Mercurial > hg > xemacs-beta
annotate man/lispref/text.texi @ 5252:378a34562cbe
Fix style, documentation for rounding functions and multiple values.
src/ChangeLog addition:
2010-08-30 Aidan Kehoe <kehoea@parhasard.net>
* floatfns.c (ceiling_one_mundane_arg, floor_one_mundane_arg)
(round_one_mundane_arg, truncate_one_mundane_arg):
INTEGERP is always available, no need to wrap calls to it with
#ifdef HAVE_BIGNUM.
(Fceiling, Ffloor, Fround, Ftruncate, Ffceiling, Fffloor)
(Ffround, Fftruncate):
Correct some code formatting here.
* doprnt.c (emacs_doprnt_1):
Remove some needless #ifdef WITH_NUMBER_TYPES, now number.h is
always #included.
man/ChangeLog addition:
2010-08-30 Aidan Kehoe <kehoea@parhasard.net>
* lispref/eval.texi (Evaluation, Multiple values):
Document our implementation of multiple values; point the reader
to the CLTL or the Hyperspec for details of exactly when values
are discarded.
* lispref/numbers.texi (Numeric Conversions): Document the
optional DIVISOR arguments to the rounding functions, and
document that they all return multiple values.
(Rounding Operations): Ditto.
* cl.texi (Multiple Values):
Document that we've moved the multiple values implementation to
core code, and cross-reference to the Lispref.
(Numerical Functions): The various rounding functions are now
identical to the built-in rounding functions, with the exception
that they return lists, not multiple values; document this.
| author | Aidan Kehoe <kehoea@parhasard.net> |
|---|---|
| date | Mon, 30 Aug 2010 15:23:42 +0100 |
| parents | 99f8ebc082d9 |
| children | 9fae6227ede5 |
| rev | line source |
|---|---|
| 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/text.info | |
| 6 @node Text, Searching and Matching, Markers, Top | |
| 7 @chapter Text | |
| 8 @cindex text | |
| 9 | |
| 10 This chapter describes the functions that deal with the text in a | |
| 11 buffer. Most examine, insert, or delete text in the current buffer, | |
| 12 often in the vicinity of point. Many are interactive. All the | |
| 13 functions that change the text provide for undoing the changes | |
| 14 (@pxref{Undo}). | |
| 15 | |
| 16 Many text-related functions operate on a region of text defined by two | |
| 17 buffer positions passed in arguments named @var{start} and @var{end}. | |
| 18 These arguments should be either markers (@pxref{Markers}) or numeric | |
| 19 character positions (@pxref{Positions}). The order of these arguments | |
| 20 does not matter; it is all right for @var{start} to be the end of the | |
| 21 region and @var{end} the beginning. For example, @code{(delete-region 1 | |
| 22 10)} and @code{(delete-region 10 1)} are equivalent. An | |
| 23 @code{args-out-of-range} error is signaled if either @var{start} or | |
| 24 @var{end} is outside the accessible portion of the buffer. In an | |
| 25 interactive call, point and the mark are used for these arguments. | |
| 26 | |
| 27 @cindex buffer contents | |
| 28 Throughout this chapter, ``text'' refers to the characters in the | |
| 29 buffer, together with their properties (when relevant). | |
| 30 | |
| 31 @menu | |
| 32 * Near Point:: Examining text in the vicinity of point. | |
| 33 * Buffer Contents:: Examining text in a general fashion. | |
| 34 * Comparing Text:: Comparing substrings of buffers. | |
| 35 * Insertion:: Adding new text to a buffer. | |
| 36 * Commands for Insertion:: User-level commands to insert text. | |
| 37 * Deletion:: Removing text from a buffer. | |
| 38 * User-Level Deletion:: User-level commands to delete text. | |
| 39 * The Kill Ring:: Where removed text sometimes is saved for later use. | |
| 40 * Undo:: Undoing changes to the text of a buffer. | |
| 41 * Maintaining Undo:: How to enable and disable undo information. | |
| 42 How to control how much information is kept. | |
| 43 * Filling:: Functions for explicit filling. | |
| 44 * Margins:: How to specify margins for filling commands. | |
| 45 * Auto Filling:: How auto-fill mode is implemented to break lines. | |
| 46 * Sorting:: Functions for sorting parts of the buffer. | |
| 47 * Columns:: Computing horizontal positions, and using them. | |
| 48 * Indentation:: Functions to insert or adjust indentation. | |
| 49 * Case Changes:: Case conversion of parts of the buffer. | |
| 50 * Text Properties:: Assigning Lisp property lists to text characters. | |
| 51 * Substitution:: Replacing a given character wherever it appears. | |
| 52 * Registers:: How registers are implemented. Accessing the text or | |
| 53 position stored in a register. | |
| 54 * Transposition:: Swapping two portions of a buffer. | |
| 55 * Change Hooks:: Supplying functions to be run when text is changed. | |
| 56 * Transformations:: MD5 and base64 support. | |
| 57 @end menu | |
| 58 | |
| 59 @node Near Point | |
| 60 @section Examining Text Near Point | |
| 61 | |
| 62 Many functions are provided to look at the characters around point. | |
| 63 Several simple functions are described here. See also @code{looking-at} | |
| 64 in @ref{Regexp Search}. | |
| 65 | |
| 66 Many of these functions take an optional @var{buffer} argument. | |
| 67 In all such cases, the current buffer will be used if this argument | |
| 68 is omitted. (In FSF Emacs, and earlier versions of XEmacs, these | |
| 69 functions usually did not have these optional @var{buffer} arguments | |
| 70 and always operated on the current buffer.) | |
| 71 | |
| 72 | |
| 434 | 73 @defun char-after &optional position buffer |
| 428 | 74 This function returns the character in the buffer at (i.e., |
| 75 immediately after) position @var{position}. If @var{position} is out of | |
| 76 range for this purpose, either before the beginning of the buffer, or at | |
| 434 | 77 or beyond the end, then the value is @code{nil}. The default for |
| 78 @var{position} is point. If optional argument @var{buffer} is | |
| 79 @code{nil}, the current buffer is assumed. | |
| 428 | 80 |
| 81 In the following example, assume that the first character in the | |
| 82 buffer is @samp{@@}: | |
| 83 | |
| 84 @example | |
| 85 @group | |
| 86 (char-to-string (char-after 1)) | |
| 87 @result{} "@@" | |
| 88 @end group | |
| 89 @end example | |
| 90 @end defun | |
| 91 | |
| 434 | 92 @defun char-before &optional position buffer |
| 93 This function returns the character in the current buffer immediately | |
| 94 before position @var{position}. If @var{position} is out of range for | |
| 95 this purpose, either at or before the beginning of the buffer, or beyond | |
| 96 the end, then the value is @code{nil}. The default for | |
| 97 @var{position} is point. If optional argument @var{buffer} is | |
| 98 @code{nil}, the current buffer is assumed. | |
| 99 @end defun | |
| 100 | |
| 428 | 101 @defun following-char &optional buffer |
| 102 This function returns the character following point in the buffer. | |
| 103 This is similar to @code{(char-after (point))}. However, if point is at | |
| 104 the end of the buffer, then the result of @code{following-char} is 0. | |
| 105 If optional argument @var{buffer} is @code{nil}, the current buffer is | |
| 106 assumed. | |
| 107 | |
| 108 Remember that point is always between characters, and the terminal | |
| 109 cursor normally appears over the character following point. Therefore, | |
| 110 the character returned by @code{following-char} is the character the | |
| 111 cursor is over. | |
| 112 | |
| 113 In this example, point is between the @samp{a} and the @samp{c}. | |
| 114 | |
| 115 @example | |
| 116 @group | |
| 117 ---------- Buffer: foo ---------- | |
| 118 Gentlemen may cry ``Pea@point{}ce! Peace!,'' | |
| 119 but there is no peace. | |
| 120 ---------- Buffer: foo ---------- | |
| 121 @end group | |
| 122 | |
| 123 @group | |
| 124 (char-to-string (preceding-char)) | |
| 125 @result{} "a" | |
| 126 (char-to-string (following-char)) | |
| 127 @result{} "c" | |
| 128 @end group | |
| 129 @end example | |
| 130 @end defun | |
| 131 | |
| 132 @defun preceding-char &optional buffer | |
| 133 This function returns the character preceding point in the buffer. | |
| 134 See above, under @code{following-char}, for an example. If | |
| 135 point is at the beginning of the buffer, @code{preceding-char} returns | |
| 136 0. If optional argument @var{buffer} is @code{nil}, the current buffer | |
| 137 is assumed. | |
| 138 @end defun | |
| 139 | |
| 140 @defun bobp &optional buffer | |
| 141 This function returns @code{t} if point is at the beginning of the | |
| 142 buffer. If narrowing is in effect, this means the beginning of the | |
| 143 accessible portion of the text. If optional argument @var{buffer} is | |
| 144 @code{nil}, the current buffer is assumed. See also @code{point-min} in | |
| 145 @ref{Point}. | |
| 146 @end defun | |
| 147 | |
| 148 @defun eobp &optional buffer | |
| 149 This function returns @code{t} if point is at the end of the buffer. | |
| 150 If narrowing is in effect, this means the end of accessible portion of | |
| 151 the text. If optional argument @var{buffer} is @code{nil}, the current | |
| 152 buffer is assumed. See also @code{point-max} in @xref{Point}. | |
| 153 @end defun | |
| 154 | |
| 155 @defun bolp &optional buffer | |
| 156 This function returns @code{t} if point is at the beginning of a line. | |
| 157 If optional argument @var{buffer} is @code{nil}, the current buffer is | |
| 158 assumed. @xref{Text Lines}. The beginning of the buffer (or its | |
| 159 accessible portion) always counts as the beginning of a line. | |
| 160 @end defun | |
| 161 | |
| 162 @defun eolp &optional buffer | |
| 163 This function returns @code{t} if point is at the end of a line. The | |
| 164 end of the buffer is always considered the end of a line. If optional | |
| 165 argument @var{buffer} is @code{nil}, the current buffer is assumed. | |
| 166 The end of the buffer (or of its accessible portion) is always considered | |
| 167 the end of a line. | |
| 168 @end defun | |
| 169 | |
| 170 @node Buffer Contents | |
| 171 @section Examining Buffer Contents | |
| 172 | |
| 173 This section describes two functions that allow a Lisp program to | |
| 174 convert any portion of the text in the buffer into a string. | |
| 175 | |
| 176 @defun buffer-substring start end &optional buffer | |
| 177 @defunx buffer-string start end &optional buffer | |
| 178 These functions are equivalent and return a string containing a copy of | |
| 179 the text of the region defined by positions @var{start} and @var{end} in | |
| 180 the buffer. If the arguments are not positions in the accessible | |
| 181 portion of the buffer, @code{buffer-substring} signals an | |
| 182 @code{args-out-of-range} error. If optional argument @var{buffer} is | |
| 183 @code{nil}, the current buffer is assumed. | |
| 184 | |
| 185 @c XEmacs feature. | |
| 186 If the region delineated by @var{start} and @var{end} contains | |
| 187 duplicable extents, they will be remembered in the string. | |
| 188 @xref{Duplicable Extents}. | |
| 189 | |
| 190 It is not necessary for @var{start} to be less than @var{end}; the | |
| 191 arguments can be given in either order. But most often the smaller | |
| 192 argument is written first. | |
| 193 | |
| 194 @example | |
| 195 @group | |
| 196 ---------- Buffer: foo ---------- | |
| 197 This is the contents of buffer foo | |
| 198 | |
| 199 ---------- Buffer: foo ---------- | |
| 200 @end group | |
| 201 | |
| 202 @group | |
| 203 (buffer-substring 1 10) | |
| 204 @result{} "This is t" | |
| 205 @end group | |
| 206 @group | |
| 207 (buffer-substring (point-max) 10) | |
| 208 @result{} "he contents of buffer foo | |
| 209 " | |
| 210 @end group | |
| 211 @end example | |
| 212 @end defun | |
| 213 | |
| 214 @ignore | |
| 215 @c `equal' in XEmacs does not compare text properties on strings | |
| 216 @defun buffer-substring-without-properties start end | |
| 217 This is like @code{buffer-substring}, except that it does not copy text | |
| 218 properties, just the characters themselves. @xref{Text Properties}. | |
| 219 Here's an example of using this function to get a word to look up in an | |
| 220 alist: | |
| 221 | |
| 222 @example | |
| 223 (setq flammable | |
| 224 (assoc (buffer-substring start end) | |
| 225 '(("wood" . t) ("paper" . t) | |
| 226 ("steel" . nil) ("asbestos" . nil)))) | |
| 227 @end example | |
| 228 | |
| 229 If this were written using @code{buffer-substring} instead, it would not | |
| 230 work reliably; any text properties that happened to be in the word | |
| 231 copied from the buffer would make the comparisons fail. | |
| 232 @end defun | |
| 233 @end ignore | |
| 234 | |
| 235 @node Comparing Text | |
| 236 @section Comparing Text | |
| 237 @cindex comparing buffer text | |
| 238 | |
| 239 This function lets you compare portions of the text in a buffer, without | |
| 240 copying them into strings first. | |
| 241 | |
| 242 @defun compare-buffer-substrings buffer1 start1 end1 buffer2 start2 end2 | |
| 243 This function lets you compare two substrings of the same buffer or two | |
| 244 different buffers. The first three arguments specify one substring, | |
| 245 giving a buffer and two positions within the buffer. The last three | |
| 246 arguments specify the other substring in the same way. You can use | |
| 247 @code{nil} for @var{buffer1}, @var{buffer2}, or both to stand for the | |
| 248 current buffer. | |
| 249 | |
| 250 The value is negative if the first substring is less, positive if the | |
| 251 first is greater, and zero if they are equal. The absolute value of | |
| 252 the result is one plus the index of the first differing characters | |
| 253 within the substrings. | |
| 254 | |
| 255 This function ignores case when comparing characters | |
| 256 if @code{case-fold-search} is non-@code{nil}. It always ignores | |
| 257 text properties. | |
| 258 | |
| 259 Suppose the current buffer contains the text @samp{foobarbar | |
| 260 haha!rara!}; then in this example the two substrings are @samp{rbar } | |
| 261 and @samp{rara!}. The value is 2 because the first substring is greater | |
| 262 at the second character. | |
| 263 | |
| 264 @example | |
| 265 (compare-buffer-substring nil 6 11 nil 16 21) | |
| 266 @result{} 2 | |
| 267 @end example | |
| 268 @end defun | |
| 269 | |
| 270 @node Insertion | |
| 271 @section Inserting Text | |
| 272 @cindex insertion of text | |
| 273 @cindex text insertion | |
| 274 | |
| 275 @dfn{Insertion} means adding new text to a buffer. The inserted text | |
| 276 goes at point---between the character before point and the character | |
| 277 after point. | |
| 278 | |
| 279 Insertion relocates markers that point at positions after the | |
| 280 insertion point, so that they stay with the surrounding text | |
| 281 (@pxref{Markers}). When a marker points at the place of insertion, | |
| 282 insertion normally doesn't relocate the marker, so that it points to the | |
| 283 beginning of the inserted text; however, certain special functions such | |
| 284 as @code{insert-before-markers} relocate such markers to point after the | |
| 285 inserted text. | |
| 286 | |
| 287 @cindex insertion before point | |
| 288 @cindex before point, insertion | |
| 289 Some insertion functions leave point before the inserted text, while | |
| 290 other functions leave it after. We call the former insertion @dfn{after | |
| 291 point} and the latter insertion @dfn{before point}. | |
| 292 | |
| 293 @c XEmacs feature. | |
| 294 If a string with non-@code{nil} extent data is inserted, the remembered | |
| 295 extents will also be inserted. @xref{Duplicable Extents}. | |
| 296 | |
| 297 Insertion functions signal an error if the current buffer is | |
| 298 read-only. | |
| 299 | |
| 300 These functions copy text characters from strings and buffers along | |
| 301 with their properties. The inserted characters have exactly the same | |
| 302 properties as the characters they were copied from. By contrast, | |
| 303 characters specified as separate arguments, not part of a string or | |
| 304 buffer, inherit their text properties from the neighboring text. | |
| 305 | |
| 306 @defun insert &rest args | |
| 307 This function inserts the strings and/or characters @var{args} into the | |
| 308 current buffer, at point, moving point forward. In other words, it | |
| 309 inserts the text before point. An error is signaled unless all | |
| 310 @var{args} are either strings or characters. The value is @code{nil}. | |
| 311 @end defun | |
| 312 | |
| 313 @defun insert-before-markers &rest args | |
| 314 This function inserts the strings and/or characters @var{args} into the | |
| 315 current buffer, at point, moving point forward. An error is signaled | |
| 316 unless all @var{args} are either strings or characters. The value is | |
| 317 @code{nil}. | |
| 318 | |
| 319 This function is unlike the other insertion functions in that it | |
| 320 relocates markers initially pointing at the insertion point, to point | |
| 321 after the inserted text. | |
| 322 @end defun | |
| 323 | |
| 324 @defun insert-string string &optional buffer | |
| 325 This function inserts @var{string} into @var{buffer} before point. | |
| 326 @var{buffer} defaults to the current buffer if omitted. This | |
| 327 function is chiefly useful if you want to insert a string in | |
| 328 a buffer other than the current one (otherwise you could just | |
| 329 use @code{insert}). | |
| 330 @end defun | |
| 331 | |
| 444 | 332 @defun insert-char character &optional count ignored buffer |
