/* Buffer insertion/deletion and gap motion for GNU Emacs.
   Copyright (C) 1985, 1986, 1993, 1994, 1995 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 2, 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; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */


#include <config.h>
#include "lisp.h"
#include "intervals.h"
#include "buffer.h"
#include "window.h"
#include "blockinput.h"

#define min(x, y) ((x) < (y) ? (x) : (y))

static void insert_from_string_1 ();
static void insert_from_buffer_1 ();
static void gap_left ();
static void gap_right ();
static void adjust_markers ();
static void adjust_point ();

/* Move gap to position `pos'.
   Note that this can quit!  */

void
move_gap (pos)
     int pos;
{
  if (pos < GPT)
    gap_left (pos, 0);
  else if (pos > GPT)
    gap_right (pos);
}

/* Move the gap to POS, which is less than the current GPT.
   If NEWGAP is nonzero, then don't update beg_unchanged and end_unchanged.  */

static void
gap_left (pos, newgap)
     register int pos;
     int newgap;
{
  register unsigned char *to, *from;
  register int i;
  int new_s1;

  pos--;

  if (!newgap)
    {
      if (unchanged_modified == MODIFF)
	{
	  beg_unchanged = pos;
	  end_unchanged = Z - pos - 1;
	}
      else
	{
	  if (Z - GPT < end_unchanged)
	    end_unchanged = Z - GPT;
	  if (pos < beg_unchanged)
	    beg_unchanged = pos;
	}
    }

  i = GPT;
  to = GAP_END_ADDR;
  from = GPT_ADDR;
  new_s1 = GPT - BEG;

  /* Now copy the characters.  To move the gap down,
     copy characters up.  */

  while (1)
    {
      /* I gets number of characters left to copy.  */
      i = new_s1 - pos;
      if (i == 0)
	break;
      /* If a quit is requested, stop copying now.
	 Change POS to be where we have actually moved the gap to.  */
      if (QUITP)
	{
	  pos = new_s1;
	  break;
	}
      /* Move at most 32000 chars before checking again for a quit.  */
      if (i > 32000)
	i = 32000;
#ifdef GAP_USE_BCOPY
      if (i >= 128
	  /* bcopy is safe if the two areas of memory do not overlap
	     or on systems where bcopy is always safe for moving upward.  */
	  && (BCOPY_UPWARD_SAFE
	      || to - from >= 128))
	{
	  /* If overlap is not safe, avoid it by not moving too many
	     characters at once.  */
	  if (!BCOPY_UPWARD_SAFE && i > to - from)
	    i = to - from;
	  new_s1 -= i;
	  from -= i, to -= i;
	  bcopy (from, to, i);
	}
      else
#endif
	{
	  new_s1 -= i;
	  while (--i >= 0)
	    *--to = *--from;
	}
    }

  /* Adjust markers, and buffer data structure, to put the gap at POS.
     POS is where the loop above stopped, which may be what was specified
     or may be where a quit was detected.  */
  adjust_markers (pos + 1, GPT, GAP_SIZE);
  GPT = pos + 1;
  QUIT;
}

static void
gap_right (pos)
     register int pos;
{
  register unsigned char *to, *from;
  register int i;
  int new_s1;

  pos--;

  if (unchanged_modified == MODIFF)
    {
      beg_unchanged = pos;
      end_unchanged = Z - pos - 1;
    }
  else
    {
      if (Z - pos - 1 < end_unchanged)
	end_unchanged = Z - pos - 1;
      if (GPT - BEG < beg_unchanged)
	beg_unchanged = GPT - BEG;
    }

  i = GPT;
  from = GAP_END_ADDR;
  to = GPT_ADDR;
  new_s1 = GPT - 1;

