|
428
|
1 @c -*-texinfo-*-
|
|
|
2 @c This is part of the XEmacs Lisp Reference Manual.
|
|
444
|
3 @c Copyright (C) 1990, 1991, 1992, 1993, 1994 Free Software Foundation, Inc.
|
|
428
|
4 @c See the file lispref.texi for copying conditions.
|
|
|
5 @setfilename ../../info/positions.info
|
|
|
6 @node Positions, Markers, Consoles and Devices, Top
|
|
|
7 @chapter Positions
|
|
|
8 @cindex position (in buffer)
|
|
|
9
|
|
|
10 A @dfn{position} is the index of a character in the text of a buffer.
|
|
|
11 More precisely, a position identifies the place between two characters
|
|
|
12 (or before the first character, or after the last character), so we can
|
|
|
13 speak of the character before or after a given position. However, we
|
|
|
14 often speak of the character ``at'' a position, meaning the character
|
|
|
15 after that position.
|
|
|
16
|
|
|
17 Positions are usually represented as integers starting from 1, but can
|
|
|
18 also be represented as @dfn{markers}---special objects that relocate
|
|
|
19 automatically when text is inserted or deleted so they stay with the
|
|
|
20 surrounding characters. @xref{Markers}.
|
|
|
21
|
|
|
22 @menu
|
|
|
23 * Point:: The special position where editing takes place.
|
|
|
24 * Motion:: Changing point.
|
|
|
25 * Excursions:: Temporary motion and buffer changes.
|
|
|
26 * Narrowing:: Restricting editing to a portion of the buffer.
|
|
|
27 @end menu
|
|
|
28
|
|
|
29 @node Point
|
|
|
30 @section Point
|
|
|
31 @cindex point
|
|
|
32
|
|
|
33 @dfn{Point} is a special buffer position used by many editing
|
|
|
34 commands, including the self-inserting typed characters and text
|
|
|
35 insertion functions. Other commands move point through the text
|
|
|
36 to allow editing and insertion at different places.
|
|
|
37
|
|
|
38 Like other positions, point designates a place between two characters
|
|
|
39 (or before the first character, or after the last character), rather
|
|
|
40 than a particular character. Usually terminals display the cursor over
|
|
|
41 the character that immediately follows point; point is actually before
|
|
|
42 the character on which the cursor sits.
|
|
|
43
|
|
|
44 @cindex point with narrowing
|
|
|
45 The value of point is a number between 1 and the buffer size plus 1.
|
|
|
46 If narrowing is in effect (@pxref{Narrowing}), then point is constrained
|
|
|
47 to fall within the accessible portion of the buffer (possibly at one end
|
|
|
48 of it).
|
|
|
49
|
|
|
50 Each buffer has its own value of point, which is independent of the
|
|
|
51 value of point in other buffers. Each window also has a value of point,
|
|
|
52 which is independent of the value of point in other windows on the same
|
|
|
53 buffer. This is why point can have different values in various windows
|
|
|
54 that display the same buffer. When a buffer appears in only one window,
|
|
|
55 the buffer's point and the window's point normally have the same value,
|
|
|
56 so the distinction is rarely important. @xref{Window Point}, for more
|
|
|
57 details.
|
|
|
58
|
|
|
59 @defun point &optional buffer
|
|
|
60 @cindex current buffer position
|
|
|
61 This function returns the value of point in @var{buffer}, as an integer.
|
|
|
62 @var{buffer} defaults to the current buffer if omitted.
|
|
|
63
|
|
|
64 @need 700
|
|
|
65 @example
|
|
|
66 @group
|
|
|
67 (point)
|
|
|
68 @result{} 175
|
|
|
69 @end group
|
|
|
70 @end example
|
|
|
71 @end defun
|
|
|
72
|
|
|
73 @defun point-min &optional buffer
|
|
|
74 This function returns the minimum accessible value of point in
|
|
|
75 @var{buffer}. This is normally 1, but if narrowing is in effect, it is
|
|
|
76 the position of the start of the region that you narrowed to.
|
|
|
77 (@xref{Narrowing}.) @var{buffer} defaults to the current buffer if
|
|
|
78 omitted.
|
|
|
79 @end defun
|
|
|
80
|
|
|
81 @defun point-max &optional buffer
|
|
|
82 This function returns the maximum accessible value of point in
|
|
|
83 @var{buffer}. This is @code{(1+ (buffer-size buffer))}, unless
|
|
|
84 narrowing is in effect, in which case it is the position of the end of
|
|
|
85 the region that you narrowed to. (@pxref{Narrowing}). @var{buffer}
|
|
|
86 defaults to the current buffer if omitted.
|
|
|
87 @end defun
|
|
|
88
|
|
|
89 @defun buffer-end flag &optional buffer
|
|
|
90 This function returns @code{(point-min buffer)} if @var{flag} is less
|
|
|
91 than 1, @code{(point-max buffer)} otherwise. The argument @var{flag}
|
|
|
92 must be a number. @var{buffer} defaults to the current buffer if
|
|
|
93 omitted.
|
|
|
94 @end defun
|
|
|
95
|
|
|
96 @defun buffer-size &optional buffer
|
|
|
97 This function returns the total number of characters in @var{buffer}.
|
|
|
98 In the absence of any narrowing (@pxref{Narrowing}), @code{point-max}
|
|
|
99 returns a value one larger than this. @var{buffer} defaults to the
|
|
|
100 current buffer if omitted.
|
|
|
101
|
|
|
102 @example
|
|
|
103 @group
|
|
|
104 (buffer-size)
|
|
|
105 @result{} 35
|
|
|
106 @end group
|
|
|
107 @group
|
|
|
108 (point-max)
|
|
|
109 @result{} 36
|
|
|
110 @end group
|
|
|
111 @end example
|
|
|
112 @end defun
|
|
|
113
|
|
|
114 @defvar buffer-saved-size
|
|
|
115 The value of this buffer-local variable is the former length of the
|
|
|
116 current buffer, as of the last time it was read in, saved or auto-saved.
|
|
|
117 @end defvar
|
|
|
118
|
|
|
119 @node Motion
|
|
|
120 @section Motion
|
|
|
121
|
|
|
122 Motion functions change the value of point, either relative to the
|
|
|
123 current value of point, relative to the beginning or end of the buffer,
|
|
|
124 or relative to the edges of the selected window. @xref{Point}.
|
|
|
125
|
|
|
126 @menu
|
|
|
127 * Character Motion:: Moving in terms of characters.
|
|
|
128 * Word Motion:: Moving in terms of words.
