1 /* undo handling for GNU Emacs.
2 Copyright (C) 1990, 1993, 1994, 2000, 2002, 2003, 2004,
3 2005 Free Software Foundation, Inc.
5 This file is part of GNU Emacs.
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)
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.
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. */
29 /* Limits controlling how much undo information to keep. */
32 EMACS_INT undo_strong_limit
;
34 Lisp_Object Vundo_outer_limit
;
36 /* Function to call when undo_outer_limit is exceeded. */
38 Lisp_Object Vundo_outer_limit_function
;
40 /* Last buffer for which undo information was recorded. */
41 Lisp_Object last_undo_buffer
;
43 Lisp_Object Qinhibit_read_only
;
45 /* Marker for function call undo list elements. */
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
54 Lisp_Object pending_boundary
;
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. */
67 /* Allocate a cons cell to be the undo boundary after this command. */
68 if (NILP (pending_boundary
))
69 pending_boundary
= Fcons (Qnil
, Qnil
);
71 if (!BUFFERP (last_undo_buffer
)
72 || current_buffer
!= XBUFFER (last_undo_buffer
))
74 XSETBUFFER (last_undo_buffer
, current_buffer
);
76 if (CONSP (current_buffer
->undo_list
))
78 /* Set AT_BOUNDARY to 1 only when we have nothing other than
79 marker adjustment before undo boundary. */
81 Lisp_Object tail
= current_buffer
->undo_list
, elt
;
89 if (NILP (elt
) || ! (CONSP (elt
) && MARKERP (XCAR (elt
))))
93 at_boundary
= NILP (elt
);
98 if (MODIFF
<= SAVE_MODIFF
)
99 record_first_change ();
101 /* If we are just after an undo boundary, and
102 point wasn't at start of deleted range, record where it was. */
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
))
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
);
113 if (last_point_position
!= pt
)
114 current_buffer
->undo_list
115 = Fcons (make_number (last_point_position
), current_buffer
->undo_list
);
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.) */
125 record_insert (beg
, length
)
128 Lisp_Object lbeg
, lend
;
130 if (EQ (current_buffer
->undo_list
, Qt
))
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
))
140 elt
= XCAR (current_buffer
->undo_list
);
142 && INTEGERP (XCAR (elt
))
143 && INTEGERP (XCDR (elt
))
144 && XINT (XCDR (elt
)) == beg
)
146 XSETCDR (elt
, make_number (beg
+ length
));
151 XSETFASTINT (lbeg
, beg
);
152 XSETINT (lend
, beg
+ length
);
153 current_buffer
->undo_list
= Fcons (Fcons (lbeg
, lend
),
154 current_buffer
->undo_list
);
157 /* Record that a deletion is about to take place,
158 of the characters in STRING, at location BEG. */
161 record_delete (beg
, string
)
167 if (EQ (current_buffer
->undo_list
, Qt
))
170 if (PT
== beg
+ SCHARS (string
))
172 XSETINT (sbeg
, -beg
);
177 XSETFASTINT (sbeg
, beg
);
181 current_buffer
->undo_list
182 = Fcons (Fcons (string
, sbeg
), current_buffer
->undo_list
);
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. */
191 record_marker_adjustment (marker
, adjustment
)
195 if (EQ (current_buffer
->undo_list
, Qt
))
198 /* Allocate a cons cell to be the undo boundary after this command. */
199 if (NILP (pending_boundary
))
200 pending_boundary
= Fcons (Qnil
, Qnil
);
202 if (!BUFFERP (last_undo_buffer
)
203 || current_buffer
!= XBUFFER (last_undo_buffer
))
205 XSETBUFFER (last_undo_buffer
, current_buffer
);
207 current_buffer
->undo_list
208 = Fcons (Fcons (marker
, make_number (adjustment
)),
209 current_buffer
->undo_list
);
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. */
217 record_change (beg
, length
)
220 record_delete (beg
, make_buffer_string (beg
, beg
+ length
, 1));
221 record_insert (beg
, length
);
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. */
229 record_first_change ()
231 Lisp_Object high
, low
;
232 struct buffer
*base_buffer
= current_buffer
;
234 if (EQ (current_buffer
->undo_list
, Qt
))
237 if (!BUFFERP (last_undo_buffer
)
238 || current_buffer
!= XBUFFER (last_undo_buffer
))
240 XSETBUFFER (last_undo_buffer
, current_buffer
);
242 if (base_buffer
->base_buffer
)
243 base_buffer
= base_buffer
->base_buffer
;
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
);
250 /* Record a change in property PROP (whose old value was VAL)
251 for LENGTH characters starting at position BEG in BUFFER. */
254 record_property_change (beg
, length
, prop
, value
, buffer
)
256 Lisp_Object prop
, value
, buffer
;
258 Lisp_Object lbeg
, lend
, entry
;
259 struct buffer
*obuf
= current_buffer
;
262 if (EQ (XBUFFER (buffer
)->undo_list
, Qt
))
265 /* Allocate a cons cell to be the undo boundary after this command. */
266 if (NILP (pending_boundary
))
267 pending_boundary
= Fcons (Qnil
, Qnil
);
269 if (!EQ (buffer
