editfns.c 142 KB
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/* Lisp functions pertaining to editing.
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Copyright (C) 1985, 1986, 1987, 1989, 1993, 1994, 1995, 1996, 1997,
  1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,
  2009, 2010 Free Software Foundation, Inc.
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This file is part of GNU Emacs.

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GNU Emacs is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
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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
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along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
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#include <config.h>
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#include <sys/types.h>
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#include <stdio.h>
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#include <setjmp.h>
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#ifdef HAVE_PWD_H
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#include <pwd.h>
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#endif

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#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

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#ifdef HAVE_SYS_UTSNAME_H
#include <sys/utsname.h>
#endif

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#include "lisp.h"

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/* systime.h includes <sys/time.h> which, on some systems, is required
   for <sys/resource.h>; thus systime.h must be included before
   <sys/resource.h> */
#include "systime.h"
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#if defined HAVE_SYS_RESOURCE_H
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#include <sys/resource.h>
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#endif

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#include <ctype.h>

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#include "intervals.h"
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#include "buffer.h"
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#include "character.h"
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#include "coding.h"
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#include "frame.h"
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#include "window.h"
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#include "blockinput.h"
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#ifdef STDC_HEADERS
#include <float.h>
#define MAX_10_EXP	DBL_MAX_10_EXP
#else
#define MAX_10_EXP	310
#endif

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#ifndef NULL
#define NULL 0
#endif

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#ifndef USER_FULL_NAME
#define USER_FULL_NAME pw->pw_gecos
#endif

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#ifndef USE_CRT_DLL
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extern char **environ;
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#endif

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#define TM_YEAR_BASE 1900

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/* Nonzero if TM_YEAR is a struct tm's tm_year value that causes
   asctime to have well-defined behavior.  */
#ifndef TM_YEAR_IN_ASCTIME_RANGE
# define TM_YEAR_IN_ASCTIME_RANGE(tm_year) \
    (1000 - TM_YEAR_BASE <= (tm_year) && (tm_year) <= 9999 - TM_YEAR_BASE)
#endif

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extern size_t emacs_strftimeu (char *, size_t, const char *,
                               const struct tm *, int);
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#ifdef WINDOWSNT
extern Lisp_Object w32_get_internal_run_time ();
#endif

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static int tm_diff (struct tm *, struct tm *);
static void find_field (Lisp_Object, Lisp_Object, Lisp_Object, int *, Lisp_Object, int *);
static void update_buffer_properties (int, int);
static Lisp_Object region_limit (int);
int lisp_time_argument (Lisp_Object, time_t *, int *);
static size_t emacs_memftimeu (char *, size_t, const char *,
                               size_t, const struct tm *, int);
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static void general_insert_function (void (*) (const unsigned char *, EMACS_INT),
				     void (*) (Lisp_Object, EMACS_INT,
					       EMACS_INT, EMACS_INT,
					       EMACS_INT, int),
				     int, int, Lisp_Object *);
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static Lisp_Object subst_char_in_region_unwind (Lisp_Object);
static Lisp_Object subst_char_in_region_unwind_1 (Lisp_Object);
static void transpose_markers (int, int, int, int, int, int, int, int);
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Lisp_Object Vbuffer_access_fontify_functions;
Lisp_Object Qbuffer_access_fontify_functions;
Lisp_Object Vbuffer_access_fontified_property;
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Lisp_Object Fuser_full_name (Lisp_Object);
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/* Non-nil means don't stop at field boundary in text motion commands.  */

Lisp_Object Vinhibit_field_text_motion;

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/* Some static data, and a function to initialize it for each run */

Lisp_Object Vsystem_name;
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Lisp_Object Vuser_real_login_name;	/* login name of current user ID */
Lisp_Object Vuser_full_name;		/* full name of current user */
Lisp_Object Vuser_login_name;		/* user name from LOGNAME or USER */
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Lisp_Object Voperating_system_release;  /* Operating System Release */
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/* Symbol for the text property used to mark fields.  */

Lisp_Object Qfield;

/* A special value for Qfield properties.  */

Lisp_Object Qboundary;


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void
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init_editfns (void)
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{
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  char *user_name;
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  register unsigned char *p;
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  struct passwd *pw;	/* password entry for the current user */
  Lisp_Object tem;

