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[emacs.git] / src / marker.c
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1 /* Markers: examining, setting and deleting.
2 Copyright (C) 1985, 1997, 1998, 2001, 2002, 2003, 2004, 2005, 2006,
3 2007, 2008, 2009 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 3 of the License, or
10 (at your option) any later version.
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. If not, see <http://www.gnu.org/licenses/>. */
21 #include <config.h>
22 #include "lisp.h"
23 #include "buffer.h"
24 #include "character.h"
26 /* Record one cached position found recently by
27 buf_charpos_to_bytepos or buf_bytepos_to_charpos. */
29 static int cached_charpos;
30 static int cached_bytepos;
31 static struct buffer *cached_buffer;
32 static int cached_modiff;
34 static void byte_char_debug_check P_ ((struct buffer *, int, int));
36 /* Nonzero means enable debugging checks on byte/char correspondences. */
38 static int byte_debug_flag;
40 void
41 clear_charpos_cache (b)
42 struct buffer *b;
44 if (cached_buffer == b)
45 cached_buffer = 0;
48 /* Converting between character positions and byte positions. */
50 /* There are several places in the buffer where we know
51 the correspondence: BEG, BEGV, PT, GPT, ZV and Z,
52 and everywhere there is a marker. So we find the one of these places
53 that is closest to the specified position, and scan from there. */
55 /* charpos_to_bytepos returns the byte position corresponding to CHARPOS. */
57 /* This macro is a subroutine of charpos_to_bytepos.
58 Note that it is desirable that BYTEPOS is not evaluated
59 except when we really want its value. */
61 #define CONSIDER(CHARPOS, BYTEPOS) \
62 { \
63 int this_charpos = (CHARPOS); \
64 int changed = 0; \
66 if (this_charpos == charpos) \
67 { \
68 int value = (BYTEPOS); \
69 if (byte_debug_flag) \
70 byte_char_debug_check (b, charpos, value); \
71 return value; \
72 } \
73 else if (this_charpos > charpos) \
74 { \
75 if (this_charpos < best_above) \
76 { \
77 best_above = this_charpos; \
78 best_above_byte = (BYTEPOS); \
79 changed = 1; \
80 } \
81 } \
82 else if (this_charpos > best_below) \
83 { \
84 best_below = this_charpos; \
85 best_below_byte = (BYTEPOS); \
86 changed = 1; \
87 } \
89 if (changed) \
90 { \
91 if (best_above - best_below == best_above_byte - best_below_byte) \
92 { \
93 int value = best_below_byte + (charpos - best_below); \
94 if (byte_debug_flag) \
95 byte_char_debug_check (b, charpos, value); \
96 return value; \
97 } \
98 } \
101 static void
102 byte_char_debug_check (b, charpos, bytepos)
103 struct buffer *b;
104 int charpos, bytepos;
106 int nchars = 0;
108 if (bytepos > BUF_GPT_BYTE (b))
110 nchars = multibyte_chars_in_text (BUF_BEG_ADDR (b),
111 BUF_GPT_BYTE (b) - BUF_BEG_BYTE (b));
112 nchars += multibyte_chars_in_text (BUF_GAP_END_ADDR (b),
113 bytepos - BUF_GPT_BYTE (b));
115 else
116 nchars = multibyte_chars_in_text (BUF_BEG_ADDR (b),
117 bytepos - BUF_BEG_BYTE (b));
119 if (charpos - 1 != nchars)
120 abort ();
124 charpos_to_bytepos (charpos)
125 int charpos;
127 return buf_charpos_to_bytepos (current_buffer, charpos);
131 buf_charpos_to_bytepos (b, charpos)
132 struct buffer *b;
133 int charpos;
135 struct Lisp_Marker *tail;
136 int best_above, best_above_byte;
137 int best_below, best_below_byte;
139 if (charpos < BUF_BEG (b) || charpos > BUF_Z (b))
140 abort ();
142 best_above = BUF_Z (b);
143 best_above_byte = BUF_Z_BYTE (b);
145 /* If this buffer has as many characters as bytes,
146 each character must be one byte.
