Commit | Line | Data |
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c6953be1 | 1 | /* undo handling for GNU Emacs. |
3a22ee35 | 2 | Copyright (C) 1990, 1993, 1994 Free Software Foundation, Inc. |
c6953be1 JB |
3 | |
4 | This file is part of GNU Emacs. | |
5 | ||
6 | GNU Emacs is distributed in the hope that it will be useful, | |
7 | but WITHOUT ANY WARRANTY. No author or distributor | |
8 | accepts responsibility to anyone for the consequences of using it | |
9 | or for whether it serves any particular purpose or works at all, | |
10 | unless he says so in writing. Refer to the GNU Emacs General Public | |
11 | License for full details. | |
12 | ||
13 | Everyone is granted permission to copy, modify and redistribute | |
14 | GNU Emacs, but only under the conditions described in the | |
15 | GNU Emacs General Public License. A copy of this license is | |
16 | supposed to have been given to you along with GNU Emacs so you | |
17 | can know your rights and responsibilities. It should be in a | |
18 | file named COPYING. Among other things, the copyright notice | |
19 | and this notice must be preserved on all copies. */ | |
20 | ||
21 | ||
18160b98 | 22 | #include <config.h> |
c6953be1 JB |
23 | #include "lisp.h" |
24 | #include "buffer.h" | |
4e665715 | 25 | #include "commands.h" |
c6953be1 JB |
26 | |
27 | /* Last buffer for which undo information was recorded. */ | |
28 | Lisp_Object last_undo_buffer; | |
29 | ||
f87a68b3 RS |
30 | Lisp_Object Qinhibit_read_only; |
31 | ||
c58632fc RS |
32 | /* The first time a command records something for undo. |
33 | it also allocates the undo-boundary object | |
34 | which will be added to the list at the end of the command. | |
35 | This ensures we can't run out of space while trying to make | |
36 | an undo-boundary. */ | |
37 | Lisp_Object pending_boundary; | |
38 | ||
c6953be1 JB |
39 | /* Record an insertion that just happened or is about to happen, |
40 | for LENGTH characters at position BEG. | |
41 | (It is possible to record an insertion before or after the fact | |
42 | because we don't need to record the contents.) */ | |
43 | ||
44 | record_insert (beg, length) | |
45 | Lisp_Object beg, length; | |
46 | { | |
47 | Lisp_Object lbeg, lend; | |
48 | ||
bdbe6f28 RS |
49 | if (EQ (current_buffer->undo_list, Qt)) |
50 | return; | |
51 | ||
c58632fc RS |
52 | /* Allocate a cons cell to be the undo boundary after this command. */ |
53 | if (NILP (pending_boundary)) | |
54 | pending_boundary = Fcons (Qnil, Qnil); | |
55 | ||
c6953be1 JB |
56 | if (current_buffer != XBUFFER (last_undo_buffer)) |
57 | Fundo_boundary (); | |
58 | XSET (last_undo_buffer, Lisp_Buffer, current_buffer); | |
59 | ||
c6953be1 JB |
60 | if (MODIFF <= current_buffer->save_modified) |
61 | record_first_change (); | |
62 | ||
63 | /* If this is following another insertion and consecutive with it | |
64 | in the buffer, combine the two. */ | |
65 | if (XTYPE (current_buffer->undo_list) == Lisp_Cons) | |
66 | { | |
67 | Lisp_Object elt; | |
68 | elt = XCONS (current_buffer->undo_list)->car; | |
69 | if (XTYPE (elt) == Lisp_Cons | |
70 | && XTYPE (XCONS (elt)->car) == Lisp_Int | |
71 | && XTYPE (XCONS (elt)->cdr) == Lisp_Int | |
213861c7 | 72 | && XINT (XCONS (elt)->cdr) == XINT (beg)) |
c6953be1 | 73 | { |
213861c7 | 74 | XSETINT (XCONS (elt)->cdr, XINT (beg) + XINT (length)); |
c6953be1 JB |
75 | return; |
76 | } | |
77 | } | |
78 | ||
213861c7 JB |
79 | lbeg = beg; |
80 | XSET (lend, Lisp_Int, XINT (beg) + XINT (length)); | |
81 | current_buffer->undo_list = Fcons (Fcons (lbeg, lend), | |
82 | current_buffer->undo_list); | |
c6953be1 JB |