  /* Set up system_name even when dumping.  */
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  init_system_name ();
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#ifndef CANNOT_DUMP
  /* Don't bother with this on initial start when just dumping out */
  if (!initialized)
    return;
#endif /* not CANNOT_DUMP */

  pw = (struct passwd *) getpwuid (getuid ());
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#ifdef MSDOS
  /* We let the real user name default to "root" because that's quite
     accurate on MSDOG and because it lets Emacs find the init file.
     (The DVX libraries override the Djgpp libraries here.)  */
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  Vuser_real_login_name = build_string (pw ? pw->pw_name : "root");
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#else
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  Vuser_real_login_name = build_string (pw ? pw->pw_name : "unknown");
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#endif
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  /* Get the effective user name, by consulting environment variables,
     or the effective uid if those are unset.  */
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  user_name = (char *) getenv ("LOGNAME");
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  if (!user_name)
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#ifdef WINDOWSNT
    user_name = (char *) getenv ("USERNAME");	/* it's USERNAME on NT */
#else  /* WINDOWSNT */
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    user_name = (char *) getenv ("USER");
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#endif /* WINDOWSNT */
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  if (!user_name)
    {
      pw = (struct passwd *) getpwuid (geteuid ());
      user_name = (char *) (pw ? pw->pw_name : "unknown");
    }
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  Vuser_login_name = build_string (user_name);
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  /* If the user name claimed in the environment vars differs from
     the real uid, use the claimed name to find the full name.  */
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  tem = Fstring_equal (Vuser_login_name, Vuser_real_login_name);
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  Vuser_full_name = Fuser_full_name (NILP (tem)? make_number (geteuid())
				     : Vuser_login_name);
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  p = (unsigned char *) getenv ("NAME");
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  if (p)
    Vuser_full_name = build_string (p);
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  else if (NILP (Vuser_full_name))
    Vuser_full_name = build_string ("unknown");
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#ifdef HAVE_SYS_UTSNAME_H
  {
    struct utsname uts;
    uname (&uts);
    Voperating_system_release = build_string (uts.release);
  }
#else
  Voperating_system_release = Qnil;
#endif
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}

DEFUN ("char-to-string", Fchar_to_string, Schar_to_string, 1, 1, 0,
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       doc: /* Convert arg CHAR to a string containing that character.
usage: (char-to-string CHAR)  */)
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  (Lisp_Object character)
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{
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  int len;
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  unsigned char str[MAX_MULTIBYTE_LENGTH];
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  CHECK_CHARACTER (character);
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  len = CHAR_STRING (XFASTINT (character), str);
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  return make_string_from_bytes (str, 1, len);
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}

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DEFUN ("byte-to-string", Fbyte_to_string, Sbyte_to_string, 1, 1, 0,
       doc: /* Convert arg BYTE to a string containing that byte.  */)
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  (Lisp_Object byte)
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{
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  unsigned char b;
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  CHECK_NUMBER (byte);
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  b = XINT (byte);
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  return make_string_from_bytes (&b, 1, 1);
}

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DEFUN ("string-to-char", Fstring_to_char, Sstring_to_char, 1, 1, 0,
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       doc: /* Convert arg STRING to a character, the first character of that string.
A multibyte character is handled correctly.  */)
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  (register Lisp_Object string)
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{
  register Lisp_Object val;
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  CHECK_STRING (string);
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  if (SCHARS (string))
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    {
      if (STRING_MULTIBYTE (string))
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	XSETFASTINT (val, STRING_CHAR (SDATA (string)));
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      else
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	XSETFASTINT (val, SREF (string, 0));
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    }
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  else
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    XSETFASTINT (val, 0);
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  return val;
}

static Lisp_Object
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buildmark (int charpos, int bytepos)
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{
  register Lisp_Object mark;
  mark = Fmake_marker ();
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  set_marker_both (mark, Qnil, charpos, bytepos);
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  return mark;
}

DEFUN ("point", Fpoint, Spoint, 0, 0, 0,
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       doc: /* Return value of point, as an integer.
Beginning of buffer is position (point-min).  */)
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  (void)
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{
  Lisp_Object temp;
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  XSETFASTINT (temp, PT);
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  return temp;
}

DEFUN ("point-marker", Fpoint_marker, Spoint_marker, 0, 0, 0,
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       doc: /* Return value of point, as a marker object.  */)
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  (void)
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{
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  return buildmark (PT, PT_BYTE);
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}

int
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clip_to_bounds (int lower, int num, int upper)
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{
  if (num < lower)
    return lower;
  else if (num > upper)
    return upper;
  else
    return num;
}

DEFUN ("goto-char", Fgoto_char, Sgoto_char, 1, 1, "NGoto char: ",
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       doc: /* Set point to POSITION, a number or marker.
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Beginning of buffer is position (point-min), end is (point-max).

