2 | ;;; | |
dea4d055 | 3 | ;;; Class finalization implementation |
abdf50aa MW |
4 | ;;; |
5 | ;;; (c) 2009 Straylight/Edgeware | |
6 | ;;; | |
7 | ||
8 | ;;;----- Licensing notice --------------------------------------------------- | |
9 | ;;; | |
e0808c47 | 10 | ;;; This file is part of the Sensible Object Design, an object system for C. |
abdf50aa MW |
11 | ;;; |
12 | ;;; SOD is free software; you can redistribute it and/or modify | |
13 | ;;; it under the terms of the GNU General Public License as published by | |
14 | ;;; the Free Software Foundation; either version 2 of the License, or | |
15 | ;;; (at your option) any later version. | |
16 | ;;; | |
17 | ;;; SOD is distributed in the hope that it will be useful, | |
18 | ;;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
20 | ;;; GNU General Public License for more details. | |
21 | ;;; | |
22 | ;;; You should have received a copy of the GNU General Public License | |
23 | ;;; along with SOD; if not, write to the Free Software Foundation, | |
24 | ;;; Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
25 | ||
26 | (cl:in-package #:sod) | |
27 | ||
28 | ;;;-------------------------------------------------------------------------- | |
dea4d055 | 29 | ;;; Class precedence lists. |
abdf50aa | 30 | |
dea4d055 MW |
31 | ;; Just for fun, we implement a wide selection of precedence list algorithms. |
32 | ;; C3 seems to be clearly the best, with fewer sharp edges for the unwary. | |
abdf50aa MW |
33 | ;; |
34 | ;; The extended precedence graph (EPG) is constructed by adding edges to the | |
35 | ;; superclass graph. If A and B are classes, then write A < B if A is a | |
36 | ;; (maybe indirect) subclass of B. For every two classes A and B, and for | |
37 | ;; every /maximal/ subclass of both A and B (i.e., every C for which C < A | |
38 | ;; and C < B, but there does not exist D such that D < A, D < B and C < D): | |
39 | ;; if A precedes B in C's direct superclass list, then draw an edge A -> B, | |
40 | ;; otherwise draw the edge B -> A. | |
41 | ;; | |
42 | ;; A linearization respects the EPG if, whenever A precedes B in the | |
43 | ;; linearization, there is a path from A to B. The EPG can be cyclic; in | |
44 | ;; that case, we don't care which order the classes in the cycle are | |
45 | ;; linearized. | |
46 | ;; | |
47 | ;; See Barrett, Cassels, Haahr, Moon, Playford, Withington, `A Monotonic | |
48 | ;; Superclass Linearization for Dylan' for more detail. | |
49 | ;; http://www.webcom.com/haahr/dylan/linearization-oopsla96.html | |
50 | ||
e2838dc5 MW |
51 | ;;; Utilities. |
52 | ||
0dca577d MW |
53 | (export 'report-class-list-merge-error) |
54 | (defun report-class-list-merge-error (class lists error) | |
55 | "Report a failure to merge superclasseses. | |
56 | ||
57 | Here, CLASS is the class whose class precedence list we're trying to | |
58 | compute; the LISTS are the individual superclass orderings being merged; | |
59 | and ERROR is an `inconsistent-merge-error' describing the problem that was | |
60 | encountered. | |
61 | ||
62 | Each of the LISTS is assumed to begin with the class from which the | |
63 | corresponding constraint originates; see `merge-class-lists'." | |
64 | ||
65 | (let* ((state (make-inheritance-path-reporter-state class)) | |
66 | (candidates (merge-error-candidates error)) | |
67 | (focus (remove-duplicates | |
68 | (remove nil | |
69 | (mapcar (lambda (list) | |
70 | (cons (car list) | |
71 | (remove-if-not | |
72 | (lambda (item) | |
73 | (member item candidates)) | |
74 | list))) | |
75 | lists) | |
76 | :key #'cddr) | |
77 | :test #'equal :key #'cdr))) | |
78 | ||
79 | (cerror*-with-location class "Ill-formed superclass graph: ~ | |
80 | can't construct class precedence list ~ | |
81 | for `~A'" | |
82 | class) | |
83 | (dolist (offenders focus) | |
84 | (let ((super (car offenders))) | |