83 | } |
84 | ||
85 | /* Record that a deletion is about to take place, | |
86 | for LENGTH characters at location BEG. */ | |
87 | ||
88 | record_delete (beg, length) | |
89 | int beg, length; | |
90 | { | |
91 | Lisp_Object lbeg, lend, sbeg; | |
e7a8b791 | 92 | int at_boundary; |
c6953be1 | 93 | |
bdbe6f28 RS |
94 | if (EQ (current_buffer->undo_list, Qt)) |
95 | return; | |
96 | ||
c58632fc RS |
97 | /* Allocate a cons cell to be the undo boundary after this command. */ |
98 | if (NILP (pending_boundary)) | |
99 | pending_boundary = Fcons (Qnil, Qnil); | |
100 | ||
c6953be1 JB |
101 | if (current_buffer != XBUFFER (last_undo_buffer)) |
102 | Fundo_boundary (); | |
103 | XSET (last_undo_buffer, Lisp_Buffer, current_buffer); | |
104 | ||
e7a8b791 RS |
105 | at_boundary = (CONSP (current_buffer->undo_list) |
106 | && NILP (XCONS (current_buffer->undo_list)->car)); | |
107 | ||
c6953be1 JB |
108 | if (MODIFF <= current_buffer->save_modified) |
109 | record_first_change (); | |
110 | ||
111 | if (point == beg + length) | |
112 | XSET (sbeg, Lisp_Int, -beg); | |
113 | else | |
114 | XFASTINT (sbeg) = beg; | |
115 | XFASTINT (lbeg) = beg; | |
116 | XFASTINT (lend) = beg + length; | |
350bce56 | 117 | |
e7a8b791 RS |
118 | /* If we are just after an undo boundary, and |
119 | point wasn't at start of deleted range, record where it was. */ | |
120 | if (at_boundary | |
121 | && last_point_position != XFASTINT (sbeg) | |
122 | && current_buffer == XBUFFER (last_point_position_buffer)) | |
350bce56 | 123 | current_buffer->undo_list |
4e665715 | 124 | = Fcons (make_number (last_point_position), current_buffer->undo_list); |
350bce56 | 125 | |
c6953be1 JB |
126 | current_buffer->undo_list |
127 | = Fcons (Fcons (Fbuffer_substring (lbeg, lend), sbeg), | |
128 | current_buffer->undo_list); | |
129 | } | |
130 | ||
131 | /* Record that a replacement is about to take place, | |
132 | for LENGTH characters at location BEG. | |
133 | The replacement does not change the number of characters. */ | |
134 | ||
135 | record_change (beg, length) | |
136 | int beg, length; | |
137 | { | |
138 | record_delete (beg, length); | |
139 | record_insert (beg, length); | |
140 | } | |
141 | \f | |
142 | /* Record that an unmodified buffer is about to be changed. | |
143 | Record the file modification date so that when undoing this entry | |
144 | we can tell whether it is obsolete because the file was saved again. */ | |
145 | ||
146 | record_first_change () | |
147 | { | |
148 | Lisp_Object high, low; | |
0736cafe RS |
149 | |
150 | if (EQ (current_buffer->undo_list, Qt)) | |
151 | return; | |
152 | ||
153 | if (current_buffer != XBUFFER (last_undo_buffer)) | |
154 | Fundo_boundary (); | |
155 | XSET (last_undo_buffer, Lisp_Buffer, current_buffer); | |
156 | ||
c6953be1 JB |
157 | XFASTINT (high) = (current_buffer->modtime >> 16) & 0xffff; |
158 | XFASTINT (low) = current_buffer->modtime & 0xffff; | |
159 | current_buffer->undo_list = Fcons (Fcons (Qt, Fcons (high, low)), current_buffer->undo_list); | |
160 | } | |
161 | ||
da9319d5 RS |
162 | /* Record a change in property PROP (whose old value was VAL) |
163 | for LENGTH characters starting at position BEG in BUFFER. */ | |
164 | ||
165 | record_property_change (beg, length, prop, value, buffer) | |
166 | int beg, length; | |
167 | Lisp_Object prop, value, buffer; | |
168 | { | |
169 | Lisp_Object lbeg, lend, entry; | |
170 | struct buffer *obuf = current_buffer; | |
171 | int boundary = 0; | |
172 | ||
0736cafe | 173 | if (EQ (XBUFFER (buffer)->undo_list, Qt)) |
bdbe6f28 RS |
174 | return; |
175 | ||
c58632fc RS |
