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c6953be1 | 1 | /* undo handling for GNU Emacs. |
ab422c4d PE |
2 | Copyright (C) 1990, 1993-1994, 2000-2013 Free Software Foundation, |
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 | { |
6396140a | 58 | int 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 | |
4b4deea2 | 78 | if (CONSP (BVAR (current_buffer, undo_list))) |
6396140a SM |
79 | { |
80 | /* Set AT_BOUNDARY to 1 only when we have nothing other than | |
81 | marker adjustment before undo boundary. */ | |
82 | ||
4b4deea2 | 83 | Lisp_Object tail = BVAR (current_buffer, undo_list), elt; |
6396140a SM |
84 | |
85 | while (1) | |
86 | { | |
87 | if (NILP (tail)) | |
88 | elt = Qnil; | |
89 | else | |
90 | elt = XCAR (tail); | |
91 | if (NILP (elt) || ! (CONSP (elt) && MARKERP (XCAR (elt)))) | |
92 | break; | |
93 | tail = XCDR (tail); | |
94 | } | |
95 | at_boundary = NILP (elt); | |
96 | } | |
97 | else | |
98 | at_boundary = 1; | |
99 | ||
ad9cdce4 | 100 | if (MODIFF <= SAVE_MODIFF) |
c6953be1 JB |
101 | record_first_change (); |
102 | ||
177c0ea7 | 103 | /* If we are just after an undo boundary, and |
6396140a SM |
104 | point wasn't at start of deleted range, record where it was. */ |
105 | if (at_boundary | |
4591d6cb SM |
106 | && current_buffer == last_boundary_buffer |
107 | && last_boundary_position != pt) | |
39eb03f1 PE |
108 | bset_undo_list (current_buffer, |
109 | Fcons (make_number (last_boundary_position), | |
110 | BVAR (current_buffer, undo_list))); | |
6396140a SM |
111 | } |
112 | ||
113 | /* Record an insertion that just happened or is about to happen, | |
114 | for LENGTH characters at position BEG. | |
115 | (It is possible to record an insertion before or after the fact | |
116 | because we don't need to record the contents.) */ | |
117 | ||
118 | void | |
d311d28c | 119 | record_insert (ptrdiff_t beg, ptrdiff_t length) |
6396140a SM |
120 | { |
121 | Lisp_Object lbeg, lend; | |
122 | ||
4b4deea2 | 123 | if (EQ (BVAR (current_buffer, undo_list), Qt)) |
6396140a SM |
124 | return; |
125 | ||
126 | record_point (beg); | |
127 | ||
c6953be1 JB |
128 | /* If this is following another insertion and consecutive with it |
129 | in the buffer, combine the two. */ | |
4b4deea2 | 130 | if (CONSP (BVAR (current_buffer, undo_list))) |
c6953be1 JB |
131 | { |
132 | Lisp_Object elt; | |
4b4deea2 | 133 | elt = XCAR (BVAR (current_buffer, undo_list)); |
38c0d37c | 134 | if (CONSP (elt) |
c1d497be KR |
135 | && INTEGERP (XCAR (elt)) |
136 | && INTEGERP (XCDR (elt)) | |
137 | && XINT (XCDR (elt)) == beg) | |
c6953be1 | 138 | { |
f3fbd155 | 139 | XSETCDR (elt, make_number (beg + length)); |
c6953be1 JB |
140 | return; |
141 | } | |
142 | } | |
143 | ||
53480e99 KH |
144 | XSETFASTINT (lbeg, beg); |
145 | XSETINT (lend, beg + length); | |
39eb03f1 PE |
146 | bset_undo_list (current_buffer, |
147 | Fcons (Fcons (lbeg, lend), BVAR (current_buffer, undo_list))); | |
c6953be1 JB |
148 | } |
149 | ||
150 | /* Record that a deletion is about to take place, | |
e928d437 | 151 | of the characters in STRING, at location BEG. */ |
c6953be1 | 152 | |
ff1aa840 | 153 | void |