| 428 | 333 This function inserts @var{count} instances of @var{character} into |
| 334 @var{buffer} before point. @var{count} must be a number, and | |
| 444 | 335 @var{character} must be a character. |
| 336 | |
| 337 If optional argument @var{buffer} is @code{nil}, the current buffer is | |
| 338 assumed. (In FSF Emacs, the third argument is called @var{inherit} and | |
| 339 refers to text properties. In XEmacs, it is always ignored.) | |
| 340 | |
| 341 This function always returns @code{nil}. | |
| 428 | 342 @end defun |
| 343 | |
| 344 @defun insert-buffer-substring from-buffer-or-name &optional start end | |
| 345 This function inserts a portion of buffer @var{from-buffer-or-name} | |
| 346 (which must already exist) into the current buffer before point. The | |
| 347 text inserted is the region from @var{start} and @var{end}. (These | |
| 348 arguments default to the beginning and end of the accessible portion of | |
| 349 that buffer.) This function returns @code{nil}. | |
| 350 | |
| 351 In this example, the form is executed with buffer @samp{bar} as the | |
| 352 current buffer. We assume that buffer @samp{bar} is initially empty. | |
| 353 | |
| 354 @example | |
| 355 @group | |
| 356 ---------- Buffer: foo ---------- | |
| 357 We hold these truths to be self-evident, that all | |
| 358 ---------- Buffer: foo ---------- | |
| 359 @end group | |
| 360 | |
| 361 @group | |
| 362 (insert-buffer-substring "foo" 1 20) | |
| 363 @result{} nil | |
| 364 | |
| 365 ---------- Buffer: bar ---------- | |
| 366 We hold these truth@point{} | |
| 367 ---------- Buffer: bar ---------- | |
| 368 @end group | |
| 369 @end example | |
| 370 @end defun | |
| 371 | |
| 372 @node Commands for Insertion | |
| 373 @section User-Level Insertion Commands | |
| 374 | |
| 375 This section describes higher-level commands for inserting text, | |
| 376 commands intended primarily for the user but useful also in Lisp | |
| 377 programs. | |
| 378 | |
| 379 @deffn Command insert-buffer from-buffer-or-name | |
| 380 This command inserts the entire contents of @var{from-buffer-or-name} | |
| 381 (which must exist) into the current buffer after point. It leaves | |
| 382 the mark after the inserted text. The value is @code{nil}. | |
| 383 @end deffn | |
| 384 | |
| 385 @deffn Command self-insert-command count | |
| 386 @cindex character insertion | |
| 387 @cindex self-insertion | |
| 388 This command inserts the last character typed; it does so @var{count} | |
| 389 times, before point, and returns @code{nil}. Most printing characters | |
| 390 are bound to this command. In routine use, @code{self-insert-command} | |
| 391 is the most frequently called function in XEmacs, but programs rarely use | |
| 392 it except to install it on a keymap. | |
| 393 | |
| 394 In an interactive call, @var{count} is the numeric prefix argument. | |
| 395 | |
| 396 This command calls @code{auto-fill-function} whenever that is | |
| 397 non-@code{nil} and the character inserted is a space or a newline | |
| 398 (@pxref{Auto Filling}). | |
| 399 | |
| 400 @c Cross refs reworded to prevent overfull hbox. --rjc 15mar92 | |
| 401 This command performs abbrev expansion if Abbrev mode is enabled and | |
| 402 the inserted character does not have word-constituent | |
| 403 syntax. (@xref{Abbrevs}, and @ref{Syntax Class Table}.) | |
| 404 | |
| 405 This is also responsible for calling @code{blink-paren-function} when | |
| 406 the inserted character has close parenthesis syntax (@pxref{Blinking}). | |
| 407 @end deffn | |
| 408 | |
| 444 | 409 @deffn Command newline &optional count |
| 428 | 410 This command inserts newlines into the current buffer before point. |
| 444 | 411 If @var{count} is supplied, that many newline characters |
| 428 | 412 are inserted. |
| 413 | |
| 414 @cindex newline and Auto Fill mode | |
| 415 This function calls @code{auto-fill-function} if the current column | |
| 416 number is greater than the value of @code{fill-column} and | |
| 444 | 417 @var{count} is @code{nil}. Typically what |
| 428 | 418 @code{auto-fill-function} does is insert a newline; thus, the overall |
| 419 result in this case is to insert two newlines at different places: one | |
| 420 at point, and another earlier in the line. @code{newline} does not | |
| 444 | 421 auto-fill if @var{count} is non-@code{nil}. |
| 428 | 422 |
| 423 This command indents to the left margin if that is not zero. | |
| 424 @xref{Margins}. | |
| 425 | |
| 426 The value returned is @code{nil}. In an interactive call, @var{count} | |
| 427 is the numeric prefix argument. | |
| 428 @end deffn | |
| 429 | |
| 430 @deffn Command split-line | |
| 431 This command splits the current line, moving the portion of the line | |
| 432 after point down vertically so that it is on the next line directly | |
| 433 below where it was before. Whitespace is inserted as needed at the | |
| 434 beginning of the lower line, using the @code{indent-to} function. | |
| 435 @code{split-line} returns the position of point. | |
| 436 | |
| 437 Programs hardly ever use this function. | |
| 438 @end deffn | |
| 439 | |
| 440 @defvar overwrite-mode | |
| 441 This variable controls whether overwrite mode is in effect: a | |
| 442 non-@code{nil} value enables the mode. It is automatically made | |
| 443 buffer-local when set in any fashion. | |
| 444 @end defvar | |
| 445 | |
| 446 @node Deletion | |
| 447 @section Deleting Text | |
| 448 | |
| 449 @cindex deletion vs killing | |
| 450 Deletion means removing part of the text in a buffer, without saving | |
| 451 it in the kill ring (@pxref{The Kill Ring}). Deleted text can't be | |
| 452 yanked, but can be reinserted using the undo mechanism (@pxref{Undo}). | |
| 453 Some deletion functions do save text in the kill ring in some special | |
| 454 cases. | |
| 455 | |
| 456 All of the deletion functions operate on the current buffer, and all | |
| 457 return a value of @code{nil}. | |
| 458 | |
| 444 | 459 @deffn Command erase-buffer &optional buffer |
| 428 | 460 This function deletes the entire text of @var{buffer}, leaving it |
| 461 empty. If the buffer is read-only, it signals a @code{buffer-read-only} | |
| 462 error. Otherwise, it deletes the text without asking for any | |
| 463 confirmation. It returns @code{nil}. @var{buffer} defaults to the | |
| 464 current buffer if omitted. | |
| 465 | |
| 466 Normally, deleting a large amount of text from a buffer inhibits further | |
| 467 auto-saving of that buffer ``because it has shrunk''. However, | |
| 468 @code{erase-buffer} does not do this, the idea being that the future | |
| 469 text is not really related to the former text, and its size should not | |
| 470 be compared with that of the former text. | |
| 444 | 471 @end deffn |
| 428 | 472 |
| 473 @deffn Command delete-region start end &optional buffer | |
| 474 This command deletes the text in @var{buffer} in the region defined by | |
| 475 @var{start} and @var{end}. The value is @code{nil}. If optional | |
| 476 argument @var{buffer} is @code{nil}, the current buffer is assumed. | |
| 477 @end deffn | |
| 478 | |
| 446 | 479 @deffn Command delete-char &optional count killp |
| 428 | 480 This command deletes @var{count} characters directly after point, or |
| 446 | 481 before point if @var{count} is negative. @var{count} defaults to @code{1}. |
| 482 If @var{killp} is non-@code{nil}, then it saves the deleted characters | |
| 483 in the kill ring. | |
| 428 | 484 |
| 485 In an interactive call, @var{count} is the numeric prefix argument, and | |
| 486 @var{killp} is the unprocessed prefix argument. Therefore, if a prefix | |
| 487 argument is supplied, the text is saved in the kill ring. If no prefix | |
| 488 argument is supplied, then one character is deleted, but not saved in | |
| 489 the kill ring. | |
| 490 | |
| 491 The value returned is always @code{nil}. | |
| 492 @end deffn | |
| 493 | |
| 446 | 494 @deffn Command delete-backward-char &optional count killp |
| 428 | 495 @cindex delete previous char |
| 496 This command deletes @var{count} characters directly before point, or | |
| 446 | 497 after point if @var{count} is negative. @var{count} defaults to 1. |
| 498 If @var{killp} is non-@code{nil}, then it saves the deleted characters | |
| 499 in the kill ring. | |
| 428 | 500 |
| 501 In an interactive call, @var{count} is the numeric prefix argument, and | |
| 502 @var{killp} is the unprocessed prefix argument. Therefore, if a prefix | |
| 503 argument is supplied, the text is saved in the kill ring. If no prefix | |
| 504 argument is supplied, then one character is deleted, but not saved in | |
| 505 the kill ring. | |
| 506 | |
| 507 The value returned is always @code{nil}. | |
| 508 @end deffn | |
| 509 | |
| 510 @deffn Command backward-delete-char-untabify count &optional killp | |
| 511 @cindex tab deletion | |
| 512 This command deletes @var{count} characters backward, changing tabs | |
| 513 into spaces. When the next character to be deleted is a tab, it is | |
| 514 first replaced with the proper number of spaces to preserve alignment | |
| 515 and then one of those spaces is deleted instead of the tab. If | |
| 516 @var{killp} is non-@code{nil}, then the command saves the deleted | |
| 517 characters in the kill ring. | |
| 518 | |
| 519 Conversion of tabs to spaces happens only if @var{count} is positive. | |
| 520 If it is negative, exactly @minus{}@var{count} characters after point | |
| 521 are deleted. | |
| 522 | |
| 523 In an interactive call, @var{count} is the numeric prefix argument, and | |
| 524 @var{killp} is the unprocessed prefix argument. Therefore, if a prefix | |
| 525 argument is supplied, the text is saved in the kill ring. If no prefix | |
| 526 argument is supplied, then one character is deleted, but not saved in | |
| 527 the kill ring. | |
| 528 | |
| 529 The value returned is always @code{nil}. | |
| 530 @end deffn | |
| 531 | |
| 532 @node User-Level Deletion | |
| 533 @section User-Level Deletion Commands | |
| 534 | |
| 535 This section describes higher-level commands for deleting text, | |
| 536 commands intended primarily for the user but useful also in Lisp | |
| 537 programs. | |
| 538 | |
| 539 @deffn Command delete-horizontal-space | |
| 540 @cindex deleting whitespace | |
| 541 This function deletes all spaces and tabs around point. It returns | |
| 542 @code{nil}. | |
| 543 | |
| 544 In the following examples, we call @code{delete-horizontal-space} four | |
| 545 times, once on each line, with point between the second and third | |
| 546 characters on the line each time. | |
| 547 | |
| 548 @example | |
| 549 @group | |
| 550 ---------- Buffer: foo ---------- | |
| 551 I @point{}thought | |
| 552 I @point{} thought | |
| 553 We@point{} thought | |
| 554 Yo@point{}u thought | |
| 555 ---------- Buffer: foo ---------- | |
| 556 @end group | |
| 557 | |
| 558 @group | |
| 559 (delete-horizontal-space) ; @r{Four times.} | |
| 560 @result{} nil | |
| 561 | |
| 562 ---------- Buffer: foo ---------- | |
| 563 Ithought | |
| 564 Ithought | |
| 565 Wethought | |
| 566 You thought | |
| 567 ---------- Buffer: foo ---------- | |
| 568 @end group | |
| 569 @end example | |
| 570 @end deffn | |
| 571 | |
| 444 | 572 @deffn Command delete-indentation &optional join-following-p |
| 428 | 573 This function joins the line point is on to the previous line, deleting |
| 574 any whitespace at the join and in some cases replacing it with one | |
| 575 space. If @var{join-following-p} is non-@code{nil}, | |
| 576 @code{delete-indentation} joins this line to the following line | |
| 577 instead. The value is @code{nil}. | |
| 578 | |
| 579 If there is a fill prefix, and the second of the lines being joined | |
| 580 starts with the prefix, then @code{delete-indentation} deletes the | |
| 581 fill prefix before joining the lines. @xref{Margins}. | |
| 582 | |
| 583 In the example below, point is located on the line starting | |
| 584 @samp{events}, and it makes no difference if there are trailing spaces | |
| 585 in the preceding line. | |
| 586 | |
| 587 @smallexample | |
| 588 @group | |
| 589 ---------- Buffer: foo ---------- | |
| 590 When in the course of human | |
| 591 @point{} events, it becomes necessary | |
| 592 ---------- Buffer: foo ---------- | |
| 593 @end group | |
| 594 | |
| 595 (delete-indentation) | |
| 596 @result{} nil | |
| 597 | |
| 598 @group | |
| 599 ---------- Buffer: foo ---------- | |
| 600 When in the course of human@point{} events, it becomes necessary | |
| 601 ---------- Buffer: foo ---------- | |
| 602 @end group | |
| 603 @end smallexample | |
| 604 | |
| 605 After the lines are joined, the function @code{fixup-whitespace} is | |
| 606 responsible for deciding whether to leave a space at the junction. | |
| 607 @end deffn | |
| 608 | |
| 444 | 609 @deffn Command fixup-whitespace |
| 428 | 610 This function replaces all the white space surrounding point with either |
| 611 one space or no space, according to the context. It returns @code{nil}. | |
| 612 | |
| 613 At the beginning or end of a line, the appropriate amount of space is | |
| 614 none. Before a character with close parenthesis syntax, or after a | |
| 615 character with open parenthesis or expression-prefix syntax, no space is | |
| 616 also appropriate. Otherwise, one space is appropriate. @xref{Syntax | |
| 617 Class Table}. | |
| 618 | |
| 619 In the example below, @code{fixup-whitespace} is called the first time | |
| 620 with point before the word @samp{spaces} in the first line. For the | |
| 621 second invocation, point is directly after the @samp{(}. | |
| 622 | |
| 623 @smallexample | |
| 624 @group | |
| 625 ---------- Buffer: foo ---------- | |
| 626 This has too many @point{}spaces | |
| 627 This has too many spaces at the start of (@point{} this list) | |
| 628 ---------- Buffer: foo ---------- | |
| 629 @end group | |
| 630 | |
| 631 @group | |
| 632 (fixup-whitespace) | |
| 633 @result{} nil | |
| 634 (fixup-whitespace) | |
| 635 @result{} nil | |
| 636 @end group | |
| 637 | |
| 638 @group | |
| 639 ---------- Buffer: foo ---------- | |
| 640 This has too many spaces | |
| 641 This has too many spaces at the start of (this list) | |
| 642 ---------- Buffer: foo ---------- | |
| 643 @end group | |
| 644 @end smallexample | |
| 444 | 645 @end deffn |
| 428 | 646 |
| 647 @deffn Command just-one-space | |
| 648 @comment !!SourceFile simple.el | |
| 649 This command replaces any spaces and tabs around point with a single | |
| 650 space. It returns @code{nil}. | |
| 651 @end deffn | |
| 652 | |
| 653 @deffn Command delete-blank-lines | |
| 654 This function deletes blank lines surrounding point. If point is on a | |
| 655 blank line with one or more blank lines before or after it, then all but | |
| 656 one of them are deleted. If point is on an isolated blank line, then it | |
| 657 is deleted. If point is on a nonblank line, the command deletes all | |
| 658 blank lines following it. | |
| 659 | |
| 660 A blank line is defined as a line containing only tabs and spaces. | |
| 661 | |
| 662 @code{delete-blank-lines} returns @code{nil}. | |
| 663 @end deffn | |
| 664 | |
| 665 @node The Kill Ring | |
| 666 @section The Kill Ring | |
| 667 @cindex kill ring | |
| 668 | |
| 669 @dfn{Kill} functions delete text like the deletion functions, but save | |
| 670 it so that the user can reinsert it by @dfn{yanking}. Most of these | |
| 671 functions have @samp{kill-} in their name. By contrast, the functions | |
| 672 whose names start with @samp{delete-} normally do not save text for | |
| 673 yanking (though they can still be undone); these are ``deletion'' | |
| 674 functions. | |
| 675 | |
| 676 Most of the kill commands are primarily for interactive use, and are | |
| 677 not described here. What we do describe are the functions provided for | |
| 678 use in writing such commands. You can use these functions to write | |
| 679 commands for killing text. When you need to delete text for internal | |
| 680 purposes within a Lisp function, you should normally use deletion | |
| 681 functions, so as not to disturb the kill ring contents. | |
| 682 @xref{Deletion}. | |
| 683 | |
| 684 Killed text is saved for later yanking in the @dfn{kill ring}. This | |
| 685 is a list that holds a number of recent kills, not just the last text | |
| 686 kill. We call this a ``ring'' because yanking treats it as having | |
| 687 elements in a cyclic order. The list is kept in the variable | |
| 688 @code{kill-ring}, and can be operated on with the usual functions for | |
| 689 lists; there are also specialized functions, described in this section, | |
| 690 that treat it as a ring. | |
| 691 | |
| 692 Some people think this use of the word ``kill'' is unfortunate, since | |
| 693 it refers to operations that specifically @emph{do not} destroy the | |
| 694 entities ``killed''. This is in sharp contrast to ordinary life, in | |
| 695 which death is permanent and ``killed'' entities do not come back to | |
| 696 life. Therefore, other metaphors have been proposed. For example, the | |
| 697 term ``cut ring'' makes sense to people who, in pre-computer days, used | |
| 698 scissors and paste to cut up and rearrange manuscripts. However, it | |
| 699 would be difficult to change the terminology now. | |
| 700 | |
| 701 @menu | |
| 702 * Kill Ring Concepts:: What text looks like in the kill ring. | |
| 703 * Kill Functions:: Functions that kill text. | |
| 704 * Yank Commands:: Commands that access the kill ring. | |
