| 1 | /* undo handling for GNU Emacs. |
| 2 | Copyright (C) 1990, 1993, 1994, 2000, 2001, 2002, 2003, 2004, |
| 3 | 2005, 2006, 2007 Free Software Foundation, Inc. |
| 4 | |
| 5 | This file is part of GNU Emacs. |
| 6 | |
| 7 | GNU Emacs is free software; you can redistribute it and/or modify |
| 8 | it under the terms of the GNU General Public License as published by |
| 9 | the Free Software Foundation; either version 2, or (at your option) |
| 10 | any later version. |
| 11 | |
| 12 | GNU Emacs is distributed in the hope that it will be useful, |
| 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 |
| 18 | along with GNU Emacs; see the file COPYING. If not, write to |
| 19 | the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, |
| 20 | Boston, MA 02110-1301, USA. */ |
| 21 | |
| 22 | |
| 23 | #include <config.h> |
| 24 | #include "lisp.h" |
| 25 | #include "buffer.h" |
| 26 | #include "commands.h" |
| 27 | #include "window.h" |
| 28 | |
| 29 | /* Limits controlling how much undo information to keep. */ |
| 30 | |
| 31 | EMACS_INT undo_limit; |
| 32 | EMACS_INT undo_strong_limit; |
| 33 | |
| 34 | Lisp_Object Vundo_outer_limit; |
| 35 | |
| 36 | /* Function to call when undo_outer_limit is exceeded. */ |
| 37 | |
| 38 | Lisp_Object Vundo_outer_limit_function; |
| 39 | |
| 40 | /* Last buffer for which undo information was recorded. */ |
| 41 | Lisp_Object last_undo_buffer; |
| 42 | |
| 43 | Lisp_Object Qinhibit_read_only; |
| 44 | |
| 45 | /* Marker for function call undo list elements. */ |
| 46 | |
| 47 | Lisp_Object Qapply; |
| 48 | |
| 49 | /* The first time a command records something for undo. |
| 50 | it also allocates the undo-boundary object |
| 51 | which will be added to the list at the end of the command. |
| 52 | This ensures we can't run out of space while trying to make |
| 53 | an undo-boundary. */ |
| 54 | Lisp_Object pending_boundary; |
| 55 | |
| 56 | /* Record point as it was at beginning of this command (if necessary) |
| 57 | And prepare the undo info for recording a change. |
| 58 | PT is the position of point that will naturally occur as a result of the |
| 59 | undo record that will be added just after this command terminates. */ |
| 60 | |
| 61 | static void |
| 62 | record_point (pt) |
| 63 | int pt; |
| 64 | { |
| 65 | int at_boundary; |
| 66 | |
| 67 | /* Allocate a cons cell to be the undo boundary after this command. */ |
| 68 | if (NILP (pending_boundary)) |
| 69 | pending_boundary = Fcons (Qnil, Qnil); |
| 70 | |
| 71 | if (!BUFFERP (last_undo_buffer) |
| 72 | || current_buffer != XBUFFER (last_undo_buffer)) |
| 73 | Fundo_boundary (); |
| 74 | XSETBUFFER (last_undo_buffer, current_buffer); |
| 75 | |
| 76 | if (CONSP (current_buffer->undo_list)) |
| 77 | { |
| 78 | /* Set AT_BOUNDARY to 1 only when we have nothing other than |
| 79 | marker adjustment before undo boundary. */ |
| 80 | |
| 81 | Lisp_Object tail = current_buffer->undo_list, elt; |
| 82 | |
| 83 | while (1) |
| 84 | { |
| 85 | if (NILP (tail)) |
| 86 | elt = Qnil; |
| 87 | else |
| 88 | elt = XCAR (tail); |
| 89 | if (NILP (elt) || ! (CONSP (elt) && MARKERP (XCAR (elt)))) |
| 90 | break; |
| 91 | tail = XCDR (tail); |
| 92 | } |
| 93 | at_boundary = NILP (elt); |
| 94 | } |
| 95 | else |
| 96 | at_boundary = 1; |
