Commit | Line | Data |
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c6953be1 | 1 | /* undo handling for GNU Emacs. |
ba318903 | 2 | Copyright (C) 1990, 1993-1994, 2000-2014 Free Software Foundation, |
ab422c4d | 3 | Inc. |
c6953be1 JB |
4 | |
5 | This file is part of GNU Emacs. | |
6 | ||
9ec0b715 | 7 | GNU Emacs is free software: you can redistribute it and/or modify |
3b7ad313 | 8 | it under the terms of the GNU General Public License as published by |
9ec0b715 GM |
9 | the Free Software Foundation, either version 3 of the License, or |
10 | (at your option) any later version. | |
3b7ad313 | 11 | |
c6953be1 | 12 | GNU Emacs is distributed in the hope that it will be useful, |
3b7ad313 EN |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | GNU General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
9ec0b715 | 18 | along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */ |
c6953be1 JB |
19 | |
20 | ||
18160b98 | 21 | #include <config.h> |
0328b6de | 22 | |
c6953be1 | 23 | #include "lisp.h" |
e5560ff7 | 24 | #include "character.h" |
c6953be1 | 25 | #include "buffer.h" |
4e665715 | 26 | #include "commands.h" |
91e25f5e | 27 | #include "window.h" |
c6953be1 JB |
28 | |
29 | /* Last buffer for which undo information was recorded. */ | |
4591d6cb | 30 | /* BEWARE: This is not traced by the GC, so never dereference it! */ |
2b96acb7 | 31 | static struct buffer *last_undo_buffer; |
4591d6cb SM |
32 | |
33 | /* Position of point last time we inserted a boundary. */ | |
2b96acb7 | 34 | static struct buffer *last_boundary_buffer; |
d311d28c | 35 | static ptrdiff_t last_boundary_position; |
c6953be1 | 36 | |
f87a68b3 RS |
37 | Lisp_Object Qinhibit_read_only; |
38 | ||
49be18c9 KS |
39 | /* Marker for function call undo list elements. */ |
40 | ||
41 | Lisp_Object Qapply; | |
42 | ||
c58632fc RS |
43 | /* The first time a command records something for undo. |
44 | it also allocates the undo-boundary object | |
45 | which will be added to the list at the end of the command. | |
46 | This ensures we can't run out of space while trying to make | |
47 | an undo-boundary. */ | |
2b96acb7 | 48 | static Lisp_Object pending_boundary; |
c58632fc | 49 | |
6396140a | 50 | /* Record point as it was at beginning of this command (if necessary) |
8abe0f97 | 51 | and prepare the undo info for recording a change. |
6396140a SM |
52 | PT is the position of point that will naturally occur as a result of the |
53 | undo record that will be added just after this command terminates. */ | |
c6953be1 | 54 | |
6396140a | 55 | static void |
d311d28c | 56 | record_point (ptrdiff_t pt) |
c6953be1 | 57 | { |
5df474aa | 58 | bool at_boundary; |
bdbe6f28 | 59 | |
4591d6cb | 60 | /* Don't record position of pt when undo_inhibit_record_point holds. */ |
8abe0f97 MR |
61 | if (undo_inhibit_record_point) |
62 | return; | |
63 | ||
c58632fc RS |
64 | /* Allocate a cons cell to be the undo boundary after this command. */ |
65 | if (NILP (pending_boundary)) | |
66 | pending_boundary = Fcons (Qnil, Qnil); | |
67 | ||
3ecc1163 MR |
68 | if ((current_buffer != last_undo_buffer) |
69 | /* Don't call Fundo_boundary for the first change. Otherwise we | |
70 | risk overwriting last_boundary_position in Fundo_boundary with | |