|
|
|
129 * Buffer End Motion:: Moving to the beginning or end of the buffer.
|
|
|
130 * Text Lines:: Moving in terms of lines of text.
|
|
|
131 * Screen Lines:: Moving in terms of lines as displayed.
|
|
|
132 * List Motion:: Moving by parsing lists and sexps.
|
|
|
133 * Skipping Characters:: Skipping characters belonging to a certain set.
|
|
|
134 @end menu
|
|
|
135
|
|
|
136 @node Character Motion
|
|
|
137 @subsection Motion by Characters
|
|
|
138
|
|
|
139 These functions move point based on a count of characters.
|
|
|
140 @code{goto-char} is the fundamental primitive; the other functions use
|
|
|
141 that.
|
|
|
142
|
|
|
143 @deffn Command goto-char position &optional buffer
|
|
|
144 This function sets point in @code{buffer} to the value @var{position}.
|
|
|
145 If @var{position} is less than 1, it moves point to the beginning of the
|
|
|
146 buffer. If @var{position} is greater than the length of the buffer, it
|
|
|
147 moves point to the end. @var{buffer} defaults to the current buffer if
|
|
|
148 omitted.
|
|
|
149
|
|
|
150 If narrowing is in effect, @var{position} still counts from the
|
|
|
151 beginning of the buffer, but point cannot go outside the accessible
|
|
|
152 portion. If @var{position} is out of range, @code{goto-char} moves
|
|
|
153 point to the beginning or the end of the accessible portion.
|
|
|
154
|
|
|
155 When this function is called interactively, @var{position} is the
|
|
|
156 numeric prefix argument, if provided; otherwise it is read from the
|
|
|
157 minibuffer.
|
|
|
158
|
|
|
159 @code{goto-char} returns @var{position}.
|
|
|
160 @end deffn
|
|
|
161
|
|
|
162 @deffn Command forward-char &optional count buffer
|
|
|
163 @c @kindex beginning-of-buffer
|
|
|
164 @c @kindex end-of-buffer
|
|
|
165 This function moves point @var{count} characters forward, towards the
|
|
|
166 end of the buffer (or backward, towards the beginning of the buffer, if
|
|
|
167 @var{count} is negative). If the function attempts to move point past
|
|
|
168 the beginning or end of the buffer (or the limits of the accessible
|
|
|
169 portion, when narrowing is in effect), an error is signaled with error
|
|
|
170 code @code{beginning-of-buffer} or @code{end-of-buffer}. @var{buffer}
|
|
|
171 defaults to the current buffer if omitted.
|
|
|
172
|
|
|
173
|
|
|
174 In an interactive call, @var{count} is the numeric prefix argument.
|
|
|
175 @end deffn
|
|
|
176
|
|
|
177 @deffn Command backward-char &optional count buffer
|
|
|
178 This function moves point @var{count} characters backward, towards the
|
|
|
179 beginning of the buffer (or forward, towards the end of the buffer, if
|
|
|
180 @var{count} is negative). If the function attempts to move point past
|
|
|
181 the beginning or end of the buffer (or the limits of the accessible
|
|
|
182 portion, when narrowing is in effect), an error is signaled with error
|
|
|
183 code @code{beginning-of-buffer} or @code{end-of-buffer}. @var{buffer}
|
|
|
184 defaults to the current buffer if omitted.
|
|
|
185
|
|
|
186
|
|
|
187 In an interactive call, @var{count} is the numeric prefix argument.
|
|
|
188 @end deffn
|
|
|
189
|
|
|
190 @node Word Motion
|
|
|
191 @subsection Motion by Words
|
|
|
192
|
|
|
193 These functions for parsing words use the syntax table to decide
|
|
|
194 whether a given character is part of a word. @xref{Syntax Tables}.
|
|
|
195
|
|
446
|
196 @deffn Command forward-word &optional count buffer
|
|
428
|
197 This function moves point forward @var{count} words (or backward if
|
|
|
198 @var{count} is negative). Normally it returns @code{t}. If this motion
|
|
|
199 encounters the beginning or end of the buffer, or the limits of the
|
|
|
200 accessible portion when narrowing is in effect, point stops there and
|
|
446
|
201 the value is @code{nil}.
|
|
|
202
|
|
|
203 @var{count} defaults to @code{1} and @var{buffer} defaults to the
|
|
|
204 current buffer.
|
|
428
|
205
|
|
|
206 In an interactive call, @var{count} is set to the numeric prefix
|
|
|
207 argument.
|
|
|
208 @end deffn
|
|
|
209
|
|
446
|
210 @deffn Command backward-word &optional count buffer
|
|
428
|
211 This function is just like @code{forward-word}, except that it moves
|
|
|
212 backward until encountering the front of a word, rather than forward.
|
|
|
213 @var{buffer} defaults to the current buffer if omitted.
|
|
|
214
|
|
|
215 In an interactive call, @var{count} is set to the numeric prefix
|
|
|
216 argument.
|
|
|
217 @end deffn
|
|
|
218
|
|
|
219 @defvar words-include-escapes
|
|
|
220 @c Emacs 19 feature
|
|
|
221 This variable affects the behavior of @code{forward-word} and everything
|
|
|
222 that uses it. If it is non-@code{nil}, then characters in the
|
|
|
223 ``escape'' and ``character quote'' syntax classes count as part of
|
|
|
224 words. Otherwise, they do not.
|
|
|
225 @end defvar
|
|
|
226
|
|
|
227 @node Buffer End Motion
|
|
|
228 @subsection Motion to an End of the Buffer
|
|
|
229
|
|
|
230 To move point to the beginning of the buffer, write:
|
|
|
231
|
|
|
232 @example
|
|
|
233 @group
|
|
|
234 (goto-char (point-min))
|
|
|
235 @end group
|
|
|
236 @end example
|
|
|
237
|
|
|
238 @noindent
|
|
|
239 Likewise, to move to the end of the buffer, use:
|
|
|
240
|
|
|
241 @example
|
|
|
242 @group
|
|
|
243 (goto-char (point-max))
|
|
|
244 @end group
|
|
|
245 @end example
|
|
|
246
|
|
|
247 Here are two commands that users use to do these things. They are
|
|
|
248 documented here to warn you not to use them in Lisp programs, because
|
|
|
249 they set the mark and display messages in the echo area.
|
|
|
250
|
|
444
|
251 @deffn Command beginning-of-buffer &optional count
|
|
428
|
252 This function moves point to the beginning of the buffer (or the limits
|
|
|
253 of the accessible portion, when narrowing is in effect), setting the
|
|
444
|
254 mark at the previous position. If @var{count} is non-@code{nil}, then it
|
|
|
255 puts point @var{count} tenths of the way from the beginning of the buffer.