147 This takes care of the case where enable-multibyte-characters is nil. */
148 if (best_above == best_above_byte)
149 return charpos;
151 best_below = BEG;
152 best_below_byte = BEG_BYTE;
154 /* We find in best_above and best_above_byte
155 the closest known point above CHARPOS,
156 and in best_below and best_below_byte
157 the closest known point below CHARPOS,
159 If at any point we can tell that the space between those
160 two best approximations is all single-byte,
161 we interpolate the result immediately. */
163 CONSIDER (BUF_PT (b), BUF_PT_BYTE (b));
164 CONSIDER (BUF_GPT (b), BUF_GPT_BYTE (b));
165 CONSIDER (BUF_BEGV (b), BUF_BEGV_BYTE (b));
166 CONSIDER (BUF_ZV (b), BUF_ZV_BYTE (b));
168 if (b == cached_buffer && BUF_MODIFF (b) == cached_modiff)
169 CONSIDER (cached_charpos, cached_bytepos);
171 for (tail = BUF_MARKERS (b); tail; tail = tail->next)
173 CONSIDER (tail->charpos, tail->bytepos);
175 /* If we are down to a range of 50 chars,
176 don't bother checking any other markers;
177 scan the intervening chars directly now. */
178 if (best_above - best_below < 50)
179 break;
182 /* We get here if we did not exactly hit one of the known places.
183 We have one known above and one known below.
184 Scan, counting characters, from whichever one is closer. */
186 if (charpos - best_below < best_above - charpos)
188 int record = charpos - best_below > 5000;
190 while (best_below != charpos)
192 best_below++;
193 BUF_INC_POS (b, best_below_byte);
196 /* If this position is quite far from the nearest known position,
197 cache the correspondence by creating a marker here.
198 It will last until the next GC. */
199 if (record)
201 Lisp_Object marker, buffer;
202 marker = Fmake_marker ();
203 XSETBUFFER (buffer, b);
204 set_marker_both (marker, buffer, best_below, best_below_byte);
207 if (byte_debug_flag)
208 byte_char_debug_check (b, charpos, best_below_byte);
210 cached_buffer = b;
211 cached_modiff = BUF_MODIFF (b);
212 cached_charpos = best_below;
213 cached_bytepos = best_below_byte;
215 return best_below_byte;
217 else
219 int record = best_above - charpos > 5000;
221 while (best_above != charpos)
223 best_above--;
224 BUF_DEC_POS (b, best_above_byte);
227 /* If this position is quite far from the nearest known position,
228 cache the correspondence by creating a marker here.
229 It will last until the next GC. */
230 if (record)
232 Lisp_Object marker, buffer;
233 marker = Fmake_marker ();
234 XSETBUFFER (buffer, b);
235 set_marker_both (marker, buffer, best_above, best_above_byte);
238 if (byte_debug_flag)
239 byte_char_debug_check (b, charpos, best_above_byte);
241 cached_buffer = b;
242 cached_modiff = BUF_MODIFF (b);
243 cached_charpos = best_above;
244 cached_bytepos = best_above_byte;
246 return best_above_byte;
250 #undef CONSIDER
252 /* Used for debugging: recompute the bytepos corresponding to CHARPOS
253 in the simplest, most reliable way. */
256 verify_bytepos (charpos)
257 int charpos;
259 int below = 1;
260 int below_byte = 1;
262 while (below != charpos)
264 below++;
265 BUF_INC_POS (current_buffer, below_byte);
268 return below_byte;
271 /* bytepos_to_charpos returns the char position corresponding to BYTEPOS. */
273 /* This macro is a subroutine of bytepos_to_charpos.
274 It is used when BYTEPOS is actually the byte position. */
276 #define CONSIDER(BYTEPOS, CHARPOS) \
278 int this_bytepos = (BYTEPOS); \
279 int changed = 0; \
281 if (this_bytepos == bytepos) \
283 int value = (CHARPOS); \
284 if (byte_debug_flag) \
285 byte_char_debug_check (b, value, bytepos); \
286 return value; \
288 else if (this_bytepos > bytepos) \
290 if (this_bytepos < best_above_byte) \
292 best_above = (CHARPOS); \
293 best_above_byte = this_bytepos; \
294 changed = 1; \
297 else if (this_bytepos > best_below_byte) \
299 best_below = (CHARPOS); \
300 best_below_byte = this_bytepos; \
301 changed = 1; \
304 if (changed) \
306 if (best_above - best_below == best_above_byte - best_below_byte) \
308 int value = best_below + (bytepos - best_below_byte); \
309 if (byte_debug_flag) \
310 byte_char_debug_check (b, value, bytepos); \
311 return value; \
317 bytepos_to_charpos (bytepos)
318 int bytepos;
320 return buf_bytepos_to_charpos (current_buffer, bytepos);
324 buf_bytepos_to_charpos (b, bytepos)
325 struct buffer *b;
326 int bytepos;
328 struct Lisp_Marker *tail;
329 int best_above, best_above_byte;
330 int best_below, best_below_byte;
332 if (bytepos < BUF_BEG_BYTE (b) || bytepos > BUF_Z_BYTE (b))
333 abort ();
335 best_above = BUF_Z (b);
336 best_above_byte = BUF_Z_BYTE (b);
338 /* If this buffer has as many characters as bytes,
339 each character must be one byte.
