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1 | ;;; -*-lisp-*- |
2 | ;;; | |
3 | ;;; Various handy utilities | |
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. |
dea4d055 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:defpackage #:sod-utilities | |
27 | (:use #:common-lisp | |
28 | ||
29 | ;; MOP from somewhere. | |
30 | #+sbcl #:sb-mop | |
31 | #+(or cmu clisp) #:mop | |
32 | #+ecl #:clos)) | |
33 | ||
34 | (cl:in-package #:sod-utilities) | |
35 | ||
36 | ;;;-------------------------------------------------------------------------- | |
37 | ;;; Macro hacks. | |
38 | ||
39 | (export 'with-gensyms) | |
40 | (defmacro with-gensyms ((&rest binds) &body body) | |
41 | "Evaluate BODY with variables bound to fresh symbols. | |
42 | ||
43 | The BINDS are a list of entries (VAR [NAME]), and a singleton list can be | |
44 | replaced by just a symbol; each VAR is bound to a fresh symbol generated | |
45 | by (gensym NAME), where NAME defaults to the symbol-name of VAR." | |
46 | `(let (,@(mapcar (lambda (bind) | |
47 | (multiple-value-bind (var name) | |
48 | (if (atom bind) | |
49 | (values bind (concatenate 'string | |
50 | (symbol-name bind) "-")) | |
51 | (destructuring-bind | |
52 | (var &optional | |
53 | (name (concatenate 'string | |
54 | (symbol-name var) "-"))) | |
55 | bind | |
56 | (values var name))) | |
57 | `(,var (gensym ,name)))) | |
58 | binds)) | |
59 | ,@body)) | |
60 | ||
61 | (eval-when (:compile-toplevel :load-toplevel :execute) | |
62 | (defun strip-quote (form) | |
63 | "If FORM looks like (quote FOO) for self-evaluating FOO, return FOO. | |
64 | ||
65 | If FORM is a symbol whose constant value is `nil' then return `nil'. | |
66 | Otherwise return FORM unchanged. This makes it easier to inspect constant | |
67 | things. This is a utility for `once-only'." | |
68 | ||
69 | (cond ((and (consp form) | |
70 | (eq (car form) 'quote) | |
71 | (cdr form) | |
72 | (null (cddr form))) | |
73 | (let ((body (cadr form))) | |
74 | (if (or (not (or (consp body) (symbolp body))) | |
75 | (member body '(t nil)) | |
76 | (keywordp body)) | |
77 | body | |
78 | form))) | |
79 | ((and (symbolp form) (boundp form) (null (symbol-value form))) | |
80 | nil) | |
81 | (t | |
82 | form)))) | |
83 | ||
84 | (export 'once-only) | |
74ca1bf5 | 85 | (defmacro once-only ((&rest binds) &body body) |
dea4d055 MW |
86 | "Macro helper for preventing repeated evaluation. |
87 | ||
88 | The syntax is actually hairier than shown: | |
89 | ||
90 | once-only ( [[ :environment ENV ]] { VAR | (VAR [VALUE-FORM]) }* ) | |
91 | { FORM }* | |
92 | ||
93 | So, the BINDS are a list of entries (VAR [VALUE-FORM]); a singleton list | |
94 | can be replaced by just a symbol VAR, and the VALUE-FORM defaults to VAR. | |
95 | But before them you can have keyword arguments. Only one is defined so | |
96 | far. See below for the crazy things that does. | |
97 | ||
98 | The result of evaluating a ONCE-ONLY form is a form with the structure | |
99 | ||
100 | (let ((#:GS1 VALUE-FORM1) | |
101 | ... | |
102 | (#:GSn VALUE-FORMn)) | |
103 | STUFF) | |
104 | ||
105 | where STUFF is the value of the BODY forms, as an implicit progn, in an | |
106 | environment with the VARs bound to the corresponding gensyms. | |
107 | ||
108 | As additional magic, if any of the VALUE-FORMs is actually constant (as | |
109 | determined by inspection, and aided by `constantp' if an :environment is | |
110 | supplied, then no gensym is constructed for it, and the VAR is bound | |
111 | directly to the constant form. Moreover, if the constant form looks like | |
112 | (quote FOO) for a self-evaluating FOO then the outer layer of quoting is | |
113 | stripped away." | |
114 | ||
115 | ;; We need an extra layer of gensyms in our expansion: we'll want the | |
116 | ;; expansion to examine the various VALUE-FORMs to find out whether they're | |
117 | ;; constant without evaluating them repeatedly. This also helps with | |
118 | ;; another problem: we explicitly encourage the rebinding of a VAR | |
119 | ;; (probably a macro argument) to a gensym which will be bound to the value | |
120 | ;; of the form previously held in VAR itself -- so the gensym and value | |
121 | ;; form must exist at the same time and we need two distinct variables. | |
122 | ||
123 | (with-gensyms ((envvar "ENV-") lets sym (bodyfunc "BODY-")) | |
124 | (let ((env nil)) | |
125 | ||
126 | ;; First things first: let's pick up the keywords. | |
127 | (loop | |
128 | (unless (and binds (keywordp (car binds))) | |
129 | (return)) | |
130 | (ecase (pop binds) | |
131 | (:environment (setf env (pop binds))))) | |
132 | ||
133 | ;; Now we'll investigate the bindings. Turn each one into a list (VAR | |
134 | ;; VALUE-FORM TEMP) where TEMP is an appropriate gensym -- see the note | |
135 | ;; above. | |
136 | (let ((canon (mapcar (lambda (bind) | |
137 | (multiple-value-bind (var form) | |
138 | (if (atom bind) | |
139 | (values bind bind) | |
140 | (destructuring-bind | |
141 | (var &optional (form var)) bind | |
142 | (values var form))) | |
143 | (list var form | |
144 | (gensym (format nil "T-~A-" | |
145 | (symbol-name var)))))) | |
146 | binds))) | |
147 | ||
148 | `(let* (,@(and env `((,envvar ,env))) | |
149 | (,lets nil) | |
150 | ,@(mapcar (lambda (bind) | |
151 | (destructuring-bind (var form temp) bind | |
152 | (declare (ignore var)) | |
153 | `(,temp ,form))) | |
154 | canon) | |
155 | ,@(mapcar (lambda (bind) | |
156 | (destructuring-bind (var form temp) bind | |
157 | (declare (ignore form)) | |
158 | `(,var | |
159 | (cond ((constantp ,temp | |
160 | ,@(and env `(,envvar))) | |
161 | (strip-quote ,temp)) | |
162 | ((symbolp ,temp) | |
163 | ,temp) | |
164 | (t | |
165 | (let ((,sym (gensym | |
166 | ,(concatenate 'string | |
167 | (symbol-name var) | |
168 | "-")))) | |
169 | (push (list ,sym ,temp) ,lets) | |
170 | ,sym)))))) | |
171 | canon)) | |
172 | (flet ((,bodyfunc () ,@body)) | |
173 | (if ,lets | |
174 | `(let (,@(nreverse ,lets)) ,(,bodyfunc)) | |
175 | (,bodyfunc)))))))) | |
176 | ||
177 | (export 'parse-body) | |
b8c698ee | 178 | (defun parse-body (body &key (docp t) (declp t)) |
dea4d055 MW |
179 | "Parse the BODY into a docstring, declarations and the body forms. |
180 | ||
181 | These are returned as three lists, so that they can be spliced into a | |
182 | macro expansion easily. The declarations are consolidated into a single | |