71 | PT of the current buffer and as a consequence not insert an | |
72 | undo boundary because last_boundary_position will equal pt in | |
73 | the test at the end of the present function (Bug#731). */ | |
74 | && (MODIFF > SAVE_MODIFF)) | |
c6953be1 | 75 | Fundo_boundary (); |
4591d6cb | 76 | last_undo_buffer = current_buffer; |
c6953be1 | 77 | |
37ea8275 BR |
78 | at_boundary = ! CONSP (BVAR (current_buffer, undo_list)) |
79 | || NILP (XCAR (BVAR (current_buffer, undo_list))); | |
6396140a | 80 | |
ad9cdce4 | 81 | if (MODIFF <= SAVE_MODIFF) |
c6953be1 JB |
82 | record_first_change (); |
83 | ||
177c0ea7 | 84 | /* If we are just after an undo boundary, and |
6396140a SM |
85 | point wasn't at start of deleted range, record where it was. */ |
86 | if (at_boundary | |
4591d6cb SM |
87 | && current_buffer == last_boundary_buffer |
88 | && last_boundary_position != pt) | |
39eb03f1 PE |
89 | bset_undo_list (current_buffer, |
90 | Fcons (make_number (last_boundary_position), | |
91 | BVAR (current_buffer, undo_list))); | |
6396140a SM |
92 | } |
93 | ||
94 | /* Record an insertion that just happened or is about to happen, | |
95 | for LENGTH characters at position BEG. | |
96 | (It is possible to record an insertion before or after the fact | |
97 | because we don't need to record the contents.) */ | |
98 | ||
99 | void | |
d311d28c | 100 | record_insert (ptrdiff_t beg, ptrdiff_t length) |
6396140a SM |
101 | { |
102 | Lisp_Object lbeg, lend; | |
103 | ||
4b4deea2 | 104 | if (EQ (BVAR (current_buffer, undo_list), Qt)) |
6396140a SM |
105 | return; |
106 | ||
107 | record_point (beg); | |
108 | ||
c6953be1 JB |
109 | /* If this is following another insertion and consecutive with it |
110 | in the buffer, combine the two. */ | |
4b4deea2 | 111 | if (CONSP (BVAR (current_buffer, undo_list))) |
c6953be1 JB |
112 | { |
113 | Lisp_Object elt; | |
4b4deea2 | 114 | elt = XCAR (BVAR (current_buffer, undo_list)); |
38c0d37c | 115 | if (CONSP (elt) |
c1d497be KR |
116 | && INTEGERP (XCAR (elt)) |
117 | && INTEGERP (XCDR (elt)) | |
118 | && XINT (XCDR (elt)) == beg) | |
c6953be1 | 119 | { |
f3fbd155 | 120 | XSETCDR (elt, make_number (beg + length)); |
c6953be1 JB |
121 | return; |
122 | } | |
123 | } | |
124 | ||
53480e99 KH |
125 | XSETFASTINT (lbeg, beg); |
126 | XSETINT (lend, beg + length); | |
39eb03f1 PE |
127 | bset_undo_list (current_buffer, |
128 | Fcons (Fcons (lbeg, lend), BVAR (current_buffer, undo_list))); | |
c6953be1 JB |
129 | } |
130 | ||
37ea8275 BR |
131 | /* Record the fact that markers in the region of FROM, TO are about to |
132 | be adjusted. This is done only when a marker points within text | |
133 | being deleted, because that's the only case where an automatic | |
134 | marker adjustment won't be inverted automatically by undoing the | |
135 | buffer modification. */ | |
136 | ||
137 | static void | |
138 | record_marker_adjustments (ptrdiff_t from, ptrdiff_t to) | |
139 | { | |
140 | Lisp_Object marker; | |
141 | register struct Lisp_Marker *m; | |
142 | register ptrdiff_t charpos, adjustment; | |
143 | ||
144 | /* Allocate a cons cell to be the undo boundary after this command. */ | |
145 | if (NILP (pending_boundary)) | |
146 | pending_boundary = Fcons (Qnil, Qnil); | |
147 | ||
148 | if (current_buffer != last_undo_buffer) | |
