unofficial mirror of emacs-devel@gnu.org 
 help / color / mirror / code / Atom feed
blob 005f66f6f249017431aafec37acdbf45e2084d13 25186 bytes (raw)
name: src/marker.c 	 # note: path name is non-authoritative(*)

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
 
/* Markers: examining, setting and deleting.
   Copyright (C) 1985, 1997-1998, 2001-2024 Free Software Foundation,
   Inc.

This file is part of GNU Emacs.

GNU Emacs is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at
your option) any later version.

GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */


#include <config.h>

/* Work around GCC bug 113253.  */
#if __GNUC__ == 13 && __GNUC_MINOR__ < 3
# pragma GCC diagnostic ignored "-Wanalyzer-deref-before-check"
#endif

#include "lisp.h"
#include "character.h"
#include "buffer.h"
#include "window.h"
#include "igc.h"

/* Record one cached position found recently by
   buf_charpos_to_bytepos or buf_bytepos_to_charpos.  */

static ptrdiff_t cached_charpos;
static ptrdiff_t cached_bytepos;
static struct buffer *cached_buffer;
static modiff_count cached_modiff;

/* Juanma Barranquero <lekktu@gmail.com> reported ~3x increased
   bootstrap time when byte_char_debug_check is enabled; so this
   is never turned on by --enable-checking configure option.  */

#ifdef MARKER_DEBUG

extern int count_markers (struct buffer *) EXTERNALLY_VISIBLE;
extern ptrdiff_t verify_bytepos (ptrdiff_t charpos) EXTERNALLY_VISIBLE;

static void
byte_char_debug_check (struct buffer *b, ptrdiff_t charpos, ptrdiff_t bytepos)
{
  ptrdiff_t nchars;

  if (NILP (BVAR (b, enable_multibyte_characters)))
    return;

  if (bytepos > BUF_GPT_BYTE (b))
    nchars
      = multibyte_chars_in_text (BUF_BEG_ADDR (b),
				 BUF_GPT_BYTE (b) - BUF_BEG_BYTE (b))
      + multibyte_chars_in_text (BUF_GAP_END_ADDR (b),
				 bytepos - BUF_GPT_BYTE (b));
  else
    nchars = multibyte_chars_in_text (BUF_BEG_ADDR (b),
				      bytepos - BUF_BEG_BYTE (b));

  if (charpos - 1 != nchars)
    emacs_abort ();
}

#else /* not MARKER_DEBUG */

#define byte_char_debug_check(b, charpos, bytepos) do { } while (0)

#endif /* MARKER_DEBUG */

void
clear_charpos_cache (struct buffer *b)
{
  if (cached_buffer == b)
    cached_buffer = 0;
}
\f
/* Converting between character positions and byte positions.  */

/* There are several places in the buffer where we know
   the correspondence: BEG, BEGV, PT, GPT, ZV and Z,
   and everywhere there is a marker.  So we find the one of these places
   that is closest to the specified position, and scan from there.  */

/* This macro is a subroutine of buf_charpos_to_bytepos.
   Note that it is desirable that BYTEPOS is not evaluated
   except when we really want its value.  */

#define CONSIDER(CHARPOS, BYTEPOS)					\
{									\
  ptrdiff_t this_charpos = (CHARPOS);					\
  bool changed = false;							\
									\
  if (this_charpos == charpos)						\
    {									\
      ptrdiff_t value = (BYTEPOS);				       	\
									\
      byte_char_debug_check (b, charpos, value);			\
      return value;							\
    }									\
  else if (this_charpos > charpos)					\
    {									\
      if (this_charpos < best_above)					\
	{								\
	  best_above = this_charpos;					\
	  best_above_byte = (BYTEPOS);					\
	  changed = true;						\
	}								\
    }									\
  else if (this_charpos > best_below)					\
    {									\
      best_below = this_charpos;					\
      best_below_byte = (BYTEPOS);					\
      changed = true;							\
    }									\
									\
  if (changed)								\
    {									\
      if (best_above - best_below == best_above_byte - best_below_byte)	\
        {								\
	  ptrdiff_t value = best_below_byte + (charpos - best_below);	\
									\
	  byte_char_debug_check (b, charpos, value);			\
	  return value;							\
	}								\
    }									\
}

static void
CHECK_MARKER (Lisp_Object x)
{
  CHECK_TYPE (MARKERP (x), Qmarkerp, x);
}