b8c698ee MW |
183 | `declare' form. If DOCP is nil then a docstring is not permitted; if |
184 | DECLP is nil, then declarations are not permitted." | |
dea4d055 MW |
185 | (let ((decls nil) |
186 | (doc nil)) | |
187 | (loop | |
188 | (cond ((null body) (return)) | |
b8c698ee | 189 | ((and declp (consp (car body)) (eq (caar body) 'declare)) |
dea4d055 | 190 | (setf decls (append decls (cdr (pop body))))) |
b8c698ee | 191 | ((and docp (stringp (car body)) (not doc) (cdr body)) |
dea4d055 MW |
192 | (setf doc (pop body))) |
193 | (t (return)))) | |
194 | (values (and doc (list doc)) | |
195 | (and decls (list (cons 'declare decls))) | |
196 | body))) | |
197 | ||
198 | ;;;-------------------------------------------------------------------------- | |
e8abb286 MW |
199 | ;;; Locatives. |
200 | ||
201 | (export '(loc locp)) | |
202 | (defstruct (loc (:predicate locp) (:constructor make-loc (reader writer))) | |
203 | "Locative data type. See `locf' and `ref'." | |
204 | (reader nil :type function) | |
205 | (writer nil :type function)) | |
206 | ||
207 | (export 'locf) | |
208 | (defmacro locf (place &environment env) | |
209 | "Slightly cheesy locatives. | |
210 | ||
211 | (locf PLACE) returns an object which, using the `ref' function, can be | |
212 | used to read or set the value of PLACE. It's cheesy because it uses | |
213 | closures rather than actually taking the address of something. Also, | |
214 | unlike Zetalisp, we don't overload `car' to do our dirty work." | |
215 | (multiple-value-bind | |
216 | (valtmps valforms newtmps setform getform) | |
217 | (get-setf-expansion place env) | |
218 | `(let* (,@(mapcar #'list valtmps valforms)) | |
219 | (make-loc (lambda () ,getform) | |
220 | (lambda (,@newtmps) ,setform))))) | |
221 | ||
222 | (export 'ref) | |
223 | (declaim (inline ref (setf ref))) | |
224 | (defun ref (loc) | |
225 | "Fetch the value referred to by a locative." | |
226 | (funcall (loc-reader loc))) | |
227 | (defun (setf ref) (new loc) | |
228 | "Store a new value in the place referred to by a locative." | |
229 | (funcall (loc-writer loc) new)) | |
230 | ||
231 | (export 'with-locatives) | |
232 | (defmacro with-locatives (locs &body body) | |
233 | "Evaluate BODY with implicit locatives. | |
234 | ||
235 | LOCS is a list of items of the form (SYM [LOC-EXPR]), where SYM is a | |
236 | symbol and LOC-EXPR evaluates to a locative. If LOC-EXPR is omitted, it | |
237 | defaults to SYM. As an abbreviation for a common case, LOCS may be a | |
238 | symbol instead of a list. | |
239 | ||
240 | The BODY is evaluated in an environment where each SYM is a symbol macro | |
241 | which expands to (ref LOC-EXPR) -- or, in fact, something similar which | |
242 | doesn't break if LOC-EXPR has side-effects. Thus, references, including | |
243 | `setf' forms, fetch or modify the thing referred to by the LOC-EXPR. | |
244 | Useful for covering over where something uses a locative." | |
245 | (setf locs (mapcar (lambda (item) | |
246 | (cond ((atom item) (list item item)) | |
247 | ((null (cdr item)) (list (car item) (car item))) | |
248 | (t item))) | |
249 | (if (listp locs) locs (list locs)))) | |
250 | (let ((tt (mapcar (lambda (l) (declare (ignore l)) (gensym)) locs)) | |
251 | (ll (mapcar #'cadr locs)) | |
252 | (ss (mapcar #'car locs))) | |
253 | `(let (,@(mapcar (lambda (tmp loc) `(,tmp ,loc)) tt ll)) | |
254 | (symbol-macrolet (,@(mapcar (lambda (sym tmp) | |
255 | `(,sym (ref ,tmp))) ss tt)) | |
256 | ,@body)))) | |
257 | ||
258 | ;;;-------------------------------------------------------------------------- | |
dea4d055 MW |
259 | ;;; Anaphorics. |
260 | ||
261 | (export 'it) | |
262 | ||
263 | (export 'aif) | |
264 | (defmacro aif (cond cons &optional (alt nil altp)) | |
265 | "If COND is not nil, evaluate CONS with `it' bound to the value of COND. | |
266 | ||
267 | Otherwise, if given, evaluate ALT; `it' isn't bound in ALT." | |
268 | (once-only (cond) | |
269 | `(if ,cond (let ((it ,cond)) ,cons) ,@(and altp `(,alt))))) | |
270 | ||
271 | (export 'awhen) | |
272 | (defmacro awhen (cond &body body) | |
273 | "If COND, evaluate BODY as a progn with `it' bound to the value of COND." | |
274 | `(let ((it ,cond)) (when it ,@body))) | |
275 | ||
3e166443 MW |
276 | (export 'aand) |
277 | (defmacro aand (&rest forms) | |
278 | "Like `and', but anaphoric. | |
279 | ||
280 | Each FORM except the first is evaluated with `it' bound to the value of | |
281 | the previous one. If there are no forms, then the result it `t'; if there | |
282 | is exactly one, then wrapping it in `aand' is pointless." | |
283 | (labels ((doit (first rest) | |
284 | (if (null rest) | |
285 | first | |
286 | `(let ((it ,first)) | |
287 | (if it ,(doit (car rest) (cdr rest)) nil))))) | |
288 | (if (null forms) | |
289 | 't | |
290 | (doit (car forms) (cdr forms))))) | |
291 | ||
dea4d055 | 292 | (export 'acond) |
bf090e02 | 293 | (defmacro acond (&body clauses &environment env) |
dea4d055 MW |
294 | "Like COND, but with `it' bound to the value of the condition. |
295 | ||
296 | Each of the CLAUSES has the form (CONDITION FORM*); if a CONDITION is | |
297 | non-nil then evaluate the FORMs with `it' bound to the non-nil value, and | |
298 | return the value of the last FORM; if there are no FORMs, then return `it' | |
299 | itself. If the CONDITION is nil then continue with the next clause; if | |
300 | all clauses evaluate to nil then the result is nil." | |
301 | (labels ((walk (clauses) | |
302 | (if (null clauses) | |
303 | `nil | |
304 | (once-only (:environment env (cond (caar clauses))) | |
305 | (if (and (constantp cond) | |
306 | (if (and (consp cond) (eq (car cond) 'quote)) | |
307 | (cadr cond) cond)) | |
308 | (if (cdar clauses) | |
309 | `(let ((it ,cond)) | |
310 | (declare (ignorable it)) | |
311 | ,@(cdar clauses)) | |
312 | cond) | |
313 | `(if ,cond | |
314 | ,(if (cdar clauses) | |
315 | `(let ((it ,cond)) | |
316 | (declare (ignorable it)) | |
317 | ,@(cdar clauses)) | |
318 | cond) | |
319 | ,(walk (cdr clauses)))))))) | |
320 | (walk clauses))) | |
321 | ||
322 | (export '(acase aecase atypecase aetypecase)) | |
323 | (defmacro acase (value &body clauses) | |
324 | `(let ((it ,value)) (case it ,@clauses))) | |
325 | (defmacro aecase (value &body clauses) | |
326 | `(let ((it ,value)) (ecase it ,@clauses))) | |