176 | /* Allocate a cons cell to be the undo boundary after this command. */ |
177 | if (NILP (pending_boundary)) | |
178 | pending_boundary = Fcons (Qnil, Qnil); | |
179 | ||
da9319d5 RS |
180 | if (!EQ (buffer, last_undo_buffer)) |
181 | boundary = 1; | |
182 | last_undo_buffer = buffer; | |
183 | ||
da9319d5 RS |
184 | /* Switch temporarily to the buffer that was changed. */ |
185 | current_buffer = XBUFFER (buffer); | |
186 | ||
187 | if (boundary) | |
188 | Fundo_boundary (); | |
189 | ||
190 | if (MODIFF <= current_buffer->save_modified) | |
191 | record_first_change (); | |
192 | ||
193 | XSET (lbeg, Lisp_Int, beg); | |
194 | XSET (lend, Lisp_Int, beg + length); | |
195 | entry = Fcons (Qnil, Fcons (prop, Fcons (value, Fcons (lbeg, lend)))); | |
196 | current_buffer->undo_list = Fcons (entry, current_buffer->undo_list); | |
197 | ||
198 | current_buffer = obuf; | |
199 | } | |
200 | ||
c6953be1 JB |
201 | DEFUN ("undo-boundary", Fundo_boundary, Sundo_boundary, 0, 0, 0, |
202 | "Mark a boundary between units of undo.\n\ | |
203 | An undo command will stop at this point,\n\ | |
204 | but another undo command will undo to the previous boundary.") | |
205 | () | |
206 | { | |
207 | Lisp_Object tem; | |
208 | if (EQ (current_buffer->undo_list, Qt)) | |
209 | return Qnil; | |
210 | tem = Fcar (current_buffer->undo_list); | |
265a9e55 | 211 | if (!NILP (tem)) |
c58632fc RS |
212 | { |
213 | /* One way or another, cons nil onto the front of the undo list. */ | |
214 | if (!NILP (pending_boundary)) | |
215 | { | |
216 | /* If we have preallocated the cons cell to use here, | |
217 | use that one. */ | |
218 | XCONS (pending_boundary)->cdr = current_buffer->undo_list; | |
219 | current_buffer->undo_list = pending_boundary; | |
220 | pending_boundary = Qnil; | |
221 | } | |
222 | else | |
223 | current_buffer->undo_list = Fcons (Qnil, current_buffer->undo_list); | |
224 | } | |
c6953be1 JB |
225 | return Qnil; |
226 | } | |
227 | ||
228 | /* At garbage collection time, make an undo list shorter at the end, | |
229 | returning the truncated list. | |
230 | MINSIZE and MAXSIZE are the limits on size allowed, as described below. | |
f06cd136 JB |
231 | In practice, these are the values of undo-limit and |
232 | undo-strong-limit. */ | |
c6953be1 JB |
233 | |
234 | Lisp_Object | |
235 | truncate_undo_list (list, minsize, maxsize) | |
236 | Lisp_Object list; | |
237 | int minsize, maxsize; | |
238 | { | |
239 | Lisp_Object prev, next, last_boundary; | |
240 | int size_so_far = 0; | |
241 | ||
242 | prev = Qnil; | |
243 | next = list; | |
244 | last_boundary = Qnil; | |
245 | ||
246 | /* Always preserve at least the most recent undo record. | |
181a18b1 JB |
247 | If the first element is an undo boundary, skip past it. |
248 | ||
249 | Skip, skip, skip the undo, skip, skip, skip the undo, | |
07627b5d JB |
250 | Skip, skip, skip the undo, skip to the undo bound'ry. |
251 | (Get it? "Skip to my Loo?") */ | |
c6953be1 | 252 | if (XTYPE (next) == Lisp_Cons |
213861c7 | 253 | && NILP (XCONS (next)->car)) |
c6953be1 JB |
254 | { |
255 | /* Add in the space occupied by this element and its chain link. */ | |
256 | size_so_far += sizeof (struct Lisp_Cons); | |
257 | ||
258 | /* Advance to next element. */ | |
259 | prev = next; | |
260 | next = XCONS (next)->cdr; | |
261 | } | |
262 | while (XTYPE (next) == Lisp_Cons | |
213861c7 | 263 | && ! NILP (XCONS (next)->car)) |
c6953be1 JB |
264 | { |
265 | Lisp_Object elt; | |
266 | elt = XCONS (next)->car; | |
267 | ||
268 | /* Add in the space occupied by this element and its chain link. */ | |
269 | size_so_far += sizeof (struct Lisp_Cons); | |