  /* Now copy the characters.  To move the gap up,
     copy characters down.  */

  while (1)
    {
      /* I gets number of characters left to copy.  */
      i = pos - new_s1;
      if (i == 0)
	break;
      /* If a quit is requested, stop copying now.
	 Change POS to be where we have actually moved the gap to.  */
      if (QUITP)
	{
	  pos = new_s1;
	  break;
	}
      /* Move at most 32000 chars before checking again for a quit.  */
      if (i > 32000)
	i = 32000;
#ifdef GAP_USE_BCOPY
      if (i >= 128
	  /* bcopy is safe if the two areas of memory do not overlap
	     or on systems where bcopy is always safe for moving downward.  */
	  && (BCOPY_DOWNWARD_SAFE
	      || from - to >= 128))
	{
	  /* If overlap is not safe, avoid it by not moving too many
	     characters at once.  */
	  if (!BCOPY_DOWNWARD_SAFE && i > from - to)
	    i = from - to;
	  new_s1 += i;
	  bcopy (from, to, i);
	  from += i, to += i;
	}
      else
#endif
	{
	  new_s1 += i;
	  while (--i >= 0)
	    *to++ = *from++;
	}
    }

  adjust_markers (GPT + GAP_SIZE, pos + 1 + GAP_SIZE, - GAP_SIZE);
  GPT = pos + 1;
  QUIT;
}

/* Add `amount' to the position of every marker in the current buffer
   whose current position is between `from' (exclusive) and `to' (inclusive).
   Also, any markers past the outside of that interval, in the direction
   of adjustment, are first moved back to the near end of the interval
   and then adjusted by `amount'.  */

static void
adjust_markers (from, to, amount)
     register int from, to, amount;
{
  Lisp_Object marker;
  register struct Lisp_Marker *m;
  register int mpos;

  marker = BUF_MARKERS (current_buffer);

  while (!NILP (marker))
    {
      m = XMARKER (marker);
      mpos = m->bufpos;
      if (amount > 0)
	{
	  if (mpos > to && mpos < to + amount)
	    mpos = to + amount;
	}
      else
	{
	  if (mpos > from + amount && mpos <= from)
	    mpos = from + amount;
	}
      if (mpos > from && mpos <= to)
	mpos += amount;
      m->bufpos = mpos;
      marker = m->chain;
    }
}

/* Adjust markers whose insertion-type is t
   for an insertion of AMOUNT characters at POS.  */

static void
adjust_markers_for_insert (pos, amount)
     register int pos, amount;
{
  Lisp_Object marker;

  marker = BUF_MARKERS (current_buffer);

  while (!NILP (marker))
    {
      register struct Lisp_Marker *m = XMARKER (marker);
      if (m->insertion_type && m->bufpos == pos)
	m->bufpos += amount;
      marker = m->chain;
    }
}

/* Add the specified amount to point.  This is used only when the value
   of point changes due to an insert or delete; it does not represent
   a conceptual change in point as a marker.  In particular, point is
   not crossing any interval boundaries, so there's no need to use the
   usual SET_PT macro.  In fact it would be incorrect to do so, because
   either the old or the new value of point is out of synch with the
   current set of intervals.  */
static void
adjust_point (amount)
     int amount;
{
  BUF_PT (current_buffer) += amount;
}

/* Make the gap INCREMENT characters longer.  */

void
make_gap (increment)
     int increment;
{
  unsigned char *result;
  Lisp_Object tem;
  int real_gap_loc;
  int old_gap_size;

  /* If we have to get more space, get enough to last a while.  */
  increment += 2000;

  /* Don't allow a buffer size that won't fit in an int
     even if it will fit in a Lisp integer.
     That won't work because so many places use `int'.  */
     
  if (Z - BEG + GAP_SIZE + increment
      >= ((unsigned) 1 << (min (BITS_PER_INT, VALBITS) - 1)))
    error ("Buffer exceeds maximum size");

  BLOCK_INPUT;
  result = BUFFER_REALLOC (BEG_ADDR, (Z - BEG + GAP_SIZE + increment));

  if (result == 0)
    {
      UNBLOCK_INPUT;
      memory_full ();
    }

  /* We can't unblock until the new address is properly stored.  */
  BEG_ADDR = result;
  UNBLOCK_INPUT;

  /* Prevent quitting in move_gap.  */
  tem = Vinhibit_quit;
  Vinhibit_quit = Qt;

  real_gap_loc = GPT;
  old_gap_size = GAP_SIZE;

  /* Call the newly allocated space a gap at the end of the whole space.  */
  GPT = Z + GAP_SIZE;
  GAP_SIZE = increment;

