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c6953be1 | 1 | /* undo handling for GNU Emacs. |
c6c5df7f | 2 | Copyright (C) 1990, 1993 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 | ||
22 | #include "config.h" | |
23 | #include "lisp.h" | |
24 | #include "buffer.h" | |
25 | ||
26 | /* Last buffer for which undo information was recorded. */ | |
27 | Lisp_Object last_undo_buffer; | |
28 | ||
f87a68b3 RS |
29 | Lisp_Object Qinhibit_read_only; |
30 | ||
c6953be1 JB |
31 | /* Record an insertion that just happened or is about to happen, |
32 | for LENGTH characters at position BEG. | |
33 | (It is possible to record an insertion before or after the fact | |
34 | because we don't need to record the contents.) */ | |
35 | ||
36 | record_insert (beg, length) | |
37 | Lisp_Object beg, length; | |
38 | { | |
39 | Lisp_Object lbeg, lend; | |
40 | ||
bdbe6f28 RS |
41 | if (EQ (current_buffer->undo_list, Qt)) |
42 | return; | |
43 | ||
c6953be1 JB |
44 | if (current_buffer != XBUFFER (last_undo_buffer)) |
45 | Fundo_boundary (); | |
46 | XSET (last_undo_buffer, Lisp_Buffer, current_buffer); | |
47 | ||
c6953be1 JB |
48 | if (MODIFF <= current_buffer->save_modified) |
49 | record_first_change (); | |
50 | ||
51 | /* If this is following another insertion and consecutive with it | |
52 | in the buffer, combine the two. */ | |
53 | if (XTYPE (current_buffer->undo_list) == Lisp_Cons) | |
54 | { | |
55 | Lisp_Object elt; | |
56 | elt = XCONS (current_buffer->undo_list)->car; | |
57 | if (XTYPE (elt) == Lisp_Cons | |
58 | && XTYPE (XCONS (elt)->car) == Lisp_Int | |
59 | && XTYPE (XCONS (elt)->cdr) == Lisp_Int | |
213861c7 | 60 | && XINT (XCONS (elt)->cdr) == XINT (beg)) |
c6953be1 | 61 | { |
213861c7 | 62 | XSETINT (XCONS (elt)->cdr, XINT (beg) + XINT (length)); |
c6953be1 JB |
63 | return; |
64 | } | |
65 | } | |
66 | ||
213861c7 JB |
67 | lbeg = beg; |
68 | XSET (lend, Lisp_Int, XINT (beg) + XINT (length)); | |
69 | current_buffer->undo_list = Fcons (Fcons (lbeg, lend), | |
70 | current_buffer->undo_list); | |
c6953be1 JB |
71 | } |
72 | ||
73 | /* Record that a deletion is about to take place, | |
74 | for LENGTH characters at location BEG. */ | |
75 | ||
76 | record_delete (beg, length) | |
77 | int beg, length; | |
78 | { | |
79 | Lisp_Object lbeg, lend, sbeg; | |
80 | ||
bdbe6f28 RS |
81 | if (EQ (current_buffer->undo_list, Qt)) |
82 | return; | |
83 | ||
c6953be1 JB |
84 | if (current_buffer != XBUFFER (last_undo_buffer)) |
85 | Fundo_boundary (); | |
86 | XSET (last_undo_buffer, Lisp_Buffer, current_buffer); | |
87 | ||
c6953be1 JB |
88 | if (MODIFF <= current_buffer->save_modified) |
89 | record_first_change (); | |
90 | ||
91 | if (point == beg + length) | |
92 | XSET (sbeg, Lisp_Int, -beg); | |
93 | else | |
94 | XFASTINT (sbeg) = beg; | |
95 | XFASTINT (lbeg) = beg; | |
96 | XFASTINT (lend) = beg + length; | |
350bce56 RS |
97 | |
98 | /* If point isn't at start of deleted range, record where it is. */ | |
d8552b2f | 99 | if (PT != XFASTINT (sbeg)) |
350bce56 RS |
100 | current_buffer->undo_list |
101 | = Fcons (make_number (PT), current_buffer->undo_list); | |
102 | ||
c6953be1 JB |
103 | current_buffer->undo_list |
104 | = Fcons (Fcons (Fbuffer_substring (lbeg, lend), sbeg), | |
105 | current_buffer->undo_list); | |
106 | } | |
107 | ||
108 | /* Record that a replacement is about to take place, | |
109 | for LENGTH characters at location BEG. | |
110 | The replacement does not change the number of characters. */ | |
111 | ||
112 | record_change (beg, length) | |
113 | int beg, length; | |
114 | { | |
115 | record_delete (beg, length); | |
116 | record_insert (beg, length); | |
117 | } | |
118 | \f | |
119 | /* Record that an unmodified buffer is about to be changed. | |