The return value is POSITION.  */)
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  (register Lisp_Object position)
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{
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  int pos;

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  if (MARKERP (position)
      && current_buffer == XMARKER (position)->buffer)
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    {
      pos = marker_position (position);
      if (pos < BEGV)
	SET_PT_BOTH (BEGV, BEGV_BYTE);
      else if (pos > ZV)
	SET_PT_BOTH (ZV, ZV_BYTE);
      else
	SET_PT_BOTH (pos, marker_byte_position (position));

      return position;
    }

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  CHECK_NUMBER_COERCE_MARKER (position);
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  pos = clip_to_bounds (BEGV, XINT (position), ZV);
  SET_PT (pos);
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  return position;
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}

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/* Return the start or end position of the region.
   BEGINNINGP non-zero means return the start.
   If there is no region active, signal an error. */

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static Lisp_Object
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region_limit (int beginningp)
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{
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  extern Lisp_Object Vmark_even_if_inactive; /* Defined in callint.c. */
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  Lisp_Object m;
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  if (!NILP (Vtransient_mark_mode)
      && NILP (Vmark_even_if_inactive)
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      && NILP (current_buffer->mark_active))
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    xsignal0 (Qmark_inactive);
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  m = Fmarker_position (current_buffer->mark);
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  if (NILP (m))
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    error ("The mark is not set now, so there is no region");
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  if ((PT < XFASTINT (m)) == (beginningp != 0))
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    m = make_number (PT);
  return m;
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}

DEFUN ("region-beginning", Fregion_beginning, Sregion_beginning, 0, 0, 0,
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       doc: /* Return position of beginning of region, as an integer.  */)
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  (void)
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{
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  return region_limit (1);
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}

DEFUN ("region-end", Fregion_end, Sregion_end, 0, 0, 0,
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       doc: /* Return position of end of region, as an integer.  */)
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  (void)
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{
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  return region_limit (0);
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}

DEFUN ("mark-marker", Fmark_marker, Smark_marker, 0, 0, 0,
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       doc: /* Return this buffer's mark, as a marker object.
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Watch out!  Moving this marker changes the mark position.
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If you set the marker not to point anywhere, the buffer will have no mark.  */)
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  (void)
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{
  return current_buffer->mark;
}
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/* Find all the overlays in the current buffer that touch position POS.
   Return the number found, and store them in a vector in VEC
   of length LEN.  */

static int
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overlays_around (int pos, Lisp_Object *vec, int len)
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{
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  Lisp_Object overlay, start, end;
  struct Lisp_Overlay *tail;
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  int startpos, endpos;
  int idx = 0;

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  for (tail = current_buffer->overlays_before; tail; tail = tail->next)
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    {
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      XSETMISC (overlay, tail);
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      end = OVERLAY_END (overlay);
      endpos = OVERLAY_POSITION (end);
      if (endpos < pos)
	  break;
      start = OVERLAY_START (overlay);
      startpos = OVERLAY_POSITION (start);
      if (startpos <= pos)
	{
	  if (idx < len)
	    vec[idx] = overlay;
	  /* Keep counting overlays even if we can't return them all.  */
	  idx++;
	}
    }

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  for (tail = current_buffer->overlays_after; tail; tail = tail->next)
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    {
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      XSETMISC (overlay, tail);
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      start = OVERLAY_START (overlay);
      startpos = OVERLAY_POSITION (start);
      if (pos < startpos)
	break;
      end = OVERLAY_END (overlay);
      endpos = OVERLAY_POSITION (end);
      if (pos <= endpos)
	{
	  if (idx < len)
	    vec[idx] = overlay;
	  idx++;
	}
    }

  return idx;
}

/* Return the value of property PROP, in OBJECT at POSITION.
   It's the value of PROP that a char inserted at POSITION would get.
   OBJECT is optional and defaults to the current buffer.
   If OBJECT is a buffer, then overlay properties are considered as well as
   text properties.
   If OBJECT is a window, then that window's buffer is used, but
   window-specific overlays are considered only if they are associated
   with OBJECT. */
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Lisp_Object
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get_pos_property (Lisp_Object position, register Lisp_Object prop, Lisp_Object object)
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{
  CHECK_NUMBER_COERCE_MARKER (position);