340 This takes care of the case where enable-multibyte-characters is nil. */
341 if (best_above == best_above_byte)
342 return bytepos;
344 best_below = BEG;
345 best_below_byte = BEG_BYTE;
347 CONSIDER (BUF_PT_BYTE (b), BUF_PT (b));
348 CONSIDER (BUF_GPT_BYTE (b), BUF_GPT (b));
349 CONSIDER (BUF_BEGV_BYTE (b), BUF_BEGV (b));
350 CONSIDER (BUF_ZV_BYTE (b), BUF_ZV (b));
352 if (b == cached_buffer && BUF_MODIFF (b) == cached_modiff)
353 CONSIDER (cached_bytepos, cached_charpos);
355 for (tail = BUF_MARKERS (b); tail; tail = tail->next)
357 CONSIDER (tail->bytepos, tail->charpos);
359 /* If we are down to a range of 50 chars,
360 don't bother checking any other markers;
361 scan the intervening chars directly now. */
362 if (best_above - best_below < 50)
363 break;
366 /* We get here if we did not exactly hit one of the known places.
367 We have one known above and one known below.
368 Scan, counting characters, from whichever one is closer. */
370 if (bytepos - best_below_byte < best_above_byte - bytepos)
372 int record = bytepos - best_below_byte > 5000;
374 while (best_below_byte < bytepos)
376 best_below++;
377 BUF_INC_POS (b, best_below_byte);
380 /* If this position is quite far from the nearest known position,
381 cache the correspondence by creating a marker here.
382 It will last until the next GC.
383 But don't do it if BUF_MARKERS is nil;
384 that is a signal from Fset_buffer_multibyte. */
385 if (record && BUF_MARKERS (b))
387 Lisp_Object marker, buffer;
388 marker = Fmake_marker ();
389 XSETBUFFER (buffer, b);
390 set_marker_both (marker, buffer, best_below, best_below_byte);
393 if (byte_debug_flag)
394 byte_char_debug_check (b, best_below, bytepos);
396 cached_buffer = b;
397 cached_modiff = BUF_MODIFF (b);
398 cached_charpos = best_below;
399 cached_bytepos = best_below_byte;
401 return best_below;
403 else
405 int record = best_above_byte - bytepos > 5000;
407 while (best_above_byte > bytepos)
409 best_above--;
410 BUF_DEC_POS (b, best_above_byte);
413 /* If this position is quite far from the nearest known position,
414 cache the correspondence by creating a marker here.
415 It will last until the next GC.
416 But don't do it if BUF_MARKERS is nil;
417 that is a signal from Fset_buffer_multibyte. */
418 if (record && BUF_MARKERS (b))
420 Lisp_Object marker, buffer;
421 marker = Fmake_marker ();
422 XSETBUFFER (buffer, b);
423 set_marker_both (marker, buffer, best_above, best_above_byte);
426 if (byte_debug_flag)
427 byte_char_debug_check (b, best_above, bytepos);
429 cached_buffer = b;
430 cached_modiff = BUF_MODIFF (b);
431 cached_charpos = best_above;
432 cached_bytepos = best_above_byte;
434 return best_above;
438 #undef CONSIDER
440 /* Operations on markers. */
442 DEFUN ("marker-buffer", Fmarker_buffer, Smarker_buffer, 1, 1, 0,
443 doc: /* Return the buffer that MARKER points into, or nil if none.
444 Returns nil if MARKER points into a dead buffer. */)
445 (marker)
446 register Lisp_Object marker;
448 register Lisp_Object buf;
449 CHECK_MARKER (marker);
450 if (XMARKER (marker)->buffer)
452 XSETBUFFER (buf, XMARKER (marker)->buffer);
453 /* If the buffer is dead, we're in trouble: the buffer pointer here
454 does not preserve the buffer from being GC'd (it's weak), so
455 markers have to be unlinked from their buffer as soon as the buffer
456 is killed. */
457 eassert (!NILP (XBUFFER (buf)->name));
458 return buf;
460 return Qnil;
463 DEFUN ("marker-position", Fmarker_position, Smarker_position, 1, 1, 0,
464 doc: /* Return the position MARKER points at, as a character number.