149 | Fundo_boundary (); | |
150 | last_undo_buffer = current_buffer; | |
151 | ||
152 | for (m = BUF_MARKERS (current_buffer); m; m = m->next) | |
153 | { | |
154 | charpos = m->charpos; | |
155 | eassert (charpos <= Z); | |
156 | ||
157 | if (from <= charpos && charpos <= to) | |
158 | { | |
159 | /* insertion_type nil markers will end up at the beginning of | |
160 | the re-inserted text after undoing a deletion, and must be | |
161 | adjusted to move them to the correct place. | |
162 | ||
163 | insertion_type t markers will automatically move forward | |
164 | upon re-inserting the deleted text, so we have to arrange | |
165 | for them to move backward to the correct position. */ | |
166 | adjustment = (m->insertion_type ? to : from) - charpos; | |
167 | ||
168 | if (adjustment) | |
169 | { | |
170 | XSETMISC (marker, m); | |
171 | bset_undo_list | |
172 | (current_buffer, | |
173 | Fcons (Fcons (marker, make_number (adjustment)), | |
174 | BVAR (current_buffer, undo_list))); | |
175 | } | |
176 | } | |
177 | } | |
178 | } | |
179 | ||
180 | /* Record that a deletion is about to take place, of the characters in | |
181 | STRING, at location BEG. Optionally record adjustments for markers | |
182 | in the region STRING occupies in the current buffer. */ | |
c6953be1 | 183 | |
ff1aa840 | 184 | void |
37ea8275 | 185 | record_delete (ptrdiff_t beg, Lisp_Object string, bool record_markers) |
c6953be1 | 186 | { |
e928d437 | 187 | Lisp_Object sbeg; |
c6953be1 | 188 | |
4b4deea2 | 189 | if (EQ (BVAR (current_buffer, undo_list), Qt)) |
bdbe6f28 RS |
190 | return; |
191 | ||
d5db4077 | 192 | if (PT == beg + SCHARS (string)) |
cbc1b668 | 193 | { |
6396140a SM |
194 | XSETINT (sbeg, -beg); |
195 | record_point (PT); | |
cbc1b668 KH |
196 | } |
197 | else | |
6396140a SM |
198 | { |
199 | XSETFASTINT (sbeg, beg); | |
200 | record_point (beg); | |
201 | } | |
350bce56 | 202 | |
37ea8275 BR |
203 | /* primitive-undo assumes marker adjustments are recorded |
204 | immediately before the deletion is recorded. See bug 16818 | |
205 | discussion. */ | |
206 | if (record_markers) | |
207 | record_marker_adjustments (beg, beg + SCHARS (string)); | |
714bced9 | 208 | |
39eb03f1 PE |
209 | bset_undo_list |
210 | (current_buffer, | |
37ea8275 | 211 | Fcons (Fcons (string, sbeg), BVAR (current_buffer, undo_list))); |
714bced9 RS |
212 | } |
213 | ||
c6953be1 JB |
214 | /* Record that a replacement is about to take place, |
215 | for LENGTH characters at location BEG. | |
e928d437 | 216 | The replacement must not change the number of characters. */ |
c6953be1 | 217 | |
ff1aa840 | 218 | void |
d311d28c | 219 | record_change (ptrdiff_t beg, ptrdiff_t length) |
c6953be1 | 220 | { |
37ea8275 | 221 | record_delete (beg, make_buffer_string (beg, beg + length, 1), false); |
c6953be1 JB |
222 | record_insert (beg, length); |
223 | } | |
224 | \f | |
225 | /* Record that an unmodified buffer is about to be changed. | |
226 | Record the file modification date so that when undoing this entry | |
227 | we can tell whether it is obsolete because the file was saved again. */ | |
228 | ||
90dd3e4f | 229 | void |
971de7fb | 230 | record_first_change (void) |
c6953be1 | 231 | { |
ad9cdce4 | 232 | struct buffer *base_buffer = current_buffer; |
0736cafe | 233 | |