| 705 * Low-Level Kill Ring:: Functions and variables for kill ring access. | |
| 706 * Internals of Kill Ring:: Variables that hold kill-ring data. | |
| 707 @end menu | |
| 708 | |
| 709 @node Kill Ring Concepts | |
| 710 @subsection Kill Ring Concepts | |
| 711 | |
| 712 The kill ring records killed text as strings in a list, most recent | |
| 713 first. A short kill ring, for example, might look like this: | |
| 714 | |
| 715 @example | |
| 716 ("some text" "a different piece of text" "even older text") | |
| 717 @end example | |
| 718 | |
| 719 @noindent | |
| 720 When the list reaches @code{kill-ring-max} entries in length, adding a | |
| 721 new entry automatically deletes the last entry. | |
| 722 | |
| 723 When kill commands are interwoven with other commands, each kill | |
| 724 command makes a new entry in the kill ring. Multiple kill commands in | |
| 725 succession build up a single entry in the kill ring, which would be | |
| 726 yanked as a unit; the second and subsequent consecutive kill commands | |
| 727 add text to the entry made by the first one. | |
| 728 | |
| 729 For yanking, one entry in the kill ring is designated the ``front'' of | |
| 730 the ring. Some yank commands ``rotate'' the ring by designating a | |
| 731 different element as the ``front.'' But this virtual rotation doesn't | |
| 732 change the list itself---the most recent entry always comes first in the | |
| 733 list. | |
| 734 | |
| 735 @node Kill Functions | |
| 736 @subsection Functions for Killing | |
| 737 | |
| 738 @code{kill-region} is the usual subroutine for killing text. Any | |
| 739 command that calls this function is a ``kill command'' (and should | |
| 740 probably have @samp{kill} in its name). @code{kill-region} puts the | |
| 741 newly killed text in a new element at the beginning of the kill ring or | |
| 742 adds it to the most recent element. It uses the @code{last-command} | |
| 743 variable to determine whether the previous command was a kill command, | |
| 744 and if so appends the killed text to the most recent entry. | |
| 745 | |
| 444 | 746 @deffn Command kill-region start end &optional verbose |
| 428 | 747 This function kills the text in the region defined by @var{start} and |
| 748 @var{end}. The text is deleted but saved in the kill ring, along with | |
| 749 its text properties. The value is always @code{nil}. | |
| 750 | |
| 751 In an interactive call, @var{start} and @var{end} are point and | |
| 752 the mark. | |
| 753 | |
| 754 @c Emacs 19 feature | |
| 755 If the buffer is read-only, @code{kill-region} modifies the kill ring | |
| 756 just the same, then signals an error without modifying the buffer. This | |
| 757 is convenient because it lets the user use all the kill commands to copy | |
| 758 text into the kill ring from a read-only buffer. | |
| 759 @end deffn | |
| 760 | |
| 761 @deffn Command copy-region-as-kill start end | |
| 762 This command saves the region defined by @var{start} and @var{end} on | |
| 763 the kill ring (including text properties), but does not delete the text | |
| 764 from the buffer. It returns @code{nil}. It also indicates the extent | |
| 765 of the text copied by moving the cursor momentarily, or by displaying a | |
| 766 message in the echo area. | |
| 767 | |
| 768 The command does not set @code{this-command} to @code{kill-region}, so a | |
| 769 subsequent kill command does not append to the same kill ring entry. | |
| 770 | |
| 771 Don't call @code{copy-region-as-kill} in Lisp programs unless you aim to | |
| 772 support Emacs 18. For Emacs 19, it is better to use @code{kill-new} or | |
| 773 @code{kill-append} instead. @xref{Low-Level Kill Ring}. | |
| 774 @end deffn | |
| 775 | |
| 776 @node Yank Commands | |
| 777 @subsection Functions for Yanking | |
| 778 | |
| 779 @dfn{Yanking} means reinserting an entry of previously killed text | |
| 780 from the kill ring. The text properties are copied too. | |
| 781 | |
| 782 @deffn Command yank &optional arg | |
| 783 @cindex inserting killed text | |
| 784 This command inserts before point the text in the first entry in the | |
| 785 kill ring. It positions the mark at the beginning of that text, and | |
| 786 point at the end. | |
| 787 | |
| 788 If @var{arg} is a list (which occurs interactively when the user | |
| 789 types @kbd{C-u} with no digits), then @code{yank} inserts the text as | |
| 790 described above, but puts point before the yanked text and puts the mark | |
| 791 after it. | |
| 792 | |
| 793 If @var{arg} is a number, then @code{yank} inserts the @var{arg}th most | |
| 794 recently killed text---the @var{arg}th element of the kill ring list. | |
| 795 | |
| 796 @code{yank} does not alter the contents of the kill ring or rotate it. | |
| 797 It returns @code{nil}. | |
| 798 @end deffn | |
| 799 | |
| 800 @deffn Command yank-pop arg | |
| 801 This command replaces the just-yanked entry from the kill ring with a | |
| 802 different entry from the kill ring. | |
| 803 | |
| 804 This is allowed only immediately after a @code{yank} or another | |
| 805 @code{yank-pop}. At such a time, the region contains text that was just | |
| 806 inserted by yanking. @code{yank-pop} deletes that text and inserts in | |
| 807 its place a different piece of killed text. It does not add the deleted | |
| 808 text to the kill ring, since it is already in the kill ring somewhere. | |
| 809 | |
| 810 If @var{arg} is @code{nil}, then the replacement text is the previous | |
| 811 element of the kill ring. If @var{arg} is numeric, the replacement is | |
| 812 the @var{arg}th previous kill. If @var{arg} is negative, a more recent | |
| 813 kill is the replacement. | |
| 814 | |
| 815 The sequence of kills in the kill ring wraps around, so that after the | |
| 816 oldest one comes the newest one, and before the newest one goes the | |
| 817 oldest. | |
| 818 | |
| 819 The value is always @code{nil}. | |
| 820 @end deffn | |
| 821 | |
| 822 @node Low-Level Kill Ring | |
| 823 @subsection Low-Level Kill Ring | |
| 824 | |
| 825 These functions and variables provide access to the kill ring at a lower | |
| 826 level, but still convenient for use in Lisp programs. They take care of | |
| 827 interaction with X Window selections. They do not exist in Emacs | |
| 828 version 18. | |
| 829 | |
| 444 | 830 @defun current-kill count &optional do-not-move |
| 428 | 831 The function @code{current-kill} rotates the yanking pointer which |
| 444 | 832 designates the ``front'' of the kill ring by @var{count} places (from newer |
| 428 | 833 kills to older ones), and returns the text at that place in the ring. |
| 834 | |
| 835 If the optional second argument @var{do-not-move} is non-@code{nil}, | |
| 836 then @code{current-kill} doesn't alter the yanking pointer; it just | |
| 444 | 837 returns the @var{count}th kill, counting from the current yanking pointer. |
| 838 | |
| 839 If @var{count} is zero, indicating a request for the latest kill, | |
| 428 | 840 @code{current-kill} calls the value of |
| 841 @code{interprogram-paste-function} (documented below) before consulting | |
| 842 the kill ring. | |
| 843 @end defun | |
| 844 | |
| 444 | 845 @defun kill-new string &optional replace |
| 846 This function makes the text @var{string} the latest entry in the kill | |
| 847 ring, and sets @code{kill-ring-yank-pointer} to point to it. | |
| 848 | |
| 849 Normally, @var{string} is added to the front of the kill ring as a new | |
| 850 entry. However, if optional argument @var{replace} is non-@code{nil}, | |
| 851 the entry previously at the front of the kill ring is discarded, and | |
| 852 @var{string} replaces it. | |
| 853 | |
| 854 This function runs the functions on @code{kill-hooks}, and also invokes | |
| 855 the value of @code{interprogram-cut-function} (see below). | |
| 428 | 856 @end defun |
| 857 | |
| 858 @defun kill-append string before-p | |
| 859 This function appends the text @var{string} to the first entry in the | |
| 860 kill ring. Normally @var{string} goes at the end of the entry, but if | |
| 861 @var{before-p} is non-@code{nil}, it goes at the beginning. This | |
| 862 function also invokes the value of @code{interprogram-cut-function} (see | |
| 863 below). | |
| 864 @end defun | |
| 865 | |
| 866 @defvar interprogram-paste-function | |
| 867 This variable provides a way of transferring killed text from other | |
| 868 programs, when you are using a window system. Its value should be | |
| 869 @code{nil} or a function of no arguments. | |
| 870 | |
| 871 If the value is a function, @code{current-kill} calls it to get the | |
| 872 ``most recent kill''. If the function returns a non-@code{nil} value, | |
| 873 then that value is used as the ``most recent kill''. If it returns | |
| 874 @code{nil}, then the first element of @code{kill-ring} is used. | |
| 875 | |
| 876 The normal use of this hook is to get the X server's primary selection | |
| 877 as the most recent kill, even if the selection belongs to another X | |
| 878 client. @xref{X Selections}. | |
| 879 @end defvar | |
| 880 | |
| 881 @defvar interprogram-cut-function | |
| 882 This variable provides a way of communicating killed text to other | |
| 883 programs, when you are using a window system. Its value should be | |
| 884 @code{nil} or a function of one argument. | |
| 885 | |
| 886 If the value is a function, @code{kill-new} and @code{kill-append} call | |
| 887 it with the new first element of the kill ring as an argument. | |
| 888 | |
| 889 The normal use of this hook is to set the X server's primary selection | |
| 890 to the newly killed text. | |
| 891 @end defvar | |
| 892 | |
| 893 @node Internals of Kill Ring | |
| 894 @subsection Internals of the Kill Ring | |
| 895 | |
| 896 The variable @code{kill-ring} holds the kill ring contents, in the | |
| 897 form of a list of strings. The most recent kill is always at the front | |
| 444 | 898 of the list. |
| 428 | 899 |
| 900 The @code{kill-ring-yank-pointer} variable points to a link in the | |
| 901 kill ring list, whose @sc{car} is the text to yank next. We say it | |
| 902 identifies the ``front'' of the ring. Moving | |
| 903 @code{kill-ring-yank-pointer} to a different link is called | |
| 904 @dfn{rotating the kill ring}. We call the kill ring a ``ring'' because | |
| 905 the functions that move the yank pointer wrap around from the end of the | |
| 906 list to the beginning, or vice-versa. Rotation of the kill ring is | |
| 907 virtual; it does not change the value of @code{kill-ring}. | |
| 908 | |
| 909 Both @code{kill-ring} and @code{kill-ring-yank-pointer} are Lisp | |
| 910 variables whose values are normally lists. The word ``pointer'' in the | |
| 911 name of the @code{kill-ring-yank-pointer} indicates that the variable's | |
| 912 purpose is to identify one element of the list for use by the next yank | |
| 913 command. | |
| 914 | |
| 915 The value of @code{kill-ring-yank-pointer} is always @code{eq} to one | |
| 916 of the links in the kill ring list. The element it identifies is the | |
| 917 @sc{car} of that link. Kill commands, which change the kill ring, also | |
| 918 set this variable to the value of @code{kill-ring}. The effect is to | |
| 919 rotate the ring so that the newly killed text is at the front. | |
| 920 | |
| 921 Here is a diagram that shows the variable @code{kill-ring-yank-pointer} | |
| 922 pointing to the second entry in the kill ring @code{("some text" "a | |
| 444 | 923 different piece of text" "yet older text")}. |
| 428 | 924 |
| 925 @example | |
| 926 @group | |
| 927 kill-ring kill-ring-yank-pointer | |
| 928 | | | |
| 929 | ___ ___ ---> ___ ___ ___ ___ | |
| 930 --> |___|___|------> |___|___|--> |___|___|--> nil | |
| 444 | 931 | | | |
| 932 | | | | |
| 933 | | -->"yet older text" | |
| 428 | 934 | | |
| 444 | 935 | --> "a different piece of text" |
| 428 | 936 | |
| 937 --> "some text" | |
| 938 @end group | |
| 939 @end example | |
| 940 | |
| 941 @noindent | |
| 942 This state of affairs might occur after @kbd{C-y} (@code{yank}) | |
| 943 immediately followed by @kbd{M-y} (@code{yank-pop}). | |
| 944 | |
| 945 @defvar kill-ring | |
| 946 This variable holds the list of killed text sequences, most recently | |
| 947 killed first. | |
| 948 @end defvar | |
| 949 | |
| 950 @defvar kill-ring-yank-pointer | |
| 951 This variable's value indicates which element of the kill ring is at the | |
| 952 ``front'' of the ring for yanking. More precisely, the value is a tail | |
| 953 of the value of @code{kill-ring}, and its @sc{car} is the kill string | |
| 954 that @kbd{C-y} should yank. | |
| 955 @end defvar | |
| 956 | |
| 957 @defopt kill-ring-max | |
| 958 The value of this variable is the maximum length to which the kill | |
| 959 ring can grow, before elements are thrown away at the end. The default | |
| 960 value for @code{kill-ring-max} is 30. | |
| 961 @end defopt | |
| 962 | |
| 963 @node Undo | |
| 964 @section Undo | |
| 965 @cindex redo | |
| 966 | |
| 967 Most buffers have an @dfn{undo list}, which records all changes made | |
| 968 to the buffer's text so that they can be undone. (The buffers that | |
| 969 don't have one are usually special-purpose buffers for which XEmacs | |
| 970 assumes that undoing is not useful.) All the primitives that modify the | |
| 971 text in the buffer automatically add elements to the front of the undo | |
| 972 list, which is in the variable @code{buffer-undo-list}. | |
| 973 | |
| 974 @defvar buffer-undo-list | |
| 975 This variable's value is the undo list of the current buffer. | |
| 976 A value of @code{t} disables the recording of undo information. | |
| 977 @end defvar | |
| 978 | |
| 979 Here are the kinds of elements an undo list can have: | |
| 980 | |
| 981 @table @code | |
| 982 @item @var{integer} | |
| 983 This kind of element records a previous value of point. Ordinary cursor | |
| 984 motion does not get any sort of undo record, but deletion commands use | |
| 985 these entries to record where point was before the command. | |
| 986 | |
| 444 | 987 @item (@var{start} . @var{end}) |
| 428 | 988 This kind of element indicates how to delete text that was inserted. |
| 444 | 989 Upon insertion, the text occupied the range @var{start}--@var{end} in the |
| 428 | 990 buffer. |
| 991 | |
| 992 @item (@var{text} . @var{position}) | |
| 993 This kind of element indicates how to reinsert text that was deleted. | |
| 994 The deleted text itself is the string @var{text}. The place to | |
| 995 reinsert it is @code{(abs @var{position})}. | |
| 996 | |
| 997 @item (t @var{high} . @var{low}) | |
| 998 This kind of element indicates that an unmodified buffer became | |
| 999 modified. The elements @var{high} and @var{low} are two integers, each | |
| 1000 recording 16 bits of the visited file's modification time as of when it | |
| 1001 was previously visited or saved. @code{primitive-undo} uses those | |
| 1002 values to determine whether to mark the buffer as unmodified once again; | |
| 1003 it does so only if the file's modification time matches those numbers. | |
| 1004 | |
| 444 | 1005 @item (nil @var{property} @var{value} @var{start} . @var{end}) |
| 428 | 1006 This kind of element records a change in a text property. |
| 1007 Here's how you might undo the change: | |
| 1008 | |
| 1009 @example | |
| 444 | 1010 (put-text-property @var{start} @var{end} @var{property} @var{value}) |
| 428 | 1011 @end example |
| 1012 | |
| 1013 @item @var{position} | |
| 1014 This element indicates where point was at an earlier time. Undoing this | |
| 1015 element sets point to @var{position}. Deletion normally creates an | |
| 1016 element of this kind as well as a reinsertion element. | |
| 1017 | |
| 1018 @item nil | |
| 1019 This element is a boundary. The elements between two boundaries are | |
| 1020 called a @dfn{change group}; normally, each change group corresponds to | |
| 1021 one keyboard command, and undo commands normally undo an entire group as | |
| 1022 a unit. | |
| 1023 @end table | |
| 1024 | |
| 1025 @defun undo-boundary | |
| 1026 This function places a boundary element in the undo list. The undo | |
| 1027 command stops at such a boundary, and successive undo commands undo | |
| 1028 to earlier and earlier boundaries. This function returns @code{nil}. | |
| 1029 | |
| 1030 The editor command loop automatically creates an undo boundary before | |
| 1031 each key sequence is executed. Thus, each undo normally undoes the | |
| 1032 effects of one command. Self-inserting input characters are an | |
| 1033 exception. The command loop makes a boundary for the first such | |
| 1034 character; the next 19 consecutive self-inserting input characters do | |
| 1035 not make boundaries, and then the 20th does, and so on as long as | |
| 1036 self-inserting characters continue. | |
| 1037 | |
| 1038 All buffer modifications add a boundary whenever the previous undoable | |
| 1039 change was made in some other buffer. This way, a command that modifies | |
| 1040 several buffers makes a boundary in each buffer it changes. | |
| 1041 | |
| 1042 Calling this function explicitly is useful for splitting the effects of | |
| 1043 a command into more than one unit. For example, @code{query-replace} | |
| 1044 calls @code{undo-boundary} after each replacement, so that the user can | |
| 1045 undo individual replacements one by one. | |
| 1046 @end defun | |
| 1047 | |
| 1048 @defun primitive-undo count list | |