d311d28c | 154 | record_delete (ptrdiff_t beg, Lisp_Object string) |
c6953be1 | 155 | { |
e928d437 | 156 | Lisp_Object sbeg; |
c6953be1 | 157 | |
4b4deea2 | 158 | if (EQ (BVAR (current_buffer, undo_list), Qt)) |
bdbe6f28 RS |
159 | return; |
160 | ||
d5db4077 | 161 | if (PT == beg + SCHARS (string)) |
cbc1b668 | 162 | { |
6396140a SM |
163 | XSETINT (sbeg, -beg); |
164 | record_point (PT); | |
cbc1b668 KH |
165 | } |
166 | else | |
6396140a SM |
167 | { |
168 | XSETFASTINT (sbeg, beg); | |
169 | record_point (beg); | |
170 | } | |
350bce56 | 171 | |
39eb03f1 PE |
172 | bset_undo_list |
173 | (current_buffer, | |
174 | Fcons (Fcons (string, sbeg), BVAR (current_buffer, undo_list))); | |
c6953be1 JB |
175 | } |
176 | ||
714bced9 RS |
177 | /* Record the fact that MARKER is about to be adjusted by ADJUSTMENT. |
178 | This is done only when a marker points within text being deleted, | |
179 | because that's the only case where an automatic marker adjustment | |
180 | won't be inverted automatically by undoing the buffer modification. */ | |
181 | ||
ff1aa840 | 182 | void |
d311d28c | 183 | record_marker_adjustment (Lisp_Object marker, ptrdiff_t adjustment) |
714bced9 | 184 | { |
4b4deea2 | 185 | if (EQ (BVAR (current_buffer, undo_list), Qt)) |
714bced9 RS |
186 | return; |
187 | ||
188 | /* Allocate a cons cell to be the undo boundary after this command. */ | |
189 | if (NILP (pending_boundary)) | |
190 | pending_boundary = Fcons (Qnil, Qnil); | |
191 | ||
4591d6cb | 192 | if (current_buffer != last_undo_buffer) |
714bced9 | 193 | Fundo_boundary (); |
4591d6cb | 194 | last_undo_buffer = current_buffer; |
714bced9 | 195 | |
39eb03f1 PE |
196 | bset_undo_list |
197 | (current_buffer, | |
198 | Fcons (Fcons (marker, make_number (adjustment)), | |
199 | BVAR (current_buffer, undo_list))); | |
714bced9 RS |
200 | } |
201 | ||
c6953be1 JB |
202 | /* Record that a replacement is about to take place, |
203 | for LENGTH characters at location BEG. | |
e928d437 | 204 | The replacement must not change the number of characters. */ |
c6953be1 | 205 | |
ff1aa840 | 206 | void |
d311d28c | 207 | record_change (ptrdiff_t beg, ptrdiff_t length) |
c6953be1 | 208 | { |
e928d437 | 209 | record_delete (beg, make_buffer_string (beg, beg + length, 1)); |
c6953be1 JB |
210 | record_insert (beg, length); |
211 | } | |
212 | \f | |
213 | /* Record that an unmodified buffer is about to be changed. | |
214 | Record the file modification date so that when undoing this entry | |
215 | we can tell whether it is obsolete because the file was saved again. */ | |
216 | ||
90dd3e4f | 217 | void |
971de7fb | 218 | record_first_change (void) |
c6953be1 | 219 | { |
ad9cdce4 | 220 | struct buffer *base_buffer = current_buffer; |
0736cafe | 221 | |
4b4deea2 | 222 | if (EQ (BVAR (current_buffer, undo_list), Qt)) |
0736cafe RS |
223 | return; |
224 | ||
4591d6cb | 225 | if (current_buffer != last_undo_buffer) |
0736cafe | 226 | Fundo_boundary (); |
4591d6cb | 227 | last_undo_buffer = current_buffer; |
0736cafe | 228 | |
ad9cdce4 RS |
229 | if (base_buffer->base_buffer) |
230 | base_buffer = base_buffer->base_buffer; | |
231 | ||
39eb03f1 PE |
232 | bset_undo_list |
233 | (current_buffer, | |