| 97 | |
| 98 | if (MODIFF <= SAVE_MODIFF) |
| 99 | record_first_change (); |
| 100 | |
| 101 | /* If we are just after an undo boundary, and |
| 102 | point wasn't at start of deleted range, record where it was. */ |
| 103 | if (at_boundary |
| 104 | && BUFFERP (last_point_position_buffer) |
| 105 | /* If we're called from batch mode, this could be nil. */ |
| 106 | && current_buffer == XBUFFER (last_point_position_buffer)) |
| 107 | { |
| 108 | /* If we have switched windows, use the point value |
| 109 | from the window we are in. */ |
| 110 | if (! EQ (last_point_position_window, selected_window)) |
| 111 | last_point_position = marker_position (XWINDOW (selected_window)->pointm); |
| 112 | |
| 113 | if (last_point_position != pt) |
| 114 | current_buffer->undo_list |
| 115 | = Fcons (make_number (last_point_position), current_buffer->undo_list); |
| 116 | } |
| 117 | } |
| 118 | |
| 119 | /* Record an insertion that just happened or is about to happen, |
| 120 | for LENGTH characters at position BEG. |
| 121 | (It is possible to record an insertion before or after the fact |
| 122 | because we don't need to record the contents.) */ |
| 123 | |
| 124 | void |
| 125 | record_insert (beg, length) |
| 126 | int beg, length; |
| 127 | { |
| 128 | Lisp_Object lbeg, lend; |
| 129 | |
| 130 | if (EQ (current_buffer->undo_list, Qt)) |
| 131 | return; |
| 132 | |
| 133 | record_point (beg); |
| 134 | |
| 135 | /* If this is following another insertion and consecutive with it |
| 136 | in the buffer, combine the two. */ |
| 137 | if (CONSP (current_buffer->undo_list)) |
| 138 | { |
| 139 | Lisp_Object elt; |
| 140 | elt = XCAR (current_buffer->undo_list); |
| 141 | if (CONSP (elt) |
| 142 | && INTEGERP (XCAR (elt)) |
| 143 | && INTEGERP (XCDR (elt)) |
| 144 | && XINT (XCDR (elt)) == beg) |
| 145 | { |
| 146 | XSETCDR (elt, make_number (beg + length)); |
| 147 | return; |
| 148 | } |
| 149 | } |
| 150 | |
| 151 | XSETFASTINT (lbeg, beg); |
| 152 | XSETINT (lend, beg + length); |
| 153 | current_buffer->undo_list = Fcons (Fcons (lbeg, lend), |
| 154 | current_buffer->undo_list); |
| 155 | } |
| 156 | |
| 157 | /* Record that a deletion is about to take place, |
| 158 | of the characters in STRING, at location BEG. */ |
| 159 | |
| 160 | void |
| 161 | record_delete (beg, string) |
| 162 | int beg; |
| 163 | Lisp_Object string; |
| 164 | { |
| 165 | Lisp_Object sbeg; |
| 166 | |
| 167 | if (EQ (current_buffer->undo_list, Qt)) |
| 168 | return; |
| 169 | |
| 170 | if (PT == beg + SCHARS (string)) |
| 171 | { |
| 172 | XSETINT (sbeg, -beg); |
| 173 | record_point (PT); |
| 174 | } |
| 175 | else |
| 176 | { |
| 177 | XSETFASTINT (sbeg, beg); |
| 178 | record_point (beg); |
| 179 | } |
| 180 | |
| 181 | current_buffer->undo_list |
| 182 | = Fcons (Fcons (string, sbeg), current_buffer->undo_list); |
| 183 | } |
| 184 | |
| 185 | /* Record the fact that MARKER is about to be adjusted by ADJUSTMENT. |
| 186 | This is done only when a marker points within text being deleted, |
| 187 | because that's the only case where an automatic marker adjustment |
| 188 | won't be inverted automatically by undoing the buffer modification. */ |
| 189 | |
| 190 | void |
| 191 | record_marker_adjustment (marker, adjustment) |