| 1049 This is the basic function for undoing elements of an undo list. | |
| 1050 It undoes the first @var{count} elements of @var{list}, returning | |
| 1051 the rest of @var{list}. You could write this function in Lisp, | |
| 1052 but it is convenient to have it in C. | |
| 1053 | |
| 1054 @code{primitive-undo} adds elements to the buffer's undo list when it | |
| 1055 changes the buffer. Undo commands avoid confusion by saving the undo | |
| 1056 list value at the beginning of a sequence of undo operations. Then the | |
| 1057 undo operations use and update the saved value. The new elements added | |
| 1058 by undoing are not part of this saved value, so they don't interfere with | |
| 1059 continuing to undo. | |
| 1060 @end defun | |
| 1061 | |
| 1062 @node Maintaining Undo | |
| 1063 @section Maintaining Undo Lists | |
| 1064 | |
| 1065 This section describes how to enable and disable undo information for | |
| 1066 a given buffer. It also explains how the undo list is truncated | |
| 1067 automatically so it doesn't get too big. | |
| 1068 | |
| 1069 Recording of undo information in a newly created buffer is normally | |
| 1070 enabled to start with; but if the buffer name starts with a space, the | |
| 1071 undo recording is initially disabled. You can explicitly enable or | |
| 1072 disable undo recording with the following two functions, or by setting | |
| 1073 @code{buffer-undo-list} yourself. | |
| 1074 | |
| 1075 @deffn Command buffer-enable-undo &optional buffer-or-name | |
| 1076 This command enables recording undo information for buffer | |
| 1077 @var{buffer-or-name}, so that subsequent changes can be undone. If no | |
| 1078 argument is supplied, then the current buffer is used. This function | |
| 1079 does nothing if undo recording is already enabled in the buffer. It | |
| 1080 returns @code{nil}. | |
| 1081 | |
| 1082 In an interactive call, @var{buffer-or-name} is the current buffer. | |
| 1083 You cannot specify any other buffer. | |
| 1084 @end deffn | |
| 1085 | |
| 444 | 1086 @deffn Command buffer-disable-undo &optional buffer |
| 1087 @deffnx Command buffer-flush-undo &optional buffer | |
| 428 | 1088 @cindex disable undo |
| 1089 This function discards the undo list of @var{buffer}, and disables | |
| 1090 further recording of undo information. As a result, it is no longer | |
| 1091 possible to undo either previous changes or any subsequent changes. If | |
| 1092 the undo list of @var{buffer} is already disabled, this function | |
| 1093 has no effect. | |
| 1094 | |
| 1095 This function returns @code{nil}. It cannot be called interactively. | |
| 1096 | |
| 1097 The name @code{buffer-flush-undo} is not considered obsolete, but the | |
| 1098 preferred name @code{buffer-disable-undo} is new as of Emacs versions | |
| 1099 19. | |
| 444 | 1100 @end deffn |
| 428 | 1101 |
| 1102 As editing continues, undo lists get longer and longer. To prevent | |
| 1103 them from using up all available memory space, garbage collection trims | |
| 1104 them back to size limits you can set. (For this purpose, the ``size'' | |
| 1105 of an undo list measures the cons cells that make up the list, plus the | |
| 1106 strings of deleted text.) Two variables control the range of acceptable | |
| 1107 sizes: @code{undo-limit} and @code{undo-strong-limit}. | |
| 1108 | |
| 1109 @defvar undo-limit | |
| 1110 This is the soft limit for the acceptable size of an undo list. The | |
| 1111 change group at which this size is exceeded is the last one kept. | |
| 1112 @end defvar | |
| 1113 | |
| 1114 @defvar undo-strong-limit | |
| 1115 This is the upper limit for the acceptable size of an undo list. The | |
| 1116 change group at which this size is exceeded is discarded itself (along | |
| 1117 with all older change groups). There is one exception: the very latest | |
| 1118 change group is never discarded no matter how big it is. | |
| 1119 @end defvar | |
| 1120 | |
| 1121 @node Filling | |
| 1122 @section Filling | |
| 1123 @cindex filling, explicit | |
| 1124 | |
| 1125 @dfn{Filling} means adjusting the lengths of lines (by moving the line | |
| 1126 breaks) so that they are nearly (but no greater than) a specified | |
| 1127 maximum width. Additionally, lines can be @dfn{justified}, which means | |
| 1128 inserting spaces to make the left and/or right margins line up | |
| 1129 precisely. The width is controlled by the variable @code{fill-column}. | |
| 1130 For ease of reading, lines should be no longer than 70 or so columns. | |
| 1131 | |
| 1132 You can use Auto Fill mode (@pxref{Auto Filling}) to fill text | |
| 1133 automatically as you insert it, but changes to existing text may leave | |
| 1134 it improperly filled. Then you must fill the text explicitly. | |
| 1135 | |
| 1136 Most of the commands in this section return values that are not | |
| 1137 meaningful. All the functions that do filling take note of the current | |
| 1138 left margin, current right margin, and current justification style | |
| 1139 (@pxref{Margins}). If the current justification style is | |
| 1140 @code{none}, the filling functions don't actually do anything. | |
| 1141 | |
| 1142 Several of the filling functions have an argument @var{justify}. | |
| 1143 If it is non-@code{nil}, that requests some kind of justification. It | |
| 1144 can be @code{left}, @code{right}, @code{full}, or @code{center}, to | |
| 1145 request a specific style of justification. If it is @code{t}, that | |
| 1146 means to use the current justification style for this part of the text | |
| 1147 (see @code{current-justification}, below). | |
| 1148 | |
| 1149 When you call the filling functions interactively, using a prefix | |
| 1150 argument implies the value @code{full} for @var{justify}. | |
| 1151 | |
| 1152 @deffn Command fill-paragraph justify | |
| 1153 @cindex filling a paragraph | |
| 1154 This command fills the paragraph at or after point. If | |
| 1155 @var{justify} is non-@code{nil}, each line is justified as well. | |
| 1156 It uses the ordinary paragraph motion commands to find paragraph | |
| 1157 boundaries. @xref{Paragraphs,,, xemacs, The XEmacs User's Manual}. | |
| 1158 @end deffn | |
| 1159 | |
| 1160 @deffn Command fill-region start end &optional justify | |
| 1161 This command fills each of the paragraphs in the region from @var{start} | |
| 1162 to @var{end}. It justifies as well if @var{justify} is | |
| 1163 non-@code{nil}. | |
| 1164 | |
| 1165 The variable @code{paragraph-separate} controls how to distinguish | |
| 1166 paragraphs. @xref{Standard Regexps}. | |
| 1167 @end deffn | |
| 1168 | |
| 1169 @deffn Command fill-individual-paragraphs start end &optional justify mail-flag | |
| 1170 This command fills each paragraph in the region according to its | |
| 1171 individual fill prefix. Thus, if the lines of a paragraph were indented | |
| 1172 with spaces, the filled paragraph will remain indented in the same | |
| 1173 fashion. | |
| 1174 | |
| 1175 The first two arguments, @var{start} and @var{end}, are the beginning | |
| 1176 and end of the region to be filled. The third and fourth arguments, | |
| 1177 @var{justify} and @var{mail-flag}, are optional. If | |
| 1178 @var{justify} is non-@code{nil}, the paragraphs are justified as | |
| 1179 well as filled. If @var{mail-flag} is non-@code{nil}, it means the | |
| 1180 function is operating on a mail message and therefore should not fill | |
| 1181 the header lines. | |
| 1182 | |
| 1183 Ordinarily, @code{fill-individual-paragraphs} regards each change in | |
| 1184 indentation as starting a new paragraph. If | |
| 1185 @code{fill-individual-varying-indent} is non-@code{nil}, then only | |
| 1186 separator lines separate paragraphs. That mode can handle indented | |
| 1187 paragraphs with additional indentation on the first line. | |
| 1188 @end deffn | |
| 1189 | |
| 1190 @defopt fill-individual-varying-indent | |
| 1191 This variable alters the action of @code{fill-individual-paragraphs} as | |
| 1192 described above. | |
| 1193 @end defopt | |
| 1194 | |
| 1195 @deffn Command fill-region-as-paragraph start end &optional justify | |
| 1196 This command considers a region of text as a paragraph and fills it. If | |
| 1197 the region was made up of many paragraphs, the blank lines between | |
| 1198 paragraphs are removed. This function justifies as well as filling when | |
| 1199 @var{justify} is non-@code{nil}. | |
| 1200 | |
| 1201 In an interactive call, any prefix argument requests justification. | |
| 1202 | |
| 1203 In Adaptive Fill mode, which is enabled by default, | |
| 1204 @code{fill-region-as-paragraph} on an indented paragraph when there is | |
| 1205 no fill prefix uses the indentation of the second line of the paragraph | |
| 1206 as the fill prefix. | |
| 1207 @end deffn | |
| 1208 | |
| 1209 @deffn Command justify-current-line how eop nosqueeze | |
| 1210 This command inserts spaces between the words of the current line so | |
| 1211 that the line ends exactly at @code{fill-column}. It returns | |
| 1212 @code{nil}. | |
| 1213 | |
| 1214 The argument @var{how}, if non-@code{nil} specifies explicitly the style | |
| 1215 of justification. It can be @code{left}, @code{right}, @code{full}, | |
| 1216 @code{center}, or @code{none}. If it is @code{t}, that means to do | |
| 1217 follow specified justification style (see @code{current-justification}, | |
| 1218 below). @code{nil} means to do full justification. | |
| 1219 | |
| 1220 If @var{eop} is non-@code{nil}, that means do left-justification when | |
| 1221 @code{current-justification} specifies full justification. This is used | |
| 1222 for the last line of a paragraph; even if the paragraph as a whole is | |
| 1223 fully justified, the last line should not be. | |
| 1224 | |
| 1225 If @var{nosqueeze} is non-@code{nil}, that means do not change interior | |
| 1226 whitespace. | |
| 1227 @end deffn | |
| 1228 | |
| 1229 @defopt default-justification | |
| 1230 This variable's value specifies the style of justification to use for | |
| 1231 text that doesn't specify a style with a text property. The possible | |
| 1232 values are @code{left}, @code{right}, @code{full}, @code{center}, or | |
| 1233 @code{none}. The default value is @code{left}. | |
| 1234 @end defopt | |
| 1235 | |
| 1236 @defun current-justification | |
| 1237 This function returns the proper justification style to use for filling | |
| 1238 the text around point. | |
| 1239 @end defun | |
| 1240 | |
| 1241 @defvar fill-paragraph-function | |
| 1242 This variable provides a way for major modes to override the filling of | |
| 1243 paragraphs. If the value is non-@code{nil}, @code{fill-paragraph} calls | |
| 1244 this function to do the work. If the function returns a non-@code{nil} | |
| 1245 value, @code{fill-paragraph} assumes the job is done, and immediately | |
| 1246 returns that value. | |
| 1247 | |
| 1248 The usual use of this feature is to fill comments in programming | |
| 1249 language modes. If the function needs to fill a paragraph in the usual | |
| 1250 way, it can do so as follows: | |
| 1251 | |
| 1252 @example | |
| 1253 (let ((fill-paragraph-function nil)) | |
| 1254 (fill-paragraph arg)) | |
| 1255 @end example | |
| 1256 @end defvar | |
| 1257 | |
| 1258 @defvar use-hard-newlines | |
| 1259 If this variable is non-@code{nil}, the filling functions do not delete | |
| 1260 newlines that have the @code{hard} text property. These ``hard | |
| 1261 newlines'' act as paragraph separators. | |
| 1262 @end defvar | |
| 1263 | |
| 1264 @node Margins | |
| 1265 @section Margins for Filling | |
| 1266 | |
| 1267 @defopt fill-prefix | |
| 1268 This variable specifies a string of text that appears at the beginning | |
| 1269 of normal text lines and should be disregarded when filling them. Any | |
| 1270 line that fails to start with the fill prefix is considered the start of | |
| 1271 a paragraph; so is any line that starts with the fill prefix followed by | |
| 1272 additional whitespace. Lines that start with the fill prefix but no | |
| 1273 additional whitespace are ordinary text lines that can be filled | |
| 1274 together. The resulting filled lines also start with the fill prefix. | |
| 1275 | |
| 1276 The fill prefix follows the left margin whitespace, if any. | |
| 1277 @end defopt | |
| 1278 | |
| 1279 @defopt fill-column | |
| 1280 This buffer-local variable specifies the maximum width of filled | |
| 1281 lines. Its value should be an integer, which is a number of columns. | |
| 1282 All the filling, justification and centering commands are affected by | |
| 1283 this variable, including Auto Fill mode (@pxref{Auto Filling}). | |
| 1284 | |
| 1285 As a practical matter, if you are writing text for other people to | |
| 1286 read, you should set @code{fill-column} to no more than 70. Otherwise | |
| 1287 the line will be too long for people to read comfortably, and this can | |
| 1288 make the text seem clumsy. | |
| 1289 @end defopt | |
| 1290 | |
| 1291 @defvar default-fill-column | |
| 1292 The value of this variable is the default value for @code{fill-column} in | |
| 1293 buffers that do not override it. This is the same as | |
| 1294 @code{(default-value 'fill-column)}. | |
| 1295 | |
| 1296 The default value for @code{default-fill-column} is 70. | |
| 1297 @end defvar | |
| 1298 | |
| 1299 @deffn Command set-left-margin from to margin | |
| 1300 This sets the @code{left-margin} property on the text from @var{from} to | |
| 1301 @var{to} to the value @var{margin}. If Auto Fill mode is enabled, this | |
| 1302 command also refills the region to fit the new margin. | |
| 1303 @end deffn | |
| 1304 | |
| 1305 @deffn Command set-right-margin from to margin | |
| 1306 This sets the @code{right-margin} property on the text from @var{from} | |
| 1307 to @var{to} to the value @var{margin}. If Auto Fill mode is enabled, | |
| 1308 this command also refills the region to fit the new margin. | |
| 1309 @end deffn | |
| 1310 | |
| 1311 @defun current-left-margin | |
| 1312 This function returns the proper left margin value to use for filling | |
| 1313 the text around point. The value is the sum of the @code{left-margin} | |
| 1314 property of the character at the start of the current line (or zero if | |
| 1315 none), and the value of the variable @code{left-margin}. | |
| 1316 @end defun | |
| 1317 | |
| 1318 @defun current-fill-column | |
| 1319 This function returns the proper fill column value to use for filling | |
| 1320 the text around point. The value is the value of the @code{fill-column} | |
| 1321 variable, minus the value of the @code{right-margin} property of the | |
| 1322 character after point. | |
| 1323 @end defun | |
| 1324 | |
| 1325 @deffn Command move-to-left-margin &optional n force | |
| 1326 This function moves point to the left margin of the current line. The | |
| 1327 column moved to is determined by calling the function | |
| 1328 @code{current-left-margin}. If the argument @var{n} is non-@code{nil}, | |
| 1329 @code{move-to-left-margin} moves forward @var{n}@minus{}1 lines first. | |
| 1330 | |
| 1331 If @var{force} is non-@code{nil}, that says to fix the line's | |
| 1332 indentation if that doesn't match the left margin value. | |
| 1333 @end deffn | |
| 1334 | |
| 444 | 1335 @defun delete-to-left-margin &optional from to |
| 428 | 1336 This function removes left margin indentation from the text |
| 1337 between @var{from} and @var{to}. The amount of indentation | |
| 1338 to delete is determined by calling @code{current-left-margin}. | |
| 1339 In no case does this function delete non-whitespace. | |
| 444 | 1340 |
| 1341 The arguments @var{from} and @var{to} are optional; the default is the | |
| 1342 whole buffer. | |
| 428 | 1343 @end defun |
| 1344 | |
| 1345 @defun indent-to-left-margin | |
| 1346 This is the default @code{indent-line-function}, used in Fundamental | |
| 1347 mode, Text mode, etc. Its effect is to adjust the indentation at the | |
| 1348 beginning of the current line to the value specified by the variable | |
| 1349 @code{left-margin}. This may involve either inserting or deleting | |
| 1350 whitespace. | |
| 1351 @end defun | |
| 1352 | |
| 1353 @defvar left-margin | |
| 1354 This variable specifies the base left margin column. In Fundamental | |
| 1355 mode, @key{LFD} indents to this column. This variable automatically | |
| 1356 becomes buffer-local when set in any fashion. | |
| 1357 @end defvar | |
| 1358 | |
| 1359 @node Auto Filling | |
| 1360 @section Auto Filling | |
| 1361 @cindex filling, automatic | |
| 1362 @cindex Auto Fill mode | |
| 1363 | |
| 1364 Auto Fill mode is a minor mode that fills lines automatically as text | |
| 1365 is inserted. This section describes the hook used by Auto Fill mode. | |
| 1366 For a description of functions that you can call explicitly to fill and | |
| 1367 justify existing text, see @ref{Filling}. | |
| 1368 | |
| 1369 Auto Fill mode also enables the functions that change the margins and | |
| 1370 justification style to refill portions of the text. @xref{Margins}. | |
| 1371 | |
| 1372 @defvar auto-fill-function | |
| 1373 The value of this variable should be a function (of no arguments) to be | |
| 1374 called after self-inserting a space or a newline. It may be @code{nil}, | |
| 1375 in which case nothing special is done in that case. | |
| 1376 | |
| 1377 The value of @code{auto-fill-function} is @code{do-auto-fill} when | |
| 1378 Auto-Fill mode is enabled. That is a function whose sole purpose is to | |
