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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 | ||
954b166e PE |
232 | bset_undo_list (current_buffer, |
233 | Fcons (Fcons (Qt, Fvisited_file_modtime ()), | |
234 | BVAR (current_buffer, undo_list))); | |
c6953be1 JB |
235 | } |
236 | ||
da9319d5 RS |
237 | /* Record a change in property PROP (whose old value was VAL) |
238 | for LENGTH characters starting at position BEG in BUFFER. */ | |
239 | ||
90dd3e4f | 240 | void |
d311d28c | 241 | record_property_change (ptrdiff_t beg, ptrdiff_t length, |
c8a66ab8 EZ |
242 | Lisp_Object prop, Lisp_Object value, |
243 | Lisp_Object buffer) | |
da9319d5 RS |
244 | { |
245 | Lisp_Object lbeg, lend, entry; | |
4591d6cb | 246 | struct buffer *obuf = current_buffer, *buf = XBUFFER (buffer); |
da9319d5 RS |
247 | int boundary = 0; |
248 | ||
4b4deea2 | 249 | if (EQ (BVAR (buf, undo_list), Qt)) |
bdbe6f28 RS |
250 | return; |
251 | ||
c58632fc RS |
252 | /* Allocate a cons cell to be the undo boundary after this command. */ |
253 | if (NILP (pending_boundary)) | |
254 | pending_boundary = Fcons (Qnil, Qnil); | |
255 | ||
4591d6cb | 256 | if (buf != last_undo_buffer) |
da9319d5 | 257 | boundary = 1; |
4591d6cb | 258 | last_undo_buffer = buf; |
da9319d5 | 259 | |
da9319d5 | 260 | /* Switch temporarily to the buffer that was changed. */ |
4591d6cb | 261 | current_buffer = buf; |
da9319d5 RS |
262 | |
263 | if (boundary) | |
264 | Fundo_boundary (); | |
265 | ||
ad9cdce4 | 266 | if (MODIFF <= SAVE_MODIFF) |
da9319d5 RS |
267 | record_first_change (); |
268 | ||
552bdbcf KH |
269 | XSETINT (lbeg, beg); |
270 | XSETINT (lend, beg + length); | |
da9319d5 | 271 | entry = Fcons (Qnil, Fcons (prop, Fcons (value, Fcons (lbeg, lend)))); |
39eb03f1 PE |
272 | bset_undo_list (current_buffer, |
273 | Fcons (entry, BVAR (current_buffer, undo_list))); | |
da9319d5 RS |
274 | |
275 | current_buffer = obuf; | |
276 | } | |
277 | ||
a7ca3326 | 278 | DEFUN ("undo-boundary", Fundo_boundary, Sundo_boundary, 0, 0, 0, |
8c1a1077 PJ |
279 | doc: /* Mark a boundary between units of undo. |
280 | An undo command will stop at this point, | |
281 | but another undo command will undo to the previous boundary. */) | |
5842a27b | 282 | (void) |
c6953be1 JB |
283 | { |
284 | Lisp_Object tem; | |
4b4deea2 | 285 | if (EQ (BVAR (current_buffer, undo_list), Qt)) |
c6953be1 | 286 | return Qnil; |
4b4deea2 | 287 | tem = Fcar (BVAR (current_buffer, undo_list)); |
265a9e55 | 288 | if (!NILP (tem)) |
c58632fc RS |
289 | { |
290 | /* One way or another, cons nil onto the front of the undo list. */ | |
291 | if (!NILP (pending_boundary)) | |
292 | { | |
293 | /* If we have preallocated the cons cell to use here, | |
294 | use that one. */ | |
4b4deea2 | 295 | XSETCDR (pending_boundary, BVAR (current_buffer, undo_list)); |
39eb03f1 | 296 | bset_undo_list (current_buffer, pending_boundary); |
c58632fc RS |
297 | pending_boundary = Qnil; |
298 | } | |
299 | else | |
39eb03f1 PE |
300 | bset_undo_list (current_buffer, |
301 | Fcons (Qnil, BVAR (current_buffer, undo_list))); | |
c58632fc | 302 | } |
4591d6cb SM |
303 | last_boundary_position = PT; |
304 | last_boundary_buffer = current_buffer; | |