, last_undo_buffer
))
271 last_undo_buffer
= buffer
;
273 /* Switch temporarily to the buffer that was changed. */
274 current_buffer
= XBUFFER (buffer
);
279 if (MODIFF
<= SAVE_MODIFF
)
280 record_first_change ();
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
);
287 current_buffer
= obuf
;
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. */)
297 if (EQ (current_buffer
->undo_list
, Qt
))
299 tem
= Fcar (current_buffer
->undo_list
);
302 /* One way or another, cons nil onto the front of the undo list. */
303 if (!NILP (pending_boundary
))
305 /* If we have preallocated the cons cell to use here,
307 XSETCDR (pending_boundary
, current_buffer
->undo_list
);
308 current_buffer
->undo_list
= pending_boundary
;
309 pending_boundary
= Qnil
;
312 current_buffer
->undo_list
= Fcons (Qnil
, current_buffer
->undo_list
);
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. */
323 truncate_undo_list (b
)
327 Lisp_Object prev
, next
, last_boundary
;
330 /* Make sure that calling undo-outer-limit-function
331 won't cause another GC. */
332 int count
= inhibit_garbage_collection ();
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
);
344 last_boundary
= Qnil
;
346 /* If the first element is an undo boundary, skip past it. */
347 if (CONSP (next
) && NILP (XCAR (next
)))
349 /* Add in the space occupied by this element and its chain link. */
350 size_so_far
+= sizeof (struct Lisp_Cons
);
352 /* Advance to next element. */
357 /* Always preserve at least the most recent undo record
358 unless it is really horribly big.
360 Skip, skip, skip the undo, skip, skip, skip the undo,
361 Skip, skip, skip the undo, skip to the undo bound'ry. */
363 while (CONSP (next
) && ! NILP (XCAR (next
)))
368 /* Add in the space occupied by this element and its chain link. */
369 size_so_far
+= sizeof (struct Lisp_Cons
);
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
)));
378 /* Advance to next element. */
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
))
389 Lisp_Object temp
= last_undo_buffer
, tem
;
391 /* Normally the function this calls is undo-outer-limit-truncate. */
392 tem
= call1 (Vundo_outer_limit_function
, make_number (size_so_far
));
395 /* The function is responsible for making
396 any desired changes in buffer-undo-list. */
397 unbind_to (count
, Qnil
);
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
;
407 last_boundary
= prev
;
409 /* Keep additional undo data, if it fits in the limits. */
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. */
421 if (size_so_far
> undo_strong_limit
)
423 last_boundary
= prev
;
424 if (size_so_far
> undo_limit
)
428 /* Add in the space occupied by this element and its chain link. */
429 size_so_far
+= sizeof (struct Lisp_Cons
);
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
)));
438 /* Advance to next element. */
443 /* If we scanned the whole list, it is short enough; don't change it. */
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. */
453 unbind_to (count
, Qnil
);
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. */)
462 struct gcpro gcpro1
, gcpro2
;
464 int count
= SPECPDL_INDEX ();
469 #if 0 /* This is a good feature, but would make undo-start
470 unable to do what is expected. */
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. */
484 /* I don't think we need to gcpro oldlist, as we use it only
485 to check for EQ. ++kfs */
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
);
492 /* Don't let `intangible' properties interfere with undo. */
493 specbind (Qinhibit_point_motion_hooks
, Qt
);
495 oldlist
= current_buffer
->undo_list
;
503 /* Exit inner loop at undo boundary. */
506 /* Handle an integer by setting point to that value. */
508 SET_PT (clip_to_bounds (BEGV
, XINT (next
), ZV
));
509 else if (CONSP (next
))
511 Lisp_Object car
, cdr
;
517 /* Element (t high . low) records previous modtime. */
518 Lisp_Object high
, low
;
520 struct buffer
*base_buffer
= current_buffer
;
524 mod_time
= (XFASTINT (high
) << 16) + XFASTINT (low
);
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 (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 Fput_text_property (beg
, end
, prop
, val
, Qnil
);
553 else if (INTEGERP (car
) && INTEGERP (cdr
))
555 /* Element (BEG . END) means range was inserted. */
557 if (XINT (car
) < BEGV
559 error ("Changes to be undone are outside visible portion of buffer");
560 /* Set point first thing, so that undoing this undo
561 does not send point back to where it is now. */
563 Fdelete_region (car
, cdr
);
565 else if (EQ (car
, Qapply
))
567 /* Element (apply FUN . ARGS) means call FUN to undo. */
568 struct buffer
*save_buffer
= current_buffer
;
574 /* Long format: (apply DELTA START END FUN . ARGS). */