270 | if (XTYPE (elt) == Lisp_Cons) | |
271 | { | |
272 | size_so_far += sizeof (struct Lisp_Cons); | |
273 | if (XTYPE (XCONS (elt)->car) == Lisp_String) | |
274 | size_so_far += (sizeof (struct Lisp_String) - 1 | |
275 | + XSTRING (XCONS (elt)->car)->size); | |
276 | } | |
277 | ||
278 | /* Advance to next element. */ | |
279 | prev = next; | |
280 | next = XCONS (next)->cdr; | |
281 | } | |
282 | if (XTYPE (next) == Lisp_Cons) | |
283 | last_boundary = prev; | |
284 | ||
285 | while (XTYPE (next) == Lisp_Cons) | |
286 | { | |
287 | Lisp_Object elt; | |
288 | elt = XCONS (next)->car; | |
289 | ||
290 | /* When we get to a boundary, decide whether to truncate | |
291 | either before or after it. The lower threshold, MINSIZE, | |
292 | tells us to truncate after it. If its size pushes past | |
293 | the higher threshold MAXSIZE as well, we truncate before it. */ | |
265a9e55 | 294 | if (NILP (elt)) |
c6953be1 JB |
295 | { |
296 | if (size_so_far > maxsize) | |
297 | break; | |
298 | last_boundary = prev; | |
299 | if (size_so_far > minsize) | |
300 | break; | |
301 | } | |
302 | ||
303 | /* Add in the space occupied by this element and its chain link. */ | |
304 | size_so_far += sizeof (struct Lisp_Cons); | |
305 | if (XTYPE (elt) == Lisp_Cons) | |
306 | { | |
307 | size_so_far += sizeof (struct Lisp_Cons); | |
308 | if (XTYPE (XCONS (elt)->car) == Lisp_String) | |
309 | size_so_far += (sizeof (struct Lisp_String) - 1 | |
310 | + XSTRING (XCONS (elt)->car)->size); | |
311 | } | |
312 | ||
313 | /* Advance to next element. */ | |
314 | prev = next; | |
315 | next = XCONS (next)->cdr; | |
316 | } | |
317 | ||
318 | /* If we scanned the whole list, it is short enough; don't change it. */ | |
265a9e55 | 319 | if (NILP (next)) |
c6953be1 JB |
320 | return list; |
321 | ||
322 | /* Truncate at the boundary where we decided to truncate. */ | |
265a9e55 | 323 | if (!NILP (last_boundary)) |
c6953be1 JB |
324 | { |
325 | XCONS (last_boundary)->cdr = Qnil; | |
326 | return list; | |
327 | } | |
328 | else | |
329 | return Qnil; | |
330 | } | |
331 | \f | |
332 | DEFUN ("primitive-undo", Fprimitive_undo, Sprimitive_undo, 2, 2, 0, | |
333 | "Undo N records from the front of the list LIST.\n\ | |
334 | Return what remains of the list.") | |
063fb61f RS |
335 | (n, list) |
336 | Lisp_Object n, list; | |
c6953be1 | 337 | { |
f87a68b3 | 338 | int count = specpdl_ptr - specpdl; |
063fb61f | 339 | register int arg = XINT (n); |
c6953be1 JB |
340 | #if 0 /* This is a good feature, but would make undo-start |
341 | unable to do what is expected. */ | |
342 | Lisp_Object tem; | |
343 | ||
344 | /* If the head of the list is a boundary, it is the boundary | |
345 | preceding this command. Get rid of it and don't count it. */ | |
346 | tem = Fcar (list); | |
265a9e55 | 347 | if (NILP (tem)) |
c6953be1 JB |
348 | list = Fcdr (list); |
349 | #endif | |
350 | ||
f87a68b3 RS |
351 | /* Don't let read-only properties interfere with undo. */ |
352 | if (NILP (current_buffer->read_only)) | |
353 | specbind (Qinhibit_read_only, Qt); | |
354 | ||
c6953be1 JB |
355 | while (arg > 0) |
356 | { | |
357 | while (1) | |
358 | { | |
350bce56 | 359 | Lisp_Object next; |
c6953be1 JB |
360 | next = Fcar (list); |
361 | list = Fcdr (list); | |
350bce56 | 362 | /* Exit inner loop at undo boundary. */ |
265a9e55 | 363 | if (NILP (next)) |
c6953be1 | 364 | break; |
350bce56 RS |
365 | /* Handle an integer by setting point to that value. */ |
366 | if (XTYPE (next) == Lisp_Int) | |
367 | SET_PT (clip_to_bounds (BEGV, XINT (next), ZV)); | |
368 | else if (XTYPE (next) == Lisp_Cons) | |
c6953be1 | 369 | { |