/* When converting bytes from/to chars, we look through the list of
   markers to try and find a good starting point (since markers keep
   track of both bytepos and charpos at the same time).
   But if there are many markers, it can take too much time to find a "good"
   marker from which to start.  Worse yet: if it takes a long time and we end
   up finding a nearby markers, we won't add a new marker to cache this
   result, so next time around we'll have to go through this same long list
   to (re)find this best marker.  So the further down the list of
   markers we go, the less demanding we are w.r.t what is a good marker.

   The previous code used INITIAL=50 and INCREMENT=0 and this lead to
   really poor performance when there are many markers.
   I haven't tried to tweak INITIAL, but experiments on my trusty Thinkpad
   T61 using various artificial test cases seem to suggest that INCREMENT=50
   might be "the best compromise": it significantly improved the
   worst case and it was rarely slower and never by much.

   The asymptotic behavior is still poor, tho, so in largish buffers with many
   overlays (e.g. 300KB and 30K overlays), it can still be a bottleneck.  */
#define BYTECHAR_DISTANCE_INITIAL 50
#define BYTECHAR_DISTANCE_INCREMENT 50

/* Return the byte position corresponding to CHARPOS in B.  */

ptrdiff_t
buf_charpos_to_bytepos (struct buffer *b, ptrdiff_t charpos)
{
  ptrdiff_t best_above, best_above_byte;
  ptrdiff_t best_below, best_below_byte;
  ptrdiff_t distance = BYTECHAR_DISTANCE_INITIAL;

  eassert (BUF_BEG (b) <= charpos && charpos <= BUF_Z (b));

  best_above = BUF_Z (b);
  best_above_byte = BUF_Z_BYTE (b);

  /* If this buffer has as many characters as bytes,
     each character must be one byte.
     This takes care of the case where enable-multibyte-characters is nil.  */
  if (best_above == best_above_byte)
    return charpos;

  best_below = BEG;
  best_below_byte = BEG_BYTE;

  /* We find in best_above and best_above_byte
     the closest known point above CHARPOS,
     and in best_below and best_below_byte
     the closest known point below CHARPOS,

     If at any point we can tell that the space between those
     two best approximations is all single-byte,
     we interpolate the result immediately.  */

  CONSIDER (BUF_PT (b), BUF_PT_BYTE (b));
  CONSIDER (BUF_GPT (b), BUF_GPT_BYTE (b));
  CONSIDER (BUF_BEGV (b), BUF_BEGV_BYTE (b));
  CONSIDER (BUF_ZV (b), BUF_ZV_BYTE (b));

  if (b == cached_buffer && BUF_MODIFF (b) == cached_modiff)
    CONSIDER (cached_charpos, cached_bytepos);

  DO_MARKERS (b, tail)
    {
      /* If we are down to a range of DISTANCE chars,
	 don't bother checking any other markers;
	 scan the intervening chars directly now.  */
      if (best_above - charpos < distance
          || charpos - best_below < distance)
	break;

      CONSIDER (tail->charpos, tail->bytepos);
      distance += BYTECHAR_DISTANCE_INCREMENT;
    }
  END_DO_MARKERS;

  /* We get here if we did not exactly hit one of the known places.
     We have one known above and one known below.
     Scan, counting characters, from whichever one is closer.  */

  eassert (best_below <= charpos && charpos <= best_above);
  if (charpos - best_below < best_above - charpos)
    {
      bool record = charpos - best_below > 5000;

      while (best_below < charpos)
	{
	  best_below++;
	  best_below_byte += buf_next_char_len (b, best_below_byte);
	}

      /* If this position is quite far from the nearest known position,
	 cache the correspondence by creating a marker here.
	 It will last until the next GC.  */
      if (record)
	build_marker (b, best_below, best_below_byte);

      byte_char_debug_check (b, best_below, best_below_byte);

      cached_buffer = b;
      cached_modiff = BUF_MODIFF (b);
      cached_charpos = best_below;
      cached_bytepos = best_below_byte;

      return best_below_byte;
    }
  else
    {
      bool record = best_above - charpos > 5000;

      while (best_above > charpos)
	{
	  best_above--;
	  best_above_byte -= buf_prev_char_len (b, best_above_byte);
	}