327 | (defmacro atypecase (value &body clauses) | |
328 | `(let ((it ,value)) (typecase it ,@clauses))) | |
329 | (defmacro aetypecase (value &body clauses) | |
330 | `(let ((it ,value)) (etypecase it ,@clauses))) | |
331 | ||
332 | (export 'asetf) | |
333 | (defmacro asetf (&rest places-and-values &environment env) | |
334 | "Anaphoric update of places. | |
335 | ||
336 | The PLACES-AND-VALUES are alternating PLACEs and VALUEs. Each VALUE is | |
337 | evaluated with IT bound to the current value stored in the corresponding | |
338 | PLACE." | |
339 | `(progn ,@(loop for (place value) on places-and-values by #'cddr | |
340 | collect (multiple-value-bind | |
341 | (temps inits newtemps setform getform) | |
342 | (get-setf-expansion place env) | |
343 | `(let* (,@(mapcar #'list temps inits) | |
344 | (it ,getform)) | |
345 | (multiple-value-bind ,newtemps ,value | |
346 | ,setform)))))) | |
347 | ||
348 | ;;;-------------------------------------------------------------------------- | |
349 | ;;; MOP hacks (not terribly demanding). | |
350 | ||
bf090e02 MW |
351 | (export 'instance-initargs) |
352 | (defgeneric instance-initargs (instance) | |
353 | (:documentation | |
354 | "Return a plausble list of initargs for INSTANCE. | |
355 | ||
356 | The idea is that you can make a copy of INSTANCE by invoking | |
357 | ||
358 | (apply #'make-instance (class-of INSTANCE) | |
359 | (instance-initargs INSTANCE)) | |
360 | ||
361 | The default implementation works by inspecting the slot definitions and | |
362 | extracting suitable initargs, so this will only succeed if enough slots | |
363 | actually have initargs specified that `initialize-instance' can fill in | |
364 | the rest correctly. | |
365 | ||
366 | The list returned is freshly consed, and you can destroy it if you like.") | |
367 | (:method ((instance standard-object)) | |
368 | (mapcan (lambda (slot) | |
369 | (aif (slot-definition-initargs slot) | |
370 | (list (car it) | |
371 | (slot-value instance (slot-definition-name slot))) | |
372 | nil)) | |
373 | (class-slots (class-of instance))))) | |
374 | ||
dea4d055 MW |
375 | (export '(copy-instance copy-instance-using-class)) |
376 | (defgeneric copy-instance-using-class (class instance &rest initargs) | |
377 | (:documentation | |
378 | "Metaobject protocol hook for `copy-instance'.") | |
379 | (:method ((class standard-class) instance &rest initargs) | |
380 | (let ((copy (allocate-instance class))) | |
381 | (dolist (slot (class-slots class)) | |
382 | (let ((name (slot-definition-name slot))) | |
383 | (when (slot-boundp instance name) | |
384 | (setf (slot-value copy name) (slot-value instance name))))) | |
385 | (apply #'shared-initialize copy nil initargs)))) | |
386 | (defun copy-instance (object &rest initargs) | |
387 | "Construct and return a copy of OBJECT. | |
388 | ||
389 | The new object has the same class as OBJECT, and the same slot values | |
390 | except where overridden by INITARGS." | |
391 | (apply #'copy-instance-using-class (class-of object) object initargs)) | |
392 | ||
9ec578d9 MW |
393 | (export '(generic-function-methods method-specializers |
394 | eql-specializer eql-specializer-object)) | |
395 | ||
dea4d055 MW |
396 | ;;;-------------------------------------------------------------------------- |
397 | ;;; List utilities. | |
398 | ||
399 | (export 'make-list-builder) | |
400 | (defun make-list-builder (&optional initial) | |
401 | "Return a simple list builder." | |
402 | ||
403 | ;; The `builder' is just a cons cell whose cdr will be the list that's | |
404 | ;; wanted. Effectively, then, we have a list that's one item longer than | |
405 | ;; we actually want. The car of this extra initial cons cell is always the | |
406 | ;; last cons in the list -- which is now well defined because there's | |
407 | ;; always at least one. | |
408 | ||
409 | (let ((builder (cons nil initial))) | |
410 | (setf (car builder) (last builder)) | |
411 | builder)) | |
412 | ||
413 | (export 'lbuild-add) | |
414 | (defun lbuild-add (builder item) | |
415 | "Add an ITEM to the end of a list BUILDER." | |
416 | (let ((new (cons item nil))) | |
417 | (setf (cdar builder) new | |
418 | (car builder) new)) | |
419 | builder) | |
420 | ||
421 | (export 'lbuild-add-list) | |
422 | (defun lbuild-add-list (builder list) | |
423 | "Add a LIST to the end of a list BUILDER. The LIST will be clobbered." | |
424 | (when list | |
425 | (setf (cdar builder) list | |
426 | (car builder) (last list))) | |
427 | builder) | |
428 | ||
429 | (export 'lbuild-list) | |
430 | (defun lbuild-list (builder) | |
431 | "Return the constructed list." | |
432 | (cdr builder)) | |
433 | ||
434 | (export 'mappend) | |
435 | (defun mappend (function list &rest more-lists) | |
69dda0c9 | 436 | "Like a nondestructive `mapcan'. |
dea4d055 MW |
437 | |
438 | Map FUNCTION over the the corresponding elements of LIST and MORE-LISTS, | |
439 | and return the result of appending all of the resulting lists." | |
440 | (reduce #'append (apply #'mapcar function list more-lists) :from-end t)) | |
441 | ||
17c7c784 MW |
442 | (export 'distinguished-point-shortest-paths) |
443 | (defun distinguished-point-shortest-paths (root neighbours-func) | |
444 | "Moderately efficient shortest-paths-from-root computation. | |
445 | ||
446 | The ROOT is a distinguished vertex in a graph. The NEIGHBOURS-FUNC | |
447 | accepts a VERTEX as its only argument, and returns a list of conses (V . | |
448 | C) for each of the VERTEX's neighbours, indicating that there is an edge | |
449 | from VERTEX to V, with cost C. | |
450 | ||
451 | The return value is a list of entries (COST . REV-PATH) for each vertex | |
452 | reachable from the ROOT; the COST is the total cost of the shortest path, | |
453 | and REV-PATH is the path from the ROOT, in reverse order -- so the first | |
454 | element is the vertex itself and the last element is the ROOT. | |
455 | ||
456 | The NEIGHBOURS-FUNC is called at most N times, and may take O(N) time to | |
457 | produce its output list. The computation as a whole takes O(N^2) time, | |
458 | where N is the number of vertices in the graph, assuming there is at most | |
459 | one edge between any pair of vertices." | |
460 | ||
461 | ;; This is a listish version of Dijkstra's shortest-path algorithm. It | |
462 | ;; could be made more efficient by using a fancy priority queue rather than | |