4b4deea2 | 234 | if (EQ (BVAR (current_buffer, undo_list), Qt)) |
0736cafe RS |
235 | return; |
236 | ||
4591d6cb | 237 | if (current_buffer != last_undo_buffer) |
0736cafe | 238 | Fundo_boundary (); |
4591d6cb | 239 | last_undo_buffer = current_buffer; |
0736cafe | 240 | |
ad9cdce4 RS |
241 | if (base_buffer->base_buffer) |
242 | base_buffer = base_buffer->base_buffer; | |
243 | ||
954b166e PE |
244 | bset_undo_list (current_buffer, |
245 | Fcons (Fcons (Qt, Fvisited_file_modtime ()), | |
246 | BVAR (current_buffer, undo_list))); | |
c6953be1 JB |
247 | } |
248 | ||
da9319d5 RS |
249 | /* Record a change in property PROP (whose old value was VAL) |
250 | for LENGTH characters starting at position BEG in BUFFER. */ | |
251 | ||
90dd3e4f | 252 | void |
d311d28c | 253 | record_property_change (ptrdiff_t beg, ptrdiff_t length, |
c8a66ab8 EZ |
254 | Lisp_Object prop, Lisp_Object value, |
255 | Lisp_Object buffer) | |
da9319d5 RS |
256 | { |
257 | Lisp_Object lbeg, lend, entry; | |
4591d6cb | 258 | struct buffer *obuf = current_buffer, *buf = XBUFFER (buffer); |
5df474aa | 259 | bool boundary = 0; |
da9319d5 | 260 | |
4b4deea2 | 261 | if (EQ (BVAR (buf, undo_list), Qt)) |
bdbe6f28 RS |
262 | return; |
263 | ||
c58632fc RS |
264 | /* Allocate a cons cell to be the undo boundary after this command. */ |
265 | if (NILP (pending_boundary)) | |
266 | pending_boundary = Fcons (Qnil, Qnil); | |
267 | ||
4591d6cb | 268 | if (buf != last_undo_buffer) |
da9319d5 | 269 | boundary = 1; |
4591d6cb | 270 | last_undo_buffer = buf; |
da9319d5 | 271 | |
da9319d5 | 272 | /* Switch temporarily to the buffer that was changed. */ |
4591d6cb | 273 | current_buffer = buf; |
da9319d5 RS |
274 | |
275 | if (boundary) | |
276 | Fundo_boundary (); | |
277 | ||
ad9cdce4 | 278 | if (MODIFF <= SAVE_MODIFF) |
da9319d5 RS |
279 | record_first_change (); |
280 | ||
552bdbcf KH |
281 | XSETINT (lbeg, beg); |
282 | XSETINT (lend, beg + length); | |
da9319d5 | 283 | entry = Fcons (Qnil, Fcons (prop, Fcons (value, Fcons (lbeg, lend)))); |
39eb03f1 PE |
284 | bset_undo_list (current_buffer, |
285 | Fcons (entry, BVAR (current_buffer, undo_list))); | |
da9319d5 RS |
286 | |
287 | current_buffer = obuf; | |
288 | } | |
289 | ||
a7ca3326 | 290 | DEFUN ("undo-boundary", Fundo_boundary, Sundo_boundary, 0, 0, 0, |
8c1a1077 PJ |
291 | doc: /* Mark a boundary between units of undo. |
292 | An undo command will stop at this point, | |
293 | but another undo command will undo to the previous boundary. */) | |
5842a27b | 294 | (void) |
c6953be1 JB |
295 | { |
296 | Lisp_Object tem; | |
4b4deea2 | 297 | if (EQ (BVAR (current_buffer, undo_list), Qt)) |
c6953be1 | 298 | return Qnil; |
4b4deea2 | 299 | tem = Fcar (BVAR (current_buffer, undo_list)); |
265a9e55 | 300 | if (!NILP (tem)) |
c58632fc RS |
301 | { |
302 | /* One way or another, cons nil onto the front of the undo list. */ | |
303 | if (!NILP (pending_boundary)) | |
304 | { | |
305 | /* If we have preallocated the cons cell to use here, | |
306 | use that one. */ | |
4b4deea2 | 307 | XSETCDR (pending_boundary, BVAR (current_buffer, undo_list)); |
39eb03f1 | 308 | bset_undo_list (current_buffer, pending_boundary); |
c58632fc RS |
309 | pending_boundary = Qnil; |
310 | } | |
311 | else | |
39eb03f1 PE |