234 | Fcons (Fcons (Qt, make_lisp_time (base_buffer->modtime)), | |
235 | BVAR (current_buffer, undo_list))); | |
c6953be1 JB |
236 | } |
237 | ||
da9319d5 RS |
238 | /* Record a change in property PROP (whose old value was VAL) |
239 | for LENGTH characters starting at position BEG in BUFFER. */ | |
240 | ||
90dd3e4f | 241 | void |
d311d28c | 242 | record_property_change (ptrdiff_t beg, ptrdiff_t length, |
c8a66ab8 EZ |
243 | Lisp_Object prop, Lisp_Object value, |
244 | Lisp_Object buffer) | |
da9319d5 RS |
245 | { |
246 | Lisp_Object lbeg, lend, entry; | |
4591d6cb | 247 | struct buffer *obuf = current_buffer, *buf = XBUFFER (buffer); |
da9319d5 RS |
248 | int boundary = 0; |
249 | ||
4b4deea2 | 250 | if (EQ (BVAR (buf, undo_list), Qt)) |
bdbe6f28 RS |
251 | return; |
252 | ||
c58632fc RS |
253 | /* Allocate a cons cell to be the undo boundary after this command. */ |
254 | if (NILP (pending_boundary)) | |
255 | pending_boundary = Fcons (Qnil, Qnil); | |
256 | ||
4591d6cb | 257 | if (buf != last_undo_buffer) |
da9319d5 | 258 | boundary = 1; |
4591d6cb | 259 | last_undo_buffer = buf; |
da9319d5 | 260 | |
da9319d5 | 261 | /* Switch temporarily to the buffer that was changed. */ |
4591d6cb | 262 | current_buffer = buf; |
da9319d5 RS |
263 | |
264 | if (boundary) | |
265 | Fundo_boundary (); | |
266 | ||
ad9cdce4 | 267 | if (MODIFF <= SAVE_MODIFF) |
da9319d5 RS |
268 | record_first_change (); |
269 | ||
552bdbcf KH |
270 | XSETINT (lbeg, beg); |
271 | XSETINT (lend, beg + length); | |
da9319d5 | 272 | entry = Fcons (Qnil, Fcons (prop, Fcons (value, Fcons (lbeg, lend)))); |
39eb03f1 PE |
273 | bset_undo_list (current_buffer, |
274 | Fcons (entry, BVAR (current_buffer, undo_list))); | |
da9319d5 RS |
275 | |
276 | current_buffer = obuf; | |
277 | } | |
278 | ||
a7ca3326 | 279 | DEFUN ("undo-boundary", Fundo_boundary, Sundo_boundary, 0, 0, 0, |
8c1a1077 PJ |
280 | doc: /* Mark a boundary between units of undo. |
281 | An undo command will stop at this point, | |
282 | but another undo command will undo to the previous boundary. */) | |
5842a27b | 283 | (void) |
c6953be1 JB |
284 | { |
285 | Lisp_Object tem; | |
4b4deea2 | 286 | if (EQ (BVAR (current_buffer, undo_list), Qt)) |
c6953be1 | 287 | return Qnil; |
4b4deea2 | 288 | tem = Fcar (BVAR (current_buffer, undo_list)); |
265a9e55 | 289 | if (!NILP (tem)) |
c58632fc RS |
290 | { |
291 | /* One way or another, cons nil onto the front of the undo list. */ | |
292 | if (!NILP (pending_boundary)) | |
293 | { | |
294 | /* If we have preallocated the cons cell to use here, | |
295 | use that one. */ | |
4b4deea2 | 296 | XSETCDR (pending_boundary, BVAR (current_buffer, undo_list)); |
39eb03f1 | 297 | bset_undo_list (current_buffer, pending_boundary); |
c58632fc RS |
298 | pending_boundary = Qnil; |
299 | } | |
300 | else | |
39eb03f1 PE |
301 | bset_undo_list (current_buffer, |
302 | Fcons (Qnil, BVAR (current_buffer, undo_list))); | |
c58632fc | 303 | } |
4591d6cb SM |
304 | last_boundary_position = PT; |
305 | last_boundary_buffer = current_buffer; | |
c6953be1 JB |
306 | return Qnil; |
307 | } | |
308 | ||
309 | /* At garbage collection time, make an undo list shorter at the end, | |
