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fd7fa35a | 1 | ;; cust-print.el -- handles print-level and print-circle. |
ecb4184d | 2 | |
9750e079 ER |
3 | ;; Copyright (C) 1992 Free Software Foundation, Inc. |
4 | ||
e5167999 ER |
5 | ;; Author: Daniel LaLiberte <liberte@cs.uiuc.edu> |
6 | ;; Version: 1.0 | |
e5167999 | 7 | ;; Adapted-By: ESR |
fd7fa35a | 8 | ;; Keyword: extensions |
ecb4184d | 9 | |
ecb4184d ER |
10 | ;; This file is part of GNU Emacs. |
11 | ||
12 | ;; GNU Emacs is free software; you can redistribute it and/or modify | |
13 | ;; it under the terms of the GNU General Public License as published by | |
e5167999 | 14 | ;; the Free Software Foundation; either version 2, or (at your option) |
ecb4184d ER |
15 | ;; any later version. |
16 | ||
17 | ;; GNU Emacs 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 GNU Emacs; see the file COPYING. If not, write to | |
24 | ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. | |
25 | ||
e5167999 ER |
26 | ;;; Commentary: |
27 | ||
ecb4184d ER |
28 | ;; This package provides a general print handler for prin1 and princ |
29 | ;; that supports print-level and print-circle, and by the way, | |
30 | ;; print-length since the standard routines are being replaced. Also, | |
31 | ;; to print custom types constructed from lists and vectors, use | |
32 | ;; custom-print-list and custom-print-vector. See the documentation | |
33 | ;; strings of these variables for more details. | |
34 | ||
35 | ;; If the results of your expressions contain circular references to | |
36 | ;; other parts of the same structure, the standard Emacs print | |
37 | ;; subroutines may fail to print with an untrappable error, | |
38 | ;; "Apparently circular structure being printed". If you only use cdr | |
39 | ;; circular lists (where cdrs of lists point back; what is the right | |
40 | ;; term here?), you can limit the length of printing with | |
41 | ;; print-length. But car circular lists and circular vectors generate | |
42 | ;; the above mentioned untrappable error in Emacs version 18. Version | |
43 | ;; 19 will support print-level, but it is often useful to get a better | |
44 | ;; print representation of circular structures; the print-circle | |
45 | ;; option may be used to print more concise representations. | |
46 | ||
47 | ;; There are two main ways to use this package. First, you may | |
48 | ;; replace prin1, princ, and some subroutines that use them by calling | |
49 | ;; install-custom-print-funcs so that any use of these functions in | |
50 | ;; lisp code will be affected. Second, you could call the custom | |
51 | ;; routines directly, thus only affecting the printing that requires | |
52 | ;; them. | |
53 | ||
54 | ;; Note that subroutines which call print subroutines directly will not | |
55 | ;; use the custom print functions. In particular, the evaluation | |
56 | ;; functions like eval-region call the print subroutines directly. | |
57 | ;; Therefore, evaluating (aref circ-list 0), which calls error | |
58 | ;; directly (because circ-list is not an array), will jump to the top | |
59 | ;; level instead of printing the circular list. | |
60 | ||
61 | ;; Obviously the right way to implement this custom-print facility | |
62 | ;; is in C. Please volunteer since I don't have the time or need. | |
63 | ||
64 | ;; Implementation design: we want to use the same list and vector | |
65 | ;; processing algorithm for all versions of prin1 and princ, since how | |
66 | ;; the processing is done depends on print-length, print-level, and | |
67 | ;; print-circle. For circle printing, a preprocessing step is | |