463 | ;; a linear search for finding the nearest live element (see below), but it | |
464 | ;; still runs pretty well. | |
465 | ||
466 | (let ((map (make-hash-table)) | |
467 | (dead nil) | |
468 | (live (list (list 0 root)))) | |
469 | (setf (gethash root map) (cons :live (car live))) | |
470 | (loop | |
471 | ;; The dead list contains a record, in output format (COST . PATH), for | |
472 | ;; each vertex whose shortest path has been finally decided. The live | |
473 | ;; list contains a record for the vertices of current interest, also in | |
474 | ;; output format; the COST for a live record shows the best cost for a | |
475 | ;; path using only dead vertices. | |
476 | ;; | |
477 | ;; Each time through here, we pull an item off the live list and | |
478 | ;; push it onto the dead list, so we do at most N iterations total. | |
479 | ||
480 | ;; If there are no more live items, then we're done; the remaining | |
481 | ;; vertices, if any, are unreachable from the ROOT. | |
482 | (when (null live) (return)) | |
483 | ||
484 | ;; Find the closest live vertex to the root. The linear scan through | |
485 | ;; the live list costs at most N time. | |
486 | (let* ((best (reduce (lambda (x y) (if (< (car x) (car y)) x y)) live)) | |
487 | (best-cost (car best)) | |
488 | (best-path (cdr best)) | |
489 | (best-vertex (car best-path))) | |
490 | ||
491 | ;; Remove the chosen vertex from the LIVE list, and add the | |
492 | ;; appropriate record to the dead list. We must have the shortest | |
493 | ;; path to this vertex now: we have the shortest path using currently | |
494 | ;; dead vertices; any other path must use at least one live vertex, | |
495 | ;; and, by construction, the path through any such vertex must be | |
496 | ;; further than the path we already have. | |
497 | ;; | |
498 | ;; Removal from the live list uses a linear scan which costs N time. | |
499 | (setf live (delete best live)) | |
500 | (push best dead) | |
501 | (setf (car (gethash best-vertex map)) :dead) | |
502 | ||
503 | ;; Work through the chosen vertex's neighbours, adding each of them | |
504 | ;; to the live list if they're not already there. If a neighbour is | |
505 | ;; already live, and we find a shorter path to it through our chosen | |
506 | ;; vertex, then update the neighbour's record. | |
507 | ;; | |
508 | ;; The chosen vertex obviously has at most N neighbours. There's no | |
509 | ;; more looping in here, so performance is as claimed. | |
510 | (dolist (neigh (funcall neighbours-func best-vertex)) | |
511 | (let* ((neigh-vertex (car neigh)) | |
512 | (neigh-cost (+ best-cost (cdr neigh))) | |
513 | (neigh-record (gethash neigh-vertex map))) | |
514 | (cond ((null neigh-record) | |
515 | ;; If the neighbour isn't known, then now's the time to | |
516 | ;; make a fresh live record for it. | |
517 | (let ((new-record (list* :live neigh-cost | |
518 | neigh-vertex best-path))) | |
519 | (push (cdr new-record) live) | |
520 | (setf (gethash neigh-vertex map) new-record))) | |
521 | ((and (eq (car neigh-record) :live) | |
522 | (< neigh-cost (cadr neigh-record))) | |
523 | ;; If the neighbour is live, and we've found a better path | |
524 | ;; to it, then update its record. | |
525 | (setf (cadr neigh-record) neigh-cost | |
526 | (cdddr neigh-record) best-path))))))) | |
527 | dead)) | |
528 | ||
38b78e87 MW |
529 | (export '(inconsistent-merge-error |
530 | merge-error-candidates merge-error-present-function)) | |
dea4d055 MW |
531 | (define-condition inconsistent-merge-error (error) |
532 | ((candidates :initarg :candidates | |
38b78e87 MW |
533 | :reader merge-error-candidates) |
534 | (present :initarg :present :initform #'identity | |
535 | :reader merge-error-present-function)) | |
dea4d055 | 536 | (:documentation |
9fb4a980 | 537 | "Reports an inconsistency in the arguments passed to `merge-lists'.") |
dea4d055 | 538 | (:report (lambda (condition stream) |
e2838dc5 MW |
539 | (format stream "Merge inconsistency: failed to decide between ~ |
540 | ~{~#[~;~A~;~A and ~A~:;~ | |
541 | ~@{~A, ~#[~;and ~A~]~}~]~}" | |
38b78e87 MW |
542 | (mapcar (merge-error-present-function condition) |
543 | (merge-error-candidates condition)))))) | |
dea4d055 MW |
544 | |
545 | (export 'merge-lists) | |
e2838dc5 | 546 | (defun merge-lists (lists &key pick (test #'eql) (present #'identity)) |
dea4d055 MW |
547 | "Return a merge of the given LISTS. |
548 | ||
e8c5a09e | 549 | The resulting list contains the items of the given LISTS, with duplicates |
dea4d055 MW |
550 | removed. The order of the resulting list is consistent with the orders of |
551 | the input LISTS in the sense that if A precedes B in some input list then | |
552 | A will also precede B in the output list. If the lists aren't consistent | |
553 | (e.g., some list contains A followed by B, and another contains B followed | |
e2838dc5 MW |
554 | by A) then an error of type `inconsistent-merge-error' is signalled. The |
555 | offending items are filtered for presentation through the PRESENT function | |
556 | before being attached to the condition, so as to produce a more useful | |
557 | diagnostic message. | |
dea4d055 MW |
558 | |
559 | Item equality is determined by TEST. | |
560 | ||
561 | If there is an ambiguity at any point -- i.e., a choice between two or | |
562 | more possible next items to emit -- then PICK is called to arbitrate. | |
563 | PICK is called with two arguments: the list of candidate next items, and | |
e8c5a09e MW |
564 | the current output list. It should return one of the candidate items. |
565 | The order of the candidates in the list given to the PICK function | |
566 | reflects their order in the input LISTS: item A will precede item B in the | |
567 | candidates list if and only if an occurrence of A appears in an earlier | |
568 | input list than any occurrence of item B. (This completely determines the | |
569 | order of the candidates: it is not possible that two candidates appear in | |
c5ef873a MW |
570 | the same input list, since that would resolve the ambiguity between them.) |
571 | If PICK is omitted then the item chosen is the one appearing in the | |
572 | earliest of the input lists: i.e., effectively, the default PICK function | |
573 | is | |
e8c5a09e MW |
574 | |
575 | (lambda (candidates output-so-far) | |
576 | (declare (ignore output-so-far)) | |
577 | (car candidates)) | |
dea4d055 MW |