|
|
428
|
256
|
|
444
|
257 In an interactive call, @var{count} is the numeric prefix argument,
|
|
|
258 if provided; otherwise @var{count} defaults to @code{nil}.
|
|
428
|
259
|
|
|
260 Don't use this function in Lisp programs!
|
|
|
261 @end deffn
|
|
|
262
|
|
444
|
263 @deffn Command end-of-buffer &optional count
|
|
428
|
264 This function moves point to the end of the buffer (or the limits of
|
|
|
265 the accessible portion, when narrowing is in effect), setting the mark
|
|
444
|
266 at the previous position. If @var{count} is non-@code{nil}, then it puts
|
|
|
267 point @var{count} tenths of the way from the end of the buffer.
|
|
428
|
268
|
|
444
|
269 In an interactive call, @var{count} is the numeric prefix argument,
|
|
|
270 if provided; otherwise @var{count} defaults to @code{nil}.
|
|
428
|
271
|
|
|
272 Don't use this function in Lisp programs!
|
|
|
273 @end deffn
|
|
|
274
|
|
|
275 @node Text Lines
|
|
|
276 @subsection Motion by Text Lines
|
|
|
277 @cindex lines
|
|
|
278
|
|
|
279 Text lines are portions of the buffer delimited by newline characters,
|
|
|
280 which are regarded as part of the previous line. The first text line
|
|
|
281 begins at the beginning of the buffer, and the last text line ends at
|
|
|
282 the end of the buffer whether or not the last character is a newline.
|
|
|
283 The division of the buffer into text lines is not affected by the width
|
|
|
284 of the window, by line continuation in display, or by how tabs and
|
|
|
285 control characters are displayed.
|
|
|
286
|
|
|
287 @deffn Command goto-line line
|
|
|
288 This function moves point to the front of the @var{line}th line,
|
|
|
289 counting from line 1 at beginning of the buffer. If @var{line} is less
|
|
|
290 than 1, it moves point to the beginning of the buffer. If @var{line} is
|
|
|
291 greater than the number of lines in the buffer, it moves point to the
|
|
|
292 end of the buffer---that is, the @emph{end of the last line} of the
|
|
|
293 buffer. This is the only case in which @code{goto-line} does not
|
|
|
294 necessarily move to the beginning of a line.
|
|
|
295
|
|
|
296 If narrowing is in effect, then @var{line} still counts from the
|
|
|
297 beginning of the buffer, but point cannot go outside the accessible
|
|
|
298 portion. So @code{goto-line} moves point to the beginning or end of the
|
|
|
299 accessible portion, if the line number specifies an inaccessible
|
|
|
300 position.
|
|
|
301
|
|
|
302 The return value of @code{goto-line} is the difference between
|
|
|
303 @var{line} and the line number of the line to which point actually was
|
|
|
304 able to move (in the full buffer, before taking account of narrowing).
|
|
|
305 Thus, the value is positive if the scan encounters the real end of the
|
|
|
306 buffer. The value is zero if scan encounters the end of the accessible
|
|
|
307 portion but not the real end of the buffer.
|
|
|
308
|
|
|
309 In an interactive call, @var{line} is the numeric prefix argument if
|
|
|
310 one has been provided. Otherwise @var{line} is read in the minibuffer.
|
|
|
311 @end deffn
|
|
|
312
|
|
|
313 @deffn Command beginning-of-line &optional count buffer
|
|
|
314 This function moves point to the beginning of the current line. With an
|
|
|
315 argument @var{count} not @code{nil} or 1, it moves forward
|
|
|
316 @var{count}@minus{}1 lines and then to the beginning of the line.
|
|
|
317 @var{buffer} defaults to the current buffer if omitted.
|
|
|
318
|
|
|
319 If this function reaches the end of the buffer (or of the accessible
|
|
|
320 portion, if narrowing is in effect), it positions point there. No error
|
|
|
321 is signaled.
|
|
|
322 @end deffn
|
|
|
323
|
|
|
324 @deffn Command end-of-line &optional count buffer
|
|
|
325 This function moves point to the end of the current line. With an
|
|
|
326 argument @var{count} not @code{nil} or 1, it moves forward
|
|
|
327 @var{count}@minus{}1 lines and then to the end of the line.
|
|
|
328 @var{buffer} defaults to the current buffer if omitted.
|
|
|
329
|
|
|
330 If this function reaches the end of the buffer (or of the accessible
|
|
|
331 portion, if narrowing is in effect), it positions point there. No error
|
|
|
332 is signaled.
|
|
|
333 @end deffn
|
|
|
334
|
|
|
335 @deffn Command forward-line &optional count buffer
|
|
|
336 @cindex beginning of line
|
|
|
337 This function moves point forward @var{count} lines, to the beginning of
|
|
|
338 the line. If @var{count} is negative, it moves point
|
|
|
339 @minus{}@var{count} lines backward, to the beginning of a line. If
|
|
|
340 @var{count} is zero, it moves point to the beginning of the current
|
|
|
341 line. @var{buffer} defaults to the current buffer if omitted.
|
|
|
342
|
|
|
343 If @code{forward-line} encounters the beginning or end of the buffer (or
|
|
|
344 of the accessible portion) before finding that many lines, it sets point
|
|
|
345 there. No error is signaled.
|
|
|
346
|
|
|
347 @code{forward-line} returns the difference between @var{count} and the
|
|
|
348 number of lines actually moved. If you attempt to move down five lines
|
|
|
349 from the beginning of a buffer that has only three lines, point stops at
|
|
|
350 the end of the last line, and the value will be 2.
|
|
|
351
|
|
|
352 In an interactive call, @var{count} is the numeric prefix argument.
|
|
|
353 @end deffn
|
|
|
354
|
|
444
|
355 @defun count-lines start end &optional ignore-invisible-lines-flag
|
|
428
|
356 @cindex lines in region
|
|
|
357 This function returns the number of lines between the positions
|
|
|
358 @var{start} and @var{end} in the current buffer. If @var{start} and
|
|
|
359 @var{end} are equal, then it returns 0. Otherwise it returns at least
|
|
|
360 1, even if @var{start} and @var{end} are on the same line. This is
|
|
|
361 because the text between them, considered in isolation, must contain at
|
|
|
362 least one line unless it is empty.
|
|
|
363
|
|
444
|
364 With optional @var{ignore-invisible-lines-flag} non-@code{nil}, lines
|
|
|
365 collapsed with selective-display are excluded from the line count.