85 | (info-with-location super | |
86 | "~{Class `~A' orders `~A' before ~ | |
87 | ~#[<BUG>~;`~A'~;`~A' and `~A'~:;~ | |
88 | ~@{`~A', ~#[~;and `~A'~]~}~]~}" | |
89 | offenders) | |
90 | (report-inheritance-path state super))))) | |
91 | ||
e2838dc5 | 92 | (export 'merge-class-lists) |
c05ed0f1 | 93 | (defun merge-class-lists (class lists pick) |
0dca577d | 94 | "Merge the LISTS of superclasses of CLASS, using PICK to break ties. |
e2838dc5 MW |
95 | |
96 | This is a convenience wrapper around the main `merge-lists' function. | |
97 | Given that class linearizations (almost?) always specify a custom | |
0dca577d MW |
98 | tiebreaker function, this isn't a keyword argument. |
99 | ||
100 | If a merge error occurs, this function translates it into a rather more | |
101 | useful form, and tries to provide helpful notes. | |
102 | ||
103 | For error reporting purposes, it's assumed that each of the LISTS begins | |
104 | with the class from which the corresponding constraint originates. This | |
105 | initial class does double-duty: it is also considered to be part of the | |
106 | list for the purpose of the merge." | |
107 | ||
c05ed0f1 | 108 | (handler-case (merge-lists lists :pick pick) |
0dca577d MW |
109 | (inconsistent-merge-error (error) |
110 | (report-class-list-merge-error class lists error) | |
111 | (continue error)))) | |
e2838dc5 | 112 | |
dea4d055 MW |
113 | ;;; Tiebreaker functions. |
114 | ||
abdf50aa MW |
115 | (defun clos-tiebreaker (candidates so-far) |
116 | "The CLOS linearization tiebreaker function. | |
117 | ||
bf090e02 MW |
118 | Intended for use with `merge-lists'. Returns the member of CANDIDATES |
119 | which has a direct subclass furthest to the right in the list SO-FAR. | |
abdf50aa MW |
120 | |
121 | This must disambiguate. The SO-FAR list cannot be empty, since the class | |
122 | under construction precedes all of the others. If two classes share a | |
123 | direct subclass then that subclass's direct superclasses list must order | |
124 | them relative to each other." | |
125 | ||
b045196c | 126 | (dolist (class (reverse so-far)) |
566c6a6a MW |
127 | (dolist (candidate candidates) |
128 | (when (member candidate (sod-class-direct-superclasses class)) | |
129 | (return-from clos-tiebreaker candidate)))) | |
130 | (error "SOD INTERNAL ERROR: Failed to break tie in CLOS")) | |
abdf50aa | 131 | |
dea4d055 MW |
132 | (defun c3-tiebreaker (candidates cpls) |
133 | "The C3 linearization tiebreaker function. | |
134 | ||
bf090e02 MW |
135 | Intended for use with `merge-lists'. Returns the member of CANDIDATES |
136 | which appears in the earliest element of CPLS, which should be the list of | |
137 | the class precedence lists of the direct superclasses of the class in | |
dea4d055 MW |
138 | question, in the order specified in the class declaration. |
139 | ||
140 | The only class in the class precedence list which does not appear in one | |
141 | of these lists is the new class itself, which must precede all of the | |
142 | others. | |
143 | ||
144 | This must disambiguate, since if two classes are in the same class | |
145 | precedence list, then one must appear in it before the other, which | |
146 | provides an ordering between them. (In this situation we return the one | |
147 | that matches earliest anyway, which would still give the right answer.) | |
148 | ||
149 | Note that this will merge the CPLs of superclasses /as they are/, not | |
150 | necessarily as C3 would have computed them. This ensures monotonicity | |
151 | assuming that the superclass CPLs are already monotonic. If they aren't, | |
152 | you're going to lose anyway." | |
153 | ||
154 | (dolist (cpl cpls) | |
155 | (dolist (candidate candidates) | |
156 | (when (member candidate cpl) | |
157 | (return-from c3-tiebreaker candidate)))) | |
a1985b3c | 158 | (error "SOD INTERNAL ERROR: Failed to break tie in C3")) |