137e23ea RS |
310 | returning the truncated list. How this is done depends on the |
311 | variables undo-limit, undo-strong-limit and undo-outer-limit. | |
312 | In some cases this works by calling undo-outer-limit-function. */ | |
313 | ||
314 | void | |
971de7fb | 315 | truncate_undo_list (struct buffer *b) |
c6953be1 | 316 | { |
137e23ea | 317 | Lisp_Object list; |
c6953be1 | 318 | Lisp_Object prev, next, last_boundary; |
d311d28c | 319 | EMACS_INT size_so_far = 0; |
c6953be1 | 320 | |
137e23ea RS |
321 | /* Make sure that calling undo-outer-limit-function |
322 | won't cause another GC. */ | |
d311d28c | 323 | ptrdiff_t count = inhibit_garbage_collection (); |
137e23ea RS |
324 | |
325 | /* Make the buffer current to get its local values of variables such | |
326 | as undo_limit. Also so that Vundo_outer_limit_function can | |
327 | tell which buffer to operate on. */ | |
66322887 | 328 | record_unwind_current_buffer (); |
137e23ea RS |
329 | set_buffer_internal (b); |
330 | ||
4b4deea2 | 331 | list = BVAR (b, undo_list); |
137e23ea | 332 | |
c6953be1 JB |
333 | prev = Qnil; |
334 | next = list; | |
335 | last_boundary = Qnil; | |
336 | ||
137e23ea | 337 | /* If the first element is an undo boundary, skip past it. */ |
c1d497be | 338 | if (CONSP (next) && NILP (XCAR (next))) |
c6953be1 JB |
339 | { |
340 | /* Add in the space occupied by this element and its chain link. */ | |
341 | size_so_far += sizeof (struct Lisp_Cons); | |
342 | ||
343 | /* Advance to next element. */ | |
344 | prev = next; | |
c1d497be | 345 | next = XCDR (next); |
c6953be1 | 346 | } |
e3d5ca1e | 347 | |
137e23ea RS |
348 | /* Always preserve at least the most recent undo record |
349 | unless it is really horribly big. | |
350 | ||
351 | Skip, skip, skip the undo, skip, skip, skip the undo, | |
352 | Skip, skip, skip the undo, skip to the undo bound'ry. */ | |
353 | ||
c1d497be | 354 | while (CONSP (next) && ! NILP (XCAR (next))) |
c6953be1 JB |
355 | { |
356 | Lisp_Object elt; | |
c1d497be | 357 | elt = XCAR (next); |
c6953be1 JB |
358 | |
359 | /* Add in the space occupied by this element and its chain link. */ | |
360 | size_so_far += sizeof (struct Lisp_Cons); | |
38c0d37c | 361 | if (CONSP (elt)) |
c6953be1 JB |
362 | { |
363 | size_so_far += sizeof (struct Lisp_Cons); | |
c1d497be | 364 | if (STRINGP (XCAR (elt))) |
c6953be1 | 365 | size_so_far += (sizeof (struct Lisp_String) - 1 |
d5db4077 | 366 | + SCHARS (XCAR (elt))); |
c6953be1 JB |
367 | } |
368 | ||
369 | /* Advance to next element. */ | |
370 | prev = next; | |
c1d497be | 371 | next = XCDR (next); |
c6953be1 | 372 | } |
e3d5ca1e | 373 | |
137e23ea RS |
374 | /* If by the first boundary we have already passed undo_outer_limit, |
375 | we're heading for memory full, so offer to clear out the list. */ | |
81c1cf71 RS |
376 | if (INTEGERP (Vundo_outer_limit) |
377 | && size_so_far > XINT (Vundo_outer_limit) | |
137e23ea RS |
378 | && !NILP (Vundo_outer_limit_function)) |
379 | { | |
4591d6cb SM |
380 | Lisp_Object tem; |
381 | struct buffer *temp = last_undo_buffer; | |
137e23ea RS |
382 | |
383 | /* Normally the function this calls is undo-outer-limit-truncate. */ | |