350bce56 RS |
370 | Lisp_Object car, cdr; |
371 | ||
372 | car = Fcar (next); | |
373 | cdr = Fcdr (next); | |
374 | if (EQ (car, Qt)) | |
c6953be1 | 375 | { |
350bce56 RS |
376 | /* Element (t high . low) records previous modtime. */ |
377 | Lisp_Object high, low; | |
378 | int mod_time; | |
379 | ||
380 | high = Fcar (cdr); | |
381 | low = Fcdr (cdr); | |
d8552b2f | 382 | mod_time = (XFASTINT (high) << 16) + XFASTINT (low); |
350bce56 RS |
383 | /* If this records an obsolete save |
384 | (not matching the actual disk file) | |
385 | then don't mark unmodified. */ | |
386 | if (mod_time != current_buffer->modtime) | |
387 | break; | |
e6dd6080 | 388 | #ifdef CLASH_DETECTION |
350bce56 | 389 | Funlock_buffer (); |
e6dd6080 | 390 | #endif /* CLASH_DETECTION */ |
350bce56 | 391 | Fset_buffer_modified_p (Qnil); |
c6953be1 | 392 | } |
d8552b2f RS |
393 | #ifdef USE_TEXT_PROPERTIES |
394 | else if (EQ (car, Qnil)) | |
da9319d5 | 395 | { |
d8552b2f | 396 | /* Element (nil prop val beg . end) is property change. */ |
da9319d5 RS |
397 | Lisp_Object beg, end, prop, val; |
398 | ||
399 | prop = Fcar (cdr); | |
400 | cdr = Fcdr (cdr); | |
401 | val = Fcar (cdr); | |
402 | cdr = Fcdr (cdr); | |
403 | beg = Fcar (cdr); | |
404 | end = Fcdr (cdr); | |
405 | ||
406 | Fput_text_property (beg, end, prop, val, Qnil); | |
407 | } | |
d8552b2f | 408 | #endif /* USE_TEXT_PROPERTIES */ |
350bce56 | 409 | else if (XTYPE (car) == Lisp_Int && XTYPE (cdr) == Lisp_Int) |
c6953be1 | 410 | { |
350bce56 RS |
411 | /* Element (BEG . END) means range was inserted. */ |
412 | Lisp_Object end; | |
413 | ||
414 | if (XINT (car) < BEGV | |
415 | || XINT (cdr) > ZV) | |
c6953be1 | 416 | error ("Changes to be undone are outside visible portion of buffer"); |
f28f04cc RS |
417 | /* Set point first thing, so that undoing this undo |
418 | does not send point back to where it is now. */ | |
350bce56 | 419 | Fgoto_char (car); |
f28f04cc | 420 | Fdelete_region (car, cdr); |
350bce56 RS |
421 | } |
422 | else if (XTYPE (car) == Lisp_String && XTYPE (cdr) == Lisp_Int) | |
423 | { | |
424 | /* Element (STRING . POS) means STRING was deleted. */ | |
425 | Lisp_Object membuf; | |
426 | int pos = XINT (cdr); | |
427 | ||
428 | membuf = car; | |
429 | if (pos < 0) | |
430 | { | |
431 | if (-pos < BEGV || -pos > ZV) | |
432 | error ("Changes to be undone are outside visible portion of buffer"); | |
433 | SET_PT (-pos); | |
434 | Finsert (1, &membuf); | |
435 | } | |
436 | else | |
437 | { | |
438 | if (pos < BEGV || pos > ZV) | |
439 | error ("Changes to be undone are outside visible portion of buffer"); | |
440 | SET_PT (pos); | |
441 | ||
442 | /* Insert before markers so that if the mark is | |
443 | currently on the boundary of this deletion, it | |
444 | ends up on the other side of the now-undeleted | |
445 | text from point. Since undo doesn't even keep | |
446 | track of the mark, this isn't really necessary, | |
447 | but it may lead to better behavior in certain | |
448 | situations. */ | |
449 | Finsert_before_markers (1, &membuf); | |
450 | SET_PT (pos); | |
451 | } | |
c6953be1 JB |
452 | } |
453 | } | |
454 | } | |
455 | arg--; | |
456 | } | |
457 | ||
f87a68b3 | 458 | return unbind_to (count, list); |
c6953be1 JB |
459 | } |
460 | ||
461 | syms_of_undo () | |
462 | { | |
f87a68b3 RS |
463 | Qinhibit_read_only = intern ("inhibit-read-only"); |
464 | staticpro (&Qinhibit_read_only); | |
465 | ||
c58632fc RS |
466 | pending_boundary = Qnil; |
467 | staticpro (&pending_boundary); | |
468 | ||
c6953be1 JB |
469 | defsubr (&Sprimitive_undo); |
470 | defsubr (&Sundo_boundary); | |
471 | } |