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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. | |
181a18b1 JB |
154 | If the first element is an undo boundary, skip past it. |
155 | ||
156 | Skip, skip, skip the undo, skip, skip, skip the undo, | |
157 | Skip, skip, skip the undo, skip to the undo bound'ry. */ | |
c6953be1 JB |
158 | if (XTYPE (next) == Lisp_Cons |
159 | && XCONS (next)->car == Qnil) | |
160 | { | |
161 | /* Add in the space occupied by this element and its chain link. */ | |
162 | size_so_far += sizeof (struct Lisp_Cons); | |
163 | ||
164 | /* Advance to next element. */ | |
165 | prev = next; | |
166 | next = XCONS (next)->cdr; | |
167 | } | |
168 | while (XTYPE (next) == Lisp_Cons | |
169 | && XCONS (next)->car != Qnil) | |
170 | { | |
171 | Lisp_Object elt; | |
172 | elt = XCONS (next)->car; | |
173 | ||
174 | /* Add in the space occupied by this element and its chain link. */ | |
175 | size_so_far += sizeof (struct Lisp_Cons); | |
176 | if (XTYPE (elt) == Lisp_Cons) | |
177 | { | |
178 | size_so_far += sizeof (struct Lisp_Cons); | |
179 | if (XTYPE (XCONS (elt)->car) == Lisp_String) | |
180 | size_so_far += (sizeof (struct Lisp_String) - 1 | |
181 | + XSTRING (XCONS (elt)->car)->size); | |
182 | } | |
183 | ||
184 | /* Advance to next element. */ | |
185 | prev = next; | |
186 | next = XCONS (next)->cdr; | |
187 | } | |
188 | if (XTYPE (next) == Lisp_Cons) | |
189 | last_boundary = prev; | |
190 | ||
191 | while (XTYPE (next) == Lisp_Cons) | |
192 | { | |
193 | Lisp_Object elt; | |
194 | elt = XCONS (next)->car; | |
195 | ||
196 | /* When we get to a boundary, decide whether to truncate | |
197 | either before or after it. The lower threshold, MINSIZE, | |
198 | tells us to truncate after it. If its size pushes past | |
199 | the higher threshold MAXSIZE as well, we truncate before it. */ | |
200 | if (NULL (elt)) | |
201 | { | |
202 | if (size_so_far > maxsize) | |
203 | break; | |
204 | last_boundary = prev; | |
205 | if (size_so_far > minsize) | |
206 | break; | |
207 | } | |
208 | ||
209 | /* Add in the space occupied by this element and its chain link. */ | |
210 | size_so_far += sizeof (struct Lisp_Cons); | |
211 | if (XTYPE (elt) == Lisp_Cons) | |
212 | { | |
213 | size_so_far += sizeof (struct Lisp_Cons); | |
214 | if (XTYPE (XCONS (elt)->car) == Lisp_String) | |
215 | size_so_far += (sizeof (struct Lisp_String) - 1 | |
216 | + XSTRING (XCONS (elt)->car)->size); | |
217 | } | |
218 | ||
219 | /* Advance to next element. */ | |
220 | prev = next; | |
221 | next = XCONS (next)->cdr; | |
222 | } | |
223 | ||
224 | /* If we scanned the whole list, it is short enough; don't change it. */ | |
225 | if (NULL (next)) | |
226 | return list; | |
227 | ||
228 | /* Truncate at the boundary where we decided to truncate. */ | |
229 | if (!NULL (last_boundary)) | |
230 | { | |
231 | XCONS (last_boundary)->cdr = Qnil; | |
232 | return list; | |
233 | } | |
234 | else | |
235 | return Qnil; | |
236 | } | |
237 | \f | |
238 | DEFUN ("primitive-undo", Fprimitive_undo, Sprimitive_undo, 2, 2, 0, | |
239 | "Undo N records from the front of the list LIST.\n\ | |
240 | Return what remains of the list.") | |
241 | (count, list) | |
242 | Lisp_Object count, list; | |
243 | { | |
244 | register int arg = XINT (count); | |
245 | #if 0 /* This is a good feature, but would make undo-start | |
246 | unable to do what is expected. */ | |
247 | Lisp_Object tem; | |
248 | ||
249 | /* If the head of the list is a boundary, it is the boundary | |
250 | preceding this command. Get rid of it and don't count it. */ | |
251 | tem = Fcar (list); | |
252 | if (NULL (tem)) | |
253 | list = Fcdr (list); | |
254 | #endif | |
255 | ||
256 | while (arg > 0) | |
257 | { | |
258 | while (1) | |
259 | { | |
260 | Lisp_Object next, car, cdr; | |
261 | next = Fcar (list); | |
262 | list = Fcdr (list); | |
263 | if (NULL (next)) | |
264 | break; | |
265 | car = Fcar (next); | |
266 | cdr = Fcdr (next); | |
267 | if (EQ (car, Qt)) | |
268 | { | |
269 | Lisp_Object high, low; | |
270 | int mod_time; | |
271 | high = Fcar (cdr); | |
272 | low = Fcdr (cdr); | |
273 | mod_time = (high << 16) + low; | |
274 | /* If this records an obsolete save | |
275 | (not matching the actual disk file) | |
276 | then don't mark unmodified. */ | |
277 | if (mod_time != current_buffer->modtime) | |
278 | break; | |
279 | #ifdef CLASH_DETECTION | |
280 | Funlock_buffer (); | |
281 | #endif /* CLASH_DETECTION */ | |
282 | Fset_buffer_modified_p (Qnil); | |
283 | } | |
284 | else if (XTYPE (car) == Lisp_Int && XTYPE (cdr) == Lisp_Int) | |
285 | { | |
286 | Lisp_Object end; | |
287 | if (XINT (car) < BEGV | |
288 | || XINT (cdr) > ZV) | |
289 | error ("Changes to be undone are outside visible portion of buffer"); | |
290 | Fdelete_region (car, cdr); | |
291 | Fgoto_char (car); | |
292 | } | |
293 | else if (XTYPE (car) == Lisp_String && XTYPE (cdr) == Lisp_Int) | |
294 | { | |
295 | Lisp_Object membuf; | |
296 | int pos = XINT (cdr); | |
297 | membuf = car; | |
298 | if (pos < 0) | |
299 | { | |
300 | if (-pos < BEGV || -pos > ZV) | |
301 | error ("Changes to be undone are outside visible portion of buffer"); | |
302 | SET_PT (-pos); | |
303 | Finsert (1, &membuf); | |
304 | } | |
305 | else | |
306 | { | |
307 | if (pos < BEGV || pos > ZV) | |
308 | error ("Changes to be undone are outside visible portion of buffer"); | |
309 | SET_PT (pos); | |
310 | Finsert (1, &membuf); | |
311 | SET_PT (pos); | |
312 | } | |
313 | } | |
314 | } | |
315 | arg--; | |
316 | } | |
317 | ||
318 | return list; | |
319 | } | |
320 | ||
321 | syms_of_undo () | |
322 | { | |
323 | defsubr (&Sprimitive_undo); | |
324 | defsubr (&Sundo_boundary); | |
325 | } |