dea4d055 MW |
159 | |
160 | ;;; Linearization functions. | |
161 | ||
11e41ddf | 162 | (export 'clos-cpl) |
abdf50aa MW |
163 | (defun clos-cpl (class) |
164 | "Compute the class precedence list of CLASS using CLOS linearization rules. | |
165 | ||
166 | We merge the direct-superclass lists of all of CLASS's superclasses, | |
bf090e02 | 167 | disambiguating using `clos-tiebreaker'. |
abdf50aa MW |
168 | |
169 | The CLOS linearization preserves local class ordering, but is not | |
170 | monotonic, and does not respect the extended precedence graph. CLOS | |
171 | linearization will succeed whenever Dylan or C3 linearization succeeds; | |
172 | the converse is not true." | |
173 | ||
174 | (labels ((superclasses (class) | |
175 | (let ((direct-supers (sod-class-direct-superclasses class))) | |
176 | (remove-duplicates (cons class | |
1f1d88f5 MW |
177 | (mappend #'superclasses |
178 | direct-supers)))))) | |
c05ed0f1 MW |
179 | (merge-class-lists class |
180 | (mapcar (lambda (c) | |
5d55bdaa MW |
181 | (cons c (sod-class-direct-superclasses c))) |
182 | (superclasses class)) | |
183 | #'clos-tiebreaker))) | |
abdf50aa | 184 | |
11e41ddf | 185 | (export 'dylan-cpl) |
abdf50aa MW |
186 | (defun dylan-cpl (class) |
187 | "Compute the class precedence list of CLASS using Dylan linearization | |
188 | rules. | |
189 | ||
190 | We merge the direct-superclass list of CLASS with the full class | |
191 | precedence lists of its direct superclasses, disambiguating using | |
bf090e02 | 192 | `clos-tiebreaker'. (Inductively, these lists will be consistent with the |
abdf50aa MW |
193 | CPLs of indirect superclasses, since those CPLs' orderings are reflected |
194 | in the CPLs of the direct superclasses.) | |
195 | ||
196 | The Dylan linearization preserves local class ordering and is monotonic, | |
197 | but does not respect the extended precedence graph. | |
198 | ||
199 | Note that this will merge the CPLs of superclasses /as they are/, not | |
200 | necessarily as Dylan would have computed them. This ensures monotonicity | |
201 | assuming that the superclass CPLs are already monotonic. If they aren't, | |
202 | you're going to lose anyway." | |
203 | ||
5d55bdaa MW |
204 | (let* ((direct-supers (sod-class-direct-superclasses class)) |
205 | (cpls (mapcar #'sod-class-precedence-list direct-supers))) | |
c05ed0f1 MW |
206 | (merge-class-lists class |
207 | (cons (cons class direct-supers) cpls) | |
5d55bdaa | 208 | #'clos-tiebreaker))) |
abdf50aa | 209 | |
11e41ddf | 210 | (export 'c3-cpl) |
abdf50aa MW |
211 | (defun c3-cpl (class) |
212 | "Compute the class precedence list of CLASS using C3 linearization rules. | |
213 | ||
214 | We merge the direct-superclass list of CLASS with the full class | |
215 | precedence lists of its direct superclasses, disambiguating using | |
bf090e02 | 216 | `c3-tiebreaker'. |
abdf50aa MW |
217 | |
218 | The C3 linearization preserves local class ordering, is monotonic, and | |
219 | respects the extended precedence graph. It is the linearization used in | |
220 | Python, Perl 6 and other languages. It is the recommended linearization | |
221 | for SOD." | |
222 | ||
223 | (let* ((direct-supers (sod-class-direct-superclasses class)) | |
224 | (cpls (mapcar #'sod-class-precedence-list direct-supers))) | |
c05ed0f1 MW |
225 | (merge-class-lists class |
226 | (cons (cons class direct-supers) cpls) | |
e2838dc5 | 227 | (lambda (candidates so-far) |
abdf50aa MW |
228 | (declare (ignore so-far)) |
229 | (c3-tiebreaker candidates cpls))))) | |
230 | ||
11e41ddf | 231 | (export 'flavors-cpl) |
abdf50aa MW |
232 | (defun flavors-cpl (class) |
233 | "Compute the class precedence list of CLASS using Flavors linearization | |
234 | rules. | |
235 | ||
236 | We do a depth-first traversal of the superclass graph, ignoring duplicates | |
237 | of classes we've already visited. Interestingly, this has the property of | |