  if (NILP (object))
    XSETBUFFER (object, current_buffer);
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  else if (WINDOWP (object))
    object = XWINDOW (object)->buffer;

  if (!BUFFERP (object))
    /* pos-property only makes sense in buffers right now, since strings
       have no overlays and no notion of insertion for which stickiness
       could be obeyed.  */
    return Fget_text_property (position, prop, object);
  else
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    {
      int posn = XINT (position);
      int noverlays;
      Lisp_Object *overlay_vec, tem;
      struct buffer *obuf = current_buffer;

      set_buffer_temp (XBUFFER (object));

      /* First try with room for 40 overlays.  */
      noverlays = 40;
      overlay_vec = (Lisp_Object *) alloca (noverlays * sizeof (Lisp_Object));
      noverlays = overlays_around (posn, overlay_vec, noverlays);

      /* If there are more than 40,
	 make enough space for all, and try again.  */
      if (noverlays > 40)
	{
	  overlay_vec = (Lisp_Object *) alloca (noverlays * sizeof (Lisp_Object));
	  noverlays = overlays_around (posn, overlay_vec, noverlays);
	}
      noverlays = sort_overlays (overlay_vec, noverlays, NULL);

      set_buffer_temp (obuf);

      /* Now check the overlays in order of decreasing priority.  */
      while (--noverlays >= 0)
	{
	  Lisp_Object ol = overlay_vec[noverlays];
	  tem = Foverlay_get (ol, prop);
	  if (!NILP (tem))
	    {
	      /* Check the overlay is indeed active at point.  */
	      Lisp_Object start = OVERLAY_START (ol), finish = OVERLAY_END (ol);
	      if ((OVERLAY_POSITION (start) == posn
		   && XMARKER (start)->insertion_type == 1)
		  || (OVERLAY_POSITION (finish) == posn
		      && XMARKER (finish)->insertion_type == 0))
		; /* The overlay will not cover a char inserted at point.  */
	      else
		{
		  return tem;
		}
	    }
	}
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      { /* Now check the text properties.  */
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	int stickiness = text_property_stickiness (prop, position, object);
	if (stickiness > 0)
	  return Fget_text_property (position, prop, object);
	else if (stickiness < 0
		 && XINT (position) > BUF_BEGV (XBUFFER (object)))
	  return Fget_text_property (make_number (XINT (position) - 1),
				     prop, object);
	else
	  return Qnil;
      }
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    }
}

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/* Find the field surrounding POS in *BEG and *END.  If POS is nil,
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   the value of point is used instead.  If BEG or END is null,
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   means don't store the beginning or end of the field.
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   BEG_LIMIT and END_LIMIT serve to limit the ranged of the returned
   results; they do not effect boundary behavior.

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   If MERGE_AT_BOUNDARY is nonzero, then if POS is at the very first
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   position of a field, then the beginning of the previous field is
   returned instead of the beginning of POS's field (since the end of a
   field is actually also the beginning of the next input field, this
   behavior is sometimes useful).  Additionally in the MERGE_AT_BOUNDARY
   true case, if two fields are separated by a field with the special
   value `boundary', and POS lies within it, then the two separated
   fields are considered to be adjacent, and POS between them, when
   finding the beginning and ending of the "merged" field.
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   Either BEG or END may be 0, in which case the corresponding value
   is not stored.  */