465 Returns nil if MARKER points nowhere. */)
466 (marker)
467 Lisp_Object marker;
469 CHECK_MARKER (marker);
470 if (XMARKER (marker)->buffer)
471 return make_number (XMARKER (marker)->charpos);
473 return Qnil;
476 DEFUN ("set-marker", Fset_marker, Sset_marker, 2, 3, 0,
477 doc: /* Position MARKER before character number POSITION in BUFFER.
478 BUFFER defaults to the current buffer.
479 If POSITION is nil, makes marker point nowhere.
480 Then it no longer slows down editing in any buffer.
481 Returns MARKER. */)
482 (marker, position, buffer)
483 Lisp_Object marker, position, buffer;
485 register int charno, bytepos;
486 register struct buffer *b;
487 register struct Lisp_Marker *m;
489 CHECK_MARKER (marker);
490 m = XMARKER (marker);
492 /* If position is nil or a marker that points nowhere,
493 make this marker point nowhere. */
494 if (NILP (position)
495 || (MARKERP (position) && !XMARKER (position)->buffer))
497 unchain_marker (m);
498 return marker;
501 if (NILP (buffer))
502 b = current_buffer;
503 else
505 CHECK_BUFFER (buffer);
506 b = XBUFFER (buffer);
507 /* If buffer is dead, set marker to point nowhere. */
508 if (EQ (b->name, Qnil))
510 unchain_marker (m);
511 return marker;
515 /* Optimize the special case where we are copying the position
516 of an existing marker, and MARKER is already in the same buffer. */
517 if (MARKERP (position) && b == XMARKER (position)->buffer
518 && b == m->buffer)
520 m->bytepos = XMARKER (position)->bytepos;
521 m->charpos = XMARKER (position)->charpos;
522 return marker;
525 CHECK_NUMBER_COERCE_MARKER (position);
527 charno = XINT (position);
529 if (charno < BUF_BEG (b))
530 charno = BUF_BEG (b);
531 if (charno > BUF_Z (b))
532 charno = BUF_Z (b);
534 bytepos = buf_charpos_to_bytepos (b, charno);
536 /* Every character is at least one byte. */
537 if (charno > bytepos)
538 abort ();
540 m->bytepos = bytepos;
541 m->charpos = charno;
543 if (m->buffer != b)
545 unchain_marker (m);
546 m->buffer = b;
547 m->next = BUF_MARKERS (b);
548 BUF_MARKERS (b) = m;
551 return marker;
554 /* This version of Fset_marker won't let the position
555 be outside the visible part. */
557 Lisp_Object
558 set_marker_restricted (marker, pos, buffer)
559 Lisp_Object marker, pos, buffer;
561 register int charno, bytepos;
562 register struct buffer *b;
563 register struct Lisp_Marker *m;
565 CHECK_MARKER (marker);
566 m = XMARKER (marker);
568 /* If position is nil or a marker that points nowhere,
569 make this marker point nowhere. */
570 if (NILP (pos)
571 || (MARKERP (pos) && !XMARKER (pos)->buffer))
573 unchain_marker (m);
574 return marker;
577 if (NILP (buffer))
578 b = current_buffer;
579 else
581 CHECK_BUFFER (buffer);
582 b = XBUFFER (buffer);
583 /* If buffer is dead, set marker to point nowhere. */
584 if (EQ (b->name, Qnil))
586 unchain_marker (m);
587 return marker;
591 /* Optimize the special case where we are copying the position
592 of an existing marker, and MARKER is already in the same buffer. */
593 if (MARKERP (pos) && b == XMARKER (pos)->buffer
