| 1 | /* undo handling for GNU Emacs. |
| 2 | Copyright (C) 1990, 1993, 1994 Free Software Foundation, Inc. |
| 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 | #include "commands.h" |
| 26 | |
| 27 | /* Last buffer for which undo information was recorded. */ |
| 28 | Lisp_Object last_undo_buffer; |
| 29 | |
| 30 | Lisp_Object Qinhibit_read_only; |
| 31 | |
| 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 | |
| 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 | int beg, length; |
| 46 | { |
| 47 | Lisp_Object lbeg, lend; |
| 48 | |
| 49 | if (EQ (current_buffer->undo_list, Qt)) |
| 50 | return; |
| 51 | |
| 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 | |
| 56 | if (current_buffer != XBUFFER (last_undo_buffer)) |
| 57 | Fundo_boundary (); |
| 58 | XSETBUFFER (last_undo_buffer, current_buffer); |
| 59 | |
| 60 | if (MODIFF <= SAVE_MODIFF) |
| 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 (CONSP (current_buffer->undo_list)) |
| 66 | { |
| 67 | Lisp_Object elt; |
| 68 | elt = XCONS (current_buffer->undo_list)->car; |
| 69 | if (CONSP (elt) |
| 70 | && INTEGERP (XCONS (elt)->car) |
| 71 | && INTEGERP (XCONS (elt)->cdr) |
| 72 | && XINT (XCONS (elt)->cdr) == beg) |
| 73 | { |
| 74 | XSETINT (XCONS (elt)->cdr, beg + length); |
| 75 | return; |
| 76 | } |
| 77 | } |
| 78 | |
| 79 | XSETFASTINT (lbeg, beg); |
| 80 | XSETINT (lend, beg + length); |
| 81 | current_buffer->undo_list = Fcons (Fcons (lbeg, lend), |
| 82 | current_buffer->undo_list); |
| 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; |
| 92 | int at_boundary; |
| 93 | |
| 94 | if (EQ (current_buffer->undo_list, Qt)) |
| 95 | return; |
| 96 | |
| 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 | |
| 101 | if (current_buffer != XBUFFER (last_undo_buffer)) |
| 102 | Fundo_boundary (); |
| 103 | XSETBUFFER (last_undo_buffer, current_buffer); |
| 104 | |
| 105 | at_boundary = (CONSP (current_buffer->undo_list) |
| 106 | && NILP (XCONS (current_buffer->undo_list)->car)); |
| 107 | |
| 108 | if (MODIFF <= SAVE_MODIFF) |
| 109 | record_first_change (); |
| 110 | |
| 111 | if (point == beg + length) |
| 112 | XSETINT (sbeg, -beg); |
| 113 | else |
| 114 | XSETFASTINT (sbeg, beg); |
| 115 | XSETFASTINT (lbeg, beg); |
| 116 | XSETFASTINT (lend, beg + length); |
| 117 | |
| 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)) |
| 123 | current_buffer->undo_list |
| 124 | = Fcons (make_number (last_point_position), current_buffer->undo_list); |
| 125 | |
| 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; |
| 149 | struct buffer *base_buffer = current_buffer; |
| 150 | |
| 151 | if (EQ (current_buffer->undo_list, Qt)) |
| 152 | return; |
| 153 | |
| 154 | if (current_buffer != XBUFFER (last_undo_buffer)) |
| 155 | Fundo_boundary (); |
| 156 | XSETBUFFER (last_undo_buffer, current_buffer); |
| 157 | |
| 158 | if (base_buffer->base_buffer) |
| 159 | base_buffer = base_buffer->base_buffer; |
| 160 | |
| 161 | XSETFASTINT (high, (base_buffer->modtime >> 16) & 0xffff); |
| 162 | XSETFASTINT (low, base_buffer->modtime & 0xffff); |
| 163 | current_buffer->undo_list = Fcons (Fcons (Qt, Fcons (high, low)), current_buffer->undo_list); |
| 164 | } |
| 165 | |
| 166 | /* Record a change in property PROP (whose old value was VAL) |
| 167 | for LENGTH characters starting at position BEG in BUFFER. */ |
| 168 | |
| 169 | record_property_change (beg, length, prop, value, buffer) |
| 170 | int beg, length; |
| 171 | Lisp_Object prop, value, buffer; |
| 172 | { |
