[bpt/emacs.git] / src / undo.c

/* undo handling for GNU Emacs.
   Copyright (C) 1990 Free Software Foundation, Inc.

This file is part of GNU Emacs.

GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY.  No author or distributor
accepts responsibility to anyone for the consequences of using it
or for whether it serves any particular purpose or works at all,
unless he says so in writing.  Refer to the GNU Emacs General Public
License for full details.

Everyone is granted permission to copy, modify and redistribute
GNU Emacs, but only under the conditions described in the
GNU Emacs General Public License.   A copy of this license is
supposed to have been given to you along with GNU Emacs so you
can know your rights and responsibilities.  It should be in a
file named COPYING.  Among other things, the copyright notice
and this notice must be preserved on all copies.  */


#include "config.h"
#include "lisp.h"
#include "buffer.h"

/* Last buffer for which undo information was recorded.  */
Lisp_Object last_undo_buffer;

/* Record an insertion that just happened or is about to happen,
   for LENGTH characters at position BEG.
   (It is possible to record an insertion before or after the fact
   because we don't need to record the contents.)  */

record_insert (beg, length)
     Lisp_Object beg, length;
{
  Lisp_Object lbeg, lend;

  if (current_buffer != XBUFFER (last_undo_buffer))
    Fundo_boundary ();
  XSET (last_undo_buffer, Lisp_Buffer, current_buffer);

  if (EQ (current_buffer->undo_list, Qt))
    return;
  if (MODIFF <= current_buffer->save_modified)
    record_first_change ();

  /* If this is following another insertion and consecutive with it
     in the buffer, combine the two.  */
  if (XTYPE (current_buffer->undo_list) == Lisp_Cons)
    {
      Lisp_Object elt;
      elt = XCONS (current_buffer->undo_list)->car;
      if (XTYPE (elt) == Lisp_Cons
	  && XTYPE (XCONS (elt)->car) == Lisp_Int
	  && XTYPE (XCONS (elt)->cdr) == Lisp_Int
	  && XINT (XCONS (elt)->cdr) == beg)
	{
	  XSETINT (XCONS (elt)->cdr, beg + length);
	  return;
	}
    }

  XFASTINT (lbeg) = beg;
  XFASTINT (lend) = beg + length;
  current_buffer->undo_list = Fcons (Fcons (lbeg, lend), current_buffer->undo_list);
}

/* Record that a deletion is about to take place,
   for LENGTH characters at location BEG.  */

record_delete (beg, length)
     int beg, length;
{
  Lisp_Object lbeg, lend, sbeg;

  if (current_buffer != XBUFFER (last_undo_buffer))
    Fundo_boundary ();
  XSET (last_undo_buffer, Lisp_Buffer, current_buffer);

  if (EQ (current_buffer->undo_list, Qt))
    return;
  if (MODIFF <= current_buffer->save_modified)
    record_first_change ();

  if (point == beg + length)
    XSET (sbeg, Lisp_Int, -beg);
  else
    XFASTINT (sbeg) = beg;
  XFASTINT (lbeg) = beg;
  XFASTINT (lend) = beg + length;
  current_buffer->undo_list
    = Fcons (Fcons (Fbuffer_substring (lbeg, lend), sbeg),
	     current_buffer->undo_list);
}

/* Record that a replacement is about to take place,
   for LENGTH characters at location BEG.
   The replacement does not change the number of characters.  */

record_change (beg, length)
     int beg, length;
{
  record_delete (beg, length);
  record_insert (beg, length);
}
\f
/* Record that an unmodified buffer is about to be changed.
   Record the file modification date so that when undoing this entry
   we can tell whether it is obsolete because the file was saved again.  */

record_first_change ()
{
  Lisp_Object high, low;
  XFASTINT (high) = (current_buffer->modtime >> 16) & 0xffff;
  XFASTINT (low) = current_buffer->modtime & 0xffff;
  current_buffer->undo_list = Fcons (Fcons (Qt, Fcons (high, low)), current_buffer->undo_list);
}

DEFUN ("undo-boundary", Fundo_boundary, Sundo_boundary, 0, 0, 0,
  "Mark a boundary between units of undo.\n\
An undo command will stop at this point,\n\
but another undo command will undo to the previous boundary.")
  ()
{
  Lisp_Object tem;
  if (EQ (current_buffer->undo_list, Qt))
    return Qnil;
  tem = Fcar (current_buffer->undo_list);
  if (!NULL (tem))
    current_buffer->undo_list = Fcons (Qnil, current_buffer->undo_list);
  return Qnil;
}