594 && b == m->buffer)
596 m->bytepos = XMARKER (pos)->bytepos;
597 m->charpos = XMARKER (pos)->charpos;
598 return marker;
601 CHECK_NUMBER_COERCE_MARKER (pos);
603 charno = XINT (pos);
605 if (charno < BUF_BEGV (b))
606 charno = BUF_BEGV (b);
607 if (charno > BUF_ZV (b))
608 charno = BUF_ZV (b);
610 bytepos = buf_charpos_to_bytepos (b, charno);
612 /* Every character is at least one byte. */
613 if (charno > bytepos)
614 abort ();
616 m->bytepos = bytepos;
617 m->charpos = charno;
619 if (m->buffer != b)
621 unchain_marker (m);
622 m->buffer = b;
623 m->next = BUF_MARKERS (b);
624 BUF_MARKERS (b) = m;
627 return marker;
630 /* Set the position of MARKER, specifying both the
631 character position and the corresponding byte position. */
633 Lisp_Object
634 set_marker_both (marker, buffer, charpos, bytepos)
635 Lisp_Object marker, buffer;
636 int charpos, bytepos;
638 register struct buffer *b;
639 register struct Lisp_Marker *m;
641 CHECK_MARKER (marker);
642 m = XMARKER (marker);
644 if (NILP (buffer))
645 b = current_buffer;
646 else
648 CHECK_BUFFER (buffer);
649 b = XBUFFER (buffer);
650 /* If buffer is dead, set marker to point nowhere. */
651 if (EQ (b->name, Qnil))
653 unchain_marker (m);
654 return marker;
658 /* In a single-byte buffer, the two positions must be equal. */
659 if (BUF_Z (b) == BUF_Z_BYTE (b)
660 && charpos != bytepos)
661 abort ();
662 /* Every character is at least one byte. */
663 if (charpos > bytepos)
664 abort ();
666 m->bytepos = bytepos;
667 m->charpos = charpos;
669 if (m->buffer != b)
671 unchain_marker (m);
672 m->buffer = b;
673 m->next = BUF_MARKERS (b);
674 BUF_MARKERS (b) = m;
677 return marker;
680 /* This version of set_marker_both won't let the position
681 be outside the visible part. */
683 Lisp_Object
684 set_marker_restricted_both (marker, buffer, charpos, bytepos)
685 Lisp_Object marker, buffer;
686 int charpos, bytepos;
688 register struct buffer *b;
689 register struct Lisp_Marker *m;
691 CHECK_MARKER (marker);
692 m = XMARKER (marker);
694 if (NILP (buffer))
695 b = current_buffer;
696 else
698 CHECK_BUFFER (buffer);
699 b = XBUFFER (buffer);
700 /* If buffer is dead, set marker to point nowhere. */
701 if (EQ (b->name, Qnil))
703 unchain_marker (m);
704 return marker;
708 if (charpos < BUF_BEGV (b))
709 charpos = BUF_BEGV (b);
710 if (charpos > BUF_ZV (b))
711 charpos = BUF_ZV (b);
712 if (bytepos < BUF_BEGV_BYTE (b))
713 bytepos = BUF_BEGV_BYTE (b);
714 if (bytepos > BUF_ZV_BYTE (b))
715 bytepos = BUF_ZV_BYTE (b);
717 /* In a single-byte buffer, the two positions must be equal. */
718 if (BUF_Z (b) == BUF_Z_BYTE (b)
719 && charpos != bytepos)
720 abort ();
721 /* Every character is at least one byte. */
722 if (charpos > bytepos)
723 abort ();
725 m->bytepos = bytepos;
726 m->charpos = charpos;
728 if (m->buffer != b)
730 unchain_marker (m);
731 m->buffer = b;
732 m->next = BUF_MARKERS (b);
733 BUF_MARKERS (b) = m;
736 return marker;
739 /* Remove MARKER from the chain of whatever buffer it is in.