| 1379 implement the usual strategy for breaking a line. | |
| 1380 | |
| 1381 @quotation | |
| 1382 In older Emacs versions, this variable was named @code{auto-fill-hook}, | |
| 1383 but since it is not called with the standard convention for hooks, it | |
| 1384 was renamed to @code{auto-fill-function} in version 19. | |
| 1385 @end quotation | |
| 1386 @end defvar | |
| 1387 | |
| 1388 @node Sorting | |
| 1389 @section Sorting Text | |
| 1390 @cindex sorting text | |
| 1391 | |
| 1392 The sorting functions described in this section all rearrange text in | |
| 1393 a buffer. This is in contrast to the function @code{sort}, which | |
| 1394 rearranges the order of the elements of a list (@pxref{Rearrangement}). | |
| 1395 The values returned by these functions are not meaningful. | |
| 1396 | |
| 1397 @defun sort-subr reverse nextrecfun endrecfun &optional startkeyfun endkeyfun | |
| 1398 This function is the general text-sorting routine that divides a buffer | |
| 1399 into records and sorts them. Most of the commands in this section use | |
| 1400 this function. | |
| 1401 | |
| 1402 To understand how @code{sort-subr} works, consider the whole accessible | |
| 1403 portion of the buffer as being divided into disjoint pieces called | |
| 1404 @dfn{sort records}. The records may or may not be contiguous; they may | |
| 1405 not overlap. A portion of each sort record (perhaps all of it) is | |
| 1406 designated as the sort key. Sorting rearranges the records in order by | |
| 1407 their sort keys. | |
| 1408 | |
| 1409 Usually, the records are rearranged in order of ascending sort key. | |
| 1410 If the first argument to the @code{sort-subr} function, @var{reverse}, | |
| 1411 is non-@code{nil}, the sort records are rearranged in order of | |
| 1412 descending sort key. | |
| 1413 | |
| 1414 The next four arguments to @code{sort-subr} are functions that are | |
| 1415 called to move point across a sort record. They are called many times | |
| 1416 from within @code{sort-subr}. | |
| 1417 | |
| 1418 @enumerate | |
| 1419 @item | |
| 1420 @var{nextrecfun} is called with point at the end of a record. This | |
| 1421 function moves point to the start of the next record. The first record | |
| 1422 is assumed to start at the position of point when @code{sort-subr} is | |
| 1423 called. Therefore, you should usually move point to the beginning of | |
| 1424 the buffer before calling @code{sort-subr}. | |
| 1425 | |
| 1426 This function can indicate there are no more sort records by leaving | |
| 1427 point at the end of the buffer. | |
| 1428 | |
| 1429 @item | |
| 1430 @var{endrecfun} is called with point within a record. It moves point to | |
| 1431 the end of the record. | |
| 1432 | |
| 1433 @item | |
| 1434 @var{startkeyfun} is called to move point from the start of a record to | |
| 1435 the start of the sort key. This argument is optional; if it is omitted, | |
| 1436 the whole record is the sort key. If supplied, the function should | |
| 1437 either return a non-@code{nil} value to be used as the sort key, or | |
| 1438 return @code{nil} to indicate that the sort key is in the buffer | |
| 1439 starting at point. In the latter case, @var{endkeyfun} is called to | |
| 1440 find the end of the sort key. | |
| 1441 | |
| 1442 @item | |
| 1443 @var{endkeyfun} is called to move point from the start of the sort key | |
| 1444 to the end of the sort key. This argument is optional. If | |
| 1445 @var{startkeyfun} returns @code{nil} and this argument is omitted (or | |
| 1446 @code{nil}), then the sort key extends to the end of the record. There | |
| 1447 is no need for @var{endkeyfun} if @var{startkeyfun} returns a | |
| 1448 non-@code{nil} value. | |
| 1449 @end enumerate | |
| 1450 | |
| 1451 As an example of @code{sort-subr}, here is the complete function | |
| 1452 definition for @code{sort-lines}: | |
| 1453 | |
| 1454 @example | |
| 1455 @group | |
| 1456 ;; @r{Note that the first two lines of doc string} | |
| 1457 ;; @r{are effectively one line when viewed by a user.} | |
| 444 | 1458 (defun sort-lines (reverse start end) |
| 428 | 1459 "Sort lines in region alphabetically. |
| 1460 Called from a program, there are three arguments: | |
| 1461 @end group | |
| 1462 @group | |
| 1463 REVERSE (non-nil means reverse order), | |
| 444 | 1464 and START and END (the region to sort)." |
| 428 | 1465 (interactive "P\nr") |
| 1466 (save-restriction | |
| 444 | 1467 (narrow-to-region start end) |
| 428 | 1468 (goto-char (point-min)) |
| 1469 (sort-subr reverse | |
| 1470 'forward-line | |
| 1471 'end-of-line))) | |
| 1472 @end group | |
| 1473 @end example | |
| 1474 | |
| 1475 Here @code{forward-line} moves point to the start of the next record, | |
| 1476 and @code{end-of-line} moves point to the end of record. We do not pass | |
| 1477 the arguments @var{startkeyfun} and @var{endkeyfun}, because the entire | |
| 1478 record is used as the sort key. | |
| 1479 | |
| 1480 The @code{sort-paragraphs} function is very much the same, except that | |
| 1481 its @code{sort-subr} call looks like this: | |
| 1482 | |
| 1483 @example | |
| 1484 @group | |
| 1485 (sort-subr reverse | |
| 444 | 1486 (function |
| 1487 (lambda () | |
| 428 | 1488 (skip-chars-forward "\n \t\f"))) |
| 1489 'forward-paragraph) | |
| 1490 @end group | |
| 1491 @end example | |
| 1492 @end defun | |
| 1493 | |
| 1494 @deffn Command sort-regexp-fields reverse record-regexp key-regexp start end | |
| 1495 This command sorts the region between @var{start} and @var{end} | |
| 1496 alphabetically as specified by @var{record-regexp} and @var{key-regexp}. | |
| 1497 If @var{reverse} is a negative integer, then sorting is in reverse | |
| 1498 order. | |
| 1499 | |
| 1500 Alphabetical sorting means that two sort keys are compared by | |
| 1501 comparing the first characters of each, the second characters of each, | |
| 1502 and so on. If a mismatch is found, it means that the sort keys are | |
| 1503 unequal; the sort key whose character is less at the point of first | |
| 1504 mismatch is the lesser sort key. The individual characters are compared | |
| 1505 according to their numerical values. Since Emacs uses the @sc{ascii} | |
| 1506 character set, the ordering in that set determines alphabetical order. | |
| 1507 @c version 19 change | |
| 1508 | |
| 1509 The value of the @var{record-regexp} argument specifies how to divide | |
| 1510 the buffer into sort records. At the end of each record, a search is | |
| 1511 done for this regular expression, and the text that matches it is the | |
| 1512 next record. For example, the regular expression @samp{^.+$}, which | |
| 1513 matches lines with at least one character besides a newline, would make | |
| 1514 each such line into a sort record. @xref{Regular Expressions}, for a | |
| 1515 description of the syntax and meaning of regular expressions. | |
| 1516 | |
| 1517 The value of the @var{key-regexp} argument specifies what part of each | |
| 1518 record is the sort key. The @var{key-regexp} could match the whole | |
| 1519 record, or only a part. In the latter case, the rest of the record has | |
| 1520 no effect on the sorted order of records, but it is carried along when | |
| 1521 the record moves to its new position. | |
| 1522 | |
| 1523 The @var{key-regexp} argument can refer to the text matched by a | |
| 1524 subexpression of @var{record-regexp}, or it can be a regular expression | |
| 1525 on its own. | |
| 1526 | |
| 1527 If @var{key-regexp} is: | |
| 1528 | |
| 1529 @table @asis | |
| 1530 @item @samp{\@var{digit}} | |
| 1531 then the text matched by the @var{digit}th @samp{\(...\)} parenthesis | |
| 1532 grouping in @var{record-regexp} is the sort key. | |
| 1533 | |
| 1534 @item @samp{\&} | |
| 1535 then the whole record is the sort key. | |
| 1536 | |
| 1537 @item a regular expression | |
| 1538 then @code{sort-regexp-fields} searches for a match for the regular | |
| 1539 expression within the record. If such a match is found, it is the sort | |
| 1540 key. If there is no match for @var{key-regexp} within a record then | |
| 1541 that record is ignored, which means its position in the buffer is not | |
| 1542 changed. (The other records may move around it.) | |
| 1543 @end table | |
| 1544 | |
| 1545 For example, if you plan to sort all the lines in the region by the | |
| 1546 first word on each line starting with the letter @samp{f}, you should | |
| 1547 set @var{record-regexp} to @samp{^.*$} and set @var{key-regexp} to | |
| 1548 @samp{\<f\w*\>}. The resulting expression looks like this: | |
| 1549 | |
| 1550 @example | |
| 1551 @group | |
| 1552 (sort-regexp-fields nil "^.*$" "\\<f\\w*\\>" | |
| 1553 (region-beginning) | |
| 1554 (region-end)) | |
| 1555 @end group | |
| 1556 @end example | |
| 1557 | |
| 1558 If you call @code{sort-regexp-fields} interactively, it prompts for | |
| 1559 @var{record-regexp} and @var{key-regexp} in the minibuffer. | |
| 1560 @end deffn | |
| 1561 | |
| 1562 @deffn Command sort-lines reverse start end | |
| 1563 This command alphabetically sorts lines in the region between | |
| 1564 @var{start} and @var{end}. If @var{reverse} is non-@code{nil}, the sort | |
| 1565 is in reverse order. | |
| 1566 @end deffn | |
| 1567 | |
| 1568 @deffn Command sort-paragraphs reverse start end | |
| 1569 This command alphabetically sorts paragraphs in the region between | |
| 1570 @var{start} and @var{end}. If @var{reverse} is non-@code{nil}, the sort | |
| 1571 is in reverse order. | |
| 1572 @end deffn | |
| 1573 | |
| 1574 @deffn Command sort-pages reverse start end | |
| 1575 This command alphabetically sorts pages in the region between | |
| 1576 @var{start} and @var{end}. If @var{reverse} is non-@code{nil}, the sort | |
| 1577 is in reverse order. | |
| 1578 @end deffn | |
| 1579 | |
| 1580 @deffn Command sort-fields field start end | |
| 1581 This command sorts lines in the region between @var{start} and | |
| 1582 @var{end}, comparing them alphabetically by the @var{field}th field | |
| 1583 of each line. Fields are separated by whitespace and numbered starting | |
| 1584 from 1. If @var{field} is negative, sorting is by the | |
| 1585 @w{@minus{}@var{field}th} field from the end of the line. This command | |
| 1586 is useful for sorting tables. | |
| 1587 @end deffn | |
| 1588 | |
| 1589 @deffn Command sort-numeric-fields field start end | |
| 1590 This command sorts lines in the region between @var{start} and | |
| 1591 @var{end}, comparing them numerically by the @var{field}th field of each | |
| 1592 line. The specified field must contain a number in each line of the | |
| 1593 region. Fields are separated by whitespace and numbered starting from | |
| 1594 1. If @var{field} is negative, sorting is by the | |
| 1595 @w{@minus{}@var{field}th} field from the end of the line. This command | |
| 1596 is useful for sorting tables. | |
| 1597 @end deffn | |
| 1598 | |
| 444 | 1599 @deffn Command sort-columns reverse &optional start end |
| 1600 This command sorts the lines in the region between @var{start} and | |
| 428 | 1601 @var{end}, comparing them alphabetically by a certain range of columns. |
| 444 | 1602 The column positions of @var{start} and @var{end} bound the range of |
| 428 | 1603 columns to sort on. |
| 1604 | |
| 1605 If @var{reverse} is non-@code{nil}, the sort is in reverse order. | |
| 1606 | |
| 1607 One unusual thing about this command is that the entire line | |
| 444 | 1608 containing position @var{start}, and the entire line containing position |
| 428 | 1609 @var{end}, are included in the region sorted. |
| 1610 | |
| 1611 Note that @code{sort-columns} uses the @code{sort} utility program, | |
| 1612 and so cannot work properly on text containing tab characters. Use | |
| 1613 @kbd{M-x @code{untabify}} to convert tabs to spaces before sorting. | |
| 1614 @end deffn | |
| 1615 | |
| 1616 @node Columns | |
| 1617 @comment node-name, next, previous, up | |
| 1618 @section Counting Columns | |
| 1619 @cindex columns | |
| 1620 @cindex counting columns | |
| 1621 @cindex horizontal position | |
| 1622 | |
| 1623 The column functions convert between a character position (counting | |
| 1624 characters from the beginning of the buffer) and a column position | |
| 1625 (counting screen characters from the beginning of a line). | |
| 1626 | |
| 1627 A character counts according to the number of columns it occupies on | |
| 1628 the screen. This means control characters count as occupying 2 or 4 | |
| 1629 columns, depending upon the value of @code{ctl-arrow}, and tabs count as | |
| 1630 occupying a number of columns that depends on the value of | |
| 1631 @code{tab-width} and on the column where the tab begins. @xref{Usual Display}. | |
| 1632 | |
| 1633 Column number computations ignore the width of the window and the | |
| 1634 amount of horizontal scrolling. Consequently, a column value can be | |
| 1635 arbitrarily high. The first (or leftmost) column is numbered 0. | |
| 1636 | |
| 444 | 1637 @defun current-column &optional buffer |
| 428 | 1638 This function returns the horizontal position of point, measured in |
| 444 | 1639 columns, counting from 0 at the left margin. |
| 1640 | |
| 1641 This is calculated by adding together the widths of all the displayed | |
| 1642 representations of the character between the start of the previous line | |
| 1643 and point. (e.g. control characters will have a width of 2 or 4, tabs | |
| 1644 will have a variable width.) | |
| 1645 | |
| 1646 Ignores the finite width of frame displaying the buffer, which means | |
| 1647 that this function may return values greater than | |
| 1648 @code{(frame-width)}. | |
| 1649 | |
| 1650 Whether the line is visible (if @code{selective-display} is t) has no effect; | |
| 1651 however, ^M is treated as end of line when @code{selective-display} is t. | |
| 1652 | |
| 1653 If @var{buffer} is nil, the current buffer is assumed. | |
| 428 | 1654 |
| 1655 For an example of using @code{current-column}, see the description of | |
| 1656 @code{count-lines} in @ref{Text Lines}. | |
| 1657 @end defun | |
| 1658 | |
| 444 | 1659 @defun move-to-column column &optional force buffer |
| 428 | 1660 This function moves point to @var{column} in the current line. The |
| 1661 calculation of @var{column} takes into account the widths of the | |
| 1662 displayed representations of the characters between the start of the | |
| 1663 line and point. | |
| 1664 | |
| 1665 If column @var{column} is beyond the end of the line, point moves to the | |
| 1666 end of the line. If @var{column} is negative, point moves to the | |
| 1667 beginning of the line. | |
| 1668 | |
| 1669 If it is impossible to move to column @var{column} because that is in | |
| 1670 the middle of a multicolumn character such as a tab, point moves to the | |
| 1671 end of that character. However, if @var{force} is non-@code{nil}, and | |
| 1672 @var{column} is in the middle of a tab, then @code{move-to-column} | |
| 1673 converts the tab into spaces so that it can move precisely to column | |
| 1674 @var{column}. Other multicolumn characters can cause anomalies despite | |
| 1675 @var{force}, since there is no way to split them. | |
| 1676 | |
| 1677 The argument @var{force} also has an effect if the line isn't long | |
| 444 | 1678 enough to reach column @var{column}; in that case, unless the value of |
| 1679 @var{force} is the special value @code{coerce}, it says to add | |
| 428 | 1680 whitespace at the end of the line to reach that column. |
| 1681 | |
|
4885
6772ce4d982b
Fix hash tables, #'member*, #'assoc*, #'eql compiler macros if bignums
Aidan Kehoe <kehoea@parhasard.net>
parents:
2256
diff
changeset
|
1682 If @var{column} is not a non-negative fixnum, an error is signaled. |
| 428 | 1683 |
| 1684 The return value is the column number actually moved to. | |
| 1685 @end defun | |
| 1686 | |
| 1687 @node Indentation | |
| 1688 @section Indentation | |
| 1689 @cindex indentation | |
| 1690 | |
| 1691 The indentation functions are used to examine, move to, and change | |
| 1692 whitespace that is at the beginning of a line. Some of the functions | |
| 1693 can also change whitespace elsewhere on a line. Columns and indentation | |
| 1694 count from zero at the left margin. | |
| 1695 | |
| 1696 @menu | |
| 1697 * Primitive Indent:: Functions used to count and insert indentation. | |
| 1698 * Mode-Specific Indent:: Customize indentation for different modes. | |
| 1699 * Region Indent:: Indent all the lines in a region. | |
| 1700 * Relative Indent:: Indent the current line based on previous lines. | |
| 1701 * Indent Tabs:: Adjustable, typewriter-like tab stops. | |
| 1702 * Motion by Indent:: Move to first non-blank character. | |
| 1703 @end menu | |
| 1704 | |
| 1705 @node Primitive Indent | |
| 1706 @subsection Indentation Primitives | |
| 1707 | |
| 1708 This section describes the primitive functions used to count and | |
| 1709 insert indentation. The functions in the following sections use these | |
| 1710 primitives. | |
| 1711 | |
| 444 | 1712 @defun current-indentation &optional buffer |
| 428 | 1713 @comment !!Type Primitive Function |
| 1714 @comment !!SourceFile indent.c | |
| 1715 This function returns the indentation of the current line, which is | |
| 1716 the horizontal position of the first nonblank character. If the | |
| 1717 contents are entirely blank, then this is the horizontal position of the | |
| 1718 end of the line. | |