578 | |
579 | The primary use of this function is in computing class precedence lists. | |
580 | By building the input lists and selecting the PICK function appropriately, | |
581 | a variety of different CPL algorithms can be implemented." | |
582 | ||
022a3499 MW |
583 | (do ((lb (make-list-builder))) |
584 | ((null lists) (lbuild-list lb)) | |
dea4d055 MW |
585 | |
586 | ;; The candidate items are the ones at the front of the input lists. | |
587 | ;; Gather them up, removing duplicates. If a candidate is somewhere in | |
588 | ;; one of the other lists other than at the front then we reject it. If | |
589 | ;; we've just rejected everything, then we can make no more progress and | |
590 | ;; the input lists were inconsistent. | |
e8c5a09e MW |
591 | (let* ((candidates (delete-duplicates (mapcar #'car lists) |
592 | :test test :from-end t)) | |
dea4d055 MW |
593 | (leasts (remove-if (lambda (item) |
594 | (some (lambda (list) | |
595 | (member item (cdr list) :test test)) | |
596 | lists)) | |
597 | candidates)) | |
598 | (winner (cond ((null leasts) | |
599 | (error 'inconsistent-merge-error | |
38b78e87 MW |
600 | :candidates candidates |
601 | :present present)) | |
dea4d055 MW |
602 | ((null (cdr leasts)) |
603 | (car leasts)) | |
604 | (pick | |
605 | (funcall pick leasts (lbuild-list lb))) | |
606 | (t (car leasts))))) | |
607 | ||
608 | ;; Check that the PICK function isn't conning us. | |
609 | (assert (member winner leasts :test test)) | |
610 | ||
611 | ;; Update the output list and remove the winning item from the input | |
612 | ;; lists. We know that it must be at the front of each input list | |
613 | ;; containing it. At this point, we discard input lists entirely when | |
614 | ;; they run out of entries. The loop ends when there are no more input | |
615 | ;; lists left, i.e., when we've munched all of the input items. | |
616 | (lbuild-add lb winner) | |
617 | (setf lists (delete nil (mapcar (lambda (list) | |
618 | (if (funcall test winner (car list)) | |
619 | (cdr list) | |
620 | list)) | |
621 | lists)))))) | |
622 | ||
623 | (export 'categorize) | |
624 | (defmacro categorize ((itemvar items &key bind) categories &body body) | |
625 | "Categorize ITEMS into lists and invoke BODY. | |
626 | ||
627 | The ITEMVAR is a symbol; as the macro iterates over the ITEMS, ITEMVAR | |
628 | will contain the current item. The BIND argument is a list of LET*-like | |
629 | clauses. The CATEGORIES are a list of clauses of the form (SYMBOL | |
630 | PREDICATE). | |
631 | ||
632 | The behaviour of the macro is as follows. ITEMVAR is assigned (not | |
633 | bound), in turn, each item in the list ITEMS. The PREDICATEs in the | |
634 | CATEGORIES list are evaluated in turn, in an environment containing | |
635 | ITEMVAR and the BINDings, until one of them evaluates to a non-nil value. | |
636 | At this point, the item is assigned to the category named by the | |
637 | corresponding SYMBOL. If none of the PREDICATEs returns non-nil then an | |
638 | error is signalled; a PREDICATE consisting only of T will (of course) | |
639 | match anything; it is detected specially so as to avoid compiler warnings. | |
640 | ||
641 | Once all of the ITEMS have been categorized in this fashion, the BODY is | |
642 | evaluated as an implicit PROGN. For each SYMBOL naming a category, a | |
643 | variable named after that symbol will be bound in the BODY's environment | |
644 | to a list of the items in that category, in the same order in which they | |
645 | were found in the list ITEMS. The final values of the macro are the final | |
646 | values of the BODY." | |
647 | ||
648 | (let* ((cat-names (mapcar #'car categories)) | |
649 | (cat-match-forms (mapcar #'cadr categories)) | |
650 | (cat-vars (mapcar (lambda (name) (gensym (concatenate 'string | |
651 | (symbol-name name) "-"))) | |
652 | cat-names)) | |
653 | (items-var (gensym "ITEMS-"))) | |
64a7e651 MW |
654 | `(let (,@(mapcar (lambda (cat-var) (list cat-var nil)) cat-vars)) |
655 | (let ((,items-var ,items)) | |
656 | (dolist (,itemvar ,items-var) | |
657 | (let* ,bind | |
658 | (cond ,@(mapcar (lambda (cat-match-form cat-var) | |
659 | `(,cat-match-form | |
660 | (push ,itemvar ,cat-var))) | |
661 | cat-match-forms cat-vars) | |
662 | ,@(and (not (member t cat-match-forms)) | |
663 | `((t (error "Failed to categorize ~A" | |
664 | ,itemvar)))))))) | |
dea4d055 MW |
665 | (let ,(mapcar (lambda (name var) |
666 | `(,name (nreverse ,var))) | |
667 | cat-names cat-vars) | |
668 | ,@body)))) | |
669 | ||
42291726 MW |
670 | (export 'partial-order-minima) |
671 | (defun partial-order-minima (items order) | |
672 | "Return a list of minimal items according to the non-strict partial ORDER. | |
673 | ||
674 | The ORDER function describes the partial order: (funcall ORDER X Y) should | |
675 | return true if X precedes or is equal to Y in the order." | |
676 | (reduce (lambda (tops this) | |
677 | (let ((new nil) (keep t)) | |
678 | (dolist (top tops) | |
679 | (cond ((funcall order top this) | |
680 | (setf keep nil) | |
681 | (push top new)) | |
682 | ((not (funcall order this top)) | |
683 | (push top new)))) | |
684 | (nreverse (if keep (cons this new) new)))) | |
685 | items | |
686 | :initial-value nil)) | |
687 | ||
64cbfb65 MW |
688 | (export 'find-duplicates) |
689 | (defun find-duplicates (report sequence &key (key #'identity) (test #'eql)) | |
690 | "Call REPORT on each pair of duplicate items in SEQUENCE. | |
691 | ||
692 | Duplicates are determined according to the KEY and TEST funcitons." | |
693 | (when (symbolp test) (setf test (symbol-function test))) | |
694 | (cond ((zerop (length sequence)) nil) | |
695 | ((or (eq test #'eq) | |
696 | (eq test #'eql) | |
697 | (eq test #'equal) | |
698 | (eq test #'equalp)) | |
699 | (let ((seen (make-hash-table :test test))) | |
700 | (map nil (lambda (item) | |
701 | (let ((k (funcall key item))) | |
702 | (multiple-value-bind (previous matchp) | |
703 | (gethash k seen) | |
704 | (if matchp (funcall report item previous) | |
705 | (setf (gethash k seen) item))))) | |
706 | sequence))) | |
707 | ((listp sequence) | |
708 | (mapl (lambda (tail) | |
709 | (let* ((item (car tail)) | |
710 | (rest (cdr tail)) | |
711 | (match (member (funcall key item) rest | |
712 | :test test :key key))) | |
713 | (when match (funcall report item (car match))))) | |
714 | sequence)) | |