c6953be1 JB |
305 | return Qnil; |
306 | } | |
307 | ||
308 | /* At garbage collection time, make an undo list shorter at the end, | |
137e23ea RS |
309 | returning the truncated list. How this is done depends on the |
310 | variables undo-limit, undo-strong-limit and undo-outer-limit. | |
311 | In some cases this works by calling undo-outer-limit-function. */ | |
312 | ||
313 | void | |
971de7fb | 314 | truncate_undo_list (struct buffer *b) |
c6953be1 | 315 | { |
137e23ea | 316 | Lisp_Object list; |
c6953be1 | 317 | Lisp_Object prev, next, last_boundary; |
d311d28c | 318 | EMACS_INT size_so_far = 0; |
c6953be1 | 319 | |
137e23ea RS |
320 | /* Make sure that calling undo-outer-limit-function |
321 | won't cause another GC. */ | |
d311d28c | 322 | ptrdiff_t count = inhibit_garbage_collection (); |
137e23ea RS |
323 | |
324 | /* Make the buffer current to get its local values of variables such | |
325 | as undo_limit. Also so that Vundo_outer_limit_function can | |
326 | tell which buffer to operate on. */ | |
66322887 | 327 | record_unwind_current_buffer (); |
137e23ea RS |
328 | set_buffer_internal (b); |
329 | ||
4b4deea2 | 330 | list = BVAR (b, undo_list); |
137e23ea | 331 | |
c6953be1 JB |
332 | prev = Qnil; |
333 | next = list; | |
334 | last_boundary = Qnil; | |
335 | ||
137e23ea | 336 | /* If the first element is an undo boundary, skip past it. */ |
c1d497be | 337 | if (CONSP (next) && NILP (XCAR (next))) |
c6953be1 JB |
338 | { |
339 | /* Add in the space occupied by this element and its chain link. */ | |
340 | size_so_far += sizeof (struct Lisp_Cons); | |
341 | ||
342 | /* Advance to next element. */ | |
343 | prev = next; | |
c1d497be | 344 | next = XCDR (next); |
c6953be1 | 345 | } |
e3d5ca1e | 346 | |
137e23ea RS |
347 | /* Always preserve at least the most recent undo record |
348 | unless it is really horribly big. | |
349 | ||
350 | Skip, skip, skip the undo, skip, skip, skip the undo, | |
351 | Skip, skip, skip the undo, skip to the undo bound'ry. */ | |
352 | ||
c1d497be | 353 | while (CONSP (next) && ! NILP (XCAR (next))) |
c6953be1 JB |
354 | { |
355 | Lisp_Object elt; | |
c1d497be | 356 | elt = XCAR (next); |
c6953be1 JB |
357 | |
358 | /* Add in the space occupied by this element and its chain link. */ | |
359 | size_so_far += sizeof (struct Lisp_Cons); | |
38c0d37c | 360 | if (CONSP (elt)) |
c6953be1 JB |
361 | { |
362 | size_so_far += sizeof (struct Lisp_Cons); | |
c1d497be | 363 | if (STRINGP (XCAR (elt))) |
c6953be1 | 364 | size_so_far += (sizeof (struct Lisp_String) - 1 |
d5db4077 | 365 | + SCHARS (XCAR (elt))); |
c6953be1 JB |
366 | } |
367 | ||
368 | /* Advance to next element. */ | |
369 | prev = next; | |
c1d497be | 370 | next = XCDR (next); |
c6953be1 | 371 | } |
e3d5ca1e | 372 | |
137e23ea RS |
373 | /* If by the first boundary we have already passed undo_outer_limit, |
374 | we're heading for memory full, so offer to clear out the list. */ | |
81c1cf71 RS |
375 | if (INTEGERP (Vundo_outer_limit) |
376 | && size_so_far > XINT (Vundo_outer_limit) | |
137e23ea RS |
377 | && !NILP (Vundo_outer_limit_function)) |
378 | { | |
4591d6cb SM |
379 | Lisp_Object tem; |
380 | struct buffer *temp = last_undo_buffer; | |
137e23ea RS |