575 Lisp_Object delta
= car
;
576 Lisp_Object start
= Fcar (cdr
);
577 Lisp_Object end
= Fcar (Fcdr (cdr
));
578 Lisp_Object start_mark
= Fcopy_marker (start
, Qnil
);
579 Lisp_Object end_mark
= Fcopy_marker (end
, Qt
);
581 cdr
= Fcdr (Fcdr (cdr
));
582 apply1 (Fcar (cdr
), Fcdr (cdr
));
584 /* Check that the function did what the entry said it
586 if (!EQ (start
, Fmarker_position (start_mark
))
587 || (XINT (delta
) + XINT (end
)
588 != marker_position (end_mark
)))
589 error ("Changes to be undone by function different than announced");
590 Fset_marker (start_mark
, Qnil
, Qnil
);
591 Fset_marker (end_mark
, Qnil
, Qnil
);
596 if (save_buffer
!= current_buffer
)
597 error ("Undo function switched buffer");
600 else if (STRINGP (car
) && INTEGERP (cdr
))
602 /* Element (STRING . POS) means STRING was deleted. */
604 int pos
= XINT (cdr
);
609 if (-pos
< BEGV
|| -pos
> ZV
)
610 error ("Changes to be undone are outside visible portion of buffer");
612 Finsert (1, &membuf
);
616 if (pos
< BEGV
|| pos
> ZV
)
617 error ("Changes to be undone are outside visible portion of buffer");
620 /* Now that we record marker adjustments
621 (caused by deletion) for undo,
622 we should always insert after markers,
623 so that undoing the marker adjustments
624 put the markers back in the right place. */
625 Finsert (1, &membuf
);
629 else if (MARKERP (car
) && INTEGERP (cdr
))
631 /* (MARKER . INTEGER) means a marker MARKER
632 was adjusted by INTEGER. */
633 if (XMARKER (car
)->buffer
)
635 make_number (marker_position (car
) - XINT (cdr
)),
636 Fmarker_buffer (car
));
644 /* Make sure an apply entry produces at least one undo entry,
645 so the test in `undo' for continuing an undo series
648 && EQ (oldlist
, current_buffer
->undo_list
))
649 current_buffer
->undo_list
650 = Fcons (list3 (Qapply
, Qcdr
, Qnil
), current_buffer
->undo_list
);
653 return unbind_to (count
, list
);
659 Qinhibit_read_only
= intern ("inhibit-read-only");
660 staticpro (&Qinhibit_read_only
);
662 Qapply
= intern ("apply");
665 pending_boundary
= Qnil
;
666 staticpro (&pending_boundary
);
668 defsubr (&Sprimitive_undo
);
669 defsubr (&Sundo_boundary
);
671 DEFVAR_INT ("undo-limit", &undo_limit
,
672 doc
: /* Keep no more undo information once it exceeds this size.
673 This limit is applied when garbage collection happens.
674 When a previous command increases the total undo list size past this
675 value, the earlier commands that came before it are forgotten.
677 The size is counted as the number of bytes occupied,
678 which includes both saved text and other data. */);
681 DEFVAR_INT ("undo-strong-limit", &undo_strong_limit
,
682 doc
: /* Don't keep more than this much size of undo information.
683 This limit is applied when garbage collection happens.
684 When a previous command increases the total undo list size past this
685 value, that command and the earlier commands that came before it are forgotten.
686 However, the most recent buffer-modifying command's undo info
687 is never discarded for this reason.
689 The size is counted as the number of bytes occupied,
690 which includes both saved text and other data. */);
691 undo_strong_limit
= 30000;
693 DEFVAR_LISP ("undo-outer-limit", &Vundo_outer_limit
,
694 doc
: /* Outer limit on size of undo information for one command.
695 At garbage collection time, if the current command has produced
696 more than this much undo information, it discards the info and displays
697 a warning. This is a last-ditch limit to prevent memory overflow.
699 The size is counted as the number of bytes occupied, which includes
700 both saved text and other data. A value of nil means no limit. In
701 this case, accumulating one huge undo entry could make Emacs crash as
702 a result of memory overflow.
704 In fact, this calls the function which is the value of
705 `undo-outer-limit-function' with one argument, the size.
706 The text above describes the behavior of the function
707 that variable usually specifies. */);
708 Vundo_outer_limit
= make_number (3000000);
710 DEFVAR_LISP ("undo-outer-limit-function", &Vundo_outer_limit_function
,
711 doc
: /* Function to call when an undo list exceeds `undo-outer-limit'.
712 This function is called with one argument, the current undo list size
713 for the most recent command (since the last undo boundary).
714 If the function returns t, that means truncation has been fully handled.
715 If it returns nil, the other forms of truncation are done.
717 Garbage collection is inhibited around the call to this function,
718 so it must make sure not to do a lot of consing. */);
719 Vundo_outer_limit_function
= Qnil
;
722 /* arch-tag: d546ee01-4aed-4ffb-bb8b-eefaae50d38a
723 (do not change this comment) */