715 | ((vectorp sequence) | |
716 | (dotimes (i (length sequence)) | |
717 | (let* ((item (aref sequence i)) | |
718 | (pos (position (funcall key item) sequence | |
719 | :key key :test test :start (1+ i)))) | |
720 | (when pos (funcall report item (aref sequence pos)))))) | |
721 | (t | |
722 | (error 'type-error :datum sequence :expected-type 'sequence)))) | |
723 | ||
dea4d055 MW |
724 | ;;;-------------------------------------------------------------------------- |
725 | ;;; Strings and characters. | |
726 | ||
727 | (export 'frob-identifier) | |
728 | (defun frob-identifier (string &key (swap-case t) (swap-hyphen t)) | |
729 | "Twiddles the case of STRING. | |
730 | ||
731 | If all the letters in STRING are uppercase, and SWAP-CASE is true, then | |
732 | switch them to lowercase; if they're all lowercase then switch them to | |
733 | uppercase. If there's a mix then leave them all alone. At the same time, | |
734 | if there are underscores but no hyphens, and SWAP-HYPHEN is true, then | |
735 | switch them to hyphens, if there are hyphens and no underscores, switch | |
736 | them underscores, and if there are both then leave them alone. | |
737 | ||
738 | This is an invertible transformation, which turns vaguely plausible Lisp | |
739 | names into vaguely plausible C names and vice versa. Lisp names with | |
740 | `funny characters' like stars and percent signs won't be any use, of | |
741 | course." | |
742 | ||
743 | ;; Work out what kind of a job we've got to do. Gather flags: bit 0 means | |
744 | ;; there are upper-case letters; bit 1 means there are lower-case letters; | |
745 | ;; bit 2 means there are hyphens; bit 3 means there are underscores. | |
746 | ;; | |
747 | ;; Consequently, (logxor flags (ash flags 1)) is interesting: bit 1 is set | |
748 | ;; if we have to frob case; bit 3 is set if we have to swap hyphens and | |
749 | ;; underscores. So use this to select functions which do bits of the | |
750 | ;; mapping, and then compose them together. | |
751 | (let* ((flags (reduce (lambda (state ch) | |
752 | (logior state | |
753 | (cond ((upper-case-p ch) 1) | |
754 | ((lower-case-p ch) 2) | |
755 | ((char= ch #\-) 4) | |
756 | ((char= ch #\_) 8) | |
757 | (t 0)))) | |
758 | string | |
759 | :initial-value 0)) | |
760 | (mask (logxor flags (ash flags 1))) | |
761 | (letter (cond ((or (not swap-case) (not (logbitp 1 mask))) | |
762 | (constantly nil)) | |
763 | ((logbitp 0 flags) | |
764 | (lambda (ch) | |
765 | (and (alpha-char-p ch) (char-downcase ch)))) | |
766 | (t | |
767 | (lambda (ch) | |
768 | (and (alpha-char-p ch) (char-upcase ch)))))) | |
769 | (uscore-hyphen (cond ((or (not (logbitp 3 mask)) (not swap-hyphen)) | |
770 | (constantly nil)) | |
771 | ((logbitp 2 flags) | |
772 | (lambda (ch) (and (char= ch #\-) #\_))) | |
773 | (t | |
774 | (lambda (ch) (and (char= ch #\_) #\-)))))) | |
775 | ||
776 | (if (logbitp 3 (logior mask (ash mask 2))) | |
777 | (map 'string (lambda (ch) | |
778 | (or (funcall letter ch) | |
779 | (funcall uscore-hyphen ch) | |
780 | ch)) | |
781 | string) | |
782 | string))) | |
783 | ||
784 | (export 'whitespace-char-p) | |
785 | (declaim (inline whitespace-char-p)) | |
786 | (defun whitespace-char-p (char) | |
787 | "Returns whether CHAR is a whitespace character. | |
788 | ||
789 | Whitespaceness is determined relative to the compile-time readtable, which | |
790 | is probably good enough for most purposes." | |
791 | (case char | |
792 | (#.(loop for i below char-code-limit | |
793 | for ch = (code-char i) | |
794 | unless (with-input-from-string (in (string ch)) | |
795 | (peek-char t in nil)) | |
796 | collect ch) t) | |
797 | (t nil))) | |
798 | ||
799 | (export 'update-position) | |
800 | (declaim (inline update-position)) | |
801 | (defun update-position (char line column) | |
802 | "Updates LINE and COLUMN appropriately for having read the character CHAR. | |
803 | ||
804 | Returns the new LINE and COLUMN numbers." | |
805 | (case char | |
806 | ((#\newline #\vt #\page) | |
807 | (values (1+ line) 0)) | |
808 | ((#\tab) | |
809 | (values line (logandc2 (+ column 8) 7))) | |
810 | (t | |
811 | (values line (1+ column))))) | |
812 | ||
813 | (export 'backtrack-position) | |
814 | (declaim (inline backtrack-position)) | |
815 | (defun backtrack-position (char line column) | |
816 | "Updates LINE and COLUMN appropriately for having unread CHAR. | |
817 | ||
818 | Well, actually an approximation for it; it will likely be wrong if the | |
819 | last character was a tab. But when the character is read again, it will | |
820 | be correct." | |
821 | ||
822 | ;; This isn't perfect: if the character doesn't actually match what was | |
823 | ;; really read then it might not actually be possible: for example, if we | |
824 | ;; push back a newline while in the middle of a line, or a tab while not at | |
825 | ;; a tab stop. In that case, we'll just lose, but hopefully not too badly. | |
826 | (case char | |
827 | ||
828 | ;; In the absence of better ideas, I'll set the column number to zero. | |
829 | ;; This is almost certainly wrong, but with a little luck nobody will ask | |
830 | ;; and it'll be all right soon. | |
831 | ((#\newline #\vt #\page) (values (1- line) 0)) | |
832 | ||
833 | ;; Winding back a single space is sufficient. If the position is | |
834 | ;; currently on a tab stop then it'll advance back here next time. If | |
835 | ;; not, we're going to lose anyway because the previous character | |
836 | ;; certainly couldn't have been a tab. | |
837 | (#\tab (values line (1- column))) | |
838 | ||
839 | ;; Anything else: just decrement the column and cross fingers. | |
840 | (t (values line (1- column))))) | |
841 | ||
842 | ;;;-------------------------------------------------------------------------- | |
843 | ;;; Functions. | |
844 | ||
845 | (export 'compose) | |
846 | (defun compose (function &rest more-functions) | |
847 | "Composition of functions. Functions are applied left-to-right. | |
848 | ||
849 | This is the reverse order of the usual mathematical notation, but I find | |
bf090e02 MW |
850 | it easier to read. It's also slightly easier to work with in programs. |
851 | That is, (compose F1 F2 ... Fn) is what a category theorist might write as | |
852 | F1 ; F2 ; ... ; Fn, rather than F1 o F2 o ... o Fn." | |
853 | ||
dea4d055 MW |
854 | (labels ((compose1 (func-a func-b) |