238 | being able to tolerate cyclic superclass graphs, though defining cyclic | |
239 | graphs is syntactically impossible in SOD. | |
240 | ||
241 | This linearization has few other redeeming features, however. In | |
242 | particular, the top class tends not to be at the end of the CPL, despite | |
243 | it being unequivocally less specific than any other class." | |
244 | ||
245 | (let ((done nil)) | |
246 | (labels ((walk (class) | |
247 | (unless (member class done) | |
248 | (push class done) | |
249 | (dolist (super (sod-class-direct-superclasses class)) | |
250 | (walk super))))) | |
251 | (walk class) | |
252 | (nreverse done)))) | |
253 | ||
11e41ddf | 254 | (export 'python-cpl) |
abdf50aa MW |
255 | (defun python-cpl (class) |
256 | "Compute the class precedence list of CLASS using the documented Python 2.2 | |
257 | linearization rules. | |
258 | ||
259 | We do a depth-first traversal of the superclass graph, retaining only the | |
260 | last occurrence of each class visited. | |
261 | ||
262 | This linearization has few redeeming features. It was never actually | |
263 | implemented; the true Python 2.2 linearization seems closer to (but | |
264 | different from) L*LOOPS." | |
265 | ||
266 | (let ((done nil)) | |
267 | (labels ((walk (class) | |
268 | (push class done) | |
269 | (dolist (super (sod-class-direct-superclasses class)) | |
270 | (walk super)))) | |
271 | (walk class) | |
272 | (delete-duplicates (nreverse done))))) | |
273 | ||
11e41ddf | 274 | (export 'l*loops-cpl) |
abdf50aa MW |
275 | (defun l*loops-cpl (class) |
276 | "Compute the class precedence list of CLASS using L*LOOPS linearization | |
277 | rules. | |
278 | ||
279 | We merge the class precedence lists of the direct superclasses of CLASS, | |
280 | disambiguating by choosing the earliest candidate which appears in a | |
281 | depth-first walk of the superclass graph. | |
282 | ||
283 | The L*LOOPS rules are monotonic and respect the extended precedence | |
284 | graph. However (unlike Dylan and CLOS) they don't respect local | |
285 | precedence order i.e., the direct-superclasses list orderings." | |
286 | ||
287 | (let ((dfs (flavors-cpl class))) | |
e2838dc5 | 288 | (cons class |
c05ed0f1 MW |
289 | (merge-class-lists class |
290 | (mapcar #'sod-class-precedence-list | |
abdf50aa | 291 | (sod-class-direct-superclasses class)) |
e2838dc5 MW |
292 | (lambda (candidates so-far) |
293 | (declare (ignore so-far)) | |
294 | (dolist (class dfs) | |
295 | (when (member class candidates) | |
296 | (return class)))))))) | |
abdf50aa | 297 | |
dea4d055 | 298 | ;;; Default function. |
abdf50aa MW |
299 | |
300 | (defmethod compute-cpl ((class sod-class)) | |
c05ed0f1 | 301 | (c3-cpl class)) |
abdf50aa MW |
302 | |
303 | ;;;-------------------------------------------------------------------------- | |
dea4d055 MW |
304 | ;;; Chains. |
305 | ||
306 | (defmethod compute-chains ((class sod-class)) | |
307 | (with-default-error-location (class) | |
308 | (with-slots (chain-link class-precedence-list) class | |
309 | (let* ((head (if chain-link | |
310 | (sod-class-chain-head chain-link) | |
311 | class)) | |
312 | (chain (cons class (and chain-link | |
313 | (sod-class-chain chain-link)))) | |
ab7e7521 | 314 | (state (make-inheritance-path-reporter-state class)) |
dea4d055 MW |
315 | (table (make-hash-table))) |
316 | ||
317 | ;; Check the chains. We work through each superclass, maintaining a | |
318 | ;; hash table keyed by class. If we encounter a class C which links | |
319 | ;; to L, then we store C as L's value; if L already has a value then | |
320 | ;; we've found an error. By the end of all of this, the classes | |
321 | ;; which don't have an entry are the chain tails. | |
322 | (dolist (super class-precedence-list) | |
ab7e7521 MW |
323 | (let* ((link (sod-class-chain-link super)) |