| 173 | Lisp_Object lbeg, lend, entry; |
| 174 | struct buffer *obuf = current_buffer; |
| 175 | int boundary = 0; |
| 176 | |
| 177 | if (EQ (XBUFFER (buffer)->undo_list, Qt)) |
| 178 | return; |
| 179 | |
| 180 | /* Allocate a cons cell to be the undo boundary after this command. */ |
| 181 | if (NILP (pending_boundary)) |
| 182 | pending_boundary = Fcons (Qnil, Qnil); |
| 183 | |
| 184 | if (!EQ (buffer, last_undo_buffer)) |
| 185 | boundary = 1; |
| 186 | last_undo_buffer = buffer; |
| 187 | |
| 188 | /* Switch temporarily to the buffer that was changed. */ |
| 189 | current_buffer = XBUFFER (buffer); |
| 190 | |
| 191 | if (boundary) |
| 192 | Fundo_boundary (); |
| 193 | |
| 194 | if (MODIFF <= SAVE_MODIFF) |
| 195 | record_first_change (); |
| 196 | |
| 197 | XSETINT (lbeg, beg); |
| 198 | XSETINT (lend, beg + length); |
| 199 | entry = Fcons (Qnil, Fcons (prop, Fcons (value, Fcons (lbeg, lend)))); |
| 200 | current_buffer->undo_list = Fcons (entry, current_buffer->undo_list); |
| 201 | |
| 202 | current_buffer = obuf; |
| 203 | } |
| 204 | |
| 205 | DEFUN ("undo-boundary", Fundo_boundary, Sundo_boundary, 0, 0, 0, |
| 206 | "Mark a boundary between units of undo.\n\ |
| 207 | An undo command will stop at this point,\n\ |
| 208 | but another undo command will undo to the previous boundary.") |
| 209 | () |
| 210 | { |
| 211 | Lisp_Object tem; |
| 212 | if (EQ (current_buffer->undo_list, Qt)) |
| 213 | return Qnil; |
| 214 | tem = Fcar (current_buffer->undo_list); |
| 215 | if (!NILP (tem)) |
| 216 | { |
| 217 | /* One way or another, cons nil onto the front of the undo list. */ |
| 218 | if (!NILP (pending_boundary)) |
| 219 | { |
| 220 | /* If we have preallocated the cons cell to use here, |
| 221 | use that one. */ |
| 222 | XCONS (pending_boundary)->cdr = current_buffer->undo_list; |
| 223 | current_buffer->undo_list = pending_boundary; |
| 224 | pending_boundary = Qnil; |
| 225 | } |
| 226 | else |
| 227 | current_buffer->undo_list = Fcons (Qnil, current_buffer->undo_list); |
| 228 | } |
| 229 | return Qnil; |
| 230 | } |
| 231 | |
| 232 | /* At garbage collection time, make an undo list shorter at the end, |
| 233 | returning the truncated list. |
| 234 | MINSIZE and MAXSIZE are the limits on size allowed, as described below. |
| 235 | In practice, these are the values of undo-limit and |
| 236 | undo-strong-limit. */ |
| 237 | |
| 238 | Lisp_Object |
| 239 | truncate_undo_list (list, minsize, maxsize) |
| 240 | Lisp_Object list; |
| 241 | int minsize, maxsize; |
| 242 | { |
| 243 | Lisp_Object prev, next, last_boundary; |
| 244 | int size_so_far = 0; |
| 245 | |
| 246 | prev = Qnil; |
| 247 | next = list; |
| 248 | last_boundary = Qnil; |
| 249 | |
| 250 | /* Always preserve at least the most recent undo record. |
| 251 | If the first element is an undo boundary, skip past it. |
| 252 | |
| 253 | Skip, skip, skip the undo, skip, skip, skip the undo, |
| 254 | Skip, skip, skip the undo, skip to the undo bound'ry. |
| 255 | (Get it? "Skip to my Loo?") */ |
| 256 | if (CONSP (next) && NILP (XCONS (next)->car)) |
| 257 | { |
| 258 | /* Add in the space occupied by this element and its chain link. */ |
| 259 | size_so_far += sizeof (struct Lisp_Cons); |
| 260 | |
| 261 | /* Advance to next element. */ |
| 262 | prev = next; |
| 263 | next = XCONS (next)->cdr; |
| 264 | } |
| 265 | while (CONSP (next) && ! NILP (XCONS (next)->car)) |
| 266 | { |
| 267 | Lisp_Object elt; |
| 268 | elt = XCONS (next)->car; |
| 269 | |