| 192 | Lisp_Object marker; |
| 193 | int adjustment; |
| 194 | { |
| 195 | if (EQ (current_buffer->undo_list, Qt)) |
| 196 | return; |
| 197 | |
| 198 | /* Allocate a cons cell to be the undo boundary after this command. */ |
| 199 | if (NILP (pending_boundary)) |
| 200 | pending_boundary = Fcons (Qnil, Qnil); |
| 201 | |
| 202 | if (!BUFFERP (last_undo_buffer) |
| 203 | || current_buffer != XBUFFER (last_undo_buffer)) |
| 204 | Fundo_boundary (); |
| 205 | XSETBUFFER (last_undo_buffer, current_buffer); |
| 206 | |
| 207 | current_buffer->undo_list |
| 208 | = Fcons (Fcons (marker, make_number (adjustment)), |
| 209 | current_buffer->undo_list); |
| 210 | } |
| 211 | |
| 212 | /* Record that a replacement is about to take place, |
| 213 | for LENGTH characters at location BEG. |
| 214 | The replacement must not change the number of characters. */ |
| 215 | |
| 216 | void |
| 217 | record_change (beg, length) |
| 218 | int beg, length; |
| 219 | { |
| 220 | record_delete (beg, make_buffer_string (beg, beg + length, 1)); |
| 221 | record_insert (beg, length); |
| 222 | } |
| 223 | \f |
| 224 | /* Record that an unmodified buffer is about to be changed. |
| 225 | Record the file modification date so that when undoing this entry |
| 226 | we can tell whether it is obsolete because the file was saved again. */ |
| 227 | |
| 228 | void |
| 229 | record_first_change () |
| 230 | { |
| 231 | Lisp_Object high, low; |
| 232 | struct buffer *base_buffer = current_buffer; |
| 233 | |
| 234 | if (EQ (current_buffer->undo_list, Qt)) |
| 235 | return; |
| 236 | |
| 237 | if (!BUFFERP (last_undo_buffer) |
| 238 | || current_buffer != XBUFFER (last_undo_buffer)) |
| 239 | Fundo_boundary (); |
| 240 | XSETBUFFER (last_undo_buffer, current_buffer); |
| 241 | |
| 242 | if (base_buffer->base_buffer) |
| 243 | base_buffer = base_buffer->base_buffer; |
| 244 | |
| 245 | XSETFASTINT (high, (base_buffer->modtime >> 16) & 0xffff); |
| 246 | XSETFASTINT (low, base_buffer->modtime & 0xffff); |
| 247 | current_buffer->undo_list = Fcons (Fcons (Qt, Fcons (high, low)), current_buffer->undo_list); |
| 248 | } |
| 249 | |
| 250 | /* Record a change in property PROP (whose old value was VAL) |
| 251 | for LENGTH characters starting at position BEG in BUFFER. */ |
| 252 | |
| 253 | void |
| 254 | record_property_change (beg, length, prop, value, buffer) |
| 255 | int beg, length; |
| 256 | Lisp_Object prop, value, buffer; |
| 257 | { |
| 258 | Lisp_Object lbeg, lend, entry; |
| 259 | struct buffer *obuf = current_buffer; |
| 260 | int boundary = 0; |
| 261 | |
| 262 | if (EQ (XBUFFER (buffer)->undo_list, Qt)) |
| 263 | return; |
| 264 | |
| 265 | /* Allocate a cons cell to be the undo boundary after this command. */ |
| 266 | if (NILP (pending_boundary)) |
| 267 | pending_boundary = Fcons (Qnil, Qnil); |
| 268 | |
| 269 | if (!EQ (buffer, last_undo_buffer)) |
| 270 | boundary = 1; |
| 271 | last_undo_buffer = buffer; |
| 272 | |
| 273 | /* Switch temporarily to the buffer that was changed. */ |
| 274 | current_buffer = XBUFFER (buffer); |
| 275 | |
| 276 | if (boundary) |
| 277 | Fundo_boundary (); |
| 278 | |
| 279 | if (MODIFF <= SAVE_MODIFF) |
| 280 | record_first_change (); |
| 281 | |
| 282 | XSETINT (lbeg, beg); |
| 283 | XSETINT (lend, beg + length); |