68 | ;; required before the final printing. Thanks to Jamie Zawinski | |
69 | ;; for motivation and algorithms. | |
70 | ||
71 | ;;========================================================= | |
72 | ;; export list: | |
73 | ||
74 | ;; print-level | |
75 | ;; print-circle | |
76 | ||
77 | ;; custom-print-list | |
78 | ;; custom-print-vector | |
79 | ;; add-custom-print-list | |
80 | ;; add-custom-print-vector | |
81 | ||
82 | ;; install-custom-print-funcs | |
83 | ;; uninstall-custom-print-funcs | |
84 | ||
85 | ;; custom-prin1 | |
86 | ;; custom-princ | |
87 | ;; custom-prin1-to-string | |
88 | ;; custom-print | |
89 | ;; custom-format | |
90 | ;; custom-message | |
91 | ;; custom-error | |
92 | ||
e5167999 | 93 | ;;; Code: |
ecb4184d ER |
94 | |
95 | (provide 'custom-print) | |
ecb4184d ER |
96 | |
97 | ;;(defvar print-length nil | |
98 | ;; "*Controls how many elements of a list, at each level, are printed. | |
99 | ;;This is defined by emacs.") | |
100 | ||
101 | (defvar print-level nil | |
102 | "*Controls how many levels deep a nested data object will print. | |
103 | ||
104 | If nil, printing proceeds recursively and may lead to | |
105 | max-lisp-eval-depth being exceeded or an untrappable error may occur: | |
fb252f97 RS |
106 | `Apparently circular structure being printed.' |
107 | Also see `print-length' and `print-circle'. | |
ecb4184d | 108 | |
fb252f97 | 109 | If non-nil, components at levels equal to or greater than `print-level' |
ecb4184d ER |
110 | are printed simply as \"#\". The object to be printed is at level 0, |
111 | and if the object is a list or vector, its top-level components are at | |
112 | level 1.") | |
113 | ||
114 | ||
115 | (defvar print-circle nil | |
116 | "*Controls the printing of recursive structures. | |
117 | ||
118 | If nil, printing proceeds recursively and may lead to | |
fb252f97 | 119 | `max-lisp-eval-depth' being exceeded or an untrappable error may occur: |
ecb4184d | 120 | \"Apparently circular structure being printed.\" Also see |
fb252f97 | 121 | `print-length' and `print-level'. |
ecb4184d ER |
122 | |
123 | If non-nil, shared substructures anywhere in the structure are printed | |
fb252f97 RS |
124 | with `#N=' before the first occurance (in the order of the print |
125 | representation) and `#N#' in place of each subsequent occurance, | |
126 | where N is a positive decimal integer. | |
ecb4184d ER |
127 | |
128 | Currently, there is no way to read this representation in Emacs.") | |
129 | ||
130 | ||
131 | (defconst custom-print-list | |
132 | nil | |
133 | ;; e.g. '((floatp . float-to-string)) | |
fb252f97 RS |
134 | "An alist for custom printing of lists. |
135 | Pairs are of the form (PRED . CONVERTER). If PREDICATE is true | |
136 | for an object, then CONVERTER is called with the object and should | |
137 | return a string to be printed with `princ'. | |
138 | Also see `custom-print-vector'.") | |
ecb4184d ER |
139 | |
140 | (defconst custom-print-vector | |
141 | nil | |
fb252f97 RS |
142 | "An alist for custom printing of vectors. |
143 | Pairs are of the form (PRED . CONVERTER). If PREDICATE is true | |
144 | for an object, then CONVERTER is called with the object and should | |
145 | return a string to be printed with `princ'. | |
146 | Also see `custom-print-list'.") | |
ecb4184d ER |
147 | |
148 | ||
149 | (defun add-custom-print-list (pred converter) | |
fb252f97 | 150 | "Add a pair of PREDICATE and CONVERTER to `custom-print-list'. |
ecb4184d ER |
151 | Any pair that has the same PREDICATE is first removed." |
152 | (setq custom-print-list (cons (cons pred converter) | |