| 1719 @end defun | |
| 1720 | |
| 444 | 1721 @deffn Command indent-to column &optional minimum buffer |
| 428 | 1722 @comment !!Type Primitive Function |
| 1723 @comment !!SourceFile indent.c | |
| 1724 This function indents from point with tabs and spaces until @var{column} | |
| 1725 is reached. If @var{minimum} is specified and non-@code{nil}, then at | |
| 1726 least that many spaces are inserted even if this requires going beyond | |
| 1727 @var{column}. Otherwise the function does nothing if point is already | |
| 1728 beyond @var{column}. The value is the column at which the inserted | |
| 444 | 1729 indentation ends. If @var{buffer} is @code{nil}, the current buffer is assumed. |
| 428 | 1730 @end deffn |
| 1731 | |
| 1732 @defopt indent-tabs-mode | |
| 1733 @comment !!SourceFile indent.c | |
| 1734 If this variable is non-@code{nil}, indentation functions can insert | |
| 1735 tabs as well as spaces. Otherwise, they insert only spaces. Setting | |
| 1736 this variable automatically makes it local to the current buffer. | |
| 1737 @end defopt | |
| 1738 | |
| 1739 @node Mode-Specific Indent | |
| 1740 @subsection Indentation Controlled by Major Mode | |
| 1741 | |
| 1742 An important function of each major mode is to customize the @key{TAB} | |
| 1743 key to indent properly for the language being edited. This section | |
| 1744 describes the mechanism of the @key{TAB} key and how to control it. | |
| 1745 The functions in this section return unpredictable values. | |
| 1746 | |
| 1747 @defvar indent-line-function | |
| 1748 This variable's value is the function to be used by @key{TAB} (and | |
| 1749 various commands) to indent the current line. The command | |
| 1750 @code{indent-according-to-mode} does no more than call this function. | |
| 1751 | |
| 1752 In Lisp mode, the value is the symbol @code{lisp-indent-line}; in C | |
| 1753 mode, @code{c-indent-line}; in Fortran mode, @code{fortran-indent-line}. | |
| 1754 In Fundamental mode, Text mode, and many other modes with no standard | |
| 1755 for indentation, the value is @code{indent-to-left-margin} (which is the | |
| 1756 default value). | |
| 1757 @end defvar | |
| 1758 | |
| 1759 @deffn Command indent-according-to-mode | |
| 1760 This command calls the function in @code{indent-line-function} to | |
| 1761 indent the current line in a way appropriate for the current major mode. | |
| 1762 @end deffn | |
| 1763 | |
| 444 | 1764 @deffn Command indent-for-tab-command &optional prefix-arg |
| 428 | 1765 This command calls the function in @code{indent-line-function} to indent |
| 1766 the current line; except that if that function is | |
| 1767 @code{indent-to-left-margin}, it calls @code{insert-tab} instead. (That | |
| 1768 is a trivial command that inserts a tab character.) | |
| 1769 @end deffn | |
| 1770 | |
| 1771 @deffn Command newline-and-indent | |
| 1772 @comment !!SourceFile simple.el | |
| 1773 This function inserts a newline, then indents the new line (the one | |
| 1774 following the newline just inserted) according to the major mode. | |
| 1775 | |
| 1776 It does indentation by calling the current @code{indent-line-function}. | |
| 1777 In programming language modes, this is the same thing @key{TAB} does, | |
| 1778 but in some text modes, where @key{TAB} inserts a tab, | |
| 1779 @code{newline-and-indent} indents to the column specified by | |
| 1780 @code{left-margin}. | |
| 1781 @end deffn | |
| 1782 | |
| 1783 @deffn Command reindent-then-newline-and-indent | |
| 1784 @comment !!SourceFile simple.el | |
| 1785 This command reindents the current line, inserts a newline at point, | |
| 1786 and then reindents the new line (the one following the newline just | |
| 1787 inserted). | |
| 1788 | |
| 1789 This command does indentation on both lines according to the current | |
| 1790 major mode, by calling the current value of @code{indent-line-function}. | |
| 1791 In programming language modes, this is the same thing @key{TAB} does, | |
| 1792 but in some text modes, where @key{TAB} inserts a tab, | |
| 1793 @code{reindent-then-newline-and-indent} indents to the column specified | |
| 1794 by @code{left-margin}. | |
| 1795 @end deffn | |
| 1796 | |
| 1797 @node Region Indent | |
| 1798 @subsection Indenting an Entire Region | |
| 1799 | |
| 1800 This section describes commands that indent all the lines in the | |
| 1801 region. They return unpredictable values. | |
| 1802 | |
| 1803 @deffn Command indent-region start end to-column | |
| 1804 This command indents each nonblank line starting between @var{start} | |
| 1805 (inclusive) and @var{end} (exclusive). If @var{to-column} is | |
| 1806 @code{nil}, @code{indent-region} indents each nonblank line by calling | |
| 1807 the current mode's indentation function, the value of | |
| 1808 @code{indent-line-function}. | |
| 1809 | |
| 1810 If @var{to-column} is non-@code{nil}, it should be an integer | |
| 1811 specifying the number of columns of indentation; then this function | |
| 1812 gives each line exactly that much indentation, by either adding or | |
| 1813 deleting whitespace. | |
| 1814 | |
| 1815 If there is a fill prefix, @code{indent-region} indents each line | |
| 1816 by making it start with the fill prefix. | |
| 1817 @end deffn | |
| 1818 | |
| 1819 @defvar indent-region-function | |
| 1820 The value of this variable is a function that can be used by | |
| 1821 @code{indent-region} as a short cut. You should design the function so | |
| 1822 that it will produce the same results as indenting the lines of the | |
| 1823 region one by one, but presumably faster. | |
| 1824 | |
| 1825 If the value is @code{nil}, there is no short cut, and | |
| 1826 @code{indent-region} actually works line by line. | |
| 1827 | |
| 1828 A short-cut function is useful in modes such as C mode and Lisp mode, | |
| 1829 where the @code{indent-line-function} must scan from the beginning of | |
| 1830 the function definition: applying it to each line would be quadratic in | |
| 1831 time. The short cut can update the scan information as it moves through | |
| 1832 the lines indenting them; this takes linear time. In a mode where | |
| 1833 indenting a line individually is fast, there is no need for a short cut. | |
| 1834 | |
| 1835 @code{indent-region} with a non-@code{nil} argument @var{to-column} has | |
| 1836 a different meaning and does not use this variable. | |
| 1837 @end defvar | |
| 1838 | |
| 1839 @deffn Command indent-rigidly start end count | |
| 1840 @comment !!SourceFile indent.el | |
| 1841 This command indents all lines starting between @var{start} | |
| 1842 (inclusive) and @var{end} (exclusive) sideways by @var{count} columns. | |
| 1843 This ``preserves the shape'' of the affected region, moving it as a | |
| 1844 rigid unit. Consequently, this command is useful not only for indenting | |
| 1845 regions of unindented text, but also for indenting regions of formatted | |
| 1846 code. | |
| 1847 | |
| 1848 For example, if @var{count} is 3, this command adds 3 columns of | |
| 1849 indentation to each of the lines beginning in the region specified. | |
| 1850 | |
| 1851 In Mail mode, @kbd{C-c C-y} (@code{mail-yank-original}) uses | |
| 1852 @code{indent-rigidly} to indent the text copied from the message being | |
| 1853 replied to. | |
| 1854 @end deffn | |
| 1855 | |
| 444 | 1856 @deffn Command indent-code-rigidly start end columns &optional nochange-regexp |
| 428 | 1857 This is like @code{indent-rigidly}, except that it doesn't alter lines |
| 1858 that start within strings or comments. | |
| 1859 | |
| 1860 In addition, it doesn't alter a line if @var{nochange-regexp} matches at | |
| 1861 the beginning of the line (if @var{nochange-regexp} is non-@code{nil}). | |
| 444 | 1862 @end deffn |
| 428 | 1863 |
| 1864 @node Relative Indent | |
| 1865 @subsection Indentation Relative to Previous Lines | |
| 1866 | |
| 1867 This section describes two commands that indent the current line | |
| 1868 based on the contents of previous lines. | |
| 1869 | |
| 1870 @deffn Command indent-relative &optional unindented-ok | |
| 1871 This command inserts whitespace at point, extending to the same | |
| 1872 column as the next @dfn{indent point} of the previous nonblank line. An | |
| 1873 indent point is a non-whitespace character following whitespace. The | |
| 1874 next indent point is the first one at a column greater than the current | |
| 1875 column of point. For example, if point is underneath and to the left of | |
| 1876 the first non-blank character of a line of text, it moves to that column | |
| 1877 by inserting whitespace. | |
| 1878 | |
| 1879 If the previous nonblank line has no next indent point (i.e., none at a | |
| 1880 great enough column position), @code{indent-relative} either does | |
| 1881 nothing (if @var{unindented-ok} is non-@code{nil}) or calls | |
| 1882 @code{tab-to-tab-stop}. Thus, if point is underneath and to the right | |
| 1883 of the last column of a short line of text, this command ordinarily | |
| 1884 moves point to the next tab stop by inserting whitespace. | |
| 1885 | |
| 1886 The return value of @code{indent-relative} is unpredictable. | |
| 1887 | |
| 1888 In the following example, point is at the beginning of the second | |
| 1889 line: | |
| 1890 | |
| 1891 @example | |
| 1892 @group | |
| 1893 This line is indented twelve spaces. | |
| 1894 @point{}The quick brown fox jumped. | |
| 1895 @end group | |
| 1896 @end example | |
| 1897 | |
| 1898 @noindent | |
| 1899 Evaluation of the expression @code{(indent-relative nil)} produces the | |
| 1900 following: | |
| 1901 | |
| 1902 @example | |
| 1903 @group | |
| 1904 This line is indented twelve spaces. | |
| 1905 @point{}The quick brown fox jumped. | |
| 1906 @end group | |
| 1907 @end example | |
| 1908 | |
| 1909 In this example, point is between the @samp{m} and @samp{p} of | |
| 1910 @samp{jumped}: | |
| 1911 | |
| 1912 @example | |
| 1913 @group | |
| 1914 This line is indented twelve spaces. | |
| 1915 The quick brown fox jum@point{}ped. | |
| 1916 @end group | |
| 1917 @end example | |
| 1918 | |
| 1919 @noindent | |
| 1920 Evaluation of the expression @code{(indent-relative nil)} produces the | |
| 1921 following: | |
| 1922 | |
| 1923 @example | |
| 1924 @group | |
| 1925 This line is indented twelve spaces. | |
| 1926 The quick brown fox jum @point{}ped. | |
| 1927 @end group | |
| 1928 @end example | |
| 1929 @end deffn | |
| 1930 | |
| 1931 @deffn Command indent-relative-maybe | |
| 1932 @comment !!SourceFile indent.el | |
| 1933 This command indents the current line like the previous nonblank line. | |
| 1934 It calls @code{indent-relative} with @code{t} as the @var{unindented-ok} | |
| 1935 argument. The return value is unpredictable. | |
| 1936 | |
| 1937 If the previous nonblank line has no indent points beyond the current | |
| 1938 column, this command does nothing. | |
| 1939 @end deffn | |
| 1940 | |
| 1941 @node Indent Tabs | |
| 1942 @subsection Adjustable ``Tab Stops'' | |
| 1943 @cindex tabs stops for indentation | |
| 1944 | |
| 1945 This section explains the mechanism for user-specified ``tab stops'' | |
| 1946 and the mechanisms that use and set them. The name ``tab stops'' is | |
| 1947 used because the feature is similar to that of the tab stops on a | |
| 1948 typewriter. The feature works by inserting an appropriate number of | |
| 1949 spaces and tab characters to reach the next tab stop column; it does not | |
| 1950 affect the display of tab characters in the buffer (@pxref{Usual | |
| 1951 Display}). Note that the @key{TAB} character as input uses this tab | |
| 1952 stop feature only in a few major modes, such as Text mode. | |
| 1953 | |
| 1954 @deffn Command tab-to-tab-stop | |
| 1955 This command inserts spaces or tabs up to the next tab stop column | |
| 1956 defined by @code{tab-stop-list}. It searches the list for an element | |
| 1957 greater than the current column number, and uses that element as the | |
| 1958 column to indent to. It does nothing if no such element is found. | |
| 1959 @end deffn | |
| 1960 | |
| 1961 @defopt tab-stop-list | |
| 1962 This variable is the list of tab stop columns used by | |
| 1963 @code{tab-to-tab-stops}. The elements should be integers in increasing | |
| 1964 order. The tab stop columns need not be evenly spaced. | |
| 1965 | |
| 1966 Use @kbd{M-x edit-tab-stops} to edit the location of tab stops | |
| 1967 interactively. | |
| 1968 @end defopt | |
| 1969 | |
| 1970 @node Motion by Indent | |
| 1971 @subsection Indentation-Based Motion Commands | |
| 1972 | |
| 1973 These commands, primarily for interactive use, act based on the | |
| 1974 indentation in the text. | |
| 1975 | |
| 444 | 1976 @deffn Command back-to-indentation |
| 428 | 1977 @comment !!SourceFile simple.el |
| 1978 This command moves point to the first non-whitespace character in the | |
| 1979 current line (which is the line in which point is located). It returns | |
| 1980 @code{nil}. | |
| 1981 @end deffn | |
| 1982 | |
| 1983 @deffn Command backward-to-indentation arg | |
| 1984 @comment !!SourceFile simple.el | |
| 1985 This command moves point backward @var{arg} lines and then to the | |
| 1986 first nonblank character on that line. It returns @code{nil}. | |
| 1987 @end deffn | |
| 1988 | |
| 1989 @deffn Command forward-to-indentation arg | |
| 1990 @comment !!SourceFile simple.el | |
| 1991 This command moves point forward @var{arg} lines and then to the first | |
| 1992 nonblank character on that line. It returns @code{nil}. | |
| 1993 @end deffn | |
| 1994 | |
| 1995 @node Case Changes | |
| 1996 @section Case Changes | |
| 1997 @cindex case changes | |
| 1998 | |
| 1999 The case change commands described here work on text in the current | |
| 2000 buffer. @xref{Character Case}, for case conversion commands that work | |
| 2001 on strings and characters. @xref{Case Tables}, for how to customize | |
| 2002 which characters are upper or lower case and how to convert them. | |
| 2003 | |
| 444 | 2004 @deffn Command capitalize-region start end &optional buffer |
| 428 | 2005 This function capitalizes all words in the region defined by |
| 2006 @var{start} and @var{end}. To capitalize means to convert each word's | |
| 2007 first character to upper case and convert the rest of each word to lower | |
| 2008 case. The function returns @code{nil}. | |
| 2009 | |
| 2010 If one end of the region is in the middle of a word, the part of the | |
| 2011 word within the region is treated as an entire word. | |
| 2012 | |
| 2013 When @code{capitalize-region} is called interactively, @var{start} and | |
| 2014 @var{end} are point and the mark, with the smallest first. | |
| 2015 | |
| 2016 @example | |
| 2017 @group | |
| 2018 ---------- Buffer: foo ---------- | |
| 2019 This is the contents of the 5th foo. | |
| 2020 ---------- Buffer: foo ---------- | |
| 2021 @end group | |
| 2022 | |
| 2023 @group | |
| 2024 (capitalize-region 1 44) | |
| 2025 @result{} nil | |
| 2026 | |
| 2027 ---------- Buffer: foo ---------- | |
| 2028 This Is The Contents Of The 5th Foo. | |
| 2029 ---------- Buffer: foo ---------- | |
| 2030 @end group | |
| 2031 @end example | |
| 2032 @end deffn | |
| 2033 | |
| 444 | 2034 @deffn Command downcase-region start end &optional buffer |
| 428 | 2035 This function converts all of the letters in the region defined by |
| 2036 @var{start} and @var{end} to lower case. The function returns | |
| 2037 @code{nil}. | |
| 2038 | |
| 2039 When @code{downcase-region} is called interactively, @var{start} and | |
| 2040 @var{end} are point and the mark, with the smallest first. | |
| 2041 @end deffn | |
| 2042 | |
| 444 | 2043 @deffn Command upcase-region start end &optional buffer |
| 428 | 2044 This function converts all of the letters in the region defined by |
| 2045 @var{start} and @var{end} to upper case. The function returns | |
| 2046 @code{nil}. | |
| 2047 | |
| 2048 When @code{upcase-region} is called interactively, @var{start} and | |
| 2049 @var{end} are point and the mark, with the smallest first. | |
| 2050 @end deffn | |
| 2051 | |
| 444 | 2052 @deffn Command capitalize-word count &optional buffer |
| 428 | 2053 This function capitalizes @var{count} words after point, moving point |
| 2054 over as it does. To capitalize means to convert each word's first | |
| 2055 character to upper case and convert the rest of each word to lower case. | |
| 2056 If @var{count} is negative, the function capitalizes the | |
| 2057 @minus{}@var{count} previous words but does not move point. The value | |
| 2058 is @code{nil}. | |
| 2059 | |
| 2060 If point is in the middle of a word, the part of the word before point | |
| 2061 is ignored when moving forward. The rest is treated as an entire word. | |
| 2062 | |
| 2063 When @code{capitalize-word} is called interactively, @var{count} is | |
| 2064 set to the numeric prefix argument. | |
| 2065 @end deffn | |
| 2066 | |
| 444 | 2067 @deffn Command downcase-word count &optional buffer |
| 428 | 2068 This function converts the @var{count} words after point to all lower |
| 2069 case, moving point over as it does. If @var{count} is negative, it | |
| 2070 converts the @minus{}@var{count} previous words but does not move point. | |
| 2071 The value is @code{nil}. | |
| 2072 | |
| 2073 When @code{downcase-word} is called interactively, @var{count} is set | |
| 2074 to the numeric prefix argument. | |
| 2075 @end deffn | |
| 2076 | |