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static void
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find_field (Lisp_Object pos, Lisp_Object merge_at_boundary, Lisp_Object beg_limit, int *beg, Lisp_Object end_limit, int *end)
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{
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  /* Fields right before and after the point.  */
  Lisp_Object before_field, after_field;
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  /* 1 if POS counts as the start of a field.  */
  int at_field_start = 0;
  /* 1 if POS counts as the end of a field.  */
  int at_field_end = 0;
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  if (NILP (pos))
    XSETFASTINT (pos, PT);
  else
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    CHECK_NUMBER_COERCE_MARKER (pos);
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  after_field
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    = get_char_property_and_overlay (pos, Qfield, Qnil, NULL);
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  before_field
    = (XFASTINT (pos) > BEGV
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       ? get_char_property_and_overlay (make_number (XINT (pos) - 1),
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					Qfield, Qnil, NULL)
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       /* Using nil here would be a more obvious choice, but it would
          fail when the buffer starts with a non-sticky field.  */
       : after_field);
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  /* See if we need to handle the case where MERGE_AT_BOUNDARY is nil
     and POS is at beginning of a field, which can also be interpreted
     as the end of the previous field.  Note that the case where if
     MERGE_AT_BOUNDARY is non-nil (see function comment) is actually the
     more natural one; then we avoid treating the beginning of a field
     specially.  */
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  if (NILP (merge_at_boundary))
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    {
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      Lisp_Object field = get_pos_property (pos, Qfield, Qnil);
      if (!EQ (field, after_field))
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	at_field_end = 1;
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      if (!EQ (field, before_field))
	at_field_start = 1;
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      if (NILP (field) && at_field_start && at_field_end)
	/* If an inserted char would have a nil field while the surrounding
	   text is non-nil, we're probably not looking at a
	   zero-length field, but instead at a non-nil field that's
	   not intended for editing (such as comint's prompts).  */
	at_field_end = at_field_start = 0;
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    }

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  /* Note about special `boundary' fields:

     Consider the case where the point (`.') is between the fields `x' and `y':

	xxxx.yyyy

     In this situation, if merge_at_boundary is true, we consider the
     `x' and `y' fields as forming one big merged field, and so the end
     of the field is the end of `y'.

     However, if `x' and `y' are separated by a special `boundary' field
     (a field with a `field' char-property of 'boundary), then we ignore
     this special field when merging adjacent fields.  Here's the same
     situation, but with a `boundary' field between the `x' and `y' fields:

	xxx.BBBByyyy

     Here, if point is at the end of `x', the beginning of `y', or
     anywhere in-between (within the `boundary' field), we merge all
     three fields and consider the beginning as being the beginning of
     the `x' field, and the end as being the end of the `y' field.  */

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  if (beg)
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    {
      if (at_field_start)
	/* POS is at the edge of a field, and we should consider it as
	   the beginning of the following field.  */
	*beg = XFASTINT (pos);
      else
	/* Find the previous field boundary.  */
	{
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	  Lisp_Object p = pos;
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	  if (!NILP (merge_at_boundary) && EQ (before_field, Qboundary))
	    /* Skip a `boundary' field.  */
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	    p = Fprevious_single_char_property_change (p, Qfield, Qnil,
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						       beg_limit);
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	  p = Fprevious_single_char_property_change (p, Qfield, Qnil,
						     beg_limit);
	  *beg = NILP (p) ? BEGV : XFASTINT (p);
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	}
    }
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  if (end)
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    {
      if (at_field_end)
	/* POS is at the edge of a field, and we should consider it as
	   the end of the previous field.  */
	*end = XFASTINT (pos);
      else
	/* Find the next field boundary.  */
	{
	  if (!NILP (merge_at_boundary) && EQ (after_field, Qboundary))
	    /* Skip a `boundary' field.  */
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	    pos = Fnext_single_char_property_change (pos, Qfield, Qnil,
						     end_limit);
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	  pos = Fnext_single_char_property_change (pos, Qfield, Qnil,
						   end_limit);
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	  *end = NILP (pos) ? ZV : XFASTINT (pos);
	}
    }
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}
628

629

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DEFUN ("delete-field", Fdelete_field, Sdelete_field, 0, 1, 0,
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       doc: /* Delete the field surrounding POS.
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A field is a region of text with the same `field' property.
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If POS is nil, the value of point is used for POS.  */)
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  (Lisp_Object pos)
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{
  int beg, end;
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  find_field (pos, Qnil, Qnil, &beg, Qnil, &end);
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  if (beg != end)
    del_range (beg, end);
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  return Qnil;
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}

DEFUN ("field-string", Ffield_string, Sfield_string, 0, 1, 0,
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       doc: /* Return the contents of the field surrounding POS as a string.
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A field is a region of text with the same `field' property.
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If POS is nil, the value of point is used for POS.  */)
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  (Lisp_Object pos)
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{
  int beg, end;
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  find_field (pos, Qnil, Qnil, &beg, Qnil, &end);
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  return make_buffer_string (beg, end, 1);
}