/* At garbage collection time, make an undo list shorter at the end,
   returning the truncated list.
   MINSIZE and MAXSIZE are the limits on size allowed, as described below.
   In practice, these are the values of undo-threshold and
   undo-high-threshold.  */

Lisp_Object
truncate_undo_list (list, minsize, maxsize)
     Lisp_Object list;
     int minsize, maxsize;
{
  Lisp_Object prev, next, last_boundary;
  int size_so_far = 0;

  prev = Qnil;
  next = list;
  last_boundary = Qnil;

  /* Always preserve at least the most recent undo record.
     If the first element is an undo boundary, skip past it.  */
  if (XTYPE (next) == Lisp_Cons
      && XCONS (next)->car == Qnil)
    {
      /* Add in the space occupied by this element and its chain link.  */
      size_so_far += sizeof (struct Lisp_Cons);

      /* Advance to next element.  */
      prev = next;
      next = XCONS (next)->cdr;
    }
  while (XTYPE (next) == Lisp_Cons
	 && XCONS (next)->car != Qnil)
    {
      Lisp_Object elt;
      elt = XCONS (next)->car;

      /* Add in the space occupied by this element and its chain link.  */
      size_so_far += sizeof (struct Lisp_Cons);
      if (XTYPE (elt) == Lisp_Cons)
	{
	  size_so_far += sizeof (struct Lisp_Cons);
	  if (XTYPE (XCONS (elt)->car) == Lisp_String)
	    size_so_far += (sizeof (struct Lisp_String) - 1
			    + XSTRING (XCONS (elt)->car)->size);
	}

      /* Advance to next element.  */
      prev = next;
      next = XCONS (next)->cdr;
    }
  if (XTYPE (next) == Lisp_Cons)
    last_boundary = prev;

  while (XTYPE (next) == Lisp_Cons)
    {
      Lisp_Object elt;
      elt = XCONS (next)->car;

      /* When we get to a boundary, decide whether to truncate
	 either before or after it.  The lower threshold, MINSIZE,
	 tells us to truncate after it.  If its size pushes past
	 the higher threshold MAXSIZE as well, we truncate before it.  */
      if (NULL (elt))
	{
	  if (size_so_far > maxsize)
	    break;
	  last_boundary = prev;
	  if (size_so_far > minsize)
	    break;
	}

      /* Add in the space occupied by this element and its chain link.  */
      size_so_far += sizeof (struct Lisp_Cons);
      if (XTYPE (elt) == Lisp_Cons)
	{
	  size_so_far += sizeof (struct Lisp_Cons);
	  if (XTYPE (XCONS (elt)->car) == Lisp_String)
	    size_so_far += (sizeof (struct Lisp_String) - 1
			    + XSTRING (XCONS (elt)->car)->size);
	}

      /* Advance to next element.  */
      prev = next;
      next = XCONS (next)->cdr;
    }

  /* If we scanned the whole list, it is short enough; don't change it.  */
  if (NULL (next))
    return list;

  /* Truncate at the boundary where we decided to truncate.  */
  if (!NULL (last_boundary))
    {
      XCONS (last_boundary)->cdr = Qnil;
      return list;
    }
  else
    return Qnil;
}
\f
DEFUN ("primitive-undo", Fprimitive_undo, Sprimitive_undo, 2, 2, 0,
  "Undo N records from the front of the list LIST.\n\
Return what remains of the list.")
  (count, list)
     Lisp_Object count, list;
{
  register int arg = XINT (count);
#if 0  /* This is a good feature, but would make undo-start
	  unable to do what is expected.  */
  Lisp_Object tem;