88fde92a KR |
384 | tem = call1 (Vundo_outer_limit_function, make_number (size_so_far)); |
385 | if (! NILP (tem)) | |
137e23ea RS |
386 | { |
387 | /* The function is responsible for making | |
388 | any desired changes in buffer-undo-list. */ | |
389 | unbind_to (count, Qnil); | |
390 | return; | |
391 | } | |
392 | /* That function probably used the minibuffer, and if so, that | |
393 | changed last_undo_buffer. Change it back so that we don't | |
394 | force next change to make an undo boundary here. */ | |
395 | last_undo_buffer = temp; | |
396 | } | |
397 | ||
38c0d37c | 398 | if (CONSP (next)) |
c6953be1 JB |
399 | last_boundary = prev; |
400 | ||
137e23ea | 401 | /* Keep additional undo data, if it fits in the limits. */ |
38c0d37c | 402 | while (CONSP (next)) |
c6953be1 JB |
403 | { |
404 | Lisp_Object elt; | |
c1d497be | 405 | elt = XCAR (next); |
c6953be1 JB |
406 | |
407 | /* When we get to a boundary, decide whether to truncate | |
137e23ea | 408 | either before or after it. The lower threshold, undo_limit, |
c6953be1 | 409 | tells us to truncate after it. If its size pushes past |
137e23ea | 410 | the higher threshold undo_strong_limit, we truncate before it. */ |
265a9e55 | 411 | if (NILP (elt)) |
c6953be1 | 412 | { |
137e23ea | 413 | if (size_so_far > undo_strong_limit) |
c6953be1 JB |
414 | break; |
415 | last_boundary = prev; | |
137e23ea | 416 | if (size_so_far > undo_limit) |
c6953be1 JB |
417 | break; |
418 | } | |
419 | ||
420 | /* Add in the space occupied by this element and its chain link. */ | |
421 | size_so_far += sizeof (struct Lisp_Cons); | |
38c0d37c | 422 | if (CONSP (elt)) |
c6953be1 JB |
423 | { |
424 | size_so_far += sizeof (struct Lisp_Cons); | |
c1d497be | 425 | if (STRINGP (XCAR (elt))) |
c6953be1 | 426 | size_so_far += (sizeof (struct Lisp_String) - 1 |
d5db4077 | 427 | + SCHARS (XCAR (elt))); |
c6953be1 JB |
428 | } |
429 | ||
430 | /* Advance to next element. */ | |
431 | prev = next; | |
c1d497be | 432 | next = XCDR (next); |
c6953be1 JB |
433 | } |
434 | ||
435 | /* If we scanned the whole list, it is short enough; don't change it. */ | |
265a9e55 | 436 | if (NILP (next)) |
137e23ea | 437 | ; |
c6953be1 | 438 | /* Truncate at the boundary where we decided to truncate. */ |
137e23ea RS |
439 | else if (!NILP (last_boundary)) |
440 | XSETCDR (last_boundary, Qnil); | |
441 | /* There's nothing we decided to keep, so clear it out. */ | |
c6953be1 | 442 | else |
39eb03f1 | 443 | bset_undo_list (b, Qnil); |
137e23ea RS |
444 | |
445 | unbind_to (count, Qnil); | |
c6953be1 | 446 | } |
71873e2b | 447 | |
c6953be1 | 448 | \f |
dfcf069d | 449 | void |
971de7fb | 450 | syms_of_undo (void) |
c6953be1 | 451 | { |
cd3520a4 JB |
452 | DEFSYM (Qinhibit_read_only, "inhibit-read-only"); |
453 | DEFSYM (Qapply, "apply"); | |
49be18c9 | 454 | |
c58632fc RS |
455 | pending_boundary = Qnil; |
456 | staticpro (&pending_boundary); | |
457 | ||
4591d6cb SM |
458 | last_undo_buffer = NULL; |
459 | last_boundary_buffer = NULL; | |
460 | ||
c6953be1 | 461 | defsubr (&Sundo_boundary); |
137e23ea | 462 | |
29208e82 | 463 | DEFVAR_INT ("undo-limit", undo_limit, |
137e23ea RS |