| 270 | /* Add in the space occupied by this element and its chain link. */ |
| 271 | size_so_far += sizeof (struct Lisp_Cons); |
| 272 | if (CONSP (elt)) |
| 273 | { |
| 274 | size_so_far += sizeof (struct Lisp_Cons); |
| 275 | if (STRINGP (XCONS (elt)->car)) |
| 276 | size_so_far += (sizeof (struct Lisp_String) - 1 |
| 277 | + XSTRING (XCONS (elt)->car)->size); |
| 278 | } |
| 279 | |
| 280 | /* Advance to next element. */ |
| 281 | prev = next; |
| 282 | next = XCONS (next)->cdr; |
| 283 | } |
| 284 | if (CONSP (next)) |
| 285 | last_boundary = prev; |
| 286 | |
| 287 | while (CONSP (next)) |
| 288 | { |
| 289 | Lisp_Object elt; |
| 290 | elt = XCONS (next)->car; |
| 291 | |
| 292 | /* When we get to a boundary, decide whether to truncate |
| 293 | either before or after it. The lower threshold, MINSIZE, |
| 294 | tells us to truncate after it. If its size pushes past |
| 295 | the higher threshold MAXSIZE as well, we truncate before it. */ |
| 296 | if (NILP (elt)) |
| 297 | { |
| 298 | if (size_so_far > maxsize) |
| 299 | break; |
| 300 | last_boundary = prev; |
| 301 | if (size_so_far > minsize) |
| 302 | break; |
| 303 | } |
| 304 | |
| 305 | /* Add in the space occupied by this element and its chain link. */ |
| 306 | size_so_far += sizeof (struct Lisp_Cons); |
| 307 | if (CONSP (elt)) |
| 308 | { |
| 309 | size_so_far += sizeof (struct Lisp_Cons); |
| 310 | if (STRINGP (XCONS (elt)->car)) |
| 311 | size_so_far += (sizeof (struct Lisp_String) - 1 |
| 312 | + XSTRING (XCONS (elt)->car)->size); |
| 313 | } |
| 314 | |
| 315 | /* Advance to next element. */ |
| 316 | prev = next; |
| 317 | next = XCONS (next)->cdr; |
| 318 | } |
| 319 | |
| 320 | /* If we scanned the whole list, it is short enough; don't change it. */ |
| 321 | if (NILP (next)) |
| 322 | return list; |
| 323 | |
| 324 | /* Truncate at the boundary where we decided to truncate. */ |
| 325 | if (!NILP (last_boundary)) |
| 326 | { |
| 327 | XCONS (last_boundary)->cdr = Qnil; |
| 328 | return list; |
| 329 | } |
| 330 | else |
| 331 | return Qnil; |
| 332 | } |
| 333 | \f |
| 334 | DEFUN ("primitive-undo", Fprimitive_undo, Sprimitive_undo, 2, 2, 0, |
| 335 | "Undo N records from the front of the list LIST.\n\ |
| 336 | Return what remains of the list.") |
| 337 | (n, list) |
| 338 | Lisp_Object n, list; |
| 339 | { |
| 340 | struct gcpro gcpro1, gcpro2; |
| 341 | Lisp_Object next; |
| 342 | int count = specpdl_ptr - specpdl; |
| 343 | register int arg; |
| 344 | #if 0 /* This is a good feature, but would make undo-start |
| 345 | unable to do what is expected. */ |
| 346 | Lisp_Object tem; |
| 347 | |
| 348 | /* If the head of the list is a boundary, it is the boundary |
| 349 | preceding this command. Get rid of it and don't count it. */ |
| 350 | tem = Fcar (list); |
| 351 | if (NILP (tem)) |
| 352 | list = Fcdr (list); |
| 353 | #endif |
| 354 | |
| 355 | CHECK_NUMBER (n, 0); |
| 356 | arg = XINT (n); |
| 357 | next = Qnil; |
| 358 | GCPRO2 (next, list); |
| 359 | |
| 360 | /* Don't let read-only properties interfere with undo. */ |
| 361 | if (NILP (current_buffer->read_only)) |
| 362 | specbind (Qinhibit_read_only, Qt); |
| 363 | |
| 364 | while (arg > 0) |
| 365 | { |
| 366 | while (1) |
| 367 | { |
| 368 | next = Fcar (list); |
| 369 | list = Fcdr (list); |
| 370 | /* Exit inner loop at undo boundary. */ |
| 371 | if (NILP (next)) |
| 372 | break; |
| 373 | /* Handle an integer by setting point to that value. */ |
| 374 | if (INTEGERP (next)) |
| 375 | SET_PT (clip_to_bounds (BEGV, XINT (next), ZV)); |