324 | (found (and link (gethash link table)))) | |
325 | (cond ((not found) (setf (gethash link table) super)) | |
326 | (t | |
327 | (cerror* "Conflicting chains in class `~A': ~ | |
328 | (`~A' and `~A' both link to `~A')" | |
329 | class super found link) | |
330 | (report-inheritance-path state super) | |
331 | (report-inheritance-path state found))))) | |
dea4d055 MW |
332 | |
333 | ;; Done. | |
334 | (values head chain | |
335 | (cons chain | |
336 | (mapcar #'sod-class-chain | |
337 | (remove-if (lambda (super) | |
338 | (gethash super table)) | |
339 | (cdr class-precedence-list))))))))) | |
340 | ||
341 | ;;;-------------------------------------------------------------------------- | |
342 | ;;; Sanity checking. | |
343 | ||
2c0aab07 MW |
344 | (defmethod check-class-initializer ((slot effective-slot) (class sod-class)) |
345 | (finalization-error (:missing-class-initializer) | |
346 | (unless (find-class-initializer slot class) | |
347 | (let ((dslot (effective-slot-direct-slot slot))) | |
348 | (cerror* "Missing initializer for class slot `~A', ~ | |
349 | defined by meta-superclass `~A' of `~A'" | |
350 | dslot (sod-slot-class dslot) class))))) | |
351 | ||
352 | (defmethod check-class-initializer | |
353 | ((slot sod-class-effective-slot) (class sod-class)) | |
354 | ;; The programmer shouldn't set an explicit initializer here. | |
355 | (finalization-error (:invalid-class-initializer) | |
356 | (let ((init (find-class-initializer slot class)) | |
357 | (dslot (effective-slot-direct-slot slot))) | |
358 | (when init | |
359 | (cerror* "Initializers not permitted for class slot `~A', ~ | |
360 | defined by meta-superclass `~A' of `~A'" | |
361 | dslot (sod-slot-class dslot) class) | |
362 | (info-with-location init "Offending initializer defined here"))))) | |
363 | ||
dea4d055 | 364 | (defmethod check-sod-class ((class sod-class)) |
dea4d055 | 365 | |
3b92d2b1 MW |
366 | ;; Check the names of things are valid. |
367 | (flet ((check-list (list what namefunc) | |
368 | (dolist (item list) | |
369 | (let ((name (funcall namefunc item))) | |
370 | (unless (valid-name-p name) | |
ab7e7521 | 371 | (cerror*-with-location item |
3b92d2b1 MW |
372 | "Invalid ~A name `~A' in class `~A'" |
373 | what name class)))))) | |
374 | (unless (valid-name-p (sod-class-name class)) | |
375 | (cerror* "Invalid class name `~A'" class)) | |
376 | (unless (valid-name-p (sod-class-nickname class)) | |
377 | (cerror* "Invalid class nickname `~A' for class `~A'" | |
378 | (sod-class-nickname class) class)) | |
379 | (check-list (sod-class-messages class) "message" #'sod-message-name) | |
380 | (check-list (sod-class-slots class) "slot" #'sod-slot-name)) | |
381 | ||
382 | ;; Check that the class doesn't define conflicting things. | |
64cbfb65 | 383 | (labels ((simple-previous (previous) |
3b92d2b1 MW |
384 | (info-with-location previous "Previous definition was here")) |
385 | (simple-complain (what namefunc) | |
386 | (lambda (item previous) | |
387 | (cerror*-with-location item | |
388 | "Duplicate ~A `~A' in class `~A'" | |
389 | what (funcall namefunc item) class) | |
390 | (simple-previous previous)))) | |
391 | ||
392 | ;; Make sure direct slots have distinct names. | |
64cbfb65 | 393 | (find-duplicates (simple-complain "slot name" #'sod-slot-name) |
ed3ce6c2 MW |
394 | (sod-class-slots class) |
395 | :key #'sod-slot-name | |
396 | :test #'equal) | |
3b92d2b1 MW |
397 | |
398 | ;; Make sure there's at most one initializer for each slot. | |
399 | (flet ((check-initializer-list (list kind) | |
64cbfb65 MW |
400 | (find-duplicates (lambda (initializer previous) |
401 | (let ((slot | |
402 | (sod-initializer-slot initializer))) | |
403 | (cerror*-with-location initializer | |
404 | "Duplicate ~ | |
405 | initializer ~ | |
406 | for ~A slot `~A' ~ | |
407 | in class `~A'" | |
408 | kind slot class) | |
409 | (simple-previous previous))) | |
