1 /* undo handling for GNU Emacs.
2 Copyright (C) 1990, 1993-1994, 2000-2012 Free Software Foundation, Inc.
4 This file is part of GNU Emacs.
6 GNU Emacs is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation, either version 3 of the License, or
9 (at your option) any later version.
11 GNU Emacs is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */
23 #include "character.h"
28 /* Last buffer for which undo information was recorded. */
29 /* BEWARE: This is not traced by the GC, so never dereference it! */
30 static struct buffer
*last_undo_buffer
;
32 /* Position of point last time we inserted a boundary. */
33 static struct buffer
*last_boundary_buffer
;
34 static ptrdiff_t last_boundary_position
;
36 Lisp_Object Qinhibit_read_only
;
38 /* Marker for function call undo list elements. */
42 /* The first time a command records something for undo.
43 it also allocates the undo-boundary object
44 which will be added to the list at the end of the command.
45 This ensures we can't run out of space while trying to make
47 static Lisp_Object pending_boundary
;
49 /* Record point as it was at beginning of this command (if necessary)
50 and prepare the undo info for recording a change.
51 PT is the position of point that will naturally occur as a result of the
52 undo record that will be added just after this command terminates. */
55 record_point (ptrdiff_t pt
)
59 /* Don't record position of pt when undo_inhibit_record_point holds. */
60 if (undo_inhibit_record_point
)
63 /* Allocate a cons cell to be the undo boundary after this command. */
64 if (NILP (pending_boundary
))
65 pending_boundary
= Fcons (Qnil
, Qnil
);
67 if ((current_buffer
!= last_undo_buffer
)
68 /* Don't call Fundo_boundary for the first change. Otherwise we
69 risk overwriting last_boundary_position in Fundo_boundary with
70 PT of the current buffer and as a consequence not insert an
71 undo boundary because last_boundary_position will equal pt in
72 the test at the end of the present function (Bug#731). */
73 && (MODIFF
> SAVE_MODIFF
))
75 last_undo_buffer
= current_buffer
;
77 if (CONSP (BVAR (current_buffer
, undo_list
)))
79 /* Set AT_BOUNDARY to 1 only when we have nothing other than
80 marker adjustment before undo boundary. */
82 Lisp_Object tail
= BVAR (current_buffer
, undo_list
), elt
;
90 if (NILP (elt
) || ! (CONSP (elt
) && MARKERP (XCAR (elt
))))
94 at_boundary
= NILP (elt
);
99 if (MODIFF
<= SAVE_MODIFF
)
100 record_first_change ();
102 /* If we are just after an undo boundary, and
103 point wasn't at start of deleted range, record where it was. */
105 && current_buffer
== last_boundary_buffer
106 && last_boundary_position
!= pt
)
107 BVAR (current_buffer
, undo_list
)
108 = Fcons (make_number (last_boundary_position
), BVAR (current_buffer
, undo_list
));
111 /* Record an insertion that just happened or is about to happen,
112 for LENGTH characters at position BEG.
113 (It is possible to record an insertion before or after the fact
114 because we don't need to record the contents.) */
117 record_insert (ptrdiff_t beg
, ptrdiff_t length
)
119 Lisp_Object lbeg
, lend
;
121 if (EQ (BVAR (current_buffer
, undo_list
), Qt
))
126 /* If this is following another insertion and consecutive with it
127 in the buffer, combine the two. */
128 if (CONSP (BVAR (current_buffer
, undo_list
)))
131 elt
= XCAR (BVAR (current_buffer
, undo_list
));
133 && INTEGERP (XCAR (elt
))
134 && INTEGERP (XCDR (elt
))
135 && XINT (XCDR (elt
)) == beg
)
137 XSETCDR (elt
, make_number (beg
+ length
));
142 XSETFASTINT (lbeg
, beg
);
143 XSETINT (lend
, beg
+ length
);
144 BVAR (current_buffer
, undo_list
) = Fcons (Fcons (lbeg
, lend
),
145 BVAR (current_buffer
, undo_list
));
148 /* Record that a deletion is about to take place,
149 of the characters in STRING, at location BEG. */
152 record_delete (ptrdiff_t beg
, Lisp_Object string
)
156 if (EQ (BVAR (current_buffer
, undo_list
), Qt
))
159 if (PT
== beg
+ SCHARS (string
))
161 XSETINT (sbeg
, -beg
);
166 XSETFASTINT (sbeg
, beg
);
170 BVAR (current_buffer
, undo_list
)
171 = Fcons (Fcons (string
, sbeg
), BVAR (current_buffer
, undo_list
));
174 /* Record the fact that MARKER is about to be adjusted by ADJUSTMENT.