153 | (delq (assq pred custom-print-list) | |
154 | custom-print-list)))) | |
155 | ;; e.g. (add-custom-print-list 'floatp 'float-to-string) | |
156 | ||
157 | ||
158 | (defun add-custom-print-vector (pred converter) | |
fb252f97 | 159 | "Add a pair of PREDICATE and CONVERTER to `custom-print-vector'. |
ecb4184d ER |
160 | Any pair that has the same PREDICATE is first removed." |
161 | (setq custom-print-vector (cons (cons pred converter) | |
162 | (delq (assq pred custom-print-vector) | |
163 | custom-print-vector)))) | |
164 | ||
165 | ||
166 | ;;==================================================== | |
167 | ;; Saving and restoring internal printing routines. | |
168 | ||
fb252f97 | 169 | (defun cust-print-set-function-cell (symbol-pair) |
ecb4184d ER |
170 | (fset (car symbol-pair) |
171 | (symbol-function (car (cdr symbol-pair))))) | |
172 | ||
173 | ||
fb252f97 RS |
174 | (if (not (fboundp 'cust-print-internal-prin1)) |
175 | (mapcar 'cust-print-set-function-cell | |
176 | '((cust-print-internal-prin1 prin1) | |
177 | (cust-print-internal-princ princ) | |
178 | (cust-print-internal-print print) | |
179 | (cust-print-internal-prin1-to-string prin1-to-string) | |
180 | (cust-print-internal-format format) | |
181 | (cust-print-internal-message message) | |
182 | (cust-print-internal-error error)))) | |
ecb4184d ER |
183 | |
184 | ||
185 | (defun install-custom-print-funcs () | |
fb252f97 RS |
186 | "Replace print functions with general, customizable, Lisp versions. |
187 | The internal subroutines are saved away, and you can reinstall them | |
188 | by running `uninstall-custom-print-funcs'." | |
ecb4184d | 189 | (interactive) |
fb252f97 | 190 | (mapcar 'cust-print-set-function-cell |
ecb4184d ER |
191 | '((prin1 custom-prin1) |
192 | (princ custom-princ) | |
193 | (print custom-print) | |
194 | (prin1-to-string custom-prin1-to-string) | |
195 | (format custom-format) | |
196 | (message custom-message) | |
197 | (error custom-error) | |
198 | ))) | |
199 | ||
200 | (defun uninstall-custom-print-funcs () | |
201 | "Reset print functions to their internal subroutines." | |
202 | (interactive) | |
fb252f97 RS |
203 | (mapcar 'cust-print-set-function-cell |
204 | '((prin1 cust-print-internal-prin1) | |
205 | (princ cust-print-internal-princ) | |
206 | (print cust-print-internal-print) | |
207 | (prin1-to-string cust-print-internal-prin1-to-string) | |
208 | (format cust-print-internal-format) | |
209 | (message cust-print-internal-message) | |
210 | (error cust-print-internal-error) | |
ecb4184d ER |
211 | ))) |
212 | ||
213 | ||
214 | ;;=============================================================== | |
215 | ;; Lisp replacements for prin1 and princ and for subrs that use prin1 | |
216 | ;; (or princ) -- so far only the printing and formatting subrs. | |
217 | ||
218 | (defun custom-prin1 (object &optional stream) | |
fb252f97 RS |
219 | "Replacement for standard `prin1'. |
220 | Uses the appropriate printer depending on the values of `print-level' | |
221 | and `print-circle' (which see). | |
ecb4184d ER |
222 | |
223 | Output the printed representation of OBJECT, any Lisp object. | |
224 | Quoting characters are printed when needed to make output that `read' | |
225 | can handle, whenever this is possible. | |
226 | Output stream is STREAM, or value of `standard-output' (which see)." | |
fb252f97 | 227 | (cust-print-top-level object stream 'cust-print-internal-prin1)) |
ecb4184d ER |
228 | |
229 | ||
230 | (defun custom-princ (object &optional stream) | |
fb252f97 RS |
231 | "Same as `custom-prin1' except no quoting." |