ed3ce6c2 MW |
410 | list |
411 | :key #'sod-initializer-slot))) | |
3b92d2b1 MW |
412 | (check-initializer-list (sod-class-instance-initializers class) |
413 | "instance") | |
414 | (check-initializer-list (sod-class-class-initializers class) | |
415 | "class")) | |
416 | ||
417 | ;; Make sure messages have distinct names. | |
64cbfb65 | 418 | (find-duplicates (simple-complain "message name" #'sod-message-name) |
ed3ce6c2 MW |
419 | (sod-class-messages class) |
420 | :key #'sod-message-name | |
421 | :test #'equal) | |
3b92d2b1 MW |
422 | |
423 | ;; Make sure methods are sufficiently distinct. | |
64cbfb65 MW |
424 | (find-duplicates (lambda (method previous) |
425 | (cerror*-with-location method | |
426 | "Duplicate ~A direct method ~ | |
427 | for message `~A' ~ | |
428 | in classs `~A'" | |
429 | (sod-method-description method) | |
430 | (sod-method-message method) | |
431 | class) | |
432 | (simple-previous previous)) | |
433 | (sod-class-methods class) | |
ed3ce6c2 MW |
434 | :key #'sod-method-function-name |
435 | :test #'equal) | |
3b92d2b1 MW |
436 | |
437 | ;; Make sure superclasses have distinct nicknames. | |
438 | (let ((state (make-inheritance-path-reporter-state class))) | |
64cbfb65 MW |
439 | (find-duplicates (lambda (super previous) |
440 | (cerror*-with-location class | |
441 | "Duplicate nickname `~A' ~ | |
442 | in superclasses of `~A': ~ | |
443 | used by `~A' and `~A'" | |
444 | (sod-class-nickname super) | |
445 | class super previous) | |
446 | (report-inheritance-path state super) | |
447 | (report-inheritance-path state previous)) | |
448 | (sod-class-precedence-list class) | |
449 | :key #'sod-class-nickname :test #'equal))) | |
3b92d2b1 MW |
450 | |
451 | ;; Check that the CHAIN-TO class is actually a proper superclass. (This | |
452 | ;; eliminates hairy things like a class being its own link.) | |
453 | (let ((link (sod-class-chain-link class))) | |
454 | (unless (or (not link) | |
455 | (member link (cdr (sod-class-precedence-list class)))) | |
67678b0b | 456 | (cerror* "In `~A', chain-to class `~A' is not a proper superclass" |
3b92d2b1 MW |
457 | class link))) |
458 | ||
459 | ;; Check that the initargs declare compatible types. Duplicate entries, | |
460 | ;; even within a class, are harmless, but at most one initarg in any | |
461 | ;; class should declare a default value. | |
462 | (let ((seen (make-hash-table :test #'equal)) | |
463 | (state (make-inheritance-path-reporter-state class))) | |
464 | (dolist (super (sod-class-precedence-list class)) | |
465 | (dolist (initarg (reverse (sod-class-initargs super))) | |
466 | (let* ((initarg-name (sod-initarg-name initarg)) | |
467 | (initarg-type (sod-initarg-type initarg)) | |
468 | (initarg-default (sod-initarg-default initarg)) | |
469 | (found (gethash initarg-name seen)) | |
470 | (found-type (and found (sod-initarg-type found))) | |
471 | (found-default (and found (sod-initarg-default found))) | |
472 | (found-class (and found (sod-initarg-class found))) | |
473 | (found-location (and found (file-location found)))) | |
474 | (with-default-error-location (initarg) | |
475 | (cond ((not found) | |
476 | (setf (gethash initarg-name seen) initarg)) | |
477 | ((not (c-type-equal-p initarg-type found-type)) | |
478 | (cerror* "Inititalization argument `~A' defined ~ | |
479 | with incompatible types: ~ | |
480 | ~A in class `~A', but ~A in class `~A'" | |
481 | initarg-name initarg-type super | |
482 | found-type found-class found-location) | |
483 | (report-inheritance-path state super)) | |
484 | ((and initarg-default found-default | |
485 | (eql super found-class)) | |
486 | (cerror* "Initialization argument `~A' redefined ~ | |
487 | with default value" | |
488 | initarg-name) | |
489 | (info-with-location found-location | |
490 | "Previous definition is here")) | |
491 | (initarg-default | |