740 Leave it "in no buffer".
742 This is called during garbage collection,
743 so we must be careful to ignore and preserve mark bits,
744 including those in chain fields of markers. */
746 void
747 unchain_marker (marker)
748 register struct Lisp_Marker *marker;
750 register struct Lisp_Marker *tail, *prev, *next;
751 register struct buffer *b;
753 b = marker->buffer;
754 if (b == 0)
755 return;
757 if (EQ (b->name, Qnil))
758 abort ();
760 marker->buffer = 0;
762 tail = BUF_MARKERS (b);
763 prev = NULL;
764 while (tail)
766 next = tail->next;
768 if (marker == tail)
770 if (!prev)
772 BUF_MARKERS (b) = next;
773 /* Deleting first marker from the buffer's chain. Crash
774 if new first marker in chain does not say it belongs
775 to the same buffer, or at least that they have the same
776 base buffer. */
777 if (next && b->text != next->buffer->text)
778 abort ();
780 else
781 prev->next = next;
782 /* We have removed the marker from the chain;
783 no need to scan the rest of the chain. */
784 return;
786 else
787 prev = tail;
788 tail = next;
791 /* Marker was not in its chain. */
792 abort ();
795 /* Return the char position of marker MARKER, as a C integer. */
798 marker_position (marker)
799 Lisp_Object marker;
801 register struct Lisp_Marker *m = XMARKER (marker);
802 register struct buffer *buf = m->buffer;
804 if (!buf)
805 error ("Marker does not point anywhere");
807 return m->charpos;
810 /* Return the byte position of marker MARKER, as a C integer. */
813 marker_byte_position (marker)
814 Lisp_Object marker;
816 register struct Lisp_Marker *m = XMARKER (marker);
817 register struct buffer *buf = m->buffer;
818 register int i = m->bytepos;
820 if (!buf)
821 error ("Marker does not point anywhere");
823 if (i < BUF_BEG_BYTE (buf) || i > BUF_Z_BYTE (buf))
824 abort ();
826 return i;
829 DEFUN ("copy-marker", Fcopy_marker, Scopy_marker, 1, 2, 0,
830 doc: /* Return a new marker pointing at the same place as MARKER.
831 If argument is a number, makes a new marker pointing
832 at that position in the current buffer.
833 The optional argument TYPE specifies the insertion type of the new marker;
834 see `marker-insertion-type'. */)
835 (marker, type)
836 register Lisp_Object marker, type;
838 register Lisp_Object new;
840 CHECK_TYPE (INTEGERP (marker) || MARKERP (marker), Qinteger_or_marker_p, marker);
842 new = Fmake_marker ();
843 Fset_marker (new, marker,
844 (MARKERP (marker) ? Fmarker_buffer (marker) : Qnil));
845 XMARKER (new)->insertion_type = !NILP (type);
846 return new;
849 DEFUN ("marker-insertion-type", Fmarker_insertion_type,
850 Smarker_insertion_type, 1, 1, 0,
851 doc: /* Return insertion type of MARKER: t if it stays after inserted text.
852 The value nil means the marker stays before text inserted there. */)
853 (marker)
854 register Lisp_Object marker;
856 CHECK_MARKER (marker);
857 return XMARKER (marker)->insertion_type ? Qt : Qnil;
860 DEFUN ("set-marker-insertion-type", Fset_marker_insertion_type,
861 Sset_marker_insertion_type, 2, 2, 0,
862 doc: /* Set the insertion-type of MARKER to TYPE.
863 If TYPE is t, it means the marker advances when you insert text at it.
864 If TYPE is nil, it means the marker stays behind when you insert text at it. */)
865 (marker, type)
866 Lisp_Object marker, type;
868 CHECK_MARKER (marker);
870 XMARKER (marker)->insertion_type = ! NILP (type);
871 return type;
874 DEFUN ("buffer-has-markers-at", Fbuffer_has_markers_at, Sbuffer_has_markers_at,
875 1, 1, 0,
876 doc: /* Return t if there are markers pointing at POSITION in the current buffer. */)
877 (position)
878 Lisp_Object position;
880 register struct Lisp_Marker *tail;
881 register int charno;
883 charno = XINT (position);
885 if (charno < BEG)
886 charno = BEG;
887 if (charno > Z)
888 charno = Z;
890 for (tail = BUF_MARKERS (current_buffer); tail; tail = tail->next)
891 if (tail->charpos == charno)
892 return Qt;
894 return Qnil;
897 /* For debugging -- count the markers in buffer BUF. */
900 count_markers (buf)
901 struct buffer *buf;
903 int total = 0;
904 struct Lisp_Marker *tail;
906 for (tail = BUF_MARKERS (buf); tail; tail = tail->next)
907 total++;
909 return total;
912 void
913 syms_of_marker ()
915 defsubr (&Smarker_position);
916 defsubr (&Smarker_buffer);
917 defsubr (&Sset_marker);
918 defsubr (&Scopy_marker);
919 defsubr (&Smarker_insertion_type);
920 defsubr (&Sset_marker_insertion_type);
921 defsubr (&Sbuffer_has_markers_at);
923 DEFVAR_BOOL ("byte-debug-flag", &byte_debug_flag,
924 doc: /* Non-nil enables debugging checks in byte/char position conversions. */);
925 byte_debug_flag = 0;
928 /* arch-tag: 50aa418f-cdd0-4838-b64b-94aa4b2a3b74
929 (do not change this comment) */