855 | (lambda (&rest args) | |
856 | (multiple-value-call func-b (apply func-a args))))) | |
857 | (reduce #'compose1 more-functions :initial-value function))) | |
858 | ||
859 | ;;;-------------------------------------------------------------------------- | |
c34b237d MW |
860 | ;;; Variables. |
861 | ||
862 | (export 'defvar-unbound) | |
863 | (defmacro defvar-unbound (var doc) | |
864 | "Make VAR a special variable with documentation DOC, but leave it unbound." | |
865 | `(eval-when (:compile-toplevel :load-toplevel :execute) | |
866 | (defvar ,var) | |
867 | (setf (documentation ',var 'variable) ',doc) | |
868 | ',var)) | |
869 | ||
870 | ;;;-------------------------------------------------------------------------- | |
dea4d055 MW |
871 | ;;; Symbols. |
872 | ||
873 | (export 'symbolicate) | |
874 | (defun symbolicate (&rest symbols) | |
875 | "Return a symbol named after the concatenation of the names of the SYMBOLS. | |
876 | ||
3109662a | 877 | The symbol is interned in the current `*package*'. Trad." |
dea4d055 MW |
878 | (intern (apply #'concatenate 'string (mapcar #'symbol-name symbols)))) |
879 | ||
880 | ;;;-------------------------------------------------------------------------- | |
881 | ;;; Object printing. | |
882 | ||
883 | (export 'maybe-print-unreadable-object) | |
884 | (defmacro maybe-print-unreadable-object | |
885 | ((object stream &rest args) &body body) | |
886 | "Print helper for usually-unreadable objects. | |
887 | ||
3109662a | 888 | If `*print-escape*' is set then print OBJECT unreadably using BODY. |
dea4d055 MW |
889 | Otherwise just print using BODY." |
890 | (with-gensyms (print) | |
891 | `(flet ((,print () ,@body)) | |
892 | (if *print-escape* | |
893 | (print-unreadable-object (,object ,stream ,@args) | |
894 | (,print)) | |
895 | (,print))))) | |
896 | ||
08b6e064 MW |
897 | (export 'print-ugly-stuff) |
898 | (defun print-ugly-stuff (stream func) | |
899 | "Print not-pretty things to the stream underlying STREAM. | |
900 | ||
901 | The Lisp pretty-printing machinery, notably `pprint-logical-block', may | |
902 | interpose additional streams between its body and the original target | |
903 | stream. This makes it difficult to make use of the underlying stream's | |
904 | special features, whatever they might be." | |
905 | ||
906 | ;; This is unpleasant. Hacky hacky. | |
907 | #.(or #+sbcl '(if (typep stream 'sb-pretty:pretty-stream) | |
908 | (let ((target (sb-pretty::pretty-stream-target stream))) | |
909 | (pprint-newline :mandatory stream) | |
910 | (funcall func target)) | |
911 | (funcall func stream)) | |
912 | #+cmu '(if (typep stream 'pp:pretty-stream) | |
913 | (let ((target (pp::pretty-stream-target stream))) | |
914 | (pprint-newline :mandatory stream) | |
915 | (funcall func target)) | |
916 | (funcall func stream)) | |
917 | '(funcall func stream))) | |
918 | ||
dea4d055 MW |
919 | ;;;-------------------------------------------------------------------------- |
920 | ;;; Iteration macros. | |
921 | ||
922 | (export 'dosequence) | |
923 | (defmacro dosequence ((var seq &key (start 0) (end nil) indexvar) | |
924 | &body body | |
925 | &environment env) | |
926 | "Macro for iterating over general sequences. | |
927 | ||
928 | Iterates over a (sub)sequence SEQ, delimited by START and END (which are | |
929 | evaluated). For each item of SEQ, BODY is invoked with VAR bound to the | |
930 | item, and INDEXVAR (if requested) bound to the item's index. (Note that | |
931 | this is different from most iteration constructs in Common Lisp, which | |
932 | work by mutating the variable.) | |
933 | ||
934 | The loop is surrounded by an anonymous BLOCK and the loop body forms an | |
935 | implicit TAGBODY, as is usual. There is no result-form, however." | |
936 | ||
937 | (once-only (:environment env seq start end) | |
938 | (with-gensyms ((ivar "INDEX-") (endvar "END-") (bodyfunc "BODY-")) | |
b8c698ee MW |
939 | (multiple-value-bind (docs decls body) (parse-body body :docp nil) |
940 | (declare (ignore docs)) | |
941 | ||
942 | (flet ((loopguts (indexp listp endvar) | |
943 | ;; Build a DO-loop to do what we want. | |
944 | (let* ((do-vars nil) | |
945 | (end-condition (if endvar | |
946 | `(>= ,ivar ,endvar) | |
947 | `(endp ,seq))) | |
948 | (item (if listp | |
949 | `(car ,seq) | |
950 | `(aref ,seq ,ivar))) | |
951 | (body-call `(,bodyfunc ,item))) | |
952 | (when listp | |
953 | (push `(,seq (nthcdr ,start ,seq) (cdr ,seq)) | |
954 | do-vars)) | |
955 | (when indexp | |
956 | (push `(,ivar ,start (1+ ,ivar)) do-vars)) | |
957 | (when indexvar | |
958 | (setf body-call (append body-call (list ivar)))) | |
959 | `(do ,do-vars (,end-condition) ,body-call)))) | |
960 | ||
961 | `(block nil | |
962 | (flet ((,bodyfunc (,var ,@(and indexvar `(,indexvar))) | |
963 | ,@decls | |
964 | (tagbody ,@body))) | |
dea4d055 MW |
965 | (etypecase ,seq |
966 | (vector | |
967 | (let ((,endvar (or ,end (length ,seq)))) | |
968 | ,(loopguts t nil endvar))) | |
969 | (list | |
970 | (if ,end | |
971 | ,(loopguts t t end) | |
b8c698ee | 972 | ,(loopguts indexvar t nil))))))))))) |
dea4d055 MW |
973 | |
974 | ;;;-------------------------------------------------------------------------- | |
4b8e5c03 MW |
975 | ;;; Structure accessor hacks. |
976 | ||
977 | (export 'define-access-wrapper) | |
978 | (defmacro define-access-wrapper (from to &key read-only) | |
979 | "Make (FROM THING) work like (TO THING). | |
980 | ||
981 | If not READ-ONLY, then also make (setf (FROM THING) VALUE) work like | |
982 | (setf (TO THING) VALUE). | |
983 | ||
984 | This is mostly useful for structure slot accessors where the slot has to | |
985 | be given an unpleasant name to avoid it being an external symbol." | |
986 | `(progn | |
987 | (declaim (inline ,from ,@(and (not read-only) `((setf ,from))))) | |
988 | (defun ,from (object) | |
989 | (,to object)) | |
990 | ,@(and (not read-only) | |
991 | `((defun (setf ,from) (value object) | |
992 | (setf (,to object) value)))))) | |
993 | ||
994 | ;;;-------------------------------------------------------------------------- | |
db6c3279 MW |
995 | ;;; Condition and error utilities. |
996 | ||
997 | (export 'designated-condition) | |
998 | (defun designated-condition (default-type datum arguments | |
999 | &key allow-pointless-arguments) | |
1000 | "Return the condition designated by DATUM and ARGUMENTS. | |