      /* If this position is quite far from the nearest known position,
	 cache the correspondence by creating a marker here.
	 It will last until the next GC.  */
      if (record)
	build_marker (b, best_above, best_above_byte);

      byte_char_debug_check (b, best_above, best_above_byte);

      cached_buffer = b;
      cached_modiff = BUF_MODIFF (b);
      cached_charpos = best_above;
      cached_bytepos = best_above_byte;

      return best_above_byte;
    }
}

#undef CONSIDER

/* This macro is a subroutine of buf_bytepos_to_charpos.
   It is used when BYTEPOS is actually the byte position.  */

#define CONSIDER(BYTEPOS, CHARPOS)					\
{									\
  ptrdiff_t this_bytepos = (BYTEPOS);					\
  int changed = false;							\
									\
  if (this_bytepos == bytepos)						\
    {									\
      ptrdiff_t value = (CHARPOS);				       	\
									\
      byte_char_debug_check (b, value, bytepos);			\
      return value;							\
    }									\
  else if (this_bytepos > bytepos)					\
    {									\
      if (this_bytepos < best_above_byte)				\
	{								\
	  best_above = (CHARPOS);					\
	  best_above_byte = this_bytepos;				\
	  changed = true;						\
	}								\
    }									\
  else if (this_bytepos > best_below_byte)				\
    {									\
      best_below = (CHARPOS);						\
      best_below_byte = this_bytepos;					\
      changed = true;							\
    }									\
									\
  if (changed)								\
    {									\
      if (best_above - best_below == best_above_byte - best_below_byte)	\
	{								\
	  ptrdiff_t value = best_below + (bytepos - best_below_byte);	\
									\
	  byte_char_debug_check (b, value, bytepos);			\
	  return value;							\
	}								\
    }									\
}

/* Return the character position corresponding to BYTEPOS in B.  */

ptrdiff_t
buf_bytepos_to_charpos (struct buffer *b, ptrdiff_t bytepos)
{
  ptrdiff_t best_above, best_above_byte;
  ptrdiff_t best_below, best_below_byte;
  ptrdiff_t distance = BYTECHAR_DISTANCE_INITIAL;

  eassert (BUF_BEG_BYTE (b) <= bytepos && bytepos <= BUF_Z_BYTE (b));

  best_above = BUF_Z (b);
  best_above_byte = BUF_Z_BYTE (b);

  /* If this buffer has as many characters as bytes,
     each character must be one byte.
     This takes care of the case where enable-multibyte-characters is nil.  */
  if (best_above == best_above_byte)
    return bytepos;

  /* Check bytepos is not in the middle of a character. */
  eassert (bytepos >= BUF_Z_BYTE (b)
           || CHAR_HEAD_P (BUF_FETCH_BYTE (b, bytepos)));

  best_below = BEG;
  best_below_byte = BEG_BYTE;

  CONSIDER (BUF_PT_BYTE (b), BUF_PT (b));
  CONSIDER (BUF_GPT_BYTE (b), BUF_GPT (b));
  CONSIDER (BUF_BEGV_BYTE (b), BUF_BEGV (b));
  CONSIDER (BUF_ZV_BYTE (b), BUF_ZV (b));

  if (b == cached_buffer && BUF_MODIFF (b) == cached_modiff)
    CONSIDER (cached_bytepos, cached_charpos);

  DO_MARKERS (b, tail)
    {
      /* If we are down to a range of DISTANCE chars,
	 don't bother checking any other markers;
	 scan the intervening chars directly now.  */
      if (best_above_byte - bytepos < distance
          || bytepos - best_below_byte < distance)
	break;

      CONSIDER (tail->bytepos, tail->charpos);
      distance += BYTECHAR_DISTANCE_INCREMENT;
    }
  END_DO_MARKERS;