| 284 | entry = Fcons (Qnil, Fcons (prop, Fcons (value, Fcons (lbeg, lend)))); |
| 285 | current_buffer->undo_list = Fcons (entry, current_buffer->undo_list); |
| 286 | |
| 287 | current_buffer = obuf; |
| 288 | } |
| 289 | |
| 290 | DEFUN ("undo-boundary", Fundo_boundary, Sundo_boundary, 0, 0, 0, |
| 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. */) |
| 294 | () |
| 295 | { |
| 296 | Lisp_Object tem; |
| 297 | if (EQ (current_buffer->undo_list, Qt)) |
| 298 | return Qnil; |
| 299 | tem = Fcar (current_buffer->undo_list); |
| 300 | if (!NILP (tem)) |
| 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. */ |
| 307 | XSETCDR (pending_boundary, current_buffer->undo_list); |
| 308 | current_buffer->undo_list = pending_boundary; |
| 309 | pending_boundary = Qnil; |
| 310 | } |
| 311 | else |
| 312 | current_buffer->undo_list = Fcons (Qnil, current_buffer->undo_list); |
| 313 | } |
| 314 | return Qnil; |
| 315 | } |
| 316 | |
| 317 | /* At garbage collection time, make an undo list shorter at the end, |
| 318 | returning the truncated list. How this is done depends on the |
| 319 | variables undo-limit, undo-strong-limit and undo-outer-limit. |
| 320 | In some cases this works by calling undo-outer-limit-function. */ |
| 321 | |
| 322 | void |
| 323 | truncate_undo_list (b) |
| 324 | struct buffer *b; |
| 325 | { |
| 326 | Lisp_Object list; |
| 327 | Lisp_Object prev, next, last_boundary; |
| 328 | int size_so_far = 0; |
| 329 | |
| 330 | /* Make sure that calling undo-outer-limit-function |
| 331 | won't cause another GC. */ |
| 332 | int count = inhibit_garbage_collection (); |
| 333 | |
| 334 | /* Make the buffer current to get its local values of variables such |
| 335 | as undo_limit. Also so that Vundo_outer_limit_function can |
| 336 | tell which buffer to operate on. */ |
| 337 | record_unwind_protect (set_buffer_if_live, Fcurrent_buffer ()); |
| 338 | set_buffer_internal (b); |
| 339 | |
| 340 | list = b->undo_list; |
| 341 | |
| 342 | prev = Qnil; |
| 343 | next = list; |
| 344 | last_boundary = Qnil; |
| 345 | |
| 346 | /* If the first element is an undo boundary, skip past it. */ |
| 347 | if (CONSP (next) && NILP (XCAR (next))) |
| 348 | { |
| 349 | /* Add in the space occupied by this element and its chain link. */ |
| 350 | size_so_far += sizeof (struct Lisp_Cons); |
| 351 | |
| 352 | /* Advance to next element. */ |
| 353 | prev = next; |
| 354 | next = XCDR (next); |
| 355 | } |
| 356 | |
| 357 | /* Always preserve at least the most recent undo record |
| 358 | unless it is really horribly big. |
| 359 | |
| 360 | Skip, skip, skip the undo, skip, skip, skip the undo, |
| 361 | Skip, skip, skip the undo, skip to the undo bound'ry. */ |
| 362 | |
| 363 | while (CONSP (next) && ! NILP (XCAR (next))) |
| 364 | { |
| 365 | Lisp_Object elt; |
| 366 | elt = XCAR (next); |
| 367 | |
| 368 | /* Add in the space occupied by this element and its chain link. */ |
| 369 | size_so_far += sizeof (struct Lisp_Cons); |
| 370 | if (CONSP (elt)) |
| 371 | { |
| 372 | size_so_far += sizeof (struct Lisp_Cons); |
| 373 | if (STRINGP (XCAR (elt))) |
| 374 | size_so_far += (sizeof (struct Lisp_String) - 1 |
| 375 | + SCHARS (XCAR (elt))); |
| 376 | } |
| 377 | |
| 378 | /* Advance to next element. */ |