232 | (cust-print-top-level object stream 'cust-print-internal-princ)) | |
ecb4184d ER |
233 | |
234 | (defun custom-prin1-to-string-func (c) | |
fb252f97 | 235 | "Stream function for `custom-prin1-to-string'." |
ecb4184d ER |
236 | (setq prin1-chars (cons c prin1-chars))) |
237 | ||
238 | (defun custom-prin1-to-string (object) | |
fb252f97 | 239 | "Replacement for standard `prin1-to-string'." |
ecb4184d ER |
240 | (let ((prin1-chars nil)) |
241 | (custom-prin1 object 'custom-prin1-to-string-func) | |
242 | (concat (nreverse prin1-chars)))) | |
243 | ||
244 | ||
245 | (defun custom-print (object &optional stream) | |
fb252f97 RS |
246 | "Replacement for standard `print'." |
247 | (cust-print-internal-princ "\n") | |
ecb4184d | 248 | (custom-prin1 object stream) |
fb252f97 | 249 | (cust-print-internal-princ "\n")) |
ecb4184d ER |
250 | |
251 | ||
252 | (defun custom-format (fmt &rest args) | |
fb252f97 | 253 | "Replacement for standard `format'. |
ecb4184d ER |
254 | |
255 | Calls format after first making strings for list or vector args. | |
fb252f97 | 256 | The format specification for such args should be `%s' in any case, so a |
ecb4184d | 257 | string argument will also work. The string is generated with |
fb252f97 RS |
258 | `custom-prin1-to-string', which quotes quotable characters." |
259 | (apply 'cust-print-internal-format fmt | |
ecb4184d ER |
260 | (mapcar (function (lambda (arg) |
261 | (if (or (listp arg) (vectorp arg)) | |
262 | (custom-prin1-to-string arg) | |
263 | arg))) | |
264 | args))) | |
265 | ||
266 | ||
267 | ||
268 | (defun custom-message (fmt &rest args) | |
fb252f97 | 269 | "Replacement for standard `message' that works like `custom-format'." |
ecb4184d ER |
270 | ;; It doesnt work to princ the result of custom-format |
271 | ;; because the echo area requires special handling | |
fb252f97 RS |
272 | ;; to avoid duplicating the output. cust-print-internal-message does it right. |
273 | ;; (cust-print-internal-princ (apply 'custom-format fmt args)) | |
274 | (apply 'cust-print-internal-message fmt | |
ecb4184d ER |
275 | (mapcar (function (lambda (arg) |
276 | (if (or (listp arg) (vectorp arg)) | |
277 | (custom-prin1-to-string arg) | |
278 | arg))) | |
279 | args))) | |
280 | ||
281 | ||
282 | (defun custom-error (fmt &rest args) | |
fb252f97 | 283 | "Replacement for standard `error' that uses `custom-format'" |
ecb4184d ER |
284 | (signal 'error (list (apply 'custom-format fmt args)))) |
285 | ||
286 | ||
287 | ;;========================================= | |
288 | ;; Support for custom prin1 and princ | |
289 | ||
fb252f97 | 290 | (defun cust-print-top-level (object stream internal-printer) |
ecb4184d ER |
291 | "Set up for printing." |
292 | (let ((standard-output (or stream standard-output)) | |
fb252f97 | 293 | (circle-table (and print-circle (cust-print-preprocess-circle-tree object))) |
ecb4184d ER |
294 | (level (or print-level -1)) |
295 | ) | |
296 | ||
fb252f97 RS |
297 | (fset 'cust-print-internal-printer internal-printer) |
298 | (fset 'cust-print-low-level-prin | |
ecb4184d ER |
299 | (cond |
300 | ((or custom-print-list | |
301 | custom-print-vector | |
302 | print-level ; comment out for version 19 | |
303 | ) | |
fb252f97 | 304 | 'cust-print-custom-object) |
ecb4184d | 305 | (circle-table |
fb252f97 RS |
306 | 'cust-print-object) |
307 | (t 'cust-print-internal-printer))) | |
308 | (fset 'cust-print-prin (if circle-table 'cust-print-circular 'cust-print-low-level-prin)) | |
ecb4184d | 309 | |
fb252f97 | 310 | (cust-print-prin object) |
ecb4184d ER |
311 | object)) |
312 | ||
313 | ||