1001 | ||
1002 | DATUM and ARGUMENTS together are a `condition designator' of (some | |
1003 | supertype of) DEFAULT-TYPE; return the condition so designated." | |
1004 | (typecase datum | |
1005 | (condition | |
1006 | (unless (or allow-pointless-arguments (null arguments)) | |
1007 | (error "Argument list provided with specific condition")) | |
1008 | datum) | |
1009 | (symbol | |
1010 | (apply #'make-condition datum arguments)) | |
1011 | ((or string function) | |
1012 | (make-condition default-type | |
1013 | :format-control datum | |
1014 | :format-arguments arguments)) | |
1015 | (t | |
1016 | (error "Unexpected condition designator datum ~S" datum)))) | |
1017 | ||
f7b60deb MW |
1018 | (export 'simple-control-error) |
1019 | (define-condition simple-control-error (control-error simple-error) | |
1020 | ()) | |
1021 | ||
1022 | (export 'invoke-associated-restart) | |
1023 | (defun invoke-associated-restart (restart condition &rest arguments) | |
1024 | "Invoke the active RESTART associated with CONDITION, with the ARGUMENTS. | |
1025 | ||
1026 | Find an active restart designated by RESTART; if CONDITION is not nil, | |
1027 | then restrict the search to restarts associated with CONDITION, and | |
1028 | restarts not associated with any condition. If no such restart is found | |
1029 | then signal an error of type `control-error'; otherwise invoke the restart | |
1030 | with the given ARGUMENTS." | |
1031 | (apply #'invoke-restart | |
1032 | (or (find-restart restart condition) | |
1033 | (error 'simple-control-error | |
1034 | :format-control "~:[Restart ~S is not active~;~ | |
1035 | No active `~(~A~)' restart~]~ | |
1036 | ~@[ for condition ~S~]" | |
1037 | :format-arguments (list (symbolp restart) | |
1038 | restart | |
1039 | condition))) | |
1040 | arguments)) | |
1041 | ||
c884ec24 MW |
1042 | (export '(enclosing-condition enclosed-condition)) |
1043 | (define-condition enclosing-condition (condition) | |
1044 | ((%enclosed-condition :initarg :condition :type condition | |
1045 | :reader enclosed-condition)) | |
1046 | (:documentation | |
1047 | "A condition which encloses another condition | |
1048 | ||
1049 | This is useful if one wants to attach additional information to an | |
1050 | existing condition. The enclosed condition can be obtained using the | |
1051 | `enclosed-condition' function.") | |
1052 | (:report (lambda (condition stream) | |
1053 | (princ (enclosed-condition condition) stream)))) | |
1054 | ||
1055 | (export 'information) | |
1056 | (define-condition information (condition) | |
1057 | ()) | |
1058 | ||
1059 | (export 'simple-information) | |
1060 | (define-condition simple-information (simple-condition information) | |
1061 | ()) | |
1062 | ||
1063 | (export 'info) | |
1064 | (defun info (datum &rest arguments) | |
1065 | "Report some useful diagnostic information. | |
1066 | ||
1067 | Establish a simple restart named `noted', and signal the condition of type | |
1068 | `information' designated by DATUM and ARGUMENTS. Return non-nil if the | |
1069 | restart was invoked, otherwise nil." | |
1070 | (restart-case | |
1071 | (signal (designated-condition 'simple-information datum arguments)) | |
1072 | (noted () :report "Noted." t))) | |
1073 | ||
1074 | (export 'noted) | |
1075 | (defun noted (&optional condition) | |
1076 | "Invoke the `noted' restart, possibly associated with the given CONDITION." | |
1077 | (invoke-associated-restart 'noted condition)) | |
1078 | ||
1079 | (export 'promiscuous-cerror) | |
1080 | (defun promiscuous-cerror (continue-string datum &rest arguments) | |
1081 | "Like standard `cerror', but robust against sneaky changes of conditions. | |
1082 | ||
1083 | It seems that `cerror' (well, at least the version in SBCL) is careful | |
1084 | to limit its restart to the specific condition it signalled. But that's | |
1085 | annoying, because `sod-parser:with-default-error-location' substitutes | |
1086 | different conditions carrying the error-location information." | |
1087 | (restart-case (apply #'error datum arguments) | |
1088 | (continue () | |
1089 | :report (lambda (stream) | |
1090 | (apply #'format stream continue-string datum arguments)) | |
1091 | nil))) | |
1092 | ||
1093 | (export 'cerror*) | |
1094 | (defun cerror* (datum &rest arguments) | |
1095 | (apply #'promiscuous-cerror "Continue" datum arguments)) | |
1096 | ||
db6c3279 | 1097 | ;;;-------------------------------------------------------------------------- |
dea4d055 MW |
1098 | ;;; CLOS hacking. |
1099 | ||
1100 | (export 'default-slot) | |
1101 | (defmacro default-slot ((instance slot &optional (slot-names t)) | |
1102 | &body value | |
1103 | &environment env) | |
1104 | "If INSTANCE's slot named SLOT is unbound, set it to VALUE. | |
1105 | ||
1106 | Only set SLOT if it's listed in SLOT-NAMES, or SLOT-NAMES is `t' (i.e., we | |
1107 | obey the `shared-initialize' protocol). SLOT-NAMES defaults to `t', so | |
1108 | you can use it in `initialize-instance' or similar without ill effects. | |
1109 | Both INSTANCE and SLOT are evaluated; VALUE is an implicit progn and only | |
1110 | evaluated if it's needed." | |
1111 | ||
1112 | (once-only (:environment env instance slot slot-names) | |
1113 | `(when ,(if (eq slot-names t) | |
1114 | `(not (slot-boundp ,instance ,slot)) | |
1115 | `(and (not (slot-boundp ,instance ,slot)) | |
1116 | (or (eq ,slot-names t) | |
1117 | (member ,slot ,slot-names)))) | |
1118 | (setf (slot-value ,instance ,slot) | |
1119 | (progn ,@value))))) | |
1120 | ||
141283ff MW |
1121 | (export 'define-on-demand-slot) |
1122 | (defmacro define-on-demand-slot (class slot (instance) &body body) | |
1123 | "Defines a slot which computes its initial value on demand. | |
1124 | ||
1125 | Sets up the named SLOT of CLASS to establish its value as the implicit | |
1126 | progn BODY, by defining an appropriate method on `slot-unbound'." | |
b8c698ee MW |
1127 | (multiple-value-bind (docs decls body) (parse-body body) |
1128 | (with-gensyms (classvar slotvar) | |
1129 | `(defmethod slot-unbound | |
1130 | (,classvar (,instance ,class) (,slotvar (eql ',slot))) | |
1131 | ,@docs ,@decls | |
1132 | (declare (ignore ,classvar)) | |
fc09e191 | 1133 | (setf (slot-value ,instance ',slot) (block ,slot ,@body)))))) |
141283ff | 1134 | |
dea4d055 | 1135 | ;;;----- That's all, folks -------------------------------------------------- |