| 379 | prev = next; |
| 380 | next = XCDR (next); |
| 381 | } |
| 382 | |
| 383 | /* If by the first boundary we have already passed undo_outer_limit, |
| 384 | we're heading for memory full, so offer to clear out the list. */ |
| 385 | if (INTEGERP (Vundo_outer_limit) |
| 386 | && size_so_far > XINT (Vundo_outer_limit) |
| 387 | && !NILP (Vundo_outer_limit_function)) |
| 388 | { |
| 389 | Lisp_Object temp = last_undo_buffer, tem; |
| 390 | |
| 391 | /* Normally the function this calls is undo-outer-limit-truncate. */ |
| 392 | tem = call1 (Vundo_outer_limit_function, make_number (size_so_far)); |
| 393 | if (! NILP (tem)) |
| 394 | { |
| 395 | /* The function is responsible for making |
| 396 | any desired changes in buffer-undo-list. */ |
| 397 | unbind_to (count, Qnil); |
| 398 | return; |
| 399 | } |
| 400 | /* That function probably used the minibuffer, and if so, that |
| 401 | changed last_undo_buffer. Change it back so that we don't |
| 402 | force next change to make an undo boundary here. */ |
| 403 | last_undo_buffer = temp; |
| 404 | } |
| 405 | |
| 406 | if (CONSP (next)) |
| 407 | last_boundary = prev; |
| 408 | |
| 409 | /* Keep additional undo data, if it fits in the limits. */ |
| 410 | while (CONSP (next)) |
| 411 | { |
| 412 | Lisp_Object elt; |
| 413 | elt = XCAR (next); |
| 414 | |
| 415 | /* When we get to a boundary, decide whether to truncate |
| 416 | either before or after it. The lower threshold, undo_limit, |
| 417 | tells us to truncate after it. If its size pushes past |
| 418 | the higher threshold undo_strong_limit, we truncate before it. */ |
| 419 | if (NILP (elt)) |
| 420 | { |
| 421 | if (size_so_far > undo_strong_limit) |
| 422 | break; |
| 423 | last_boundary = prev; |
| 424 | if (size_so_far > undo_limit) |
| 425 | break; |
| 426 | } |
| 427 | |
| 428 | /* Add in the space occupied by this element and its chain link. */ |
| 429 | size_so_far += sizeof (struct Lisp_Cons); |
| 430 | if (CONSP (elt)) |
| 431 | { |
| 432 | size_so_far += sizeof (struct Lisp_Cons); |
| 433 | if (STRINGP (XCAR (elt))) |
| 434 | size_so_far += (sizeof (struct Lisp_String) - 1 |
| 435 | + SCHARS (XCAR (elt))); |
| 436 | } |
| 437 | |
| 438 | /* Advance to next element. */ |
| 439 | prev = next; |
| 440 | next = XCDR (next); |
| 441 | } |
| 442 | |
| 443 | /* If we scanned the whole list, it is short enough; don't change it. */ |
| 444 | if (NILP (next)) |
| 445 | ; |
| 446 | /* Truncate at the boundary where we decided to truncate. */ |
| 447 | else if (!NILP (last_boundary)) |
| 448 | XSETCDR (last_boundary, Qnil); |
| 449 | /* There's nothing we decided to keep, so clear it out. */ |
| 450 | else |
| 451 | b->undo_list = Qnil; |
| 452 | |
| 453 | unbind_to (count, Qnil); |
| 454 | } |
| 455 | \f |
| 456 | DEFUN ("primitive-undo", Fprimitive_undo, Sprimitive_undo, 2, 2, 0, |
| 457 | doc: /* Undo N records from the front of the list LIST. |
| 458 | Return what remains of the list. */) |
| 459 | (n, list) |
| 460 | Lisp_Object n, list; |
| 461 | { |
| 462 | struct gcpro gcpro1, gcpro2; |
| 463 | Lisp_Object next; |
| 464 | int count = SPECPDL_INDEX (); |
| 465 | register int arg; |
| 466 | Lisp_Object oldlist; |
| 467 | int did_apply = 0; |
| 468 | |
| 469 | #if 0 /* This is a good feature, but would make undo-start |