fb252f97 RS |
314 | ;; Test object type and print accordingly. |
315 | (defun cust-print-object (object) | |
316 | ;; Could be called as either cust-print-low-level-prin or cust-print-prin. | |
ecb4184d | 317 | (cond |
fb252f97 RS |
318 | ((null object) (cust-print-internal-printer object)) |
319 | ((consp object) (cust-print-list object)) | |
320 | ((vectorp object) (cust-print-vector object)) | |
ecb4184d | 321 | ;; All other types, just print. |
fb252f97 | 322 | (t (cust-print-internal-printer object)))) |
ecb4184d ER |
323 | |
324 | ||
fb252f97 RS |
325 | ;; Test object type and print accordingly. |
326 | (defun cust-print-custom-object (object) | |
327 | ;; Could be called as either cust-print-low-level-prin or cust-print-prin. | |
ecb4184d | 328 | (cond |
fb252f97 | 329 | ((null object) (cust-print-internal-printer object)) |
ecb4184d ER |
330 | |
331 | ((consp object) | |
332 | (or (and custom-print-list | |
fb252f97 RS |
333 | (cust-print-custom-object1 object custom-print-list)) |
334 | (cust-print-list object))) | |
ecb4184d ER |
335 | |
336 | ((vectorp object) | |
337 | (or (and custom-print-vector | |
fb252f97 RS |
338 | (cust-print-custom-object1 object custom-print-vector)) |
339 | (cust-print-vector object))) | |
ecb4184d ER |
340 | |
341 | ;; All other types, just print. | |
fb252f97 | 342 | (t (cust-print-internal-printer object)))) |
ecb4184d ER |
343 | |
344 | ||
fb252f97 RS |
345 | ;; Helper for cust-print-custom-object. |
346 | ;; Print the custom OBJECT using the custom type ALIST. | |
347 | ;; For the first predicate that matches the object, the corresponding | |
348 | ;; converter is evaluated with the object and the string that results is | |
349 | ;; printed with princ. Return nil if no predicte matches the object. | |
350 | (defun cust-print-custom-object1 (object alist) | |
ecb4184d ER |
351 | (while (and alist (not (funcall (car (car alist)) object))) |
352 | (setq alist (cdr alist))) | |
353 | ;; If alist is not null, then something matched. | |
354 | (if alist | |
fb252f97 | 355 | (cust-print-internal-princ |
ecb4184d ER |
356 | (funcall (cdr (car alist)) object) ; returns string |
357 | ))) | |
358 | ||
359 | ||
fb252f97 RS |
360 | (defun cust-print-circular (object) |
361 | "Printer for `prin1' and `princ' that handles circular structures. | |
ecb4184d | 362 | If OBJECT appears multiply, and has not yet been printed, |
fb252f97 | 363 | prefix with label; if it has been printed, use `#N#' instead. |
ecb4184d ER |
364 | Otherwise, print normally." |
365 | (let ((tag (assq object circle-table))) | |
366 | (if tag | |
367 | (let ((id (cdr tag))) | |
368 | (if (> id 0) | |
369 | (progn | |
370 | ;; Already printed, so just print id. | |
fb252f97 RS |
371 | (cust-print-internal-princ "#") |
372 | (cust-print-internal-princ id) | |
373 | (cust-print-internal-princ "#")) | |
ecb4184d ER |
374 | ;; Not printed yet, so label with id and print object. |
375 | (setcdr tag (- id)) ; mark it as printed | |
fb252f97 RS |
376 | (cust-print-internal-princ "#") |
377 | (cust-print-internal-princ (- id)) | |
378 | (cust-print-internal-princ "=") | |
379 | (cust-print-low-level-prin object) | |
ecb4184d ER |
380 | )) |
381 | ;; Not repeated in structure. | |
fb252f97 | 382 | (cust-print-low-level-prin object)))) |
ecb4184d ER |
383 | |
384 | ||
385 | ;;================================================ | |
386 | ;; List and vector processing for print functions. | |
387 | ||
fb252f97 RS |
388 | ;; Print a list using print-length, print-level, and print-circle. |
389 | (defun cust-print-list (list) | |
ecb4184d | 390 | (if (= level 0) |