  /* If the head of the list is a boundary, it is the boundary
     preceding this command.  Get rid of it and don't count it.  */
  tem = Fcar (list);
  if (NULL (tem))
    list = Fcdr (list);
#endif

  while (arg > 0)
    {
      while (1)
	{
	  Lisp_Object next, car, cdr;
	  next = Fcar (list);
	  list = Fcdr (list);
	  if (NULL (next))
	    break;
	  car = Fcar (next);
	  cdr = Fcdr (next);
	  if (EQ (car, Qt))
	    {
	      Lisp_Object high, low;
	      int mod_time;
	      high = Fcar (cdr);
	      low = Fcdr (cdr);
	      mod_time = (high << 16) + low;
	      /* If this records an obsolete save
		 (not matching the actual disk file)
		 then don't mark unmodified.  */
	      if (mod_time != current_buffer->modtime)
		break;
#ifdef CLASH_DETECTION
	      Funlock_buffer ();
#endif /* CLASH_DETECTION */
	      Fset_buffer_modified_p (Qnil);
	    }
	  else if (XTYPE (car) == Lisp_Int && XTYPE (cdr) == Lisp_Int)
	    {
	      Lisp_Object end;
	      if (XINT (car) < BEGV
		  || XINT (cdr) > ZV)
		error ("Changes to be undone are outside visible portion of buffer");
	      Fdelete_region (car, cdr);
	      Fgoto_char (car);
	    }
	  else if (XTYPE (car) == Lisp_String && XTYPE (cdr) == Lisp_Int)
	    {
	      Lisp_Object membuf;
	      int pos = XINT (cdr);
	      membuf = car;
	      if (pos < 0)
		{
		  if (-pos < BEGV || -pos > ZV)
		    error ("Changes to be undone are outside visible portion of buffer");
		  SET_PT (-pos);
		  Finsert (1, &membuf);
		}
	      else
		{
		  if (pos < BEGV || pos > ZV)
		    error ("Changes to be undone are outside visible portion of buffer");
		  SET_PT (pos);
		  Finsert (1, &membuf);
		  SET_PT (pos);
		}
	    }
	}
      arg--;
    }