| 470 | unable to do what is expected. */ |
| 471 | Lisp_Object tem; |
| 472 | |
| 473 | /* If the head of the list is a boundary, it is the boundary |
| 474 | preceding this command. Get rid of it and don't count it. */ |
| 475 | tem = Fcar (list); |
| 476 | if (NILP (tem)) |
| 477 | list = Fcdr (list); |
| 478 | #endif |
| 479 | |
| 480 | CHECK_NUMBER (n); |
| 481 | arg = XINT (n); |
| 482 | next = Qnil; |
| 483 | GCPRO2 (next, list); |
| 484 | /* I don't think we need to gcpro oldlist, as we use it only |
| 485 | to check for EQ. ++kfs */ |
| 486 | |
| 487 | /* In a writable buffer, enable undoing read-only text that is so |
| 488 | because of text properties. */ |
| 489 | if (NILP (current_buffer->read_only)) |
| 490 | specbind (Qinhibit_read_only, Qt); |
| 491 | |
| 492 | /* Don't let `intangible' properties interfere with undo. */ |
| 493 | specbind (Qinhibit_point_motion_hooks, Qt); |
| 494 | |
| 495 | oldlist = current_buffer->undo_list; |
| 496 | |
| 497 | while (arg > 0) |
| 498 | { |
| 499 | while (CONSP (list)) |
| 500 | { |
| 501 | next = XCAR (list); |
| 502 | list = XCDR (list); |
| 503 | /* Exit inner loop at undo boundary. */ |
| 504 | if (NILP (next)) |
| 505 | break; |
| 506 | /* Handle an integer by setting point to that value. */ |
| 507 | if (INTEGERP (next)) |
| 508 | SET_PT (clip_to_bounds (BEGV, XINT (next), ZV)); |
| 509 | else if (CONSP (next)) |
| 510 | { |
| 511 | Lisp_Object car, cdr; |
| 512 | |
| 513 | car = XCAR (next); |
| 514 | cdr = XCDR (next); |
| 515 | if (EQ (car, Qt)) |
| 516 | { |
| 517 | /* Element (t high . low) records previous modtime. */ |
| 518 | Lisp_Object high, low; |
| 519 | int mod_time; |
| 520 | struct buffer *base_buffer = current_buffer; |
| 521 | |
| 522 | high = Fcar (cdr); |
| 523 | low = Fcdr (cdr); |
| 524 | mod_time = (XFASTINT (high) << 16) + XFASTINT (low); |
| 525 | |
| 526 | if (current_buffer->base_buffer) |
| 527 | base_buffer = current_buffer->base_buffer; |
| 528 | |
| 529 | /* If this records an obsolete save |
| 530 | (not matching the actual disk file) |
| 531 | then don't mark unmodified. */ |
| 532 | if (mod_time != base_buffer->modtime) |
| 533 | continue; |
| 534 | #ifdef CLASH_DETECTION |
| 535 | Funlock_buffer (); |
| 536 | #endif /* CLASH_DETECTION */ |
| 537 | Fset_buffer_modified_p (Qnil); |
| 538 | } |
| 539 | else if (EQ (car, Qnil)) |
| 540 | { |
| 541 | /* Element (nil PROP VAL BEG . END) is property change. */ |
| 542 | Lisp_Object beg, end, prop, val; |
| 543 | |
| 544 | prop = Fcar (cdr); |
| 545 | cdr = Fcdr (cdr); |
| 546 | val = Fcar (cdr); |
| 547 | cdr = Fcdr (cdr); |
| 548 | beg = Fcar (cdr); |
| 549 | end = Fcdr (cdr); |
| 550 | |
| 551 | if (XINT (beg) < BEGV || XINT (end) > ZV) |
| 552 | error ("Changes to be undone are outside visible portion of buffer"); |
| 553 | Fput_text_property (beg, end, prop, val, Qnil); |
| 554 | } |
| 555 | else if (INTEGERP (car) && INTEGERP (cdr)) |
| 556 | { |
| 557 | /* Element (BEG . END) means range was inserted. */ |
| 558 | |
| 559 | if (XINT (car) < BEGV |
| 560 | || XINT (cdr) > ZV) |
| 561 | error ("Changes to be undone are outside visible portion of buffer"); |
| 562 | /* Set point first thing, so that undoing this undo |
| 563 | does not send point back to where it is now. */ |