|
|
|
366
|
|
|
367 @strong{Note:} The expression to return the current line number is not
|
|
|
368 obvious:
|
|
|
369
|
|
|
370 @example
|
|
|
371 (1+ (count-lines 1 (point-at-bol)))
|
|
|
372 @end example
|
|
|
373
|
|
428
|
374 Here is an example of using @code{count-lines}:
|
|
|
375
|
|
|
376 @example
|
|
|
377 @group
|
|
|
378 (defun current-line ()
|
|
|
379 "Return the vertical position of point@dots{}"
|
|
|
380 (+ (count-lines (window-start) (point))
|
|
|
381 (if (= (current-column) 0) 1 0)
|
|
|
382 -1))
|
|
|
383 @end group
|
|
|
384 @end example
|
|
|
385 @end defun
|
|
|
386
|
|
|
387 @ignore
|
|
|
388 @c ================
|
|
|
389 The @code{previous-line} and @code{next-line} commands are functions
|
|
|
390 that should not be used in programs. They are for users and are
|
|
|
391 mentioned here only for completeness.
|
|
|
392
|
|
|
393 @deffn Command previous-line count
|
|
|
394 @cindex goal column
|
|
|
395 This function moves point up @var{count} lines (down if @var{count}
|
|
|
396 is negative). In moving, it attempts to keep point in the ``goal column''
|
|
|
397 (normally the same column that it was at the beginning of the move).
|
|
|
398
|
|
|
399 If there is no character in the target line exactly under the current
|
|
|
400 column, point is positioned after the character in that line which
|
|
|
401 spans this column, or at the end of the line if it is not long enough.
|
|
|
402
|
|
|
403 If it attempts to move beyond the top or bottom of the buffer (or clipped
|
|
|
404 region), then point is positioned in the goal column in the top or
|
|
|
405 bottom line. No error is signaled.
|
|
|
406
|
|
|
407 In an interactive call, @var{count} will be the numeric
|
|
|
408 prefix argument.
|
|
|
409
|
|
|
410 The command @code{set-goal-column} can be used to create a semipermanent
|
|
|
411 goal column to which this command always moves. Then it does not try to
|
|
|
412 move vertically.
|
|
|
413
|
|
|
414 If you are thinking of using this in a Lisp program, consider using
|
|
|
415 @code{forward-line} with a negative argument instead. It is usually easier
|
|
|
416 to use and more reliable (no dependence on goal column, etc.).
|
|
|
417 @end deffn
|
|
|
418
|
|
|
419 @deffn Command next-line count
|
|
|
420 This function moves point down @var{count} lines (up if @var{count}
|
|
|
421 is negative). In moving, it attempts to keep point in the ``goal column''
|
|
|
422 (normally the same column that it was at the beginning of the move).
|
|
|
423
|
|
|
424 If there is no character in the target line exactly under the current
|
|
|
425 column, point is positioned after the character in that line which
|
|
|
426 spans this column, or at the end of the line if it is not long enough.
|
|
|
427
|
|
|
428 If it attempts to move beyond the top or bottom of the buffer (or clipped
|
|
|
429 region), then point is positioned in the goal column in the top or
|
|
|
430 bottom line. No error is signaled.
|
|
|
431
|
|
|
432 In the case where the @var{count} is 1, and point is on the last
|
|
|
433 line of the buffer (or clipped region), a new empty line is inserted at the
|
|
|
434 end of the buffer (or clipped region) and point moved there.
|
|
|
435
|
|
|
436 In an interactive call, @var{count} will be the numeric
|
|
|
437 prefix argument.
|
|
|
438
|
|
|
439 The command @code{set-goal-column} can be used to create a semipermanent
|
|
|
440 goal column to which this command always moves. Then it does not try to
|
|
|
441 move vertically.
|
|
|
442
|
|
|
443 If you are thinking of using this in a Lisp program, consider using
|
|
|
444 @code{forward-line} instead. It is usually easier
|
|
|
445 to use and more reliable (no dependence on goal column, etc.).
|
|
|
446 @end deffn
|
|
|
447
|
|
|
448 @c ================
|
|
|
449 @end ignore
|
|
|
450
|
|
|
451 Also see the functions @code{bolp} and @code{eolp} in @ref{Near Point}.
|
|
|
452 These functions do not move point, but test whether it is already at the
|
|
|
453 beginning or end of a line.
|
|
|
454
|
|
|
455 @node Screen Lines
|
|
|
456 @subsection Motion by Screen Lines
|
|
|
457
|
|
|
458 The line functions in the previous section count text lines, delimited
|
|
|
459 only by newline characters. By contrast, these functions count screen
|
|
|
460 lines, which are defined by the way the text appears on the screen. A
|
|
|
461 text line is a single screen line if it is short enough to fit the width
|
|
|
462 of the selected window, but otherwise it may occupy several screen
|
|
|
463 lines.
|
|
|
464
|
|
|
465 In some cases, text lines are truncated on the screen rather than
|
|
|
466 continued onto additional screen lines. In these cases,
|
|
|
467 @code{vertical-motion} moves point much like @code{forward-line}.
|
|
|
468 @xref{Truncation}.
|
|
|
469
|
|
|
470 Because the width of a given string depends on the flags that control
|
|
|
471 the appearance of certain characters, @code{vertical-motion} behaves
|
|
|
472 differently, for a given piece of text, depending on the buffer it is
|
|
|
473 in, and even on the selected window (because the width, the truncation
|
|
|
474 flag, and display table may vary between windows). @xref{Usual
|
|
|
475 Display}.
|
|
|
476
|
|
|
477 These functions scan text to determine where screen lines break, and
|
|
|
478 thus take time proportional to the distance scanned. If you intend to
|
|
|
479 use them heavily, Emacs provides caches which may improve the
|
|
|
480 performance of your code. @xref{Text Lines, cache-long-line-scans}.
|
|
|
481
|
|
|
482
|
|
|
483 @defun vertical-motion count &optional window pixels
|
|
|
484 This function moves point to the start of the frame line @var{count}
|
|
|
485 frame lines down from the frame line containing point. If @var{count}
|
|
|
486 is negative, it moves up instead. The optional second argument
|
|
444
|
487 @var{window} may be used to specify a window other than the
|
|
428
|
488 selected window in which to perform the motion.
|
|
|
489
|
|
|
490 Normally, @code{vertical-motion} returns the number of lines moved. The
|
|
|
491 value may be less in absolute value than @var{count} if the beginning or
|
|
|
492 end of the buffer was reached. If the optional third argument,
|
|
|
493 @var{pixels} is non-@code{nil}, the vertical pixel height of the motion
|
|
|
494 which took place is returned instead of the actual number of lines
|
|
|
495 moved. A motion of zero lines returns the height of the current line.