175 This is done only when a marker points within text being deleted,
176 because that's the only case where an automatic marker adjustment
177 won't be inverted automatically by undoing the buffer modification. */
180 record_marker_adjustment (Lisp_Object marker
, ptrdiff_t adjustment
)
182 if (EQ (BVAR (current_buffer
, undo_list
), Qt
))
185 /* Allocate a cons cell to be the undo boundary after this command. */
186 if (NILP (pending_boundary
))
187 pending_boundary
= Fcons (Qnil
, Qnil
);
189 if (current_buffer
!= last_undo_buffer
)
191 last_undo_buffer
= current_buffer
;
193 BVAR (current_buffer
, undo_list
)
194 = Fcons (Fcons (marker
, make_number (adjustment
)),
195 BVAR (current_buffer
, undo_list
));
198 /* Record that a replacement is about to take place,
199 for LENGTH characters at location BEG.
200 The replacement must not change the number of characters. */
203 record_change (ptrdiff_t beg
, ptrdiff_t length
)
205 record_delete (beg
, make_buffer_string (beg
, beg
+ length
, 1));
206 record_insert (beg
, length
);
209 /* Record that an unmodified buffer is about to be changed.
210 Record the file modification date so that when undoing this entry
211 we can tell whether it is obsolete because the file was saved again. */
214 record_first_change (void)
216 struct buffer
*base_buffer
= current_buffer
;
218 if (EQ (BVAR (current_buffer
, undo_list
), Qt
))
221 if (current_buffer
!= last_undo_buffer
)
223 last_undo_buffer
= current_buffer
;
225 if (base_buffer
->base_buffer
)
226 base_buffer
= base_buffer
->base_buffer
;
228 BVAR (current_buffer
, undo_list
) =
229 Fcons (Fcons (Qt
, make_lisp_time (base_buffer
->modtime
)),
230 BVAR (current_buffer
, undo_list
));
233 /* Record a change in property PROP (whose old value was VAL)
234 for LENGTH characters starting at position BEG in BUFFER. */
237 record_property_change (ptrdiff_t beg
, ptrdiff_t length
,
238 Lisp_Object prop
, Lisp_Object value
,
241 Lisp_Object lbeg
, lend
, entry
;
242 struct buffer
*obuf
= current_buffer
, *buf
= XBUFFER (buffer
);
245 if (EQ (BVAR (buf
, undo_list
), Qt
))
248 /* Allocate a cons cell to be the undo boundary after this command. */
249 if (NILP (pending_boundary
))
250 pending_boundary
= Fcons (Qnil
, Qnil
);
252 if (buf
!= last_undo_buffer
)
254 last_undo_buffer
= buf
;
256 /* Switch temporarily to the buffer that was changed. */
257 current_buffer
= buf
;
262 if (MODIFF
<= SAVE_MODIFF
)
263 record_first_change ();
266 XSETINT (lend
, beg
+ length
);
267 entry
= Fcons (Qnil
, Fcons (prop
, Fcons (value
, Fcons (lbeg
, lend
))));
268 BVAR (current_buffer
, undo_list
) = Fcons (entry
, BVAR (current_buffer
, undo_list
));
270 current_buffer
= obuf
;
273 DEFUN ("undo-boundary", Fundo_boundary
, Sundo_boundary
, 0, 0, 0,
274 doc
: /* Mark a boundary between units of undo.
275 An undo command will stop at this point,
276 but another undo command will undo to the previous boundary. */)
280 if (EQ (BVAR (current_buffer
, undo_list
), Qt
))
282 tem
= Fcar (BVAR (current_buffer
, undo_list
));
285 /* One way or another, cons nil onto the front of the undo list. */
286 if (!NILP (pending_boundary
))
288 /* If we have preallocated the cons cell to use here,
290 XSETCDR (pending_boundary
, BVAR (current_buffer
, undo_list
));
291 BVAR (current_buffer
, undo_list
) = pending_boundary
;
292 pending_boundary
= Qnil
;
295 BVAR (current_buffer
, undo_list
) = Fcons (Qnil
, BVAR (current_buffer
, undo_list
));
297 last_boundary_position
= PT
;
298 last_boundary_buffer
= current_buffer
;
302 /* At garbage collection time, make an undo list shorter at the end,
303 returning the truncated list. How this is done depends on the
304 variables undo-limit, undo-strong-limit and undo-outer-limit.