DEFUN ("field-string-no-properties", Ffield_string_no_properties, Sfield_string_no_properties, 0, 1, 0,
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       doc: /* Return the contents of the field around POS, without text properties.
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A field is a region of text with the same `field' property.
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If POS is nil, the value of point is used for POS.  */)
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  (Lisp_Object pos)
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{
  int beg, end;
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  find_field (pos, Qnil, Qnil, &beg, Qnil, &end);
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  return make_buffer_string (beg, end, 0);
}

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DEFUN ("field-beginning", Ffield_beginning, Sfield_beginning, 0, 3, 0,
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       doc: /* Return the beginning of the field surrounding POS.
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A field is a region of text with the same `field' property.
If POS is nil, the value of point is used for POS.
If ESCAPE-FROM-EDGE is non-nil and POS is at the beginning of its
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field, then the beginning of the *previous* field is returned.
If LIMIT is non-nil, it is a buffer position; if the beginning of the field
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is before LIMIT, then LIMIT will be returned instead.  */)
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  (Lisp_Object pos, Lisp_Object escape_from_edge, Lisp_Object limit)
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{
  int beg;
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  find_field (pos, escape_from_edge, limit, &beg, Qnil, 0);
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  return make_number (beg);
}

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DEFUN ("field-end", Ffield_end, Sfield_end, 0, 3, 0,
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       doc: /* Return the end of the field surrounding POS.
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A field is a region of text with the same `field' property.
If POS is nil, the value of point is used for POS.
If ESCAPE-FROM-EDGE is non-nil and POS is at the end of its field,
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then the end of the *following* field is returned.
If LIMIT is non-nil, it is a buffer position; if the end of the field
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is after LIMIT, then LIMIT will be returned instead.  */)
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  (Lisp_Object pos, Lisp_Object escape_from_edge, Lisp_Object limit)
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{
  int end;
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  find_field (pos, escape_from_edge, Qnil, 0, limit, &end);
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  return make_number (end);
}

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DEFUN ("constrain-to-field", Fconstrain_to_field, Sconstrain_to_field, 2, 5, 0,
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       doc: /* Return the position closest to NEW-POS that is in the same field as OLD-POS.
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A field is a region of text with the same `field' property.
If NEW-POS is nil, then the current point is used instead, and set to the
constrained position if that is different.

If OLD-POS is at the boundary of two fields, then the allowable
positions for NEW-POS depends on the value of the optional argument
ESCAPE-FROM-EDGE: If ESCAPE-FROM-EDGE is nil, then NEW-POS is
constrained to the field that has the same `field' char-property
as any new characters inserted at OLD-POS, whereas if ESCAPE-FROM-EDGE
is non-nil, NEW-POS is constrained to the union of the two adjacent
fields.  Additionally, if two fields are separated by another field with
the special value `boundary', then any point within this special field is
also considered to be `on the boundary'.

If the optional argument ONLY-IN-LINE is non-nil and constraining
NEW-POS would move it to a different line, NEW-POS is returned
unconstrained.  This useful for commands that move by line, like
\\[next-line] or \\[beginning-of-line], which should generally respect field boundaries
only in the case where they can still move to the right line.

If the optional argument INHIBIT-CAPTURE-PROPERTY is non-nil, and OLD-POS has
a non-nil property of that name, then any field boundaries are ignored.

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Field boundaries are not noticed if `inhibit-field-text-motion' is non-nil.  */)
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  (Lisp_Object new_pos, Lisp_Object old_pos, Lisp_Object escape_from_edge, Lisp_Object only_in_line, Lisp_Object inhibit_capture_property)
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{
  /* If non-zero, then the original point, before re-positioning.  */
  int orig_point = 0;
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  int fwd;
  Lisp_Object prev_old, prev_new;
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  if (NILP (new_pos))
    /* Use the current point, and afterwards, set it.  */
    {
      orig_point = PT;
      XSETFASTINT (new_pos, PT);
    }