  /* We get here if we did not exactly hit one of the known places.
     We have one known above and one known below.
     Scan, counting characters, from whichever one is closer.  */

  if (bytepos - best_below_byte < best_above_byte - bytepos)
    {
      bool record = bytepos - best_below_byte > 5000;

      while (best_below_byte < bytepos)
	{
	  best_below++;
	  best_below_byte += buf_next_char_len (b, best_below_byte);
	}

      /* If this position is quite far from the nearest known position,
	 cache the correspondence by creating a marker here.
	 It will last until the next GC.
	 But don't do it if BUF_MARKERS is nil;
	 that is a signal from Fset_buffer_multibyte.  */
      if (record && BUF_MARKERS (b))
	build_marker (b, best_below, best_below_byte);

      byte_char_debug_check (b, best_below, best_below_byte);

      cached_buffer = b;
      cached_modiff = BUF_MODIFF (b);
      cached_charpos = best_below;
      cached_bytepos = best_below_byte;

      return best_below;
    }
  else
    {
      bool record = best_above_byte - bytepos > 5000;

      while (best_above_byte > bytepos)
	{
	  best_above--;
	  best_above_byte -= buf_prev_char_len (b, best_above_byte);
	}

      /* If this position is quite far from the nearest known position,
	 cache the correspondence by creating a marker here.
	 It will last until the next GC.
	 But don't do it if BUF_MARKERS is nil;
	 that is a signal from Fset_buffer_multibyte.  */
      if (record && BUF_MARKERS (b))
	build_marker (b, best_above, best_above_byte);
      byte_char_debug_check (b, best_above, best_above_byte);

      cached_buffer = b;
      cached_modiff = BUF_MODIFF (b);
      cached_charpos = best_above;
      cached_bytepos = best_above_byte;

      return best_above;
    }
}

#undef CONSIDER
\f
/* Operations on markers. */

DEFUN ("marker-buffer", Fmarker_buffer, Smarker_buffer, 1, 1, 0,
       doc: /* Return the buffer that MARKER points into, or nil if none.
Returns nil if MARKER points into a dead buffer.  */)
  (register Lisp_Object marker)
{
  register Lisp_Object buf;
  CHECK_MARKER (marker);
  if (XMARKER (marker)->buffer)
    {
      XSETBUFFER (buf, XMARKER (marker)->buffer);
      /* If the buffer is dead, we're in trouble: the buffer pointer here
	 does not preserve the buffer from being GC'd (it's weak), so
	 markers have to be unlinked from their buffer as soon as the buffer
	 is killed.  */
      eassert (BUFFER_LIVE_P (XBUFFER (buf)));
      return buf;
    }
  return Qnil;
}

DEFUN ("marker-position", Fmarker_position, Smarker_position, 1, 1, 0,
       doc: /* Return the position of MARKER, or nil if it points nowhere.  */)
  (Lisp_Object marker)
{
  CHECK_MARKER (marker);
  if (XMARKER (marker)->buffer)
    return make_fixnum (XMARKER (marker)->charpos);

  return Qnil;
}

DEFUN ("marker-last-position", Fmarker_last_position, Smarker_last_position, 1, 1, 0,
       doc: /* Return last position of MARKER in its buffer.
This is like `marker-position' with one exception:  If the buffer of
MARKER is dead, it returns the last position of MARKER in that buffer
before it was killed.  */)
  (Lisp_Object marker)
{
  CHECK_MARKER (marker);

  return make_fixnum (XMARKER (marker)->charpos);
}

/* Change M so it points to B at CHARPOS and BYTEPOS.  */

static void
attach_marker (struct Lisp_Marker *m, struct buffer *b,
	       ptrdiff_t charpos, ptrdiff_t bytepos)
{
  /* In a single-byte buffer, two positions must be equal.
     Otherwise, every character is at least one byte.  */
  if (BUF_Z (b) == BUF_Z_BYTE (b))
    eassert (charpos == bytepos);
  else
    eassert (charpos <= bytepos);

  m->charpos = charpos;
  m->bytepos = bytepos;

  if (m->buffer != b)
    {
      unchain_marker (m);
      m->buffer = b;
#ifdef HAVE_MPS
      igc_add_marker (b, m);
#else
      m->next = BUF_MARKERS (b);
      BUF_MARKERS (b) = m;
#endif
    }
}