| 444 | 2077 @deffn Command upcase-word count &optional buffer |
| 428 | 2078 This function converts the @var{count} words after point to all upper |
| 2079 case, moving point over as it does. If @var{count} is negative, it | |
| 2080 converts the @minus{}@var{count} previous words but does not move point. | |
| 2081 The value is @code{nil}. | |
| 2082 | |
| 2083 When @code{upcase-word} is called interactively, @var{count} is set to | |
| 2084 the numeric prefix argument. | |
| 2085 @end deffn | |
| 2086 | |
| 2087 @node Text Properties | |
| 2088 @section Text Properties | |
| 2089 @cindex text properties | |
| 2090 @cindex attributes of text | |
| 2091 @cindex properties of text | |
| 2092 | |
| 2093 Text properties are an alternative interface to extents | |
| 2094 (@pxref{Extents}), and are built on top of them. They are useful when | |
| 2095 you want to view textual properties as being attached to the characters | |
| 2096 themselves rather than to intervals of characters. The text property | |
| 2097 interface is compatible with FSF Emacs. | |
| 2098 | |
| 2099 Each character position in a buffer or a string can have a @dfn{text | |
| 2100 property list}, much like the property list of a symbol (@pxref{Property | |
| 2101 Lists}). The properties belong to a particular character at a | |
| 2102 particular place, such as, the letter @samp{T} at the beginning of this | |
| 2103 sentence or the first @samp{o} in @samp{foo}---if the same character | |
| 2104 occurs in two different places, the two occurrences generally have | |
| 2105 different properties. | |
| 2106 | |
| 2107 Each property has a name and a value. Both of these can be any Lisp | |
| 2108 object, but the name is normally a symbol. The usual way to access the | |
| 2109 property list is to specify a name and ask what value corresponds to it. | |
| 2110 | |
| 2111 @ignore | |
| 2112 If a character has a @code{category} property, we call it the | |
| 2113 @dfn{category} of the character. It should be a symbol. The properties | |
| 2114 of the symbol serve as defaults for the properties of the character. | |
| 2115 @end ignore | |
| 2116 Note that FSF Emacs also looks at the @code{category} property to find | |
| 2117 defaults for text properties. We consider this too bogus to implement. | |
| 2118 | |
| 2119 Copying text between strings and buffers preserves the properties | |
| 2120 along with the characters; this includes such diverse functions as | |
|
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Aidan Kehoe <kehoea@parhasard.net>
parents:
4885
diff
changeset
|
2121 @code{subseq}, @code{insert}, and @code{buffer-substring}. |
| 428 | 2122 |
| 2123 @menu | |
| 2124 * Examining Properties:: Looking at the properties of one character. | |
| 2125 * Changing Properties:: Setting the properties of a range of text. | |
| 2126 * Property Search:: Searching for where a property changes value. | |
| 2127 * Special Properties:: Particular properties with special meanings. | |
| 2128 * Saving Properties:: Saving text properties in files, and reading | |
| 2129 them back. | |
| 2256 | 2130 * Fields:: Emacs-compatible text fields. |
| 428 | 2131 @end menu |
| 2132 | |
| 2133 @node Examining Properties | |
| 2134 @subsection Examining Text Properties | |
| 2135 | |
| 2136 The simplest way to examine text properties is to ask for the value of | |
| 2137 a particular property of a particular character. For that, use | |
| 2138 @code{get-text-property}. Use @code{text-properties-at} to get the | |
| 2139 entire property list of a character. @xref{Property Search}, for | |
| 2140 functions to examine the properties of a number of characters at once. | |
| 2141 | |
| 2142 These functions handle both strings and buffers. (Keep in mind that | |
| 2143 positions in a string start from 0, whereas positions in a buffer start | |
| 2144 from 1.) | |
| 2145 | |
| 444 | 2146 @defun get-text-property pos prop &optional object at-flag |
| 428 | 2147 This function returns the value of the @var{prop} property of the |
| 2148 character after position @var{pos} in @var{object} (a buffer or string). | |
| 2149 The argument @var{object} is optional and defaults to the current | |
| 2150 buffer. | |
| 2151 @ignore @c Bogus as hell! | |
| 2152 If there is no @var{prop} property strictly speaking, but the character | |
| 2153 has a category that is a symbol, then @code{get-text-property} returns | |
| 2154 the @var{prop} property of that symbol. | |
| 2155 @end ignore | |
| 2156 @end defun | |
| 2157 | |
| 444 | 2158 @defun get-char-property pos prop &optional object at-flag |
| 428 | 2159 This function is like @code{get-text-property}, except that it checks |
| 2160 all extents, not just text-property extents. | |
| 2161 | |
| 2162 @ignore Does not apply in XEmacs | |
| 2163 The argument @var{object} may be a string, a buffer, or a window. If it | |
| 2164 is a window, then the buffer displayed in that window is used for text | |
| 2165 properties and overlays, but only the overlays active for that window | |
| 2166 are considered. If @var{object} is a buffer, then all overlays in that | |
| 2167 buffer are considered, as well as text properties. If @var{object} is a | |
| 2168 string, only text properties are considered, since strings never have | |
| 2169 overlays. | |
| 2170 @end ignore | |
| 2171 @end defun | |
| 2172 | |
| 2173 @defun text-properties-at position &optional object | |
| 2174 This function returns the entire property list of the character at | |
| 2175 @var{position} in the string or buffer @var{object}. If @var{object} is | |
| 2176 @code{nil}, it defaults to the current buffer. | |
| 2177 @end defun | |
| 2178 | |
| 2179 @defvar default-text-properties | |
| 2180 This variable holds a property list giving default values for text | |
| 2181 properties. Whenever a character does not specify a value for a | |
| 2182 property, the value stored in this list is used instead. Here is | |
| 2183 an example: | |
| 2184 | |
| 2185 @example | |
| 2186 (setq default-text-properties '(foo 69)) | |
| 2187 ;; @r{Make sure character 1 has no properties of its own.} | |
| 2188 (set-text-properties 1 2 nil) | |
| 2189 ;; @r{What we get, when we ask, is the default value.} | |
| 2190 (get-text-property 1 'foo) | |
| 2191 @result{} 69 | |
| 2192 @end example | |
| 2193 @end defvar | |
| 2194 | |
| 2195 @node Changing Properties | |
| 2196 @subsection Changing Text Properties | |
| 2197 | |
| 2198 The primitives for changing properties apply to a specified range of | |
| 2199 text. The function @code{set-text-properties} (see end of section) sets | |
| 2200 the entire property list of the text in that range; more often, it is | |
| 2201 useful to add, change, or delete just certain properties specified by | |
| 2202 name. | |
| 2203 | |
| 2204 Since text properties are considered part of the buffer's contents, and | |
| 2205 can affect how the buffer looks on the screen, any change in the text | |
| 2206 properties is considered a buffer modification. Buffer text property | |
| 2207 changes are undoable (@pxref{Undo}). | |
| 2208 | |
| 2209 @defun put-text-property start end prop value &optional object | |
| 2210 This function sets the @var{prop} property to @var{value} for the text | |
| 2211 between @var{start} and @var{end} in the string or buffer @var{object}. | |
| 2212 If @var{object} is @code{nil}, it defaults to the current buffer. | |
| 2213 @end defun | |
| 2214 | |
| 2215 @defun add-text-properties start end props &optional object | |
| 2216 This function modifies the text properties for the text between | |
| 2217 @var{start} and @var{end} in the string or buffer @var{object}. If | |
| 2218 @var{object} is @code{nil}, it defaults to the current buffer. | |
| 2219 | |
| 2220 The argument @var{props} specifies which properties to change. It | |
| 2221 should have the form of a property list (@pxref{Property Lists}): a list | |
| 2222 whose elements include the property names followed alternately by the | |
| 2223 corresponding values. | |
| 2224 | |
| 2225 The return value is @code{t} if the function actually changed some | |
| 2226 property's value; @code{nil} otherwise (if @var{props} is @code{nil} or | |
| 2227 its values agree with those in the text). | |
| 2228 | |
| 2229 For example, here is how to set the @code{comment} and @code{face} | |
| 2230 properties of a range of text: | |
| 2231 | |
| 2232 @example | |
| 2233 (add-text-properties @var{start} @var{end} | |
| 2234 '(comment t face highlight)) | |
| 2235 @end example | |
| 2236 @end defun | |
| 2237 | |
| 2238 @defun remove-text-properties start end props &optional object | |
| 2239 This function deletes specified text properties from the text between | |
| 2240 @var{start} and @var{end} in the string or buffer @var{object}. If | |
| 2241 @var{object} is @code{nil}, it defaults to the current buffer. | |
| 2242 | |
| 2243 The argument @var{props} specifies which properties to delete. It | |
| 2244 should have the form of a property list (@pxref{Property Lists}): a list | |
| 2245 whose elements are property names alternating with corresponding values. | |
| 2246 But only the names matter---the values that accompany them are ignored. | |
| 2247 For example, here's how to remove the @code{face} property. | |
| 2248 | |
| 2249 @example | |
| 2250 (remove-text-properties @var{start} @var{end} '(face nil)) | |
| 2251 @end example | |
| 2252 | |
| 2253 The return value is @code{t} if the function actually changed some | |
| 2254 property's value; @code{nil} otherwise (if @var{props} is @code{nil} or | |
| 2255 if no character in the specified text had any of those properties). | |
| 2256 @end defun | |
| 2257 | |
| 2258 @defun set-text-properties start end props &optional object | |
| 2259 This function completely replaces the text property list for the text | |
| 2260 between @var{start} and @var{end} in the string or buffer @var{object}. | |
| 2261 If @var{object} is @code{nil}, it defaults to the current buffer. | |
| 2262 | |
| 2263 The argument @var{props} is the new property list. It should be a list | |
| 2264 whose elements are property names alternating with corresponding values. | |
| 2265 | |
| 2266 After @code{set-text-properties} returns, all the characters in the | |
| 2267 specified range have identical properties. | |
| 2268 | |
| 2269 If @var{props} is @code{nil}, the effect is to get rid of all properties | |
| 2270 from the specified range of text. Here's an example: | |
| 2271 | |
| 2272 @example | |
| 2273 (set-text-properties @var{start} @var{end} nil) | |
| 2274 @end example | |
| 2275 @end defun | |
| 2276 | |
| 2277 See also the function @code{buffer-substring-without-properties} | |
| 2278 (@pxref{Buffer Contents}) which copies text from the buffer | |
| 2279 but does not copy its properties. | |
| 2280 | |
| 2281 @node Property Search | |
| 2282 @subsection Property Search Functions | |
| 2283 | |
| 2284 In typical use of text properties, most of the time several or many | |
| 2285 consecutive characters have the same value for a property. Rather than | |
| 2286 writing your programs to examine characters one by one, it is much | |
| 2287 faster to process chunks of text that have the same property value. | |
| 2288 | |
| 2289 Here are functions you can use to do this. They use @code{eq} for | |
| 2290 comparing property values. In all cases, @var{object} defaults to the | |
| 2291 current buffer. | |
| 2292 | |
| 2293 For high performance, it's very important to use the @var{limit} | |
| 2294 argument to these functions, especially the ones that search for a | |
| 2295 single property---otherwise, they may spend a long time scanning to the | |
| 2296 end of the buffer, if the property you are interested in does not change. | |
| 2297 | |
| 2298 Remember that a position is always between two characters; the position | |
| 2299 returned by these functions is between two characters with different | |
| 2300 properties. | |
| 2301 | |
| 2302 @defun next-property-change pos &optional object limit | |
| 2303 The function scans the text forward from position @var{pos} in the | |
| 2304 string or buffer @var{object} till it finds a change in some text | |
| 2305 property, then returns the position of the change. In other words, it | |
| 2306 returns the position of the first character beyond @var{pos} whose | |
| 2307 properties are not identical to those of the character just after | |
| 2308 @var{pos}. | |
| 2309 | |
| 2310 If @var{limit} is non-@code{nil}, then the scan ends at position | |
| 444 | 2311 @var{limit}. If there is no property change before that point, |
| 428 | 2312 @code{next-property-change} returns @var{limit}. |
| 2313 | |
| 2314 The value is @code{nil} if the properties remain unchanged all the way | |
| 2315 to the end of @var{object} and @var{limit} is @code{nil}. If the value | |
| 2316 is non-@code{nil}, it is a position greater than or equal to @var{pos}. | |
| 2317 The value equals @var{pos} only when @var{limit} equals @var{pos}. | |
| 2318 | |
| 2319 Here is an example of how to scan the buffer by chunks of text within | |
| 2320 which all properties are constant: | |
| 2321 | |
| 2322 @smallexample | |
| 2323 (while (not (eobp)) | |
| 2324 (let ((plist (text-properties-at (point))) | |
| 2325 (next-change | |
| 2326 (or (next-property-change (point) (current-buffer)) | |
| 2327 (point-max)))) | |
| 2328 @r{Process text from point to @var{next-change}@dots{}} | |
| 2329 (goto-char next-change))) | |
| 2330 @end smallexample | |
| 2331 @end defun | |
| 2332 | |
| 2333 @defun next-single-property-change pos prop &optional object limit | |
| 2334 The function scans the text forward from position @var{pos} in the | |
| 2335 string or buffer @var{object} till it finds a change in the @var{prop} | |
| 2336 property, then returns the position of the change. In other words, it | |
| 2337 returns the position of the first character beyond @var{pos} whose | |
| 2338 @var{prop} property differs from that of the character just after | |
| 2339 @var{pos}. | |
| 2340 | |
| 2341 If @var{limit} is non-@code{nil}, then the scan ends at position | |
| 444 | 2342 @var{limit}. If there is no property change before that point, |
| 428 | 2343 @code{next-single-property-change} returns @var{limit}. |
| 2344 | |
| 2345 The value is @code{nil} if the property remains unchanged all the way to | |
| 2346 the end of @var{object} and @var{limit} is @code{nil}. If the value is | |
| 2347 non-@code{nil}, it is a position greater than or equal to @var{pos}; it | |
| 2348 equals @var{pos} only if @var{limit} equals @var{pos}. | |
| 2349 @end defun | |
| 2350 | |
| 2351 @defun previous-property-change pos &optional object limit | |
| 444 | 2352 This is like @code{next-property-change}, but scans backward from @var{pos} |
| 428 | 2353 instead of forward. If the value is non-@code{nil}, it is a position |
| 2354 less than or equal to @var{pos}; it equals @var{pos} only if @var{limit} | |
| 2355 equals @var{pos}. | |
| 2356 @end defun | |
| 2357 | |
| 2358 @defun previous-single-property-change pos prop &optional object limit | |
| 444 | 2359 This is like @code{next-single-property-change}, but scans backward from |
| 428 | 2360 @var{pos} instead of forward. If the value is non-@code{nil}, it is a |
| 2361 position less than or equal to @var{pos}; it equals @var{pos} only if | |
| 2362 @var{limit} equals @var{pos}. | |
| 2363 @end defun | |
| 2364 | |
| 2365 @defun text-property-any start end prop value &optional object | |
| 2366 This function returns non-@code{nil} if at least one character between | |
| 2367 @var{start} and @var{end} has a property @var{prop} whose value is | |
| 2368 @var{value}. More precisely, it returns the position of the first such | |
| 2369 character. Otherwise, it returns @code{nil}. | |
| 2370 | |
| 2371 The optional fifth argument, @var{object}, specifies the string or | |
| 2372 buffer to scan. Positions are relative to @var{object}. The default | |
| 2373 for @var{object} is the current buffer. | |
| 2374 @end defun | |
| 2375 | |
| 2376 @defun text-property-not-all start end prop value &optional object | |
| 2377 This function returns non-@code{nil} if at least one character between | |
| 2378 @var{start} and @var{end} has a property @var{prop} whose value differs | |
| 2379 from @var{value}. More precisely, it returns the position of the | |
| 2380 first such character. Otherwise, it returns @code{nil}. | |
| 2381 | |
| 2382 The optional fifth argument, @var{object}, specifies the string or | |
| 2383 buffer to scan. Positions are relative to @var{object}. The default | |
| 2384 for @var{object} is the current buffer. | |
| 2385 @end defun | |
| 2386 | |
| 2387 @node Special Properties | |
| 2388 @subsection Properties with Special Meanings | |
| 2389 | |
| 2390 The predefined properties are the same as those for extents. | |
| 2391 @xref{Extent Properties}. | |
| 2392 | |
| 2393 @ignore Changed in XEmacs | |
| 2394 (deleted section describing FSF Emacs special text properties) | |
| 2395 @end ignore | |
| 2396 | |
| 2397 @node Saving Properties | |
| 2398 @subsection Saving Text Properties in Files | |
| 2399 @cindex text properties in files | |
| 2400 @cindex saving text properties | |
| 2401 | |
| 2402 You can save text properties in files, and restore text properties | |
| 444 | 2403 when inserting the files, using these two hooks: |
| 428 | 2404 |
| 2405 @defvar write-region-annotate-functions | |