|
|
|
496
|
|
|
497 Note that @code{vertical-motion} sets @var{window}'s buffer's point, not
|
|
|
498 @var{window}'s point. (This differs from FSF Emacs, which buggily always
|
|
|
499 sets current buffer's point, regardless of @var{window}.)
|
|
|
500 @end defun
|
|
|
501
|
|
|
502 @defun vertical-motion-pixels count &optional window how
|
|
|
503 This function moves point to the start of the frame line @var{pixels}
|
|
|
504 vertical pixels down from the frame line containing point, or up if
|
|
|
505 @var{pixels} is negative. The optional second argument @var{window} is
|
|
|
506 the window to move in, and defaults to the selected window. The
|
|
|
507 optional third argument @var{how} specifies the stopping condition. A
|
|
|
508 negative integer indicates that the motion should be no more
|
|
|
509 than @var{pixels}. A positive value indicates that the
|
|
|
510 motion should be at least @var{pixels}. Any other value indicates
|
|
|
511 that the motion should be as close as possible to @var{pixels}.
|
|
|
512 @end defun
|
|
|
513
|
|
|
514 @deffn Command move-to-window-line count &optional window
|
|
|
515 This function moves point with respect to the text currently displayed
|
|
|
516 in @var{window}, which defaults to the selected window. It moves point
|
|
|
517 to the beginning of the screen line @var{count} screen lines from the
|
|
|
518 top of the window. If @var{count} is negative, that specifies a
|
|
|
519 position @w{@minus{}@var{count}} lines from the bottom (or the last line
|
|
|
520 of the buffer, if the buffer ends above the specified screen position).
|
|
|
521
|
|
|
522 If @var{count} is @code{nil}, then point moves to the beginning of the
|
|
|
523 line in the middle of the window. If the absolute value of @var{count}
|
|
|
524 is greater than the size of the window, then point moves to the place
|
|
|
525 that would appear on that screen line if the window were tall enough.
|
|
|
526 This will probably cause the next redisplay to scroll to bring that
|
|
|
527 location onto the screen.
|
|
|
528
|
|
|
529 In an interactive call, @var{count} is the numeric prefix argument.
|
|
|
530
|
|
|
531 The value returned is the window line number point has moved to, with
|
|
|
532 the top line in the window numbered 0.
|
|
|
533 @end deffn
|
|
|
534
|
|
|
535 @ignore Not in XEmacs
|
|
|
536 @defun compute-motion from frompos to topos width offsets window
|
|
|
537 This function scans the current buffer, calculating screen positions.
|
|
|
538 It scans the buffer forward from position @var{from}, assuming that is
|
|
|
539 at screen coordinates @var{frompos}, to position @var{to} or coordinates
|
|
|
540 @var{topos}, whichever comes first. It returns the ending buffer
|
|
|
541 position and screen coordinates.
|
|
|
542
|
|
|
543 The coordinate arguments @var{frompos} and @var{topos} are cons cells of
|
|
|
544 the form @code{(@var{hpos} . @var{vpos})}.
|
|
|
545
|
|
|
546 The argument @var{width} is the number of columns available to display
|
|
|
547 text; this affects handling of continuation lines. Use the value
|
|
|
548 returned by @code{window-width} for the window of your choice;
|
|
|
549 normally, use @code{(window-width @var{window})}.
|
|
|
550
|
|
|
551 The argument @var{offsets} is either @code{nil} or a cons cell of the
|
|
|
552 form @code{(@var{hscroll} . @var{tab-offset})}. Here @var{hscroll} is
|
|
|
553 the number of columns not being displayed at the left margin; most
|
|
|
554 callers get this from @code{window-hscroll}. Meanwhile,
|
|
|
555 @var{tab-offset} is the offset between column numbers on the screen and
|
|
|
556 column numbers in the buffer. This can be nonzero in a continuation
|
|
|
557 line, when the previous screen lines' widths do not add up to a multiple
|
|
|
558 of @code{tab-width}. It is always zero in a non-continuation line.
|
|
|
559
|
|
|
560 The window @var{window} serves only to specify which display table to
|
|
|
561 use. @code{compute-motion} always operates on the current buffer,
|
|
|
562 regardless of what buffer is displayed in @var{window}.
|
|
|
563
|
|
|
564 The return value is a list of five elements:
|
|
|
565
|
|
|
566 @example
|
|
|
567 (@var{pos} @var{vpos} @var{hpos} @var{prevhpos} @var{contin})
|
|
|
568 @end example
|
|
|
569
|
|
|
570 @noindent
|
|
|
571 Here @var{pos} is the buffer position where the scan stopped, @var{vpos}
|
|
|
572 is the vertical screen position, and @var{hpos} is the horizontal screen
|
|
|
573 position.
|
|
|
574
|
|
|
575 The result @var{prevhpos} is the horizontal position one character back
|
|
|
576 from @var{pos}. The result @var{contin} is @code{t} if the last line
|
|
|
577 was continued after (or within) the previous character.
|
|
|
578
|
|
|
579 For example, to find the buffer position of column @var{col} of line
|
|
|
580 @var{line} of a certain window, pass the window's display start location
|
|
|
581 as @var{from} and the window's upper-left coordinates as @var{frompos}.
|
|
|
582 Pass the buffer's @code{(point-max)} as @var{to}, to limit the scan to
|
|
|
583 the end of the accessible portion of the buffer, and pass @var{line} and
|
|
|
584 @var{col} as @var{topos}. Here's a function that does this:
|
|
|
585
|
|
|
586 @example
|
|
|
587 (defun coordinates-of-position (col line)
|
|
|
588 (car (compute-motion (window-start)
|
|
|
589 '(0 . 0)
|
|
|
590 (point-max)
|
|
|
591 (cons col line)
|
|
|
592 (window-width)
|
|
|
593 (cons (window-hscroll) 0)
|
|
|
594 (selected-window))))
|
|
|
595 @end example
|
|
|
596
|
|
|
597 When you use @code{compute-motion} for the minibuffer, you need to use
|
|
|
598 @code{minibuffer-prompt-width} to get the horizontal position of the
|
|
|
599 beginning of the first screen line. @xref{Minibuffer Misc}.