305 In some cases this works by calling undo-outer-limit-function. */
308 truncate_undo_list (struct buffer
*b
)
311 Lisp_Object prev
, next
, last_boundary
;
312 EMACS_INT size_so_far
= 0;
314 /* Make sure that calling undo-outer-limit-function
315 won't cause another GC. */
316 ptrdiff_t count
= inhibit_garbage_collection ();
318 /* Make the buffer current to get its local values of variables such
319 as undo_limit. Also so that Vundo_outer_limit_function can
320 tell which buffer to operate on. */
321 record_unwind_protect (set_buffer_if_live
, Fcurrent_buffer ());
322 set_buffer_internal (b
);
324 list
= BVAR (b
, undo_list
);
328 last_boundary
= Qnil
;
330 /* If the first element is an undo boundary, skip past it. */
331 if (CONSP (next
) && NILP (XCAR (next
)))
333 /* Add in the space occupied by this element and its chain link. */
334 size_so_far
+= sizeof (struct Lisp_Cons
);
336 /* Advance to next element. */
341 /* Always preserve at least the most recent undo record
342 unless it is really horribly big.
344 Skip, skip, skip the undo, skip, skip, skip the undo,
345 Skip, skip, skip the undo, skip to the undo bound'ry. */
347 while (CONSP (next
) && ! NILP (XCAR (next
)))
352 /* Add in the space occupied by this element and its chain link. */
353 size_so_far
+= sizeof (struct Lisp_Cons
);
356 size_so_far
+= sizeof (struct Lisp_Cons
);
357 if (STRINGP (XCAR (elt
)))
358 size_so_far
+= (sizeof (struct Lisp_String
) - 1
359 + SCHARS (XCAR (elt
)));
362 /* Advance to next element. */
367 /* If by the first boundary we have already passed undo_outer_limit,
368 we're heading for memory full, so offer to clear out the list. */
369 if (INTEGERP (Vundo_outer_limit
)
370 && size_so_far
> XINT (Vundo_outer_limit
)
371 && !NILP (Vundo_outer_limit_function
))
374 struct buffer
*temp
= last_undo_buffer
;
376 /* Normally the function this calls is undo-outer-limit-truncate. */
377 tem
= call1 (Vundo_outer_limit_function
, make_number (size_so_far
));
380 /* The function is responsible for making
381 any desired changes in buffer-undo-list. */
382 unbind_to (count
, Qnil
);
385 /* That function probably used the minibuffer, and if so, that
386 changed last_undo_buffer. Change it back so that we don't
387 force next change to make an undo boundary here. */
388 last_undo_buffer
= temp
;
392 last_boundary
= prev
;
394 /* Keep additional undo data, if it fits in the limits. */
400 /* When we get to a boundary, decide whether to truncate
401 either before or after it. The lower threshold, undo_limit,
402 tells us to truncate after it. If its size pushes past
403 the higher threshold undo_strong_limit, we truncate before it. */
406 if (size_so_far
> undo_strong_limit
)
408 last_boundary
= prev
;
409 if (size_so_far
> undo_limit
)
413 /* Add in the space occupied by this element and its chain link. */
414 size_so_far
+= sizeof (struct Lisp_Cons
);
417 size_so_far
+= sizeof (struct Lisp_Cons
);
418 if (STRINGP (XCAR (elt
)))
419 size_so_far
+= (sizeof (struct Lisp_String
) - 1
420 + SCHARS (XCAR (elt
)));
423 /* Advance to next element. */
428 /* If we scanned the whole list, it is short enough; don't change it. */
431 /* Truncate at the boundary where we decided to truncate. */
432 else if (!NILP (last_boundary
))
433 XSETCDR (last_boundary
, Qnil
);
434 /* There's nothing we decided to keep, so clear it out. */
436 BVAR (b
, undo_list
) = Qnil
;
438 unbind_to (count
, Qnil
);
441 static void user_error (const char*) NO_RETURN
;
442 static void user_error (const char *msg
)
444 xsignal1 (Quser_error
, build_string (msg
));
448 DEFUN ("primitive-undo", Fprimitive_undo
, Sprimitive_undo
, 2, 2, 0,
449 doc
: /* Undo N records from the front of the list LIST.
450 Return what remains of the list. */)
451 (Lisp_Object n
, Lisp_Object list
)
453 struct gcpro gcpro1
, gcpro2
;
455 ptrdiff_t count
= SPECPDL_INDEX ();
456 register EMACS_INT arg
;
460 #if 0 /* This is a good feature, but would make undo-start
461 unable to do what is expected. */
464 /* If the head of the list is a boundary, it is the boundary
465 preceding this command. Get rid of it and don't count it. */
475 /* I don't think we need to gcpro oldlist, as we use it only
476 to check for EQ. ++kfs */
478 /* In a writable buffer, enable undoing read-only text that is so
479 because of text properties. */
480 if (NILP (BVAR (current_buffer
, read_only
)))
481 specbind (Qinhibit_read_only
, Qt
);
483 /* Don't let `intangible' properties interfere with undo. */
484 specbind (Qinhibit_point_motion_hooks
, Qt
);
486 oldlist
= BVAR (current_buffer
, undo_list
);
494 /* Exit inner loop at undo boundary. */
497 /* Handle an integer by setting point to that value. */
499 SET_PT (clip_to_bounds (BEGV
, XINT (next
), ZV
));
500 else if (CONSP (next
))
502 Lisp_Object car
, cdr
;
508 /* Element (t . TIME) records previous modtime.