312 | bset_undo_list (current_buffer, |
313 | Fcons (Qnil, BVAR (current_buffer, undo_list))); | |
c58632fc | 314 | } |
4591d6cb SM |
315 | last_boundary_position = PT; |
316 | last_boundary_buffer = current_buffer; | |
c6953be1 JB |
317 | return Qnil; |
318 | } | |
319 | ||
320 | /* At garbage collection time, make an undo list shorter at the end, | |
137e23ea RS |
321 | returning the truncated list. How this is done depends on the |
322 | variables undo-limit, undo-strong-limit and undo-outer-limit. | |
323 | In some cases this works by calling undo-outer-limit-function. */ | |
324 | ||
325 | void | |
971de7fb | 326 | truncate_undo_list (struct buffer *b) |
c6953be1 | 327 | { |
137e23ea | 328 | Lisp_Object list; |
c6953be1 | 329 | Lisp_Object prev, next, last_boundary; |
d311d28c | 330 | EMACS_INT size_so_far = 0; |
c6953be1 | 331 | |
137e23ea RS |
332 | /* Make sure that calling undo-outer-limit-function |
333 | won't cause another GC. */ | |
d311d28c | 334 | ptrdiff_t count = inhibit_garbage_collection (); |
137e23ea RS |
335 | |
336 | /* Make the buffer current to get its local values of variables such | |
337 | as undo_limit. Also so that Vundo_outer_limit_function can | |
338 | tell which buffer to operate on. */ | |
66322887 | 339 | record_unwind_current_buffer (); |
137e23ea RS |
340 | set_buffer_internal (b); |
341 | ||
4b4deea2 | 342 | list = BVAR (b, undo_list); |
137e23ea | 343 | |
c6953be1 JB |
344 | prev = Qnil; |
345 | next = list; | |
346 | last_boundary = Qnil; | |
347 | ||
137e23ea | 348 | /* If the first element is an undo boundary, skip past it. */ |
c1d497be | 349 | if (CONSP (next) && NILP (XCAR (next))) |
c6953be1 JB |
350 | { |
351 | /* Add in the space occupied by this element and its chain link. */ | |
352 | size_so_far += sizeof (struct Lisp_Cons); | |
353 | ||
354 | /* Advance to next element. */ | |
355 | prev = next; | |
c1d497be | 356 | next = XCDR (next); |
c6953be1 | 357 | } |
e3d5ca1e | 358 | |
137e23ea RS |
359 | /* Always preserve at least the most recent undo record |
360 | unless it is really horribly big. | |
361 | ||
362 | Skip, skip, skip the undo, skip, skip, skip the undo, | |
363 | Skip, skip, skip the undo, skip to the undo bound'ry. */ | |
364 | ||
c1d497be | 365 | while (CONSP (next) && ! NILP (XCAR (next))) |
c6953be1 JB |
366 | { |
367 | Lisp_Object elt; | |
c1d497be | 368 | elt = XCAR (next); |
c6953be1 JB |
369 | |
370 | /* Add in the space occupied by this element and its chain link. */ | |
371 | size_so_far += sizeof (struct Lisp_Cons); | |
38c0d37c | 372 | if (CONSP (elt)) |
c6953be1 JB |
373 | { |
374 | size_so_far += sizeof (struct Lisp_Cons); | |
c1d497be | 375 | if (STRINGP (XCAR (elt))) |
c6953be1 | 376 | size_so_far += (sizeof (struct Lisp_String) - 1 |
d5db4077 | 377 | + SCHARS (XCAR (elt))); |
c6953be1 JB |
378 | } |
379 | ||
380 | /* Advance to next element. */ | |
381 | prev = next; | |
c1d497be | 382 | next = XCDR (next); |
c6953be1 | 383 | } |
e3d5ca1e | 384 | |
137e23ea RS |
385 | /* If by the first boundary we have already passed undo_outer_limit, |
386 | we're heading for memory full, so offer to clear out the list. */ | |
81c1cf71 RS |
387 | if (INTEGERP (Vundo_outer_limit) |
388 | && size_so_far > XINT (Vundo_outer_limit) | |
137e23ea RS |
389 | && !NILP (Vundo_outer_limit_function)) |