/* If BUFFER is nil, return current buffer pointer.  Next, check
   whether BUFFER is a buffer object and return buffer pointer
   corresponding to BUFFER if BUFFER is live, or NULL otherwise.  */

static struct buffer *
live_buffer (Lisp_Object buffer)
{
  struct buffer *b = decode_buffer (buffer);
  return BUFFER_LIVE_P (b) ? b : NULL;
}

/* Internal function to set MARKER in BUFFER at POSITION.  Non-zero
   RESTRICTED means limit the POSITION by the visible part of BUFFER.  */

static Lisp_Object
set_marker_internal (Lisp_Object marker, Lisp_Object position,
		     Lisp_Object buffer, bool restricted)
{
  struct Lisp_Marker *m;
  struct buffer *b = live_buffer (buffer);

  CHECK_MARKER (marker);
  m = XMARKER (marker);

  /* Set MARKER to point nowhere if BUFFER is dead, or
     POSITION is nil or a marker points to nowhere.  */
  if (NILP (position)
      || (MARKERP (position) && !XMARKER (position)->buffer)
      || !b)
    unchain_marker (m);

  /* Optimize the special case where we are copying the position of
     an existing marker, and MARKER is already in the same buffer.  */
  else if (MARKERP (position) && b == XMARKER (position)->buffer
	   && b == m->buffer)
    {
      m->bytepos = XMARKER (position)->bytepos;
      m->charpos = XMARKER (position)->charpos;
    }

  else
    {
      register ptrdiff_t charpos, bytepos;

      /* Do not use CHECK_FIXNUM_COERCE_MARKER because we
	 don't want to call buf_charpos_to_bytepos if POSITION
	 is a marker and so we know the bytepos already.  */
      if (FIXNUMP (position))
	{
#if EMACS_INT_MAX > PTRDIFF_MAX
	  /* A --with-wide-int build.  */
	  EMACS_INT cpos = XFIXNUM (position);
	  if (cpos > PTRDIFF_MAX)
	    cpos = PTRDIFF_MAX;
	  charpos = cpos;
	  bytepos = -1;
#else
	  charpos = XFIXNUM (position), bytepos = -1;
#endif
	}
      else if (MARKERP (position))
	{
	  charpos = XMARKER (position)->charpos;
	  bytepos = XMARKER (position)->bytepos;
	}
      else
	wrong_type_argument (Qinteger_or_marker_p, position);

      charpos = clip_to_bounds
	(restricted ? BUF_BEGV (b) : BUF_BEG (b), charpos,
	 restricted ? BUF_ZV (b) : BUF_Z (b));
      /* Don't believe BYTEPOS if it comes from a different buffer,
	 since that buffer might have a very different correspondence
	 between character and byte positions.  */
      if (bytepos == -1
	  || !(MARKERP (position) && XMARKER (position)->buffer == b))
	bytepos = buf_charpos_to_bytepos (b, charpos);
      else
	bytepos = clip_to_bounds
	  (restricted ? BUF_BEGV_BYTE (b) : BUF_BEG_BYTE (b),
	   bytepos, restricted ? BUF_ZV_BYTE (b) : BUF_Z_BYTE (b));

      attach_marker (m, b, charpos, bytepos);
    }

#ifdef HAVE_TEXT_CONVERSION

  /* If B is the buffer's mark and there is a window displaying B, and
     text conversion is enabled while the mark is active, redisplay
     the buffer.

     propagate_window_redisplay will propagate this redisplay to the
     window, which will eventually reach
     mark_window_display_accurate_1.  At that point,
     report_point_change will be told to update the mark as seen by
     the input method.