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  CHECK_NUMBER_COERCE_MARKER (new_pos);
  CHECK_NUMBER_COERCE_MARKER (old_pos);

  fwd = (XFASTINT (new_pos) > XFASTINT (old_pos));

  prev_old = make_number (XFASTINT (old_pos) - 1);
  prev_new = make_number (XFASTINT (new_pos) - 1);
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  if (NILP (Vinhibit_field_text_motion)
      && !EQ (new_pos, old_pos)
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      && (!NILP (Fget_char_property (new_pos, Qfield, Qnil))
          || !NILP (Fget_char_property (old_pos, Qfield, Qnil))
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          /* To recognize field boundaries, we must also look at the
             previous positions; we could use `get_pos_property'
             instead, but in itself that would fail inside non-sticky
             fields (like comint prompts).  */
          || (XFASTINT (new_pos) > BEGV
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              && !NILP (Fget_char_property (prev_new, Qfield, Qnil)))
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          || (XFASTINT (old_pos) > BEGV
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              && !NILP (Fget_char_property (prev_old, Qfield, Qnil))))
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      && (NILP (inhibit_capture_property)
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          /* Field boundaries are again a problem; but now we must
             decide the case exactly, so we need to call
             `get_pos_property' as well.  */
          || (NILP (get_pos_property (old_pos, inhibit_capture_property, Qnil))
              && (XFASTINT (old_pos) <= BEGV
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                  || NILP (Fget_char_property (old_pos, inhibit_capture_property, Qnil))
                  || NILP (Fget_char_property (prev_old, inhibit_capture_property, Qnil))))))
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    /* It is possible that NEW_POS is not within the same field as
       OLD_POS; try to move NEW_POS so that it is.  */
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    {
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      int shortage;
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      Lisp_Object field_bound;

      if (fwd)
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	field_bound = Ffield_end (old_pos, escape_from_edge, new_pos);
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      else
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	field_bound = Ffield_beginning (old_pos, escape_from_edge, new_pos);
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      if (/* See if ESCAPE_FROM_EDGE caused FIELD_BOUND to jump to the
             other side of NEW_POS, which would mean that NEW_POS is
             already acceptable, and it's not necessary to constrain it
             to FIELD_BOUND.  */
	  ((XFASTINT (field_bound) < XFASTINT (new_pos)) ? fwd : !fwd)
	  /* NEW_POS should be constrained, but only if either
	     ONLY_IN_LINE is nil (in which case any constraint is OK),
	     or NEW_POS and FIELD_BOUND are on the same line (in which
	     case the constraint is OK even if ONLY_IN_LINE is non-nil). */
	  && (NILP (only_in_line)
	      /* This is the ONLY_IN_LINE case, check that NEW_POS and
		 FIELD_BOUND are on the same line by seeing whether
		 there's an intervening newline or not.  */
	      || (scan_buffer ('\n',
			       XFASTINT (new_pos), XFASTINT (field_bound),
			       fwd ? -1 : 1, &shortage, 1),
		  shortage != 0)))
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	/* Constrain NEW_POS to FIELD_BOUND.  */
	new_pos = field_bound;

      if (orig_point && XFASTINT (new_pos) != orig_point)
	/* The NEW_POS argument was originally nil, so automatically set PT. */
	SET_PT (XFASTINT (new_pos));
    }

  return new_pos;
}
802

803

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DEFUN ("line-beginning-position",
       Fline_beginning_position, Sline_beginning_position, 0, 1, 0,
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       doc: /* Return the character position of the first character on the current line.
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With argument N not nil or 1, move forward N - 1 lines first.
If scan reaches end of buffer, return that position.
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This function constrains the returned position to the current field
unless that would be on a different line than the original,
unconstrained result.  If N is nil or 1, and a front-sticky field
starts at point, the scan stops as soon as it starts.  To ignore field
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boundaries bind `inhibit-field-text-motion' to t.
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This function does not move point.  */)
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  (Lisp_Object n)
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{
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  int orig, orig_byte, end;
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  int count = SPECPDL_INDEX ();
  specbind (Qinhibit_point_motion_hooks, Qt);
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  if (NILP (n))
    XSETFASTINT (n, 1);
  else
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    CHECK_NUMBER (n);
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  orig = PT;
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  orig_byte = PT_BYTE;
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  Fforward_line (make_number (XINT (n) - 1));
  end = PT;
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  SET_PT_BOTH (orig, orig_byte);
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  unbind_to (count, Qnil);

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  /* Return END constrained to the current input field.  */
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  return Fconstrain_to_field (make_number (end), make_number (orig),
			      XINT (n) != 1 ? Qt : Qnil,
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			      Qt, Qnil);
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}

843
DEFUN ("line-end-position", Fline_end_position, Sline_end_position, 0, 1, 0,
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       doc: /* Return the character position of the last character on the current line.
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With argument N not nil or 1, move forward N - 1 lines first.
If scan reaches end of buffer, return that position.
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This function constrains the returned position to the current field
unless that would be on a different line than the original,
unconstrained result.  If N is nil or 1, and a rear-sticky field ends
at point, the scan stops as soon as it starts.  To ignore field
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boundaries bind `inhibit-field-text-motion' to t.