120 | Record the file modification date so that when undoing this entry | |
121 | we can tell whether it is obsolete because the file was saved again. */ | |
122 | ||
123 | record_first_change () | |
124 | { | |
125 | Lisp_Object high, low; | |
126 | XFASTINT (high) = (current_buffer->modtime >> 16) & 0xffff; | |
127 | XFASTINT (low) = current_buffer->modtime & 0xffff; | |
128 | current_buffer->undo_list = Fcons (Fcons (Qt, Fcons (high, low)), current_buffer->undo_list); | |
129 | } | |
130 | ||
da9319d5 RS |
131 | /* Record a change in property PROP (whose old value was VAL) |
132 | for LENGTH characters starting at position BEG in BUFFER. */ | |
133 | ||
134 | record_property_change (beg, length, prop, value, buffer) | |
135 | int beg, length; | |
136 | Lisp_Object prop, value, buffer; | |
137 | { | |
138 | Lisp_Object lbeg, lend, entry; | |
139 | struct buffer *obuf = current_buffer; | |
140 | int boundary = 0; | |
141 | ||
bdbe6f28 RS |
142 | if (EQ (current_buffer->undo_list, Qt)) |
143 | return; | |
144 | ||
da9319d5 RS |
145 | if (!EQ (buffer, last_undo_buffer)) |
146 | boundary = 1; | |
147 | last_undo_buffer = buffer; | |
148 | ||
da9319d5 RS |
149 | /* Switch temporarily to the buffer that was changed. */ |
150 | current_buffer = XBUFFER (buffer); | |
151 | ||
152 | if (boundary) | |
153 | Fundo_boundary (); | |
154 | ||
155 | if (MODIFF <= current_buffer->save_modified) | |
156 | record_first_change (); | |
157 | ||
158 | XSET (lbeg, Lisp_Int, beg); | |
159 | XSET (lend, Lisp_Int, beg + length); | |
160 | entry = Fcons (Qnil, Fcons (prop, Fcons (value, Fcons (lbeg, lend)))); | |
161 | current_buffer->undo_list = Fcons (entry, current_buffer->undo_list); | |
162 | ||
163 | current_buffer = obuf; | |
164 | } | |
165 | ||
c6953be1 JB |
166 | DEFUN ("undo-boundary", Fundo_boundary, Sundo_boundary, 0, 0, 0, |
167 | "Mark a boundary between units of undo.\n\ | |
168 | An undo command will stop at this point,\n\ | |
169 | but another undo command will undo to the previous boundary.") | |
170 | () | |
171 | { | |
172 | Lisp_Object tem; | |
173 | if (EQ (current_buffer->undo_list, Qt)) | |
174 | return Qnil; | |
175 | tem = Fcar (current_buffer->undo_list); | |
265a9e55 | 176 | if (!NILP (tem)) |
c6953be1 JB |
177 | current_buffer->undo_list = Fcons (Qnil, current_buffer->undo_list); |
178 | return Qnil; | |
179 | } | |
180 | ||
181 | /* At garbage collection time, make an undo list shorter at the end, | |
182 | returning the truncated list. | |
183 | MINSIZE and MAXSIZE are the limits on size allowed, as described below. | |
f06cd136 JB |
184 | In practice, these are the values of undo-limit and |
185 | undo-strong-limit. */ | |
c6953be1 JB |
186 | |
187 | Lisp_Object | |
188 | truncate_undo_list (list, minsize, maxsize) | |
189 | Lisp_Object list; | |
190 | int minsize, maxsize; | |
191 | { | |
192 | Lisp_Object prev, next, last_boundary; | |
193 | int size_so_far = 0; | |
194 | ||
195 | prev = Qnil; | |
196 | next = list; | |
197 | last_boundary = Qnil; | |
198 | ||
199 | /* Always preserve at least the most recent undo record. | |
181a18b1 JB |
200 | If the first element is an undo boundary, skip past it. |
201 | ||
202 | Skip, skip, skip the undo, skip, skip, skip the undo, | |
07627b5d JB |
203 | Skip, skip, skip the undo, skip to the undo bound'ry. |
204 | (Get it? "Skip to my Loo?") */ | |
c6953be1 | 205 | if (XTYPE (next) == Lisp_Cons |
213861c7 | 206 | && NILP (XCONS (next)->car)) |
c6953be1 JB |
207 | { |
208 | /* Add in the space occupied by this element and its chain link. */ | |
209 | size_so_far += sizeof (struct Lisp_Cons); | |
210 | ||
211 | /* Advance to next element. */ | |
212 | prev = next; | |
213 | next = XCONS (next)->cdr; | |