  /* Move the new gap down to be consecutive with the end of the old one.
     This adjusts the markers properly too.  */
  gap_left (real_gap_loc + old_gap_size, 1);

  /* Now combine the two into one large gap.  */
  GAP_SIZE += old_gap_size;
  GPT = real_gap_loc;

  Vinhibit_quit = tem;
}

/* Insert a string of specified length before point.
   DO NOT use this for the contents of a Lisp string or a Lisp buffer!
   prepare_to_modify_buffer could relocate the text.  */

void
insert (string, length)
     register unsigned char *string;
     register length;
{
  if (length > 0)
    {
      insert_1 (string, length, 0, 1);
      signal_after_change (PT-length, 0, length);
    }
}

void
insert_and_inherit (string, length)
     register unsigned char *string;
     register length;
{
  if (length > 0)
    {
      insert_1 (string, length, 1, 1);
      signal_after_change (PT-length, 0, length);
    }
}

void
insert_1 (string, length, inherit, prepare)
     register unsigned char *string;
     register int length;
     int inherit, prepare;
{
  register Lisp_Object temp;

  if (prepare)
    prepare_to_modify_buffer (PT, PT);

  if (PT != GPT)
    move_gap (PT);
  if (GAP_SIZE < length)
    make_gap (length - GAP_SIZE);

  record_insert (PT, length);
  MODIFF++;

  bcopy (string, GPT_ADDR, length);

#ifdef USE_TEXT_PROPERTIES
  if (BUF_INTERVALS (current_buffer) != 0)
    /* Only defined if Emacs is compiled with USE_TEXT_PROPERTIES.  */
    offset_intervals (current_buffer, PT, length);
#endif

  GAP_SIZE -= length;
  GPT += length;
  ZV += length;
  Z += length;
  adjust_overlays_for_insert (PT, length);
  adjust_markers_for_insert (PT, length);
  adjust_point (length);

#ifdef USE_TEXT_PROPERTIES
  if (!inherit && BUF_INTERVALS (current_buffer) != 0)
    Fset_text_properties (make_number (PT - length), make_number (PT),
			  Qnil, Qnil);
#endif
}

/* Insert the part of the text of STRING, a Lisp object assumed to be
   of type string, consisting of the LENGTH characters starting at
   position POS.  If the text of STRING has properties, they are absorbed
   into the buffer.

   It does not work to use `insert' for this, because a GC could happen
   before we bcopy the stuff into the buffer, and relocate the string
   without insert noticing.  */

void
insert_from_string (string, pos, length, inherit)
     Lisp_Object string;
     register int pos, length;
     int inherit;
{
  if (length > 0)
    {
      insert_from_string_1 (string, pos, length, inherit);
      signal_after_change (PT-length, 0, length);
    }
}

static void
insert_from_string_1 (string, pos, length, inherit)
     Lisp_Object string;
     register int pos, length;
     int inherit;
{
  register Lisp_Object temp;
  struct gcpro gcpro1;

  /* Make sure point-max won't overflow after this insertion.  */
  XSETINT (temp, length + Z);
  if (length + Z != XINT (temp))
    error ("maximum buffer size exceeded");

  GCPRO1 (string);
  prepare_to_modify_buffer (PT, PT);

  if (PT != GPT)
    move_gap (PT);
  if (GAP_SIZE < length)
    make_gap (length - GAP_SIZE);

  record_insert (PT, length);
  MODIFF++;
  UNGCPRO;

  bcopy (XSTRING (string)->data, GPT_ADDR, length);

  /* Only defined if Emacs is compiled with USE_TEXT_PROPERTIES */
  offset_intervals (current_buffer, PT, length);

  GAP_SIZE -= length;
  GPT += length;
  ZV += length;
  Z += length;
  adjust_overlays_for_insert (PT, length);
  adjust_markers_for_insert (PT, length);

  /* Only defined if Emacs is compiled with USE_TEXT_PROPERTIES */
  graft_intervals_into_buffer (XSTRING (string)->intervals, PT, length,
			       current_buffer, inherit);

  adjust_point (length);
}

/* Insert text from BUF, starting at POS and having length LENGTH, into the
   current buffer.  If the text in BUF has properties, they are absorbed
   into the current buffer.