|
|
|
600 @end defun
|
|
|
601 @end ignore
|
|
|
602
|
|
|
603 @node List Motion
|
|
444
|
604 @subsection Moving over Balanced Expressions
|
|
428
|
605 @cindex sexp motion
|
|
|
606 @cindex Lisp expression motion
|
|
|
607 @cindex list motion
|
|
|
608
|
|
|
609 Here are several functions concerned with balanced-parenthesis
|
|
|
610 expressions (also called @dfn{sexps} in connection with moving across
|
|
|
611 them in XEmacs). The syntax table controls how these functions interpret
|
|
|
612 various characters; see @ref{Syntax Tables}. @xref{Parsing
|
|
|
613 Expressions}, for lower-level primitives for scanning sexps or parts of
|
|
446
|
614 sexps. For user-level commands, see @ref{Lists and Sexps,,, xemacs, XEmacs
|
|
428
|
615 Reference Manual}.
|
|
|
616
|
|
|
617 @deffn Command forward-list &optional arg
|
|
|
618 This function moves forward across @var{arg} balanced groups of
|
|
|
619 parentheses. (Other syntactic entities such as words or paired string
|
|
|
620 quotes are ignored.) @var{arg} defaults to 1 if omitted. If @var{arg}
|
|
|
621 is negative, move backward across that many groups of parentheses.
|
|
|
622 @end deffn
|
|
|
623
|
|
444
|
624 @deffn Command backward-list &optional count
|
|
|
625 This function moves backward across @var{count} balanced groups of
|
|
428
|
626 parentheses. (Other syntactic entities such as words or paired string
|
|
444
|
627 quotes are ignored.) @var{count} defaults to 1 if omitted. If
|
|
|
628 @var{count} is negative, move forward across that many groups of
|
|
|
629 parentheses.
|
|
428
|
630 @end deffn
|
|
|
631
|
|
444
|
632 @deffn Command up-list &optional count
|
|
|
633 This function moves forward out of @var{count} levels of parentheses.
|
|
428
|
634 A negative argument means move backward but still to a less deep spot.
|
|
|
635 @end deffn
|
|
|
636
|
|
444
|
637 @deffn Command down-list &optional count
|
|
|
638 This function moves forward into @var{count} levels of parentheses.
|
|
|
639 A negative argument means move backward but still go deeper in
|
|
|
640 parentheses (@minus{}@var{count} levels).
|
|
428
|
641 @end deffn
|
|
|
642
|
|
444
|
643 @deffn Command forward-sexp &optional count
|
|
|
644 This function moves forward across @var{count} balanced expressions.
|
|
428
|
645 Balanced expressions include both those delimited by parentheses and
|
|
444
|
646 other kinds, such as words and string constants. @var{count} defaults to
|
|
|
647 1 if omitted. If @var{count} is negative, move backward across that many
|
|
428
|
648 balanced expressions. For example,
|
|
|
649
|
|
|
650 @example
|
|
|
651 @group
|
|
|
652 ---------- Buffer: foo ----------
|
|
|
653 (concat@point{} "foo " (car x) y z)
|
|
|
654 ---------- Buffer: foo ----------
|
|
|
655 @end group
|
|
|
656
|
|
|
657 @group
|
|
|
658 (forward-sexp 3)
|
|
|
659 @result{} nil
|
|
|
660
|
|
|
661 ---------- Buffer: foo ----------
|
|
|
662 (concat "foo " (car x) y@point{} z)
|
|
|
663 ---------- Buffer: foo ----------
|
|
|
664 @end group
|
|
|
665 @end example
|
|
|
666 @end deffn
|
|
|
667
|
|
444
|
668 @deffn Command backward-sexp &optional count
|
|
|
669 This function moves backward across @var{count} balanced expressions.
|
|
|
670 @var{count} defaults to 1 if omitted. If @var{count} is negative, move
|
|
428
|
671 forward across that many balanced expressions.
|
|
|
672 @end deffn
|
|
|
673
|
|
444
|
674 @deffn Command beginning-of-defun &optional count
|
|
|
675 This function moves back to the @var{count}th beginning of a defun.
|
|
|
676 If @var{count} is negative, this actually moves forward, but it still
|
|
|
677 moves to the beginning of a defun, not to the end of one. @var{count}
|
|
|
678 defaults to 1 if omitted.
|
|
428
|
679 @end deffn
|
|
|
680
|
|
444
|
681 @deffn Command end-of-defun &optional count
|
|
|
682 This function moves forward to the @var{count}th end of a defun.
|
|
|
683 If @var{count} is negative, this actually moves backward, but it still
|
|
|
684 moves to the end of a defun, not to the beginning of one. @var{count}
|
|
|
685 defaults to 1 if omitted.
|
|
428
|
686 @end deffn
|
|
|
687
|
|
|
688 @defopt defun-prompt-regexp
|
|
|
689 If non-@code{nil}, this variable holds a regular expression that
|
|
|
690 specifies what text can appear before the open-parenthesis that starts a
|
|
|
691 defun. That is to say, a defun begins on a line that starts with a
|
|
|
692 match for this regular expression, followed by a character with
|
|
|
693 open-parenthesis syntax.
|
|
|
694 @end defopt
|
|
|
695
|
|
|
696 @node Skipping Characters
|
|
|
697 @subsection Skipping Characters
|
|
|
698 @cindex skipping characters
|
|
|
699
|
|
|
700 The following two functions move point over a specified set of
|
|
|
701 characters. For example, they are often used to skip whitespace. For
|
|
|
702 related functions, see @ref{Motion and Syntax}.
|
|
|
703
|
|
|
704 @defun skip-chars-forward character-set &optional limit buffer
|
|
|
705 This function moves point in @var{buffer} forward, skipping over a
|
|
|
706 given set of characters. It examines the character following point,
|
|
|
707 then advances point if the character matches @var{character-set}. This
|
|
|
708 continues until it reaches a character that does not match. The
|
|
|
709 function returns @code{nil}. @var{buffer} defaults to the current
|
|
|
710 buffer if omitted.
|
|
|
711
|
|
|
712 The argument @var{character-set} is like the inside of a
|
|
|
713 @samp{[@dots{}]} in a regular expression except that @samp{]} is never
|
|
|
714 special and @samp{\} quotes @samp{^}, @samp{-} or @samp{\}. Thus,
|
|
|
715 @code{"a-zA-Z"} skips over all letters, stopping before the first
|
|
|
716 non-letter, and @code{"^a-zA-Z}" skips non-letters stopping before the
|
|
|
717 first letter. @xref{Regular Expressions}.
|
|
|
718
|
|
|
719 If @var{limit} is supplied (it must be a number or a marker), it
|
|
|
720 specifies the maximum position in the buffer that point can be skipped
|
|
|
721 to. Point will stop at or before @var{limit}.