464 | doc: /* Keep no more undo information once it exceeds this size. |
465 | This limit is applied when garbage collection happens. | |
466 | When a previous command increases the total undo list size past this | |
467 | value, the earlier commands that came before it are forgotten. | |
468 | ||
469 | The size is counted as the number of bytes occupied, | |
470 | which includes both saved text and other data. */); | |
2159bd06 | 471 | undo_limit = 80000; |
137e23ea | 472 | |
29208e82 | 473 | DEFVAR_INT ("undo-strong-limit", undo_strong_limit, |
137e23ea RS |
474 | doc: /* Don't keep more than this much size of undo information. |
475 | This limit is applied when garbage collection happens. | |
476 | When a previous command increases the total undo list size past this | |
477 | value, that command and the earlier commands that came before it are forgotten. | |
478 | However, the most recent buffer-modifying command's undo info | |
479 | is never discarded for this reason. | |
480 | ||
481 | The size is counted as the number of bytes occupied, | |
482 | which includes both saved text and other data. */); | |
2159bd06 | 483 | undo_strong_limit = 120000; |
137e23ea | 484 | |
29208e82 | 485 | DEFVAR_LISP ("undo-outer-limit", Vundo_outer_limit, |
137e23ea RS |
486 | doc: /* Outer limit on size of undo information for one command. |
487 | At garbage collection time, if the current command has produced | |
62d776fd LT |
488 | more than this much undo information, it discards the info and displays |
489 | a warning. This is a last-ditch limit to prevent memory overflow. | |
137e23ea | 490 | |
62d776fd LT |
491 | The size is counted as the number of bytes occupied, which includes |
492 | both saved text and other data. A value of nil means no limit. In | |
493 | this case, accumulating one huge undo entry could make Emacs crash as | |
494 | a result of memory overflow. | |
137e23ea RS |
495 | |
496 | In fact, this calls the function which is the value of | |
497 | `undo-outer-limit-function' with one argument, the size. | |
498 | The text above describes the behavior of the function | |
499 | that variable usually specifies. */); | |
2159bd06 | 500 | Vundo_outer_limit = make_number (12000000); |
137e23ea | 501 | |
29208e82 | 502 | DEFVAR_LISP ("undo-outer-limit-function", Vundo_outer_limit_function, |
137e23ea RS |
503 | doc: /* Function to call when an undo list exceeds `undo-outer-limit'. |
504 | This function is called with one argument, the current undo list size | |
505 | for the most recent command (since the last undo boundary). | |
506 | If the function returns t, that means truncation has been fully handled. | |
507 | If it returns nil, the other forms of truncation are done. | |
508 | ||
509 | Garbage collection is inhibited around the call to this function, | |
510 | so it must make sure not to do a lot of consing. */); | |
511 | Vundo_outer_limit_function = Qnil; | |
8abe0f97 | 512 | |
29208e82 | 513 | DEFVAR_BOOL ("undo-inhibit-record-point", undo_inhibit_record_point, |
8abe0f97 MR |
514 | doc: /* Non-nil means do not record `point' in `buffer-undo-list'. */); |
515 | undo_inhibit_record_point = 0; | |
c6953be1 | 516 | } |