214 | } | |
215 | while (XTYPE (next) == Lisp_Cons | |
213861c7 | 216 | && ! NILP (XCONS (next)->car)) |
c6953be1 JB |
217 | { |
218 | Lisp_Object elt; | |
219 | elt = XCONS (next)->car; | |
220 | ||
221 | /* Add in the space occupied by this element and its chain link. */ | |
222 | size_so_far += sizeof (struct Lisp_Cons); | |
223 | if (XTYPE (elt) == Lisp_Cons) | |
224 | { | |
225 | size_so_far += sizeof (struct Lisp_Cons); | |
226 | if (XTYPE (XCONS (elt)->car) == Lisp_String) | |
227 | size_so_far += (sizeof (struct Lisp_String) - 1 | |
228 | + XSTRING (XCONS (elt)->car)->size); | |
229 | } | |
230 | ||
231 | /* Advance to next element. */ | |
232 | prev = next; | |
233 | next = XCONS (next)->cdr; | |
234 | } | |
235 | if (XTYPE (next) == Lisp_Cons) | |
236 | last_boundary = prev; | |
237 | ||
238 | while (XTYPE (next) == Lisp_Cons) | |
239 | { | |
240 | Lisp_Object elt; | |
241 | elt = XCONS (next)->car; | |
242 | ||
243 | /* When we get to a boundary, decide whether to truncate | |
244 | either before or after it. The lower threshold, MINSIZE, | |
245 | tells us to truncate after it. If its size pushes past | |
246 | the higher threshold MAXSIZE as well, we truncate before it. */ | |
265a9e55 | 247 | if (NILP (elt)) |
c6953be1 JB |
248 | { |
249 | if (size_so_far > maxsize) | |
250 | break; | |
251 | last_boundary = prev; | |
252 | if (size_so_far > minsize) | |
253 | break; | |
254 | } | |
255 | ||
256 | /* Add in the space occupied by this element and its chain link. */ | |
257 | size_so_far += sizeof (struct Lisp_Cons); | |
258 | if (XTYPE (elt) == Lisp_Cons) | |
259 | { | |
260 | size_so_far += sizeof (struct Lisp_Cons); | |
261 | if (XTYPE (XCONS (elt)->car) == Lisp_String) | |
262 | size_so_far += (sizeof (struct Lisp_String) - 1 | |
263 | + XSTRING (XCONS (elt)->car)->size); | |
264 | } | |
265 | ||
266 | /* Advance to next element. */ | |
267 | prev = next; | |
268 | next = XCONS (next)->cdr; | |
269 | } | |
270 | ||
271 | /* If we scanned the whole list, it is short enough; don't change it. */ | |
265a9e55 | 272 | if (NILP (next)) |
c6953be1 JB |
273 | return list; |
274 | ||
275 | /* Truncate at the boundary where we decided to truncate. */ | |
265a9e55 | 276 | if (!NILP (last_boundary)) |
c6953be1 JB |
277 | { |
278 | XCONS (last_boundary)->cdr = Qnil; | |
279 | return list; | |
280 | } | |
281 | else | |
282 | return Qnil; | |
283 | } | |
284 | \f | |
285 | DEFUN ("primitive-undo", Fprimitive_undo, Sprimitive_undo, 2, 2, 0, | |
286 | "Undo N records from the front of the list LIST.\n\ | |
287 | Return what remains of the list.") | |
288 | (count, list) | |
289 | Lisp_Object count, list; | |
290 | { | |
f87a68b3 | 291 | int count = specpdl_ptr - specpdl; |
c6953be1 JB |
292 | register int arg = XINT (count); |
293 | #if 0 /* This is a good feature, but would make undo-start | |
294 | unable to do what is expected. */ | |
295 | Lisp_Object tem; | |
296 | ||
297 | /* If the head of the list is a boundary, it is the boundary | |
298 | preceding this command. Get rid of it and don't count it. */ | |
299 | tem = Fcar (list); | |
265a9e55 | 300 | if (NILP (tem)) |
c6953be1 JB |
301 | list = Fcdr (list); |
302 | #endif | |
303 | ||
f87a68b3 RS |
304 | /* Don't let read-only properties interfere with undo. */ |
305 | if (NILP (current_buffer->read_only)) | |
306 | specbind (Qinhibit_read_only, Qt); | |
307 | ||
c6953be1 JB |
308 | while (arg > 0) |
309 | { | |
310 | while (1) | |
311 | { | |
350bce56 | 312 | Lisp_Object next; |
c6953be1 JB |
313 | next = Fcar (list); |
314 | list = Fcdr (list); | |
350bce56 | 315 | /* Exit inner loop at undo boundary. */ |
265a9e55 | 316 | if (NILP (next)) |
c6953be1 | 317 | break; |
350bce56 RS |