fb252f97 | 391 | (cust-print-internal-princ "#") |
ecb4184d | 392 | (let ((level (1- level))) |
fb252f97 | 393 | (cust-print-internal-princ "(") |
ecb4184d ER |
394 | (let ((length (or print-length 0))) |
395 | ||
396 | ;; Print the first element always (even if length = 0). | |
fb252f97 | 397 | (cust-print-prin (car list)) |
ecb4184d | 398 | (setq list (cdr list)) |
fb252f97 | 399 | (if list (cust-print-internal-princ " ")) |
ecb4184d ER |
400 | (setq length (1- length)) |
401 | ||
402 | ;; Print the rest of the elements. | |
403 | (while (and list (/= 0 length)) | |
404 | (if (and (listp list) | |
405 | (not (assq list circle-table))) | |
406 | (progn | |
fb252f97 | 407 | (cust-print-prin (car list)) |
ecb4184d ER |
408 | (setq list (cdr list))) |
409 | ||
410 | ;; cdr is not a list, or it is in circle-table. | |
fb252f97 RS |
411 | (cust-print-internal-princ ". ") |
412 | (cust-print-prin list) | |
ecb4184d ER |
413 | (setq list nil)) |
414 | ||
415 | (setq length (1- length)) | |
fb252f97 | 416 | (if list (cust-print-internal-princ " "))) |
ecb4184d | 417 | |
fb252f97 RS |
418 | (if (and list (= length 0)) (cust-print-internal-princ "...")) |
419 | (cust-print-internal-princ ")")))) | |
ecb4184d ER |
420 | list) |
421 | ||
422 | ||
fb252f97 RS |
423 | ;; Print a vector according to print-length, print-level, and print-circle. |
424 | (defun cust-print-vector (vector) | |
ecb4184d | 425 | (if (= level 0) |
fb252f97 | 426 | (cust-print-internal-princ "#") |
ecb4184d ER |
427 | (let ((level (1- level)) |
428 | (i 0) | |
429 | (len (length vector))) | |
fb252f97 | 430 | (cust-print-internal-princ "[") |
ecb4184d ER |
431 | |
432 | (if print-length | |
433 | (setq len (min print-length len))) | |
434 | ;; Print the elements | |
435 | (while (< i len) | |
fb252f97 | 436 | (cust-print-prin (aref vector i)) |
ecb4184d | 437 | (setq i (1+ i)) |
fb252f97 | 438 | (if (< i (length vector)) (cust-print-internal-princ " "))) |
ecb4184d | 439 | |
fb252f97 RS |
440 | (if (< i (length vector)) (cust-print-internal-princ "...")) |
441 | (cust-print-internal-princ "]") | |
ecb4184d ER |
442 | )) |
443 | vector) | |
444 | ||
445 | ||
446 | ;;================================== | |
447 | ;; Circular structure preprocessing | |
448 | ||
fb252f97 | 449 | (defun cust-print-preprocess-circle-tree (object) |
ecb4184d ER |
450 | ;; Fill up the table. |
451 | (let (;; Table of tags for each object in an object to be printed. | |
452 | ;; A tag is of the form: | |
453 | ;; ( <object> <nil-t-or-id-number> ) | |
454 | ;; The id-number is generated after the entire table has been computed. | |
455 | ;; During walk through, the real circle-table lives in the cdr so we | |
456 | ;; can use setcdr to add new elements instead of having to setq the | |
457 | ;; variable sometimes (poor man's locf). | |
458 | (circle-table (list nil))) | |
fb252f97 | 459 | (cust-print-walk-circle-tree object) |
ecb4184d ER |
460 | |
461 | ;; Reverse table so it is in the order that the objects will be printed. | |
462 | ;; This pass could be avoided if we always added to the end of the | |
463 | ;; table with setcdr in walk-circle-tree. | |
464 | (setcdr circle-table (nreverse (cdr circle-table))) | |
465 | ||
466 | ;; Walk through the table, assigning id-numbers to those | |
467 | ;; objects which will be printed using #N= syntax. Delete those | |
468 | ;; objects which will be printed only once (to speed up assq later). | |
469 | (let ((rest circle-table) | |
470 | (id -1)) | |
471 | (while (cdr rest) | |
472 | (let ((tag (car (cdr rest)))) | |
473 | (cond ((cdr tag) | |