390 | { | |
4591d6cb SM |
391 | Lisp_Object tem; |
392 | struct buffer *temp = last_undo_buffer; | |
137e23ea RS |
393 | |
394 | /* Normally the function this calls is undo-outer-limit-truncate. */ | |
88fde92a KR |
395 | tem = call1 (Vundo_outer_limit_function, make_number (size_so_far)); |
396 | if (! NILP (tem)) | |
137e23ea RS |
397 | { |
398 | /* The function is responsible for making | |
399 | any desired changes in buffer-undo-list. */ | |
400 | unbind_to (count, Qnil); | |
401 | return; | |
402 | } | |
403 | /* That function probably used the minibuffer, and if so, that | |
404 | changed last_undo_buffer. Change it back so that we don't | |
405 | force next change to make an undo boundary here. */ | |
406 | last_undo_buffer = temp; | |
407 | } | |
408 | ||
38c0d37c | 409 | if (CONSP (next)) |
c6953be1 JB |
410 | last_boundary = prev; |
411 | ||
137e23ea | 412 | /* Keep additional undo data, if it fits in the limits. */ |
38c0d37c | 413 | while (CONSP (next)) |
c6953be1 JB |
414 | { |
415 | Lisp_Object elt; | |
c1d497be | 416 | elt = XCAR (next); |
c6953be1 JB |
417 | |
418 | /* When we get to a boundary, decide whether to truncate | |
137e23ea | 419 | either before or after it. The lower threshold, undo_limit, |
c6953be1 | 420 | tells us to truncate after it. If its size pushes past |
137e23ea | 421 | the higher threshold undo_strong_limit, we truncate before it. */ |
265a9e55 | 422 | if (NILP (elt)) |
c6953be1 | 423 | { |
137e23ea | 424 | if (size_so_far > undo_strong_limit) |
c6953be1 JB |
425 | break; |
426 | last_boundary = prev; | |
137e23ea | 427 | if (size_so_far > undo_limit) |
c6953be1 JB |
428 | break; |
429 | } | |
430 | ||
431 | /* Add in the space occupied by this element and its chain link. */ | |
432 | size_so_far += sizeof (struct Lisp_Cons); | |
38c0d37c | 433 | if (CONSP (elt)) |
c6953be1 JB |
434 | { |
435 | size_so_far += sizeof (struct Lisp_Cons); | |
c1d497be | 436 | if (STRINGP (XCAR (elt))) |
c6953be1 | 437 | size_so_far += (sizeof (struct Lisp_String) - 1 |
d5db4077 | 438 | + SCHARS (XCAR (elt))); |
c6953be1 JB |
439 | } |
440 | ||
441 | /* Advance to next element. */ | |
442 | prev = next; | |
c1d497be | 443 | next = XCDR (next); |
c6953be1 JB |
444 | } |
445 | ||
446 | /* If we scanned the whole list, it is short enough; don't change it. */ | |
265a9e55 | 447 | if (NILP (next)) |
137e23ea | 448 | ; |
c6953be1 | 449 | /* Truncate at the boundary where we decided to truncate. */ |
137e23ea RS |
450 | else if (!NILP (last_boundary)) |
451 | XSETCDR (last_boundary, Qnil); | |
452 | /* There's nothing we decided to keep, so clear it out. */ | |
c6953be1 | 453 | else |
39eb03f1 | 454 | bset_undo_list (b, Qnil); |
137e23ea RS |
455 | |
456 | unbind_to (count, Qnil); | |
c6953be1 | 457 | } |
71873e2b | 458 | |
c6953be1 | 459 | \f |
dfcf069d | 460 | void |
971de7fb | 461 | syms_of_undo (void) |
c6953be1 | 462 | { |
cd3520a4 JB |
463 | DEFSYM (Qinhibit_read_only, "inhibit-read-only"); |
464 | DEFSYM (Qapply, "apply"); | |
49be18c9 | 465 | |
c58632fc RS |
466 | pending_boundary = Qnil; |
467 | staticpro (&pending_boundary); | |
468 | ||
4591d6cb SM |
469 | last_undo_buffer = NULL; |
470 | last_boundary_buffer = NULL; | |
471 | ||
c6953be1 | 472 | defsubr (&Sundo_boundary); |