  return list;
}

syms_of_undo ()
{
  defsubr (&Sprimitive_undo);
  defsubr (&Sundo_boundary);
}
Commit	Line	Data
c6953be1 JB	1	/* undo handling for GNU Emacs.
	2	Copyright (C) 1990 Free Software Foundation, Inc.
	3
	4	This file is part of GNU Emacs.
	5
	6	GNU Emacs is distributed in the hope that it will be useful,
	7	but WITHOUT ANY WARRANTY. No author or distributor
	8	accepts responsibility to anyone for the consequences of using it
	9	or for whether it serves any particular purpose or works at all,
	10	unless he says so in writing. Refer to the GNU Emacs General Public
	11	License for full details.
	12
	13	Everyone is granted permission to copy, modify and redistribute
	14	GNU Emacs, but only under the conditions described in the
	15	GNU Emacs General Public License. A copy of this license is
	16	supposed to have been given to you along with GNU Emacs so you
	17	can know your rights and responsibilities. It should be in a
	18	file named COPYING. Among other things, the copyright notice
	19	and this notice must be preserved on all copies. */
	20
	21
	22	#include "config.h"
	23	#include "lisp.h"
	24	#include "buffer.h"
	25
	26	/* Last buffer for which undo information was recorded. */
	27	Lisp_Object last_undo_buffer;
	28
	29	/* Record an insertion that just happened or is about to happen,
	30	for LENGTH characters at position BEG.
	31	(It is possible to record an insertion before or after the fact
	32	because we don't need to record the contents.) */
	33
	34	record_insert (beg, length)
	35	Lisp_Object beg, length;
	36	{
	37	Lisp_Object lbeg, lend;
	38
	39	if (current_buffer != XBUFFER (last_undo_buffer))
	40	Fundo_boundary ();
	41	XSET (last_undo_buffer, Lisp_Buffer, current_buffer);
	42
	43	if (EQ (current_buffer->undo_list, Qt))
	44	return;
	45	if (MODIFF <= current_buffer->save_modified)
	46	record_first_change ();
	47
	48	/* If this is following another insertion and consecutive with it
	49	in the buffer, combine the two. */
	50	if (XTYPE (current_buffer->undo_list) == Lisp_Cons)
	51	{
	52	Lisp_Object elt;
	53	elt = XCONS (current_buffer->undo_list)->car;
	54	if (XTYPE (elt) == Lisp_Cons
	55	&& XTYPE (XCONS (elt)->car) == Lisp_Int
	56	&& XTYPE (XCONS (elt)->cdr) == Lisp_Int
	57	&& XINT (XCONS (elt)->cdr) == beg)
	58	{
	59	XSETINT (XCONS (elt)->cdr, beg + length);
	60	return;
	61	}
	62	}
	63
	64	XFASTINT (lbeg) = beg;
65	XFASTINT (lend) = beg + length;
66	current_buffer->undo_list = Fcons (Fcons (lbeg, lend), current_buffer->undo_list);
67	}
68
69	/* Record that a deletion is about to take place,
70	for LENGTH characters at location BEG. */
71
72	record_delete (beg, length)
73	int beg, length;
74	{
75	Lisp_Object lbeg, lend, sbeg;
76
77	if (current_buffer != XBUFFER (last_undo_buffer))
78	Fundo_boundary ();
79	XSET (last_undo_buffer, Lisp_Buffer, current_buffer);
80
81	if (EQ (current_buffer->undo_list, Qt))
82	return;
83	if (MODIFF <= current_buffer->save_modified)
84	record_first_change ();
85
86	if (point == beg + length)
87	XSET (sbeg, Lisp_Int, -beg);
88	else
89	XFASTINT (sbeg) = beg;
90	XFASTINT (lbeg) = beg;
91	XFASTINT (lend) = beg + length;
92	current_buffer->undo_list
93	= Fcons (Fcons (Fbuffer_substring (lbeg, lend), sbeg),
94	current_buffer->undo_list);
95	}
96
97	/* Record that a replacement is about to take place,
98	for LENGTH characters at location BEG.
99	The replacement does not change the number of characters. */
100
101	record_change (beg, length)
102	int beg, length;
103	{
104	record_delete (beg, length);
105	record_insert (beg, length);
106	}
107	\f
108	/* Record that an unmodified buffer is about to be changed.
109	Record the file modification date so that when undoing this entry
110	we can tell whether it is obsolete because the file was saved again. */
111
112	record_first_change ()
113	{
114	Lisp_Object high, low;
115	XFASTINT (high) = (current_buffer->modtime >> 16) & 0xffff;
116	XFASTINT (low) = current_buffer->modtime & 0xffff;
117	current_buffer->undo_list = Fcons (Fcons (Qt, Fcons (high, low)), current_buffer->undo_list);
118	}
119
120	DEFUN ("undo-boundary", Fundo_boundary, Sundo_boundary, 0, 0, 0,
121	"Mark a boundary between units of undo.\n\
122	An undo command will stop at this point,\n\
123	but another undo command will undo to the previous boundary.")
124	()
125	{
126	Lisp_Object tem;
127	if (EQ (current_buffer->undo_list, Qt))
128	return Qnil;
129	tem = Fcar (current_buffer->undo_list);
130	if (!NULL (tem))
131	current_buffer->undo_list = Fcons (Qnil, current_buffer->undo_list);
132	return Qnil;
133	}
134
135	/* At garbage collection time, make an undo list shorter at the end,
136	returning the truncated list.
137	MINSIZE and MAXSIZE are the limits on size allowed, as described below.
138	In practice, these are the values of undo-threshold and