|
|
|
722
|
|
|
723 In the following example, point is initially located directly before the
|
|
|
724 @samp{T}. After the form is evaluated, point is located at the end of
|
|
|
725 that line (between the @samp{t} of @samp{hat} and the newline). The
|
|
|
726 function skips all letters and spaces, but not newlines.
|
|
|
727
|
|
|
728 @example
|
|
|
729 @group
|
|
|
730 ---------- Buffer: foo ----------
|
|
|
731 I read "@point{}The cat in the hat
|
|
|
732 comes back" twice.
|
|
|
733 ---------- Buffer: foo ----------
|
|
|
734 @end group
|
|
|
735
|
|
|
736 @group
|
|
|
737 (skip-chars-forward "a-zA-Z ")
|
|
|
738 @result{} nil
|
|
|
739
|
|
|
740 ---------- Buffer: foo ----------
|
|
|
741 I read "The cat in the hat@point{}
|
|
|
742 comes back" twice.
|
|
|
743 ---------- Buffer: foo ----------
|
|
|
744 @end group
|
|
|
745 @end example
|
|
|
746 @end defun
|
|
|
747
|
|
|
748 @defun skip-chars-backward character-set &optional limit buffer
|
|
|
749 This function moves point backward, skipping characters that match
|
|
|
750 @var{character-set}, until @var{limit}. It just like
|
|
|
751 @code{skip-chars-forward} except for the direction of motion.
|
|
|
752 @end defun
|
|
|
753
|
|
|
754 @node Excursions
|
|
|
755 @section Excursions
|
|
|
756 @cindex excursion
|
|
|
757
|
|
|
758 It is often useful to move point ``temporarily'' within a localized
|
|
|
759 portion of the program, or to switch buffers temporarily. This is
|
|
|
760 called an @dfn{excursion}, and it is done with the @code{save-excursion}
|
|
|
761 special form. This construct saves the current buffer and its values of
|
|
|
762 point and the mark so they can be restored after the completion of the
|
|
|
763 excursion.
|
|
|
764
|
|
|
765 The forms for saving and restoring the configuration of windows are
|
|
|
766 described elsewhere (see @ref{Window Configurations} and @pxref{Frame
|
|
|
767 Configurations}).
|
|
|
768
|
|
|
769 @defspec save-excursion forms@dots{}
|
|
|
770 @cindex mark excursion
|
|
|
771 @cindex point excursion
|
|
|
772 @cindex current buffer excursion
|
|
|
773 The @code{save-excursion} special form saves the identity of the current
|
|
|
774 buffer and the values of point and the mark in it, evaluates
|
|
|
775 @var{forms}, and finally restores the buffer and its saved values of
|
|
|
776 point and the mark. All three saved values are restored even in case of
|
|
|
777 an abnormal exit via @code{throw} or error (@pxref{Nonlocal Exits}).
|
|
|
778
|
|
|
779 The @code{save-excursion} special form is the standard way to switch
|
|
|
780 buffers or move point within one part of a program and avoid affecting
|
|
|
781 the rest of the program. It is used more than 500 times in the Lisp
|
|
|
782 sources of XEmacs.
|
|
|
783
|
|
|
784 @code{save-excursion} does not save the values of point and the mark for
|
|
|
785 other buffers, so changes in other buffers remain in effect after
|
|
|
786 @code{save-excursion} exits.
|
|
|
787
|
|
|
788 @cindex window excursions
|
|
|
789 Likewise, @code{save-excursion} does not restore window-buffer
|
|
|
790 correspondences altered by functions such as @code{switch-to-buffer}.
|
|
|
791 One way to restore these correspondences, and the selected window, is to
|
|
|
792 use @code{save-window-excursion} inside @code{save-excursion}
|
|
|
793 (@pxref{Window Configurations}).
|
|
|
794
|
|
|
795 The value returned by @code{save-excursion} is the result of the last of
|
|
|
796 @var{forms}, or @code{nil} if no @var{forms} are given.
|
|
|
797
|
|
|
798 @example
|
|
|
799 @group
|
|
|
800 (save-excursion
|
|
|
801 @var{forms})
|
|
|
802 @equiv{}
|
|
|
803 (let ((old-buf (current-buffer))
|
|
|
804 (old-pnt (point-marker))
|
|
|
805 (old-mark (copy-marker (mark-marker))))
|
|
|
806 (unwind-protect
|
|
|
807 (progn @var{forms})
|
|
|
808 (set-buffer old-buf)
|
|
|
809 (goto-char old-pnt)
|
|
|
810 (set-marker (mark-marker) old-mark)))
|
|
|
811 @end group
|
|
|
812 @end example
|
|
|
813 @end defspec
|
|
|
814
|
|
|
815 @defspec save-current-buffer forms@dots{}
|
|
|
816 This special form is similar to @code{save-excursion} but it only
|
|
|
817 saves and restores the current buffer. Beginning with XEmacs 20.3,
|
|
|
818 @code{save-current-buffer} is a primitive.
|
|
|
819 @end defspec
|
|
|
820
|
|
|
821 @defspec with-current-buffer buffer forms@dots{}
|
|
|
822 This special form evaluates @var{forms} with @var{buffer} as the current
|
|
|
823 buffer. It returns the value of the last form.
|
|
|
824 @end defspec
|
|
|
825
|
|
444
|
826 @defspec with-temp-file filename forms@dots{}
|
|
428
|
827 This special form creates a new buffer, evaluates @var{forms} there, and
|
|
444
|
828 writes the buffer to @var{filename}. It returns the value of the last form
|
|
428
|
829 evaluated.
|
|
|
830 @end defspec
|
|
|
831
|
|
|
832 @defspec save-selected-window forms@dots{}
|
|
|
833 This special form is similar to @code{save-excursion} but it saves and
|
|
|
834 restores the selected window and nothing else.
|
|
|
835 @end defspec
|
|
|
836
|
|
|
837 @node Narrowing
|
|
|
838 @section Narrowing
|
|
|
839 @cindex narrowing
|
|
|
840 @cindex restriction (in a buffer)
|
|
|
841 @cindex accessible portion (of a buffer)
|
|
|
842
|
|
|
843 @dfn{Narrowing} means limiting the text addressable by XEmacs editing
|
|
|
844 commands to a limited range of characters in a buffer. The text that
|
|
|
845 remains addressable is called the @dfn{accessible portion} of the
|
|
|
846 buffer.
|
|
|
847
|
|
|
848 Narrowing is specified with two buffer positions which become the
|
|
|
849 beginning and end of the accessible portion. For most editing commands
|
|
|
850 and most Emacs primitives, these positions replace the values of the
|
|
|
851 beginning and end of the buffer. While narrowing is in effect, no text
|
|
|
852 outside the accessible portion is displayed, and point cannot move
|
|
|
853 outside the accessible portion.