137e23ea | 473 | |
29208e82 | 474 | DEFVAR_INT ("undo-limit", undo_limit, |
137e23ea RS |
475 | doc: /* Keep no more undo information once it exceeds this size. |
476 | This limit is applied when garbage collection happens. | |
477 | When a previous command increases the total undo list size past this | |
478 | value, the earlier commands that came before it are forgotten. | |
479 | ||
480 | The size is counted as the number of bytes occupied, | |
481 | which includes both saved text and other data. */); | |
2159bd06 | 482 | undo_limit = 80000; |
137e23ea | 483 | |
29208e82 | 484 | DEFVAR_INT ("undo-strong-limit", undo_strong_limit, |
137e23ea RS |
485 | doc: /* Don't keep more than this much size of undo information. |
486 | This limit is applied when garbage collection happens. | |
487 | When a previous command increases the total undo list size past this | |
488 | value, that command and the earlier commands that came before it are forgotten. | |
489 | However, the most recent buffer-modifying command's undo info | |
490 | is never discarded for this reason. | |
491 | ||
492 | The size is counted as the number of bytes occupied, | |
493 | which includes both saved text and other data. */); | |
2159bd06 | 494 | undo_strong_limit = 120000; |
137e23ea | 495 | |
29208e82 | 496 | DEFVAR_LISP ("undo-outer-limit", Vundo_outer_limit, |
137e23ea RS |
497 | doc: /* Outer limit on size of undo information for one command. |
498 | At garbage collection time, if the current command has produced | |
62d776fd LT |
499 | more than this much undo information, it discards the info and displays |
500 | a warning. This is a last-ditch limit to prevent memory overflow. | |
137e23ea | 501 | |
62d776fd LT |
502 | The size is counted as the number of bytes occupied, which includes |
503 | both saved text and other data. A value of nil means no limit. In | |
504 | this case, accumulating one huge undo entry could make Emacs crash as | |
505 | a result of memory overflow. | |
137e23ea RS |
506 | |
507 | In fact, this calls the function which is the value of | |
508 | `undo-outer-limit-function' with one argument, the size. | |
509 | The text above describes the behavior of the function | |
510 | that variable usually specifies. */); | |
2159bd06 | 511 | Vundo_outer_limit = make_number (12000000); |
137e23ea | 512 | |
29208e82 | 513 | DEFVAR_LISP ("undo-outer-limit-function", Vundo_outer_limit_function, |
137e23ea RS |
514 | doc: /* Function to call when an undo list exceeds `undo-outer-limit'. |
515 | This function is called with one argument, the current undo list size | |
516 | for the most recent command (since the last undo boundary). | |
517 | If the function returns t, that means truncation has been fully handled. | |
518 | If it returns nil, the other forms of truncation are done. | |
519 | ||
520 | Garbage collection is inhibited around the call to this function, | |
521 | so it must make sure not to do a lot of consing. */); | |
522 | Vundo_outer_limit_function = Qnil; | |
8abe0f97 | 523 | |
29208e82 | 524 | DEFVAR_BOOL ("undo-inhibit-record-point", undo_inhibit_record_point, |
8abe0f97 MR |
525 | doc: /* Non-nil means do not record `point' in `buffer-undo-list'. */); |
526 | undo_inhibit_record_point = 0; | |
c6953be1 | 527 | } |