854
This function does not move point.  */)
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  (Lisp_Object n)
856
{
857
  int end_pos;
858
  int orig = PT;
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  if (NILP (n))
    XSETFASTINT (n, 1);
  else
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    CHECK_NUMBER (n);
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  end_pos = find_before_next_newline (orig, 0, XINT (n) - (XINT (n) <= 0));

  /* Return END_POS constrained to the current input field.  */
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  return Fconstrain_to_field (make_number (end_pos), make_number (orig),
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			      Qnil, Qt, Qnil);
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}
871

872

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Lisp_Object
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save_excursion_save (void)
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{
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  int visible = (XBUFFER (XWINDOW (selected_window)->buffer)
		 == current_buffer);
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  return Fcons (Fpoint_marker (),
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		Fcons (Fcopy_marker (current_buffer->mark, Qnil),
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		       Fcons (visible ? Qt : Qnil,
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			      Fcons (current_buffer->mark_active,
				     selected_window))));
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}

Lisp_Object
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save_excursion_restore (Lisp_Object info)
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{
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  Lisp_Object tem, tem1, omark, nmark;
  struct gcpro gcpro1, gcpro2, gcpro3;
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  int visible_p;
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  tem = Fmarker_buffer (XCAR (info));
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  /* If buffer being returned to is now deleted, avoid error */
  /* Otherwise could get error here while unwinding to top level
     and crash */
  /* In that case, Fmarker_buffer returns nil now.  */
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  if (NILP (tem))
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    return Qnil;
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  omark = nmark = Qnil;
  GCPRO3 (info, omark, nmark);

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  Fset_buffer (tem);
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  /* Point marker.  */
  tem = XCAR (info);
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  Fgoto_char (tem);
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  unchain_marker (XMARKER (tem));
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  /* Mark marker.  */
  info = XCDR (info);
  tem = XCAR (info);
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  omark = Fmarker_position (current_buffer->mark);
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  Fset_marker (current_buffer->mark, tem, Fcurrent_buffer ());
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  nmark = Fmarker_position (tem);
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  unchain_marker (XMARKER (tem));
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  /* visible */
  info = XCDR (info);
  visible_p = !NILP (XCAR (info));
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#if 0 /* We used to make the current buffer visible in the selected window
	 if that was true previously.  That avoids some anomalies.
	 But it creates others, and it wasn't documented, and it is simpler
	 and cleaner never to alter the window/buffer connections.  */
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  tem1 = Fcar (tem);
  if (!NILP (tem1)
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      && current_buffer != XBUFFER (XWINDOW (selected_window)->buffer))
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    Fswitch_to_buffer (Fcurrent_buffer (), Qnil);
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#endif /* 0 */
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  /* Mark active */
  info = XCDR (info);
  tem = XCAR (info);
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  tem1 = current_buffer->mark_active;
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  current_buffer->mark_active = tem;

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  if (!NILP (Vrun_hooks))
    {
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      /* If mark is active now, and either was not active
	 or was at a different place, run the activate hook.  */
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      if (! NILP (current_buffer->mark_active))
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	{
	  if (! EQ (omark, nmark))
	    call1 (Vrun_hooks, intern ("activate-mark-hook"));
	}
      /* If mark has ceased to be active, run deactivate hook.  */
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      else if (! NILP (tem1))
	call1 (Vrun_hooks, intern ("deactivate-mark-hook"));
    }
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  /* If buffer was visible in a window, and a different window was
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     selected, and the old selected window is still showing this
     buffer, restore point in that window.  */
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  tem = XCDR (info);
  if (visible_p
      && !EQ (tem, selected_window)
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      && (tem1 = XWINDOW (tem)->buffer,
	  (/* Window is live...  */
	   BUFFERP (tem1)
	   /* ...and it shows the current buffer.  */
	   && XBUFFER (tem1) == current_buffer)))
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    Fset_window_point (tem, make_number (PT));

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  UNGCPRO;
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  return Qnil;
}

DEFUN ("save-excursion", Fsave_excursion, Ssave_excursion, 0, UNEVALLED, 0,
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       doc: /* Save point, mark, and current buffer; execute BODY; restore those things.
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