| 564 | Fgoto_char (car); |
| 565 | Fdelete_region (car, cdr); |
| 566 | } |
| 567 | else if (EQ (car, Qapply)) |
| 568 | { |
| 569 | /* Element (apply FUN . ARGS) means call FUN to undo. */ |
| 570 | struct buffer *save_buffer = current_buffer; |
| 571 | |
| 572 | car = Fcar (cdr); |
| 573 | cdr = Fcdr (cdr); |
| 574 | if (INTEGERP (car)) |
| 575 | { |
| 576 | /* Long format: (apply DELTA START END FUN . ARGS). */ |
| 577 | Lisp_Object delta = car; |
| 578 | Lisp_Object start = Fcar (cdr); |
| 579 | Lisp_Object end = Fcar (Fcdr (cdr)); |
| 580 | Lisp_Object start_mark = Fcopy_marker (start, Qnil); |
| 581 | Lisp_Object end_mark = Fcopy_marker (end, Qt); |
| 582 | |
| 583 | cdr = Fcdr (Fcdr (cdr)); |
| 584 | apply1 (Fcar (cdr), Fcdr (cdr)); |
| 585 | |
| 586 | /* Check that the function did what the entry said it |
| 587 | would do. */ |
| 588 | if (!EQ (start, Fmarker_position (start_mark)) |
| 589 | || (XINT (delta) + XINT (end) |
| 590 | != marker_position (end_mark))) |
| 591 | error ("Changes to be undone by function different than announced"); |
| 592 | Fset_marker (start_mark, Qnil, Qnil); |
| 593 | Fset_marker (end_mark, Qnil, Qnil); |
| 594 | } |
| 595 | else |
| 596 | apply1 (car, cdr); |
| 597 | |
| 598 | if (save_buffer != current_buffer) |
| 599 | error ("Undo function switched buffer"); |
| 600 | did_apply = 1; |
| 601 | } |
| 602 | else if (STRINGP (car) && INTEGERP (cdr)) |
| 603 | { |
| 604 | /* Element (STRING . POS) means STRING was deleted. */ |
| 605 | Lisp_Object membuf; |
| 606 | int pos = XINT (cdr); |
| 607 | |
| 608 | membuf = car; |
| 609 | if (pos < 0) |
| 610 | { |
| 611 | if (-pos < BEGV || -pos > ZV) |
| 612 | error ("Changes to be undone are outside visible portion of buffer"); |
| 613 | SET_PT (-pos); |
| 614 | Finsert (1, &membuf); |
| 615 | } |
| 616 | else |
| 617 | { |
| 618 | if (pos < BEGV || pos > ZV) |
| 619 | error ("Changes to be undone are outside visible portion of buffer"); |
| 620 | SET_PT (pos); |
| 621 | |
| 622 | /* Now that we record marker adjustments |
| 623 | (caused by deletion) for undo, |
| 624 | we should always insert after markers, |
| 625 | so that undoing the marker adjustments |
| 626 | put the markers back in the right place. */ |
| 627 | Finsert (1, &membuf); |
| 628 | SET_PT (pos); |
| 629 | } |
| 630 | } |
| 631 | else if (MARKERP (car) && INTEGERP (cdr)) |
| 632 | { |
| 633 | /* (MARKER . INTEGER) means a marker MARKER |
| 634 | was adjusted by INTEGER. */ |
| 635 | if (XMARKER (car)->buffer) |
| 636 | Fset_marker (car, |
| 637 | make_number (marker_position (car) - XINT (cdr)), |
| 638 | Fmarker_buffer (car)); |
| 639 | } |
| 640 | } |
| 641 | } |
| 642 | arg--; |
| 643 | } |
| 644 | |
| 645 | |
| 646 | /* Make sure an apply entry produces at least one undo entry, |
| 647 | so the test in `undo' for continuing an undo series |
| 648 | will work right. */ |
| 649 | if (did_apply |
| 650 | && EQ (oldlist, current_buffer->undo_list)) |
| 651 | current_buffer->undo_list |
| 652 | = Fcons (list3 (Qapply, Qcdr, Qnil), current_buffer->undo_list); |
| 653 | |
| 654 | UNGCPRO; |
| 655 | return unbind_to (count, list); |
| 656 | } |
| 657 | \f |
| 658 | void |
| 659 | syms_of_undo () |
| 660 | { |
| 661 | Qinhibit_read_only = intern ("inhibit-read-only"); |