   It does not work to use `insert' for this, because a malloc could happen
   and relocate BUF's text before the bcopy happens.  */

void
insert_from_buffer (buf, pos, length, inherit)
     struct buffer *buf;
     int pos, length;
     int inherit;
{
  if (length > 0)
    {
      insert_from_buffer_1 (buf, pos, length, inherit);
      signal_after_change (PT-length, 0, length);
    }
}

static void
insert_from_buffer_1 (buf, pos, length, inherit)
     struct buffer *buf;
     int pos, length;
     int inherit;
{
  register Lisp_Object temp;
  int chunk;

  /* Make sure point-max won't overflow after this insertion.  */
  XSETINT (temp, length + Z);
  if (length + Z != XINT (temp))
    error ("maximum buffer size exceeded");

  prepare_to_modify_buffer (PT, PT);

  if (PT != GPT)
    move_gap (PT);
  if (GAP_SIZE < length)
    make_gap (length - GAP_SIZE);

  record_insert (PT, length);
  MODIFF++;

  if (pos < BUF_GPT (buf))
    {
      chunk = BUF_GPT (buf) - pos;
      if (chunk > length)
	chunk = length;
      bcopy (BUF_CHAR_ADDRESS (buf, pos), GPT_ADDR, chunk);
    }
  else
    chunk = 0;
  if (chunk < length)
    bcopy (BUF_CHAR_ADDRESS (buf, pos + chunk),
	   GPT_ADDR + chunk, length - chunk);

#ifdef USE_TEXT_PROPERTIES
  if (BUF_INTERVALS (current_buffer) != 0)
    offset_intervals (current_buffer, PT, length);
#endif

  GAP_SIZE -= length;
  GPT += length;
  ZV += length;
  Z += length;
  adjust_overlays_for_insert (PT, length);
  adjust_markers_for_insert (PT, length);
  adjust_point (length);

  /* Only defined if Emacs is compiled with USE_TEXT_PROPERTIES */
  graft_intervals_into_buffer (copy_intervals (BUF_INTERVALS (buf),
					       pos, length),
			       PT - length, length, current_buffer, inherit);
}

/* Insert the character C before point */

void
insert_char (c)
     unsigned char c;
{
  insert (&c, 1);
}

/* Insert the null-terminated string S before point */

void
insert_string (s)
     char *s;
{
  insert (s, strlen (s));
}

/* Like `insert' except that all markers pointing at the place where
   the insertion happens are adjusted to point after it.
   Don't use this function to insert part of a Lisp string,
   since gc could happen and relocate it.  */

void
insert_before_markers (string, length)
     unsigned char *string;
     register int length;
{
  if (length > 0)
    {
      register int opoint = PT;
      insert_1 (string, length, 0, 1);
      adjust_markers (opoint - 1, opoint, length);
      signal_after_change (PT-length, 0, length);
    }
}

void
insert_before_markers_and_inherit (string, length)
     unsigned char *string;
     register int length;
{
  if (length > 0)
    {
      register int opoint = PT;
      insert_1 (string, length, 1, 1);
      adjust_markers (opoint - 1, opoint, length);
      signal_after_change (PT-length, 0, length);
    }
}

/* Insert part of a Lisp string, relocating markers after.  */

void
insert_from_string_before_markers (string, pos, length, inherit)
     Lisp_Object string;
     register int pos, length;
     int inherit;
{
  if (length > 0)
    {
      register int opoint = PT;
      insert_from_string_1 (string, pos, length, inherit);
      adjust_markers (opoint - 1, opoint, length);
      signal_after_change (PT-length, 0, length);
    }
}

/* Delete characters in current buffer
   from FROM up to (but not including) TO.  */

void
del_range (from, to)
     register int from, to;
{
  del_range_1 (from, to, 1);
}

/* Like del_range; PREPARE says whether to call prepare_to_modify_buffer.  */

void
del_range_1 (from, to, prepare)
     register int from, to, prepare;
{
  register int numdel;