     This is done all the way in (the seemingly irrelevant) redisplay
     because the selection reported to the input method is actually what
     is visible on screen, namely w->last_point.  */

  if (m->buffer
      && EQ (marker, BVAR (m->buffer, mark))
      && !NILP (BVAR (m->buffer, mark_active))
      && buffer_window_count (m->buffer))
    bset_redisplay (m->buffer);

#endif

  return marker;
}

DEFUN ("set-marker", Fset_marker, Sset_marker, 2, 3, 0,
       doc: /* Position MARKER before character number POSITION in BUFFER.
If BUFFER is omitted or nil, it defaults to the current buffer.  If
POSITION is nil, makes marker point nowhere so it no longer slows down
editing in any buffer.  Returns MARKER.  */)
  (Lisp_Object marker, Lisp_Object position, Lisp_Object buffer)
{
  return set_marker_internal (marker, position, buffer, false);
}

/* Like the above, but won't let the position be outside the visible part.  */

Lisp_Object
set_marker_restricted (Lisp_Object marker, Lisp_Object position,
		       Lisp_Object buffer)
{
  return set_marker_internal (marker, position, buffer, true);
}

/* Set the position of MARKER, specifying both the
   character position and the corresponding byte position.  */

Lisp_Object
set_marker_both (Lisp_Object marker, Lisp_Object buffer,
		 ptrdiff_t charpos, ptrdiff_t bytepos)
{
  register struct Lisp_Marker *m;
  register struct buffer *b = live_buffer (buffer);

  CHECK_MARKER (marker);
  m = XMARKER (marker);

  if (b)
    attach_marker (m, b, charpos, bytepos);
  else
    unchain_marker (m);
  return marker;
}

/* Like the above, but won't let the position be outside the visible part.  */

Lisp_Object
set_marker_restricted_both (Lisp_Object marker, Lisp_Object buffer,
			    ptrdiff_t charpos, ptrdiff_t bytepos)
{
  register struct Lisp_Marker *m;
  register struct buffer *b = live_buffer (buffer);

  CHECK_MARKER (marker);
  m = XMARKER (marker);

  if (b)
    {
      attach_marker
	(m, b,
	 clip_to_bounds (BUF_BEGV (b), charpos, BUF_ZV (b)),
	 clip_to_bounds (BUF_BEGV_BYTE (b), bytepos, BUF_ZV_BYTE (b)));
    }
  else
    unchain_marker (m);
  return marker;
}

/* Detach a marker so that it no longer points anywhere and no longer
   slows down editing.  Do not free the marker, though, as a change
   function could have inserted it into an undo list (Bug#30931).  */

void
detach_marker (Lisp_Object marker)
{
  Fset_marker (marker, Qnil, Qnil);
}

/* Remove MARKER from the chain of whatever buffer it is in.  Set its
   buffer NULL.  */

void
unchain_marker (register struct Lisp_Marker *marker)
{
  register struct buffer *b = marker->buffer;

  if (b)
    {
#ifdef HAVE_MPS
      igc_remove_marker (b, marker);
#else
      register struct Lisp_Marker *tail, **prev;

      /* No dead buffers here.  */
      eassert (BUFFER_LIVE_P (b));

      marker->buffer = NULL;
      prev = &BUF_MARKERS (b);

      for (tail = BUF_MARKERS (b); tail; prev = &tail->next, tail = *prev)
	if (marker == tail)
	  {
	    if (*prev == BUF_MARKERS (b))
	      {
		/* Deleting first marker from the buffer's chain.  Crash
		   if new first marker in chain does not say it belongs
		   to the same buffer, or at least that they have the same
		   base buffer.  */
		if (tail->next && b->text != tail->next->buffer->text)
		  emacs_abort ();
	      }
	    *prev = tail->next;
	    /* We have removed the marker from the chain;
	       no need to scan the rest of the chain.  */
	    break;
	  }

      /* Error if marker was not in it's chain.  */
      eassert (tail != NULL);
#endif
    }
}

/* Return the char position of marker MARKER, as a C integer.  */

ptrdiff_t
marker_position (Lisp_Object marker)
{
  register struct Lisp_Marker *m = XMARKER (marker);
  register struct buffer *buf = m->buffer;

  if (!buf)
    error ("Marker does not point anywhere");

  eassert (BUF_BEG (buf) <= m->charpos && m->charpos <= BUF_Z (buf));

  return m->charpos;
}

/* Return the byte position of marker MARKER, as a C integer.  */

ptrdiff_t
marker_byte_position (Lisp_Object marker)
{
  register struct Lisp_Marker *m = XMARKER (marker);
  register struct buffer *buf = m->buffer;

  if (!buf)
    error ("Marker does not point anywhere");