318 | /* Handle an integer by setting point to that value. */ |
319 | if (XTYPE (next) == Lisp_Int) | |
320 | SET_PT (clip_to_bounds (BEGV, XINT (next), ZV)); | |
321 | else if (XTYPE (next) == Lisp_Cons) | |
c6953be1 | 322 | { |
350bce56 RS |
323 | Lisp_Object car, cdr; |
324 | ||
325 | car = Fcar (next); | |
326 | cdr = Fcdr (next); | |
327 | if (EQ (car, Qt)) | |
c6953be1 | 328 | { |
350bce56 RS |
329 | /* Element (t high . low) records previous modtime. */ |
330 | Lisp_Object high, low; | |
331 | int mod_time; | |
332 | ||
333 | high = Fcar (cdr); | |
334 | low = Fcdr (cdr); | |
d8552b2f | 335 | mod_time = (XFASTINT (high) << 16) + XFASTINT (low); |
350bce56 RS |
336 | /* If this records an obsolete save |
337 | (not matching the actual disk file) | |
338 | then don't mark unmodified. */ | |
339 | if (mod_time != current_buffer->modtime) | |
340 | break; | |
e6dd6080 | 341 | #ifdef CLASH_DETECTION |
350bce56 | 342 | Funlock_buffer (); |
e6dd6080 | 343 | #endif /* CLASH_DETECTION */ |
350bce56 | 344 | Fset_buffer_modified_p (Qnil); |
c6953be1 | 345 | } |
d8552b2f RS |
346 | #ifdef USE_TEXT_PROPERTIES |
347 | else if (EQ (car, Qnil)) | |
da9319d5 | 348 | { |
d8552b2f | 349 | /* Element (nil prop val beg . end) is property change. */ |
da9319d5 RS |
350 | Lisp_Object beg, end, prop, val; |
351 | ||
352 | prop = Fcar (cdr); | |
353 | cdr = Fcdr (cdr); | |
354 | val = Fcar (cdr); | |
355 | cdr = Fcdr (cdr); | |
356 | beg = Fcar (cdr); | |
357 | end = Fcdr (cdr); | |
358 | ||
359 | Fput_text_property (beg, end, prop, val, Qnil); | |
360 | } | |
d8552b2f | 361 | #endif /* USE_TEXT_PROPERTIES */ |
350bce56 | 362 | else if (XTYPE (car) == Lisp_Int && XTYPE (cdr) == Lisp_Int) |
c6953be1 | 363 | { |
350bce56 RS |
364 | /* Element (BEG . END) means range was inserted. */ |
365 | Lisp_Object end; | |
366 | ||
367 | if (XINT (car) < BEGV | |
368 | || XINT (cdr) > ZV) | |
c6953be1 | 369 | error ("Changes to be undone are outside visible portion of buffer"); |
f28f04cc RS |
370 | /* Set point first thing, so that undoing this undo |
371 | does not send point back to where it is now. */ | |
350bce56 | 372 | Fgoto_char (car); |
f28f04cc | 373 | Fdelete_region (car, cdr); |
350bce56 RS |
374 | } |
375 | else if (XTYPE (car) == Lisp_String && XTYPE (cdr) == Lisp_Int) | |
376 | { | |
377 | /* Element (STRING . POS) means STRING was deleted. */ | |
378 | Lisp_Object membuf; | |
379 | int pos = XINT (cdr); | |
380 | ||
381 | membuf = car; | |
382 | if (pos < 0) | |
383 | { | |
384 | if (-pos < BEGV || -pos > ZV) | |
385 | error ("Changes to be undone are outside visible portion of buffer"); | |
386 | SET_PT (-pos); | |
387 | Finsert (1, &membuf); | |
388 | } | |
389 | else | |
390 | { | |
391 | if (pos < BEGV || pos > ZV) | |
392 | error ("Changes to be undone are outside visible portion of buffer"); | |
393 | SET_PT (pos); | |
394 | ||
395 | /* Insert before markers so that if the mark is | |
396 | currently on the boundary of this deletion, it | |
397 | ends up on the other side of the now-undeleted | |
398 | text from point. Since undo doesn't even keep | |
399 | track of the mark, this isn't really necessary, | |
400 | but it may lead to better behavior in certain | |
401 | situations. */ | |
402 | Finsert_before_markers (1, &membuf); | |
403 | SET_PT (pos); | |
404 | } | |
c6953be1 JB |
405 | } |
406 | } | |
407 | } | |
408 | arg--; | |
409 | } | |
410 | ||
f87a68b3 | 411 | return unbind_to (count, list); |
c6953be1 JB |
412 | } |
413 | ||
414 | syms_of_undo () | |
415 | { | |
f87a68b3 RS |
416 | Qinhibit_read_only = intern ("inhibit-read-only"); |
417 | staticpro (&Qinhibit_read_only); | |
418 | ||
c6953be1 JB |
419 | defsubr (&Sprimitive_undo); |
420 | defsubr (&Sundo_boundary); | |
421 | } |