| 376 | else if (CONSP (next)) |
| 377 | { |
| 378 | Lisp_Object car, cdr; |
| 379 | |
| 380 | car = Fcar (next); |
| 381 | cdr = Fcdr (next); |
| 382 | if (EQ (car, Qt)) |
| 383 | { |
| 384 | /* Element (t high . low) records previous modtime. */ |
| 385 | Lisp_Object high, low; |
| 386 | int mod_time; |
| 387 | struct buffer *base_buffer = current_buffer; |
| 388 | |
| 389 | high = Fcar (cdr); |
| 390 | low = Fcdr (cdr); |
| 391 | mod_time = (XFASTINT (high) << 16) + XFASTINT (low); |
| 392 | |
| 393 | if (current_buffer->base_buffer) |
| 394 | base_buffer = current_buffer->base_buffer; |
| 395 | |
| 396 | /* If this records an obsolete save |
| 397 | (not matching the actual disk file) |
| 398 | then don't mark unmodified. */ |
| 399 | if (mod_time != base_buffer->modtime) |
| 400 | continue; |
| 401 | #ifdef CLASH_DETECTION |
| 402 | Funlock_buffer (); |
| 403 | #endif /* CLASH_DETECTION */ |
| 404 | Fset_buffer_modified_p (Qnil); |
| 405 | } |
| 406 | #ifdef USE_TEXT_PROPERTIES |
| 407 | else if (EQ (car, Qnil)) |
| 408 | { |
| 409 | /* Element (nil prop val beg . end) is property change. */ |
| 410 | Lisp_Object beg, end, prop, val; |
| 411 | |
| 412 | prop = Fcar (cdr); |
| 413 | cdr = Fcdr (cdr); |
| 414 | val = Fcar (cdr); |
| 415 | cdr = Fcdr (cdr); |
| 416 | beg = Fcar (cdr); |
| 417 | end = Fcdr (cdr); |
| 418 | |
| 419 | Fput_text_property (beg, end, prop, val, Qnil); |
| 420 | } |
| 421 | #endif /* USE_TEXT_PROPERTIES */ |
| 422 | else if (INTEGERP (car) && INTEGERP (cdr)) |
| 423 | { |
| 424 | /* Element (BEG . END) means range was inserted. */ |
| 425 | Lisp_Object end; |
| 426 | |
| 427 | if (XINT (car) < BEGV |
| 428 | || XINT (cdr) > ZV) |
| 429 | error ("Changes to be undone are outside visible portion of buffer"); |
| 430 | /* Set point first thing, so that undoing this undo |
| 431 | does not send point back to where it is now. */ |
| 432 | Fgoto_char (car); |
| 433 | Fdelete_region (car, cdr); |
| 434 | } |
| 435 | else if (STRINGP (car) && INTEGERP (cdr)) |
| 436 | { |
| 437 | /* Element (STRING . POS) means STRING was deleted. */ |
| 438 | Lisp_Object membuf; |
| 439 | int pos = XINT (cdr); |
| 440 | |
| 441 | membuf = car; |
| 442 | if (pos < 0) |
| 443 | { |
| 444 | if (-pos < BEGV || -pos > ZV) |
| 445 | error ("Changes to be undone are outside visible portion of buffer"); |
| 446 | SET_PT (-pos); |
| 447 | Finsert (1, &membuf); |
| 448 | } |
| 449 | else |
| 450 | { |
| 451 | if (pos < BEGV || pos > ZV) |
| 452 | error ("Changes to be undone are outside visible portion of buffer"); |
| 453 | SET_PT (pos); |
| 454 | |
| 455 | /* Insert before markers so that if the mark is |
| 456 | currently on the boundary of this deletion, it |
| 457 | ends up on the other side of the now-undeleted |
| 458 | text from point. Since undo doesn't even keep |
| 459 | track of the mark, this isn't really necessary, |
| 460 | but it may lead to better behavior in certain |
| 461 | situations. */ |
| 462 | Finsert_before_markers (1, &membuf); |
| 463 | SET_PT (pos); |
| 464 | } |
| 465 | } |
| 466 | } |
| 467 | } |
| 468 | arg--; |
| 469 | } |
| 470 | |
| 471 | UNGCPRO; |
| 472 | return unbind_to (count, list); |
| 473 | } |
| 474 | |
| 475 | syms_of_undo () |
| 476 | { |
| 477 | Qinhibit_read_only = intern ("inhibit-read-only"); |
| 478 | staticpro (&Qinhibit_read_only); |
| 479 | |
| 480 | pending_boundary = Qnil; |
| 481 | staticpro (&pending_boundary); |
| 482 | |
| 483 | defsubr (&Sprimitive_undo); |
| 484 | defsubr (&Sundo_boundary); |
| 485 | } |