  eassert (BUF_BEG_BYTE (buf) <= m->bytepos && m->bytepos <= BUF_Z_BYTE (buf));

  return m->bytepos;
}
\f
DEFUN ("copy-marker", Fcopy_marker, Scopy_marker, 0, 2, 0,
       doc: /* Return a new marker pointing at the same place as MARKER.
If argument is a number, makes a new marker pointing
at that position in the current buffer.
If MARKER is not specified, the new marker does not point anywhere.
The optional argument TYPE specifies the insertion type of the new marker;
see `marker-insertion-type'.  */)
  (register Lisp_Object marker, Lisp_Object type)
{
  register Lisp_Object new;

  if (!NILP (marker))
  CHECK_TYPE (FIXNUMP (marker) || MARKERP (marker), Qinteger_or_marker_p, marker);

  new = Fmake_marker ();
  Fset_marker (new, marker,
	       (MARKERP (marker) ? Fmarker_buffer (marker) : Qnil));
  XMARKER (new)->insertion_type = !NILP (type);
  return new;
}

DEFUN ("marker-insertion-type", Fmarker_insertion_type,
       Smarker_insertion_type, 1, 1, 0,
       doc: /* Return insertion type of MARKER: t if it stays after inserted text.
The value nil means the marker stays before text inserted there.  */)
  (register Lisp_Object marker)
{
  CHECK_MARKER (marker);
  return XMARKER (marker)->insertion_type ? Qt : Qnil;
}

DEFUN ("set-marker-insertion-type", Fset_marker_insertion_type,
       Sset_marker_insertion_type, 2, 2, 0,
       doc: /* Set the insertion-type of MARKER to TYPE.
If TYPE is t, it means the marker advances when you insert text at it.
If TYPE is nil, it means the marker stays behind when you insert text at it.  */)
  (Lisp_Object marker, Lisp_Object type)
{
  CHECK_MARKER (marker);

  XMARKER (marker)->insertion_type = ! NILP (type);
  return type;
}

#ifdef MARKER_DEBUG

/* For debugging -- count the markers in buffer BUF.  */

int
count_markers (struct buffer *buf)
{
  int total = 0;
  struct Lisp_Marker *tail;

  for (tail = BUF_MARKERS (buf); tail; tail = tail->next)
    total++;

  return total;
}

/* For debugging -- recompute the bytepos corresponding
   to CHARPOS in the simplest, most reliable way.  */

ptrdiff_t
verify_bytepos (ptrdiff_t charpos)
{
  ptrdiff_t below = BEG;
  ptrdiff_t below_byte = BEG_BYTE;

  while (below != charpos)
    {
      below++;
      below_byte += buf_next_char_len (current_buffer, below_byte);
    }

  return below_byte;
}

#endif /* MARKER_DEBUG */
\f
void
syms_of_marker (void)
{
  defsubr (&Smarker_position);
  defsubr (&Smarker_last_position);
  defsubr (&Smarker_buffer);
  defsubr (&Sset_marker);
  defsubr (&Scopy_marker);
  defsubr (&Smarker_insertion_type);
  defsubr (&Sset_marker_insertion_type);
}

debug log:

solving 005f66f6f24 ...
found 005f66f6f24 in https://yhetil.org/emacs-devel/87a5hqsq2l.fsf_-_@gmail.com/
found 5db46e599ae in https://git.savannah.gnu.org/cgit/emacs.git
preparing index
index prepared:
100644 5db46e599ae01e2ee8784aa6fd2dcfff5196f226	src/marker.c

applying [1/1] https://yhetil.org/emacs-devel/87a5hqsq2l.fsf_-_@gmail.com/
diff --git a/src/marker.c b/src/marker.c
index 5db46e599ae..005f66f6f24 100644

Checking patch src/marker.c...
Applied patch src/marker.c cleanly.

index at:
100644 005f66f6f249017431aafec37acdbf45e2084d13	src/marker.c

(*) Git path names are given by the tree(s) the blob belongs to.
    Blobs themselves have no identifier aside from the hash of its contents.^

Code repositories for project(s) associated with this public inbox

	https://git.savannah.gnu.org/cgit/emacs.git

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).