|
|
|
854
|
|
|
855 Values such as positions or line numbers, which usually count from the
|
|
|
856 beginning of the buffer, do so despite narrowing, but the functions
|
|
|
857 which use them refuse to operate on text that is inaccessible.
|
|
|
858
|
|
|
859 The commands for saving buffers are unaffected by narrowing; they save
|
|
|
860 the entire buffer regardless of any narrowing.
|
|
|
861
|
|
|
862 @deffn Command narrow-to-region start end &optional buffer
|
|
|
863 This function sets the accessible portion of @var{buffer} to start at
|
|
|
864 @var{start} and end at @var{end}. Both arguments should be character
|
|
|
865 positions. @var{buffer} defaults to the current buffer if omitted.
|
|
|
866
|
|
|
867 In an interactive call, @var{start} and @var{end} are set to the bounds
|
|
|
868 of the current region (point and the mark, with the smallest first).
|
|
|
869 @end deffn
|
|
|
870
|
|
|
871 @deffn Command narrow-to-page &optional move-count
|
|
|
872 This function sets the accessible portion of the current buffer to
|
|
|
873 include just the current page. An optional first argument
|
|
|
874 @var{move-count} non-@code{nil} means to move forward or backward by
|
|
|
875 @var{move-count} pages and then narrow. The variable
|
|
|
876 @code{page-delimiter} specifies where pages start and end
|
|
|
877 (@pxref{Standard Regexps}).
|
|
|
878
|
|
|
879 In an interactive call, @var{move-count} is set to the numeric prefix
|
|
|
880 argument.
|
|
|
881 @end deffn
|
|
|
882
|
|
|
883 @deffn Command widen &optional buffer
|
|
|
884 @cindex widening
|
|
|
885 This function cancels any narrowing in @var{buffer}, so that the
|
|
|
886 entire contents are accessible. This is called @dfn{widening}.
|
|
|
887 It is equivalent to the following expression:
|
|
|
888
|
|
|
889 @example
|
|
|
890 (narrow-to-region 1 (1+ (buffer-size)))
|
|
|
891 @end example
|
|
|
892
|
|
|
893 @var{buffer} defaults to the current buffer if omitted.
|
|
|
894 @end deffn
|
|
|
895
|
|
|
896 @defspec save-restriction body@dots{}
|
|
|
897 This special form saves the current bounds of the accessible portion,
|
|
|
898 evaluates the @var{body} forms, and finally restores the saved bounds,
|
|
|
899 thus restoring the same state of narrowing (or absence thereof) formerly
|
|
|
900 in effect. The state of narrowing is restored even in the event of an
|
|
|
901 abnormal exit via @code{throw} or error (@pxref{Nonlocal Exits}).
|
|
|
902 Therefore, this construct is a clean way to narrow a buffer temporarily.
|
|
|
903
|
|
|
904 The value returned by @code{save-restriction} is that returned by the
|
|
|
905 last form in @var{body}, or @code{nil} if no body forms were given.
|
|
|
906
|
|
|
907 @c Wordy to avoid overfull hbox. --rjc 16mar92
|
|
|
908 @strong{Caution:} it is easy to make a mistake when using the
|
|
|
909 @code{save-restriction} construct. Read the entire description here
|
|
|
910 before you try it.
|
|
|
911
|
|
|
912 If @var{body} changes the current buffer, @code{save-restriction} still
|
|
|
913 restores the restrictions on the original buffer (the buffer whose
|
|
|
914 restrictions it saved from), but it does not restore the identity of the
|
|
|
915 current buffer.
|
|
|
916
|
|
|
917 @code{save-restriction} does @emph{not} restore point and the mark; use
|
|
|
918 @code{save-excursion} for that. If you use both @code{save-restriction}
|
|
|
919 and @code{save-excursion} together, @code{save-excursion} should come
|
|
|
920 first (on the outside). Otherwise, the old point value would be
|
|
|
921 restored with temporary narrowing still in effect. If the old point
|
|
|
922 value were outside the limits of the temporary narrowing, this would
|
|
|
923 fail to restore it accurately.
|
|
|
924
|
|
|
925 The @code{save-restriction} special form records the values of the
|
|
|
926 beginning and end of the accessible portion as distances from the
|
|
|
927 beginning and end of the buffer. In other words, it records the amount
|
|
|
928 of inaccessible text before and after the accessible portion.
|
|
|
929
|
|
|
930 This method yields correct results if @var{body} does further narrowing.
|
|
|
931 However, @code{save-restriction} can become confused if the body widens
|
|
|
932 and then make changes outside the range of the saved narrowing. When
|
|
|
933 this is what you want to do, @code{save-restriction} is not the right
|
|
|
934 tool for the job. Here is what you must use instead:
|
|
|
935
|
|
|
936 @example
|
|
|
937 @group
|
|
444
|
938 (let ((start (point-min-marker))
|
|
428
|
939 (end (point-max-marker)))
|
|
|
940 (unwind-protect
|
|
|
941 (progn @var{body})
|
|
|
942 (save-excursion
|
|
444
|
943 (set-buffer (marker-buffer start))
|
|
|
944 (narrow-to-region start end))))
|
|
428
|
945 @end group
|
|
|
946 @end example
|
|
|
947
|
|
|
948 Here is a simple example of correct use of @code{save-restriction}:
|
|
|
949
|
|
|
950 @example
|
|
|
951 @group
|
|
|
952 ---------- Buffer: foo ----------
|
|
|
953 This is the contents of foo
|
|
|
954 This is the contents of foo
|
|
|
955 This is the contents of foo@point{}
|
|
|
956 ---------- Buffer: foo ----------
|
|
|
957 @end group
|
|
|
958
|
|
|
959 @group
|
|
|
960 (save-excursion
|
|
|
961 (save-restriction
|
|
|
962 (goto-char 1)
|
|
|
963 (forward-line 2)
|
|
|
964 (narrow-to-region 1 (point))
|
|
|
965 (goto-char (point-min))
|
|
|
966 (replace-string "foo" "bar")))
|
|
|
967
|
|
|
968 ---------- Buffer: foo ----------
|
|
|
969 This is the contents of bar
|
|
|
970 This is the contents of bar
|
|
|
971 This is the contents of foo@point{}
|
|
|
972 ---------- Buffer: foo ----------
|
|
|
973 @end group
|
|
|
974 @end example
|
|
|
975 @end defspec
|