  /* Make args be valid */
  if (from < BEGV)
    from = BEGV;
  if (to > ZV)
    to = ZV;

  if ((numdel = to - from) <= 0)
    return;

  /* Make sure the gap is somewhere in or next to what we are deleting.  */
  if (from > GPT)
    gap_right (from);
  if (to < GPT)
    gap_left (to, 0);

  if (prepare)
    prepare_to_modify_buffer (from, to);

  record_delete (from, numdel);
  MODIFF++;

  /* Relocate point as if it were a marker.  */
  if (from < PT)
    adjust_point (from - (PT < to ? PT : to));

  /* Only defined if Emacs is compiled with USE_TEXT_PROPERTIES */
  offset_intervals (current_buffer, from, - numdel);

  /* Relocate all markers pointing into the new, larger gap
     to point at the end of the text before the gap.  */
  adjust_markers (to + GAP_SIZE, to + GAP_SIZE, - numdel - GAP_SIZE);

  /* Adjust the overlay center as needed.  This must be done after
     adjusting the markers that bound the overlays.  */
  adjust_overlays_for_delete (from, numdel);

  GAP_SIZE += numdel;
  ZV -= numdel;
  Z -= numdel;
  GPT = from;

  if (GPT - BEG < beg_unchanged)
    beg_unchanged = GPT - BEG;
  if (Z - GPT < end_unchanged)
    end_unchanged = Z - GPT;

  evaporate_overlays (from);
  signal_after_change (from, numdel, 0);
}

/* Call this if you're about to change the region of BUFFER from START
   to END.  This checks the read-only properties of the region, calls
   the necessary modification hooks, and warns the next redisplay that
   it should pay attention to that area.  */
void
modify_region (buffer, start, end)
     struct buffer *buffer;
     int start, end;
{
  struct buffer *old_buffer = current_buffer;

  if (buffer != old_buffer)
    set_buffer_internal (buffer);

  prepare_to_modify_buffer (start, end);

  if (start - 1 < beg_unchanged || unchanged_modified == MODIFF)
    beg_unchanged = start - 1;
  if (Z - end < end_unchanged
      || unchanged_modified == MODIFF)
    end_unchanged = Z - end;

  if (MODIFF <= SAVE_MODIFF)
    record_first_change ();
  MODIFF++;

  buffer->point_before_scroll = Qnil;

  if (buffer != old_buffer)
    set_buffer_internal (old_buffer);
}

/* Check that it is okay to modify the buffer between START and END.
   Run the before-change-function, if any.  If intervals are in use,
   verify that the text to be modified is not read-only, and call
   any modification properties the text may have. */

void
prepare_to_modify_buffer (start, end)
     Lisp_Object start, end;
{
  if (!NILP (current_buffer->read_only))
    Fbarf_if_buffer_read_only ();

  /* Only defined if Emacs is compiled with USE_TEXT_PROPERTIES */
  if (BUF_INTERVALS (current_buffer) != 0)
    verify_interval_modification (current_buffer, start, end);

#ifdef CLASH_DETECTION
  if (!NILP (current_buffer->file_truename)
      /* Make binding buffer-file-name to nil effective.  */
      && !NILP (current_buffer->filename)
      && SAVE_MODIFF >= MODIFF)
    lock_file (current_buffer->file_truename);
#else
  /* At least warn if this file has changed on disk since it was visited.  */
  if (!NILP (current_buffer->filename)
      && SAVE_MODIFF >= MODIFF
      && NILP (Fverify_visited_file_modtime (Fcurrent_buffer ()))
      && !NILP (Ffile_exists_p (current_buffer->filename)))
    call1 (intern ("ask-user-about-supersession-threat"),
	   current_buffer->filename);
#endif /* not CLASH_DETECTION */

  signal_before_change (start, end);

  if (current_buffer->newline_cache)
    invalidate_region_cache (current_buffer,
                             current_buffer->newline_cache,
                             start - BEG, Z - end);
  if (current_buffer->width_run_cache)
    invalidate_region_cache (current_buffer,
                             current_buffer->width_run_cache,
                             start - BEG, Z - end);