381 | |
382 | /* Normally the function this calls is undo-outer-limit-truncate. */ | |
88fde92a KR |
383 | tem = call1 (Vundo_outer_limit_function, make_number (size_so_far)); |
384 | if (! NILP (tem)) | |
137e23ea RS |
385 | { |
386 | /* The function is responsible for making | |
387 | any desired changes in buffer-undo-list. */ | |
388 | unbind_to (count, Qnil); | |
389 | return; | |
390 | } | |
391 | /* That function probably used the minibuffer, and if so, that | |
392 | changed last_undo_buffer. Change it back so that we don't | |
393 | force next change to make an undo boundary here. */ | |
394 | last_undo_buffer = temp; | |
395 | } | |
396 | ||
38c0d37c | 397 | if (CONSP (next)) |
c6953be1 JB |
398 | last_boundary = prev; |
399 | ||
137e23ea | 400 | /* Keep additional undo data, if it fits in the limits. */ |
38c0d37c | 401 | while (CONSP (next)) |
c6953be1 JB |
402 | { |
403 | Lisp_Object elt; | |
c1d497be | 404 | elt = XCAR (next); |
c6953be1 JB |
405 | |
406 | /* When we get to a boundary, decide whether to truncate | |
137e23ea | 407 | either before or after it. The lower threshold, undo_limit, |
c6953be1 | 408 | tells us to truncate after it. If its size pushes past |
137e23ea | 409 | the higher threshold undo_strong_limit, we truncate before it. */ |
265a9e55 | 410 | if (NILP (elt)) |
c6953be1 | 411 | { |
137e23ea | 412 | if (size_so_far > undo_strong_limit) |
c6953be1 JB |
413 | break; |
414 | last_boundary = prev; | |
137e23ea | 415 | if (size_so_far > undo_limit) |
c6953be1 JB |
416 | break; |
417 | } | |
418 | ||
419 | /* Add in the space occupied by this element and its chain link. */ | |
420 | size_so_far += sizeof (struct Lisp_Cons); | |
38c0d37c | 421 | if (CONSP (elt)) |
c6953be1 JB |
422 | { |
423 | size_so_far += sizeof (struct Lisp_Cons); | |
c1d497be | 424 | if (STRINGP (XCAR (elt))) |
c6953be1 | 425 | size_so_far += (sizeof (struct Lisp_String) - 1 |
d5db4077 | 426 | + SCHARS (XCAR (elt))); |
c6953be1 JB |
427 | } |
428 | ||
429 | /* Advance to next element. */ | |
430 | prev = next; | |
c1d497be | 431 | next = XCDR (next); |
c6953be1 JB |
432 | } |
433 | ||
434 | /* If we scanned the whole list, it is short enough; don't change it. */ | |
265a9e55 | 435 | if (NILP (next)) |
137e23ea | 436 | ; |
c6953be1 | 437 | /* Truncate at the boundary where we decided to truncate. */ |
137e23ea RS |
438 | else if (!NILP (last_boundary)) |
439 | XSETCDR (last_boundary, Qnil); | |
440 | /* There's nothing we decided to keep, so clear it out. */ | |
c6953be1 | 441 | else |
39eb03f1 | 442 | bset_undo_list (b, Qnil); |
137e23ea RS |
443 | |
444 | unbind_to (count, Qnil); | |
c6953be1 | 445 | } |
71873e2b | 446 | |
c6953be1 | 447 | \f |
dfcf069d | 448 | void |
971de7fb | 449 | syms_of_undo (void) |
c6953be1 | 450 | { |
cd3520a4 JB |
451 | DEFSYM (Qinhibit_read_only, "inhibit-read-only"); |
452 | DEFSYM (Qapply, "apply"); | |
49be18c9 | 453 | |
c58632fc RS |
454 | pending_boundary = Qnil; |
455 | staticpro (&pending_boundary); | |
456 | ||
4591d6cb SM |
457 | last_undo_buffer = NULL; |
458 | last_boundary_buffer = NULL; | |
459 | ||
c6953be1 | 460 | defsubr (&Sundo_boundary); |
137e23ea | 461 | |
29208e82 | 462 | DEFVAR_INT ("undo-limit", undo_limit, |