509 Preserve any flag of NONEXISTENT_MODTIME_NSECS or
510 UNKNOWN_MODTIME_NSECS. */
511 struct buffer
*base_buffer
= current_buffer
;
515 && CONSP (XCDR (cdr
))
516 && CONSP (XCDR (XCDR (cdr
)))
517 && CONSP (XCDR (XCDR (XCDR (cdr
))))
518 && INTEGERP (XCAR (XCDR (XCDR (XCDR (cdr
)))))
519 && XINT (XCAR (XCDR (XCDR (XCDR (cdr
))))) < 0)
522 XINT (XCAR (XCDR (XCDR (XCDR (cdr
))))) / 1000);
524 mod_time
= lisp_time_argument (cdr
, 0);
526 if (current_buffer
->base_buffer
)
527 base_buffer
= current_buffer
->base_buffer
;
529 /* If this records an obsolete save
530 (not matching the actual disk file)
531 then don't mark unmodified. */
532 if (EMACS_TIME_NE (mod_time
, base_buffer
->modtime
))
534 #ifdef CLASH_DETECTION
536 #endif /* CLASH_DETECTION */
537 Fset_buffer_modified_p (Qnil
);
539 else if (EQ (car
, Qnil
))
541 /* Element (nil PROP VAL BEG . END) is property change. */
542 Lisp_Object beg
, end
, prop
, val
;
551 if (XINT (beg
) < BEGV
|| XINT (end
) > ZV
)
552 user_error ("Changes to be undone are outside visible portion of buffer");
553 Fput_text_property (beg
, end
, prop
, val
, Qnil
);
555 else if (INTEGERP (car
) && INTEGERP (cdr
))
557 /* Element (BEG . END) means range was inserted. */
559 if (XINT (car
) < BEGV
561 user_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. */
565 Fdelete_region (car
, cdr
);
567 else if (EQ (car
, Qapply
))
569 /* Element (apply FUN . ARGS) means call FUN to undo. */
570 struct buffer
*save_buffer
= current_buffer
;
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
);
583 cdr
= Fcdr (Fcdr (cdr
));
584 apply1 (Fcar (cdr
), Fcdr (cdr
));
586 /* Check that the function did what the entry said it
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
);
598 if (save_buffer
!= current_buffer
)
599 error ("Undo function switched buffer");
602 else if (STRINGP (car
) && INTEGERP (cdr
))
604 /* Element (STRING . POS) means STRING was deleted. */
606 EMACS_INT pos
= XINT (cdr
);
611 if (-pos
< BEGV
|| -pos
> ZV
)
612 user_error ("Changes to be undone are outside visible portion of buffer");
614 Finsert (1, &membuf
);
618 if (pos
< BEGV
|| pos
> ZV
)
619 user_error ("Changes to be undone are outside visible portion of buffer");
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
);
631 else if (MARKERP (car
) && INTEGERP (cdr
))
633 /* (MARKER . INTEGER) means a marker MARKER
634 was adjusted by INTEGER. */
635 if (XMARKER (car
)->buffer
)
637 make_number (marker_position (car
) - XINT (cdr
)),
638 Fmarker_buffer (car
));
646 /* Make sure an apply entry produces at least one undo entry,
647 so the test in `undo' for continuing an undo series
650 && EQ (oldlist
, BVAR (current_buffer
, undo_list
)))
651 BVAR (current_buffer
, undo_list
)
652 = Fcons (list3 (Qapply
, Qcdr
, Qnil
), BVAR (current_buffer
, undo_list
));
655 return unbind_to (count
, list
);
661 DEFSYM (Qinhibit_read_only
, "inhibit-read-only");
662 DEFSYM (Qapply
, "apply");
664 pending_boundary
= Qnil
;
665 staticpro (&pending_boundary
);
667 last_undo_buffer
= NULL
;
668 last_boundary_buffer
= NULL
;
670 defsubr (&Sprimitive_undo
);
671 defsubr (&Sundo_boundary
);
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.
679 The size is counted as the number of bytes occupied,
680 which includes both saved text and other data. */);
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.
691 The size is counted as the number of bytes occupied,
692 which includes both saved text and other data. */);
693 undo_strong_limit
= 120000;
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.
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.
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 (12000000);
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.
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
;
723 DEFVAR_BOOL ("undo-inhibit-record-point", undo_inhibit_record_point
,
724 doc
: /* Non-nil means do not record `point' in `buffer-undo-list'. */);
725 undo_inhibit_record_point
= 0;