| 662 | staticpro (&Qinhibit_read_only); |
| 663 | |
| 664 | Qapply = intern ("apply"); |
| 665 | staticpro (&Qapply); |
| 666 | |
| 667 | pending_boundary = Qnil; |
| 668 | staticpro (&pending_boundary); |
| 669 | |
| 670 | defsubr (&Sprimitive_undo); |
| 671 | defsubr (&Sundo_boundary); |
| 672 | |
| 673 | DEFVAR_INT ("undo-limit", &undo_limit, |
| 674 | doc: /* Keep no more undo information once it exceeds this size. |
| 675 | This limit is applied when garbage collection happens. |
| 676 | When a previous command increases the total undo list size past this |
| 677 | value, the earlier commands that came before it are forgotten. |
| 678 | |
| 679 | The size is counted as the number of bytes occupied, |
| 680 | which includes both saved text and other data. */); |
| 681 | undo_limit = 20000; |
| 682 | |
| 683 | DEFVAR_INT ("undo-strong-limit", &undo_strong_limit, |
| 684 | doc: /* Don't keep more than this much size of undo information. |
| 685 | This limit is applied when garbage collection happens. |
| 686 | When a previous command increases the total undo list size past this |
| 687 | value, that command and the earlier commands that came before it are forgotten. |
| 688 | However, the most recent buffer-modifying command's undo info |
| 689 | is never discarded for this reason. |
| 690 | |
| 691 | The size is counted as the number of bytes occupied, |
| 692 | which includes both saved text and other data. */); |
| 693 | undo_strong_limit = 30000; |
| 694 | |
| 695 | DEFVAR_LISP ("undo-outer-limit", &Vundo_outer_limit, |
| 696 | doc: /* Outer limit on size of undo information for one command. |
| 697 | At garbage collection time, if the current command has produced |
| 698 | more than this much undo information, it discards the info and displays |
| 699 | a warning. This is a last-ditch limit to prevent memory overflow. |
| 700 | |
| 701 | The size is counted as the number of bytes occupied, which includes |
| 702 | both saved text and other data. A value of nil means no limit. In |
| 703 | this case, accumulating one huge undo entry could make Emacs crash as |
| 704 | a result of memory overflow. |
| 705 | |
| 706 | In fact, this calls the function which is the value of |
| 707 | `undo-outer-limit-function' with one argument, the size. |
| 708 | The text above describes the behavior of the function |
| 709 | that variable usually specifies. */); |
| 710 | Vundo_outer_limit = make_number (3000000); |
| 711 | |
| 712 | DEFVAR_LISP ("undo-outer-limit-function", &Vundo_outer_limit_function, |
| 713 | doc: /* Function to call when an undo list exceeds `undo-outer-limit'. |
| 714 | This function is called with one argument, the current undo list size |
| 715 | for the most recent command (since the last undo boundary). |
| 716 | If the function returns t, that means truncation has been fully handled. |
| 717 | If it returns nil, the other forms of truncation are done. |
| 718 | |
| 719 | Garbage collection is inhibited around the call to this function, |
| 720 | so it must make sure not to do a lot of consing. */); |
| 721 | Vundo_outer_limit_function = Qnil; |
| 722 | } |
| 723 | |
| 724 | /* arch-tag: d546ee01-4aed-4ffb-bb8b-eefaae50d38a |
| 725 | (do not change this comment) */ |