  Vdeactivate_mark = Qt;
}

/* Signal a change to the buffer immediately before it happens.
   START and END are the bounds of the text to be changed,
   as Lisp objects.  */

void
signal_before_change (start, end)
     Lisp_Object start, end;
{
  /* If buffer is unmodified, run a special hook for that case.  */
  if (SAVE_MODIFF >= MODIFF
      && !NILP (Vfirst_change_hook)
      && !NILP (Vrun_hooks))
    call1 (Vrun_hooks, Qfirst_change_hook);

  /* Run the before-change-function if any.
     We don't bother "binding" this variable to nil
     because it is obsolete anyway and new code should not use it.  */
  if (!NILP (Vbefore_change_function))
    call2 (Vbefore_change_function, start, end);

  /* Now run the before-change-functions if any.  */
  if (!NILP (Vbefore_change_functions))
    {
      Lisp_Object args[3];
      Lisp_Object before_change_functions;
      Lisp_Object after_change_functions;
      struct gcpro gcpro1, gcpro2;

      /* "Bind" before-change-functions and after-change-functions
	 to nil--but in a way that errors don't know about.
	 That way, if there's an error in them, they will stay nil.  */
      before_change_functions = Vbefore_change_functions;
      after_change_functions = Vafter_change_functions;
      Vbefore_change_functions = Qnil;
      Vafter_change_functions = Qnil;
      GCPRO2 (before_change_functions, after_change_functions);

      /* Actually run the hook functions.  */
      args[0] = Qbefore_change_functions;
      args[1] = start;
      args[2] = end;
      run_hook_list_with_args (before_change_functions, 3, args);

      /* "Unbind" the variables we "bound" to nil.  */
      Vbefore_change_functions = before_change_functions;
      Vafter_change_functions = after_change_functions;
      UNGCPRO;
    }

  if (!NILP (current_buffer->overlays_before)
      || !NILP (current_buffer->overlays_after))
    report_overlay_modification (start, end, 0, start, end, Qnil);
}

/* Signal a change immediately after it happens.
   POS is the address of the start of the changed text.
   LENDEL is the number of characters of the text before the change.
   (Not the whole buffer; just the part that was changed.)
   LENINS is the number of characters in the changed text.

   (Hence POS + LENINS - LENDEL is the position after the changed text.)  */

void
signal_after_change (pos, lendel, lenins)
     int pos, lendel, lenins;
{
  /* Run the after-change-function if any.
     We don't bother "binding" this variable to nil
     because it is obsolete anyway and new code should not use it.  */
  if (!NILP (Vafter_change_function))
    call3 (Vafter_change_function,
	   make_number (pos), make_number (pos + lenins),
	   make_number (lendel));

  if (!NILP (Vafter_change_functions))
    {
      Lisp_Object args[4];
      Lisp_Object before_change_functions;
      Lisp_Object after_change_functions;
      struct gcpro gcpro1, gcpro2;

      /* "Bind" before-change-functions and after-change-functions
	 to nil--but in a way that errors don't know about.
	 That way, if there's an error in them, they will stay nil.  */
      before_change_functions = Vbefore_change_functions;
      after_change_functions = Vafter_change_functions;
      Vbefore_change_functions = Qnil;
      Vafter_change_functions = Qnil;
      GCPRO2 (before_change_functions, after_change_functions);

      /* Actually run the hook functions.  */
      args[0] = Qafter_change_functions;
      XSETFASTINT (args[1], pos);
      XSETFASTINT (args[2], pos + lenins);
      XSETFASTINT (args[3], lendel);
      run_hook_list_with_args (after_change_functions,
			       4, args);

      /* "Unbind" the variables we "bound" to nil.  */
      Vbefore_change_functions = before_change_functions;
      Vafter_change_functions = after_change_functions;
      UNGCPRO;
    }

  if (!NILP (current_buffer->overlays_before)
      || !NILP (current_buffer->overlays_after))
    report_overlay_modification (make_number (pos),
				 make_number (pos + lenins - lendel),
				 1,
				 make_number (pos), make_number (pos + lenins),
				 make_number (lendel));

  /* After an insertion, call the text properties
     insert-behind-hooks or insert-in-front-hooks.  */
  if (lendel == 0)
    report_interval_modification (pos, pos + lenins);
}