139	undo-high-threshold. */
140
141	Lisp_Object
142	truncate_undo_list (list, minsize, maxsize)
143	Lisp_Object list;
144	int minsize, maxsize;
145	{
146	Lisp_Object prev, next, last_boundary;
147	int size_so_far = 0;
148
149	prev = Qnil;
150	next = list;
151	last_boundary = Qnil;
152
153	/* Always preserve at least the most recent undo record.
154	If the first element is an undo boundary, skip past it. */
155	if (XTYPE (next) == Lisp_Cons
156	&& XCONS (next)->car == Qnil)
157	{
158	/* Add in the space occupied by this element and its chain link. */
159	size_so_far += sizeof (struct Lisp_Cons);
160
161	/* Advance to next element. */
162	prev = next;
163	next = XCONS (next)->cdr;
164	}
165	while (XTYPE (next) == Lisp_Cons
166	&& XCONS (next)->car != Qnil)
167	{
168	Lisp_Object elt;
169	elt = XCONS (next)->car;
170
171	/* Add in the space occupied by this element and its chain link. */
172	size_so_far += sizeof (struct Lisp_Cons);
173	if (XTYPE (elt) == Lisp_Cons)
174	{
175	size_so_far += sizeof (struct Lisp_Cons);
176	if (XTYPE (XCONS (elt)->car) == Lisp_String)
177	size_so_far += (sizeof (struct Lisp_String) - 1
178	+ XSTRING (XCONS (elt)->car)->size);
179	}
180
181	/* Advance to next element. */
182	prev = next;
183	next = XCONS (next)->cdr;
184	}
185	if (XTYPE (next) == Lisp_Cons)
186	last_boundary = prev;
187
188	while (XTYPE (next) == Lisp_Cons)
189	{
190	Lisp_Object elt;
191	elt = XCONS (next)->car;
192
193	/* When we get to a boundary, decide whether to truncate
194	either before or after it. The lower threshold, MINSIZE,
195	tells us to truncate after it. If its size pushes past
196	the higher threshold MAXSIZE as well, we truncate before it. */
197	if (NULL (elt))
198	{
199	if (size_so_far > maxsize)
200	break;
201	last_boundary = prev;
202	if (size_so_far > minsize)
203	break;
204	}
205
206	/* Add in the space occupied by this element and its chain link. */
207	size_so_far += sizeof (struct Lisp_Cons);
208	if (XTYPE (elt) == Lisp_Cons)
209	{
210	size_so_far += sizeof (struct Lisp_Cons);
211	if (XTYPE (XCONS (elt)->car) == Lisp_String)
212	size_so_far += (sizeof (struct Lisp_String) - 1
213	+ XSTRING (XCONS (elt)->car)->size);
214	}
215
216	/* Advance to next element. */
217	prev = next;
218	next = XCONS (next)->cdr;
219	}
220
221	/* If we scanned the whole list, it is short enough; don't change it. */
222	if (NULL (next))
223	return list;
224
225	/* Truncate at the boundary where we decided to truncate. */
226	if (!NULL (last_boundary))
227	{
228	XCONS (last_boundary)->cdr = Qnil;
229	return list;
230	}
231	else
232	return Qnil;
233	}
234	\f
235	DEFUN ("primitive-undo", Fprimitive_undo, Sprimitive_undo, 2, 2, 0,
236	"Undo N records from the front of the list LIST.\n\
237	Return what remains of the list.")
238	(count, list)
239	Lisp_Object count, list;
240	{
241	register int arg = XINT (count);
242	#if 0 /* This is a good feature, but would make undo-start
243	unable to do what is expected. */
244	Lisp_Object tem;
245
246	/* If the head of the list is a boundary, it is the boundary
247	preceding this command. Get rid of it and don't count it. */
248	tem = Fcar (list);
249	if (NULL (tem))
250	list = Fcdr (list);
251	#endif
252
253	while (arg > 0)
254	{
255	while (1)
256	{
257	Lisp_Object next, car, cdr;
258	next = Fcar (list);
259	list = Fcdr (list);
260	if (NULL (next))
261	break;
262	car = Fcar (next);
263	cdr = Fcdr (next);
264	if (EQ (car, Qt))
265	{
266	Lisp_Object high, low;
267	int mod_time;
268	high = Fcar (cdr);
269	low = Fcdr (cdr);
270	mod_time = (high << 16) + low;
271	/* If this records an obsolete save
272	(not matching the actual disk file)
273	then don't mark unmodified. */
274	if (mod_time != current_buffer->modtime)
275	break;
276	#ifdef CLASH_DETECTION
277	Funlock_buffer ();
278	#endif /* CLASH_DETECTION */
279	Fset_buffer_modified_p (Qnil);
280	}
281	else if (XTYPE (car) == Lisp_Int && XTYPE (cdr) == Lisp_Int)
282	{
283	Lisp_Object end;
284	if (XINT (car) < BEGV
285	\|\| XINT (cdr) > ZV)
286	error ("Changes to be undone are outside visible portion of buffer");
287	Fdelete_region (car, cdr);
288	Fgoto_char (car);
289	}
290	else if (XTYPE (car) == Lisp_String && XTYPE (cdr) == Lisp_Int)
291	{
292	Lisp_Object membuf;
293	int pos = XINT (cdr);
294	membuf = car;
295	if (pos < 0)
296	{
297	if (-pos < BEGV \|\| -pos > ZV)
298	error ("Changes to be undone are outside visible portion of buffer");
299	SET_PT (-pos);
300	Finsert (1, &membuf);
301	}
302	else
303	{
304	if (pos < BEGV \|\| pos > ZV)
305	error ("Changes to be undone are outside visible portion of buffer");
306	SET_PT (pos);
307	Finsert (1, &membuf);
308	SET_PT (pos);
309	}
310	}
311	}
312	arg--;
313	}
314
315	return list;
316	}
317
318	syms_of_undo ()
319	{
320	defsubr (&Sprimitive_undo);
321	defsubr (&Sundo_boundary);
322	}