492 | (setf (gethash initarg-name seen) initarg)))))))) | |
493 | ||
494 | ;; Check for circularity in the superclass graph. Since the superclasses | |
495 | ;; should already be acyclic, it suffices to check that our class is not | |
496 | ;; a superclass of any of its own direct superclasses. | |
497 | (let ((circle (find-if (lambda (super) | |
498 | (sod-subclass-p super class)) | |
499 | (sod-class-direct-superclasses class)))) | |
500 | (when circle | |
501 | (cerror* "`~A' is already a superclass of `~A'" class circle) | |
502 | (report-inheritance-path (make-inheritance-path-reporter-state class) | |
503 | circle))) | |
504 | ||
505 | ;; Check that the class has a unique root superclass. | |
506 | (find-root-superclass class) | |
507 | ||
508 | ;; Check that the metaclass is a subclass of each direct superclass's | |
509 | ;; metaclass. | |
510 | (finalization-error (:bad-metaclass) | |
511 | (let ((meta (sod-class-metaclass class))) | |
512 | (dolist (super (sod-class-direct-superclasses class)) | |
513 | (let ((supermeta (sod-class-metaclass super))) | |
514 | (unless (sod-subclass-p meta supermeta) | |
515 | (cerror* "Metaclass `~A' of `~A' isn't a subclass of `~A'" | |
516 | meta class supermeta) | |
517 | (info-with-location super | |
518 | "Direct superclass `~A' defined here ~ | |
519 | has metaclass `~A'" | |
2c0aab07 MW |
520 | super supermeta)))))) |
521 | ||
51af043f MW |
522 | ;; Check that all of the messages we can be sent have coherent collections |
523 | ;; of applicable methods. This can go wrong, for example, if we inherit | |
524 | ;; methods with differently typed keyword arguments. | |
525 | (finalization-error (:mismatched-applicable-methods) | |
526 | (dolist (super (sod-class-precedence-list class)) | |
527 | (dolist (message (sod-class-messages super)) | |
528 | (let ((methods (sod-message-applicable-methods message class))) | |
529 | (sod-message-check-methods message class methods))))) | |
530 | ||
2c0aab07 MW |
531 | ;; Check that an initializer is available for every slot in the class's |
532 | ;; metaclass. Skip this and trust the caller if the metaclass isn't | |
533 | ;; finalized yet: in that case, we must be bootstrapping, and we must hope | |
534 | ;; that the caller knows what they're doing. | |
535 | (let* ((meta (sod-class-metaclass class)) | |
536 | (ilayout (and (eq (sod-class-state meta) :finalized) | |
537 | (sod-class-ilayout meta)))) | |
538 | (dolist (ichain (and ilayout (ilayout-ichains ilayout))) | |
539 | (dolist (item (cdr (ichain-body ichain))) | |
540 | (when (typep item 'islots) | |
541 | (dolist (slot (islots-slots item)) | |
542 | (check-class-initializer slot class))))))) | |
dea4d055 MW |
543 | |
544 | ;;;-------------------------------------------------------------------------- | |
545 | ;;; Finalization. | |
546 | ||
32bb097f MW |
547 | (defmethod finalize-sod-class :around ((class sod-class)) |
548 | "Common functionality for `finalize-sod-class'. | |
dea4d055 | 549 | |
32bb097f MW |
550 | * If an attempt to finalize the CLASS has been made before, then we |
551 | don't try again. Similarly, attempts to finalize a class recursively | |
552 | will fail. | |
dea4d055 | 553 | |
32bb097f MW |
554 | * A condition handler is established to keep track of whether any errors |
555 | are signalled during finalization. The CLASS is only marked as | |
556 | successfully finalized if no (unhandled) errors are encountered." | |
dea4d055 MW |
557 | (with-default-error-location (class) |
558 | (ecase (sod-class-state class) | |
559 | ((nil) | |
560 | ||
32bb097f | 561 | ;; If this fails, leave the class marked as a loss. |
16f9fb72 | 562 | (setf (slot-value class 'state) :broken) |
dea4d055 | 563 | |
e45a106d MW |
564 | ;; Invoke the finalization method proper. If it signals any |
565 | ;; continuable errors, take note of them so that we can report failure | |