137e23ea RS |
463 | doc: /* Keep no more undo information once it exceeds this size. |
464 | This limit is applied when garbage collection happens. | |
465 | When a previous command increases the total undo list size past this | |
466 | value, the earlier commands that came before it are forgotten. | |
467 | ||
468 | The size is counted as the number of bytes occupied, | |
469 | which includes both saved text and other data. */); | |
2159bd06 | 470 | undo_limit = 80000; |
137e23ea | 471 | |
29208e82 | 472 | DEFVAR_INT ("undo-strong-limit", undo_strong_limit, |
137e23ea RS |
473 | doc: /* Don't keep more than this much size of undo information. |
474 | This limit is applied when garbage collection happens. | |
475 | When a previous command increases the total undo list size past this | |
476 | value, that command and the earlier commands that came before it are forgotten. | |
477 | However, the most recent buffer-modifying command's undo info | |
478 | is never discarded for this reason. | |
479 | ||
480 | The size is counted as the number of bytes occupied, | |
481 | which includes both saved text and other data. */); | |
2159bd06 | 482 | undo_strong_limit = 120000; |
137e23ea | 483 | |
29208e82 | 484 | DEFVAR_LISP ("undo-outer-limit", Vundo_outer_limit, |
137e23ea RS |
485 | doc: /* Outer limit on size of undo information for one command. |
486 | At garbage collection time, if the current command has produced | |
62d776fd LT |
487 | more than this much undo information, it discards the info and displays |
488 | a warning. This is a last-ditch limit to prevent memory overflow. | |
137e23ea | 489 | |
62d776fd LT |
490 | The size is counted as the number of bytes occupied, which includes |
491 | both saved text and other data. A value of nil means no limit. In | |
492 | this case, accumulating one huge undo entry could make Emacs crash as | |
493 | a result of memory overflow. | |
137e23ea RS |
494 | |
495 | In fact, this calls the function which is the value of | |
496 | `undo-outer-limit-function' with one argument, the size. | |
497 | The text above describes the behavior of the function | |
498 | that variable usually specifies. */); | |
2159bd06 | 499 | Vundo_outer_limit = make_number (12000000); |
137e23ea | 500 | |
29208e82 | 501 | DEFVAR_LISP ("undo-outer-limit-function", Vundo_outer_limit_function, |
137e23ea RS |
502 | doc: /* Function to call when an undo list exceeds `undo-outer-limit'. |
503 | This function is called with one argument, the current undo list size | |
504 | for the most recent command (since the last undo boundary). | |
505 | If the function returns t, that means truncation has been fully handled. | |
506 | If it returns nil, the other forms of truncation are done. | |
507 | ||
508 | Garbage collection is inhibited around the call to this function, | |
509 | so it must make sure not to do a lot of consing. */); | |
510 | Vundo_outer_limit_function = Qnil; | |
8abe0f97 | 511 | |
29208e82 | 512 | DEFVAR_BOOL ("undo-inhibit-record-point", undo_inhibit_record_point, |
8abe0f97 MR |
513 | doc: /* Non-nil means do not record `point' in `buffer-undo-list'. */); |
514 | undo_inhibit_record_point = 0; | |
c6953be1 | 515 | } |