474 | (setcdr tag id) | |
475 | (setq id (1- id)) | |
476 | (setq rest (cdr rest))) | |
477 | ;; Else delete this object. | |
478 | (t (setcdr rest (cdr (cdr rest)))))) | |
479 | )) | |
480 | ;; Drop the car. | |
481 | (cdr circle-table) | |
482 | )) | |
483 | ||
484 | ||
485 | ||
fb252f97 | 486 | (defun cust-print-walk-circle-tree (object) |
ecb4184d ER |
487 | (let (read-equivalent-p tag) |
488 | (while object | |
489 | (setq read-equivalent-p (or (numberp object) (symbolp object)) | |
490 | tag (and (not read-equivalent-p) | |
491 | (assq object (cdr circle-table)))) | |
492 | (cond (tag | |
493 | ;; Seen this object already, so note that. | |
494 | (setcdr tag t)) | |
495 | ||
496 | ((not read-equivalent-p) | |
497 | ;; Add a tag for this object. | |
498 | (setcdr circle-table | |
499 | (cons (list object) | |
500 | (cdr circle-table))))) | |
501 | (setq object | |
502 | (cond | |
503 | (tag ;; No need to descend since we have already. | |
504 | nil) | |
505 | ||
506 | ((consp object) | |
507 | ;; Walk the car of the list recursively. | |
fb252f97 | 508 | (cust-print-walk-circle-tree (car object)) |
ecb4184d ER |
509 | ;; But walk the cdr with the above while loop |
510 | ;; to avoid problems with max-lisp-eval-depth. | |
511 | ;; And it should be faster than recursion. | |
512 | (cdr object)) | |
513 | ||
514 | ((vectorp object) | |
515 | ;; Walk the vector. | |
516 | (let ((i (length object)) | |
517 | (j 0)) | |
518 | (while (< j i) | |
fb252f97 | 519 | (cust-print-walk-circle-tree (aref object j)) |
ecb4184d ER |
520 | (setq j (1+ j)))))))))) |
521 | ||
522 | ||
523 | ||
524 | ;;======================================= | |
525 | ||
526 | (quote | |
527 | examples | |
528 | ||
529 | (progn | |
530 | ;; Create some circular structures. | |
531 | (setq circ-sym (let ((x (make-symbol "FOO"))) (list x x))) | |
532 | (setq circ-list (list 'a 'b (vector 1 2 3 4) 'd 'e 'f)) | |
533 | (setcar (nthcdr 3 circ-list) circ-list) | |
534 | (aset (nth 2 circ-list) 2 circ-list) | |
535 | (setq dotted-circ-list (list 'a 'b 'c)) | |
536 | (setcdr (cdr (cdr dotted-circ-list)) dotted-circ-list) | |
537 | (setq circ-vector (vector 1 2 3 4 (list 'a 'b 'c 'd) 6 7)) | |
538 | (aset circ-vector 5 (make-symbol "-gensym-")) | |
539 | (setcar (cdr (aref circ-vector 4)) (aref circ-vector 5)) | |
540 | nil) | |
541 | ||
542 | (install-custom-print-funcs) | |
543 | ;; (setq print-circle t) | |
544 | ||
545 | (let ((print-circle t)) | |
546 | (or (equal (prin1-to-string circ-list) "#1=(a b [1 2 #1# 4] #1# e f)") | |
547 | (error "circular object with array printing"))) | |
548 | ||
549 | (let ((print-circle t)) | |
550 | (or (equal (prin1-to-string dotted-circ-list) "#1=(a b c . #1#)") | |
551 | (error "circular object with array printing"))) | |
552 | ||
553 | (let* ((print-circle t) | |
554 | (x (list 'p 'q)) | |
555 | (y (list (list 'a 'b) x 'foo x))) | |
556 | (setcdr (cdr (cdr (cdr y))) (cdr y)) | |
557 | (or (equal (prin1-to-string y) "((a b) . #1=(#2=(p q) foo #2# . #1#))" | |
558 | ) | |
559 | (error "circular list example from CL manual"))) | |
560 | ||
561 | ;; There's no special handling of uninterned symbols in custom-print. | |
562 | (let ((print-circle nil)) | |
563 | (or (equal (prin1-to-string circ-sym) "(#:FOO #:FOO)") | |
564 | (error "uninterned symbols in list"))) | |
565 | (let ((print-circle t)) | |
566 | (or (equal (prin1-to-string circ-sym) "(#1=FOO #1#)") | |
567 | (error "circular uninterned symbols in list"))) | |
568 | ||
569 | (uninstall-custom-print-funcs) | |
570 | ) | |
571 | ||
fd7fa35a | 572 | ;;; cust-print.el ends here |