566 | ;; properly. | |
567 | ;; | |
568 | ;; Catch: we get called recursively to clean up superclasses and | |
569 | ;; metaclasses, but there should only be one such handler, so don't | |
570 | ;; add another. (In turn, this means that other methods mustn't | |
571 | ;; actually trap their significant errors.) | |
572 | (let ((have-handler-p (boundp '*finalization-errors*)) | |
573 | (*finalization-errors* nil) | |
574 | (*finalization-error-token* nil)) | |
575 | (catch '%finalization-failed | |
576 | (if have-handler-p (call-next-method) | |
577 | (handler-bind ((error (lambda (cond) | |
578 | (declare (ignore cond)) | |
579 | (pushnew *finalization-error-token* | |
580 | *finalization-errors* | |
581 | :test #'equal) | |
582 | :decline))) | |
583 | (call-next-method))) | |
584 | (when *finalization-errors* (finalization-failed)) | |
585 | (setf (slot-value class 'state) :finalized) | |
586 | t))) | |
dea4d055 | 587 | |
32bb097f | 588 | ;; If the class is broken, we're not going to be able to fix it now. |
dea4d055 MW |
589 | (:broken |
590 | nil) | |
591 | ||
32bb097f | 592 | ;; If we already finalized it, there's no point doing it again. |
dea4d055 MW |
593 | (:finalized |
594 | t)))) | |
abdf50aa | 595 | |
32bb097f MW |
596 | (defmethod finalize-sod-class ((class sod-class)) |
597 | ||
598 | ;; CLONE-AND-HACK WARNING: Note that `bootstrap-classes' has a (very brief) | |
599 | ;; clone of the CPL and chain establishment code. If the interface changes | |
600 | ;; then `bootstrap-classes' will need to be changed too. | |
601 | ||
32bb097f MW |
602 | ;; Finalize all of the superclasses. There's some special pleading here to |
603 | ;; make bootstrapping work: we don't try to finalize the metaclass if we're | |
604 | ;; a root class (no direct superclasses -- because in that case the | |
605 | ;; metaclass will have to be a subclass of us!), or if it's equal to us. | |
e45a106d MW |
606 | ;; This is enough to tie the knot at the top of the class graph. If we |
607 | ;; can't manage this then we're doomed. | |
608 | (flet ((try-finalizing (what other-class) | |
609 | (unless (finalize-sod-class other-class) | |
610 | (cerror* "Class `~A' has broken ~A `~A'" class what other-class) | |
611 | (info-with-location other-class | |
612 | "Class `~A' defined here" other-class) | |
613 | (finalization-failed)))) | |
614 | (let ((supers (sod-class-direct-superclasses class)) | |
615 | (meta (sod-class-metaclass class))) | |
616 | (dolist (super supers) | |
617 | (try-finalizing "direct superclass" super)) | |
618 | (unless (or (null supers) (eq class meta)) | |
619 | (try-finalizing "metaclass" meta)))) | |
32bb097f MW |
620 | |
621 | ;; Stash the class's type. | |
622 | (setf (slot-value class '%type) | |
623 | (make-class-type (sod-class-name class))) | |
624 | ||
625 | ;; Clobber the lists of items if they've not been set. | |
626 | (dolist (slot '(slots instance-initializers class-initializers | |
627 | messages methods)) | |
628 | (unless (slot-boundp class slot) | |
629 | (setf (slot-value class slot) nil))) | |
630 | ||
e45a106d MW |
631 | ;; If the CPL hasn't been done yet, compute it. If we can't manage this |
632 | ;; then there's no hope at all. | |
633 | (unless (slot-boundp class 'class-precedence-list) | |
634 | (restart-case | |
635 | (setf (slot-value class 'class-precedence-list) (compute-cpl class)) | |
636 | (continue () :report "Continue" | |
637 | (finalization-failed)))) | |
32bb097f MW |
638 | |
639 | ;; Check that the class is fairly sane. | |
640 | (check-sod-class class) | |
641 | ||
642 | ;; Determine the class's layout. | |
643 | (setf (values (slot-value class 'chain-head) | |
644 | (slot-value class 'chain) | |
645 | (slot-value class 'chains)) | |
646 | (compute-chains class))) | |
647 | ||
abdf50aa | 648 | ;;;----- That's all, folks -------------------------------------------------- |