| 2406 This variable's value is a list of functions for @code{write-region} to | |
| 2407 run to encode text properties in some fashion as annotations to the text | |
| 2408 being written in the file. @xref{Writing to Files}. | |
| 2409 | |
| 2410 Each function in the list is called with two arguments: the start and | |
| 2411 end of the region to be written. These functions should not alter the | |
| 2412 contents of the buffer. Instead, they should return lists indicating | |
| 2413 annotations to write in the file in addition to the text in the | |
| 2414 buffer. | |
| 2415 | |
| 2416 Each function should return a list of elements of the form | |
| 2417 @code{(@var{position} . @var{string})}, where @var{position} is an | |
| 2418 integer specifying the relative position in the text to be written, and | |
| 2419 @var{string} is the annotation to add there. | |
| 2420 | |
| 2421 Each list returned by one of these functions must be already sorted in | |
| 2422 increasing order by @var{position}. If there is more than one function, | |
| 2423 @code{write-region} merges the lists destructively into one sorted list. | |
| 2424 | |
| 2425 When @code{write-region} actually writes the text from the buffer to the | |
| 2426 file, it intermixes the specified annotations at the corresponding | |
| 2427 positions. All this takes place without modifying the buffer. | |
| 2428 @end defvar | |
| 2429 | |
| 2430 @defvar after-insert-file-functions | |
| 2431 This variable holds a list of functions for @code{insert-file-contents} | |
| 2432 to call after inserting a file's contents. These functions should scan | |
| 2433 the inserted text for annotations, and convert them to the text | |
| 2434 properties they stand for. | |
| 2435 | |
| 2436 Each function receives one argument, the length of the inserted text; | |
| 2437 point indicates the start of that text. The function should scan that | |
| 2438 text for annotations, delete them, and create the text properties that | |
| 2439 the annotations specify. The function should return the updated length | |
| 2440 of the inserted text, as it stands after those changes. The value | |
| 2441 returned by one function becomes the argument to the next function. | |
| 2442 | |
| 2443 These functions should always return with point at the beginning of | |
| 2444 the inserted text. | |
| 2445 | |
| 2446 The intended use of @code{after-insert-file-functions} is for converting | |
| 2447 some sort of textual annotations into actual text properties. But other | |
| 2448 uses may be possible. | |
| 2449 @end defvar | |
| 2450 | |
| 2451 We invite users to write Lisp programs to store and retrieve text | |
| 2452 properties in files, using these hooks, and thus to experiment with | |
| 444 | 2453 various data formats and find good ones. Eventually we hope users |
| 428 | 2454 will produce good, general extensions we can install in Emacs. |
| 2455 | |
| 2456 We suggest not trying to handle arbitrary Lisp objects as property | |
| 2457 names or property values---because a program that general is probably | |
| 2458 difficult to write, and slow. Instead, choose a set of possible data | |
| 2459 types that are reasonably flexible, and not too hard to encode. | |
| 2460 | |
| 2461 @xref{Format Conversion}, for a related feature. | |
| 2462 | |
| 2256 | 2463 @node Fields |
| 2464 @subsection Fields | |
| 2465 @cindex text fields | |
| 2466 @cindex fields | |
| 2467 | |
| 2468 Emacs supplies a notion of a @emph{text field}, which is a region of | |
| 2469 text where every character has the same value of the @code{field} | |
| 2470 property. It is used to identify regions of a buffer used for | |
| 2471 communicating with an external process, for example. XEmacs supplies a | |
| 2472 compatible interface. In XEmacs, the @code{field} property can be set | |
| 2473 as either an extent property or a text property, mirroring the Emacs | |
| 2474 capability of using either overlays or text properties. | |
| 2475 | |
| 2476 The field manipulating functions take a buffer position as the | |
| 2477 field-identifying argument, defaulting to point. This really means the | |
| 2478 field containing that buffer position. Consecutive buffer positions | |
| 2479 with no @code{field} property are considered an ``empty'' field. There | |
| 2480 is some ambiguity when a specified buffer position falls at the very | |
| 2481 beginning or the very end of a field: does it belong to the preceding or | |
| 2482 the following field? The answer depends on the openness or closedness | |
| 2483 of the corresponding extents (@pxref{Extent Endpoints}). A buffer | |
| 2484 position corresponds to the field whose property would be inherited by a | |
| 2485 character inserted at that position. If the buffer position is between | |
| 2486 an end-open and a start-open extent, then it corresponds to an empty | |
| 2487 field at that position, since an inserted character will belong to | |
| 2488 neither extent. | |
| 2489 | |
| 2490 @defvar inhibit-field-text-motion | |
| 2491 This variable controls whether the text motion commands notice fields or | |
| 2492 not. When it is nil (the default), commands such as beginning-of-line | |
| 2493 will try to move only within fields. | |
| 2494 @end defvar | |
| 2495 | |
| 2496 @defun make-field value from to &optional buffer | |
| 2497 There is no Emacs counterpart to this function. The default open and | |
| 2498 closedness of extents in XEmacs is opposite to the default for Emacs | |
| 2499 overlays. Hence, fields based on extents in XEmacs behave differently | |
| 2500 from the equivalent fields based on overlays in Emacs. This function | |
| 2501 creates a field with value @var{value} over the region @var{from} to | |
| 2502 @var{to} in @var{buffer}, which defaults to the current buffer, with the | |
| 2503 default Emacs open and closedness. | |
| 2504 @end defun | |
| 2505 | |
| 2506 @defun find-field &optional pos merge-at-boundary beg-limit end-limit | |
| 2507 There is no (Lisp-visible) Emacs counterpart to this function. It is | |
| 2508 the workhorse for the other functions. It returns a dotted pair | |
| 2509 @code{(start . stop)} holding the endpoints of the field matching a | |
| 2510 specification. If @var{pos} is non-@code{nil}, it specifies a buffer | |
| 2511 position whose enclosing field should be found; otherwise, the value of | |
| 2512 point is used. | |
| 2513 | |
| 2514 If @var{merge-at-boundary} is non-@code{nil}, then two changes are made | |
| 2515 to the search algorithm. First, if @var{pos} is at the very first | |
| 2516 position of a field, then the beginning of the previous field is | |
| 2517 returned instead of the beginning of @var{pos}'s field. Second, if the | |
| 2518 value of the @code{field} property at @var{pos} is the symbol | |
| 2519 @code{boundary}, then the beginning of the field before the boundary | |
| 2520 field and the end of the field after the boundary field are returned. | |
| 2521 | |
| 2522 If @var{beg-limit} is a buffer position, and the start position that | |
| 2523 would be returned is less than @var{beg-limit}, then @var{beg-limit} is | |
| 2524 returned instead. Likewise, if @var{end-limit} is a buffer position, | |
| 2525 and the stop position that would be returned is greater than | |
| 2526 @var{end-limit}, then @var{end-limit} is returned instead. | |
| 2527 @end defun | |
| 2528 | |
| 2529 @defun delete-field &optional pos | |
| 2530 Delete the text of the field at @var{pos}. | |
| 2531 @end defun | |
| 2532 | |
| 2533 @defun field-string &optional pos | |
| 2534 Return the contents of the field at @var{pos} as a string. | |
| 2535 @end defun | |
| 2536 | |
| 2537 @defun field-string-no-properties &optional pos | |
| 2538 Return the contents of the field at @var{pos} as a string, without text | |
| 2539 properties. | |
| 2540 @end defun | |
| 2541 | |
| 2542 @defun field-beginning &optional pos escape-from-edge limit | |
| 2543 Return the beginning of the field at @var{pos}. If | |
| 2544 @var{escape-from-edge} is non-nil and @var{pos} is at the beginning of a | |
| 2545 field, then the beginning of the field that ends at @var{pos} is | |
| 2546 returned instead. If @var{limit} is a buffer position and the returned | |
| 2547 value would be less than @var{limit}, then @var{limit} is returned | |
| 2548 instead. | |
| 2549 @end defun | |
| 2550 | |
| 2551 @defun field-end &optional pos escape-from-edge limit | |
| 2552 Return the end of the field at @var{pos}. If @var{escape-from-edge} is | |
| 2553 non-nil and @var{pos} is at the end of a field, then the end of the | |
| 2554 field that begins at @var{pos} is returned instead. If @var{limit} is a | |
| 2555 buffer position and the returned value would be greater than | |
| 2556 @var{limit}, then @var{limit} is returned instead. | |
| 2557 @end defun | |
| 2558 | |
| 2559 @defun constrain-to-field new-pos old-pos &optional escape-from-edge only-in-line inhibit-capture-property | |
| 2560 Return the position closest to @var{new-pos} that is in the same field | |
| 2561 as @var{old-pos}. If @var{new-pos} is @code{nil}, then the value of | |
| 2562 point is used instead @emph{and} point is set to the value that is | |
| 2563 returned. | |
| 2564 | |
| 2565 If @var{escape-from-edge} is non-@code{nil} and @var{old-pos} is at the | |
| 2566 boundary of two fields, then the two adjacent fields are considered one | |
| 2567 field. Furthermore, if @var{new-pos} is in a field whose @code{field} | |
| 2568 property is the symbol @code{boundary}, then the preceding field, the | |
| 2569 boundary field, and the following field are considered one field. | |
| 2570 | |
| 2571 If @var{only-in-line} is non-@code{nil} and the returned position would | |
| 2572 be on a different line than @var{new-pos}, return @var{new-pos} instead. | |
| 2573 | |
| 2574 If @var{inhibit-capture-property} is non-@code{nil} and the character at | |
| 2575 @var{old-pos} has a property of the same name as the value of | |
| 2576 @var{inhibit-capture-property}, then all field boundaries are ignored; | |
| 2577 i.e., @var{new-pos} is returned. | |
| 2578 | |
| 2579 If @var{inhibit-field-text-motion} is non-@code{nil}, then all field | |
| 2580 boundaries are ignored and this function always returns @var{new-pos}. | |
| 2581 @end defun | |
| 2582 | |
| 428 | 2583 @node Substitution |
| 2584 @section Substituting for a Character Code | |
| 2585 | |
| 2586 The following functions replace characters within a specified region | |
| 2587 based on their character codes. | |
| 2588 | |
| 2589 @defun subst-char-in-region start end old-char new-char &optional noundo | |
| 2590 @cindex replace characters | |
| 2591 This function replaces all occurrences of the character @var{old-char} | |
| 2592 with the character @var{new-char} in the region of the current buffer | |
| 2593 defined by @var{start} and @var{end}. | |
| 2594 | |
| 2595 @cindex Outline mode | |
| 2596 @cindex undo avoidance | |
| 2597 If @var{noundo} is non-@code{nil}, then @code{subst-char-in-region} does | |
| 2598 not record the change for undo and does not mark the buffer as modified. | |
| 2599 This feature is used for controlling selective display (@pxref{Selective | |
| 2600 Display}). | |
| 2601 | |
| 2602 @code{subst-char-in-region} does not move point and returns | |
| 2603 @code{nil}. | |
| 2604 | |
| 2605 @example | |
| 2606 @group | |
| 2607 ---------- Buffer: foo ---------- | |
| 2608 This is the contents of the buffer before. | |
| 2609 ---------- Buffer: foo ---------- | |
| 2610 @end group | |
| 2611 | |
| 2612 @group | |
| 2613 (subst-char-in-region 1 20 ?i ?X) | |
| 2614 @result{} nil | |
| 2615 | |
| 2616 ---------- Buffer: foo ---------- | |
| 2617 ThXs Xs the contents of the buffer before. | |
| 2618 ---------- Buffer: foo ---------- | |
| 2619 @end group | |
| 2620 @end example | |
| 2621 @end defun | |
| 2622 | |
| 2623 @defun translate-region start end table | |
| 2624 This function applies a translation table to the characters in the | |
| 2625 buffer between positions @var{start} and @var{end}. The translation | |
| 2626 table @var{table} can be either a string, a vector, or a char-table. | |
| 2627 | |
| 444 | 2628 If @var{table} is a string, its @var{n}th element is the mapping for the |
| 428 | 2629 character with code @var{n}. |
| 2630 | |
| 2631 If @var{table} is a vector, its @var{n}th element is the mapping for | |
| 2632 character with code @var{n}. Legal mappings are characters, strings, or | |
| 2633 @code{nil} (meaning don't replace.) | |
| 2634 | |
| 2635 If @var{table} is a char-table, its elements describe the mapping | |
| 2636 between characters and their replacements. The char-table should be of | |
| 2637 type @code{char} or @code{generic}. | |
| 2638 | |
| 2639 When the @var{table} is a string or vector and its length is less than | |
| 2640 the total number of characters (256 without Mule), any characters with | |
| 2641 codes larger than the length of @var{table} are not altered by the | |
| 2642 translation. | |
| 2643 | |
| 2644 The return value of @code{translate-region} is the number of | |
| 2645 characters that were actually changed by the translation. This does | |
| 2646 not count characters that were mapped into themselves in the | |
| 2647 translation table. | |
| 2648 | |
| 2649 @strong{NOTE}: Prior to XEmacs 21.2, the @var{table} argument was | |
| 2650 allowed only to be a string. This is still the case in FSF Emacs. | |
| 2651 | |
| 2652 The following example creates a char-table that is passed to | |
| 2653 @code{translate-region}, which translates character @samp{a} to | |
| 2654 @samp{the letter a}, removes character @samp{b}, and translates | |
| 2655 character @samp{c} to newline. | |
| 2656 | |
| 2657 @example | |
| 2658 @group | |
| 2659 ---------- Buffer: foo ---------- | |
| 2660 Here is a sentence in the buffer. | |
| 2661 ---------- Buffer: foo ---------- | |
| 2662 @end group | |
| 2663 | |
| 2664 @group | |
| 2665 (let ((table (make-char-table 'generic))) | |
| 2666 (put-char-table ?a "the letter a" table) | |
| 2667 (put-char-table ?b "" table) | |
| 2668 (put-char-table ?c ?\n table) | |
| 2669 (translate-region (point-min) (point-max) table)) | |
| 2670 @result{} 3 | |
| 2671 | |
| 2672 ---------- Buffer: foo ---------- | |
| 2673 Here is the letter a senten | |
| 2674 e in the uffer. | |
| 2675 ---------- Buffer: foo ---------- | |
| 2676 @end group | |
| 2677 @end example | |
| 2678 @end defun | |
| 2679 | |
| 2680 @node Registers | |
| 2681 @section Registers | |
| 2682 @cindex registers | |
| 2683 | |
| 2684 A register is a sort of variable used in XEmacs editing that can hold a | |
| 2685 marker, a string, a rectangle, a window configuration (of one frame), or | |
| 2686 a frame configuration (of all frames). Each register is named by a | |
| 2687 single character. All characters, including control and meta characters | |
| 2688 (but with the exception of @kbd{C-g}), can be used to name registers. | |
| 2689 Thus, there are 255 possible registers. A register is designated in | |
| 2690 Emacs Lisp by a character that is its name. | |
| 2691 | |
| 2692 The functions in this section return unpredictable values unless | |
| 2693 otherwise stated. | |
| 2694 @c Will change in version 19 | |
| 2695 | |
| 2696 @defvar register-alist | |
| 2697 This variable is an alist of elements of the form @code{(@var{name} . | |
| 2698 @var{contents})}. Normally, there is one element for each XEmacs | |
| 2699 register that has been used. | |
| 2700 | |
|
4885
6772ce4d982b
Fix hash tables, #'member*, #'assoc*, #'eql compiler macros if bignums
Aidan Kehoe <kehoea@parhasard.net>
parents:
2256
diff
changeset
|
2701 The object @var{name} is a character identifying the |
| 428 | 2702 register. The object @var{contents} is a string, marker, or list |
| 2703 representing the register contents. A string represents text stored in | |
| 2704 the register. A marker represents a position. A list represents a | |
| 2705 rectangle; its elements are strings, one per line of the rectangle. | |
| 2706 @end defvar | |
| 2707 | |
| 444 | 2708 @defun get-register register |
| 428 | 2709 This function returns the contents of the register |
| 444 | 2710 @var{register}, or @code{nil} if it has no contents. |
| 428 | 2711 @end defun |
| 2712 | |
| 444 | 2713 @defun set-register register value |
| 2714 This function sets the contents of register @var{register} to @var{value}. | |
| 428 | 2715 A register can be set to any value, but the other register functions |
| 2716 expect only certain data types. The return value is @var{value}. | |
| 2717 @end defun | |
| 2718 | |
| 444 | 2719 @deffn Command view-register register |
| 2720 This command displays what is contained in register @var{register}. | |
| 428 | 2721 @end deffn |
| 2722 | |
| 2723 @ignore | |
| 444 | 2724 @deffn Command point-to-register register |
| 428 | 2725 This command stores both the current location of point and the current |
| 444 | 2726 buffer in register @var{register} as a marker. |
| 428 | 2727 @end deffn |
| 2728 | |
| 444 | 2729 @deffn Command jump-to-register register |
| 2730 @deffnx Command register-to-point register | |
| 428 | 2731 @comment !!SourceFile register.el |
| 444 | 2732 This command restores the status recorded in register @var{register}. |
| 2733 | |
| 2734 If @var{register} contains a marker, it moves point to the position | |
| 2735 stored in the marker. Since both the buffer and the location within the | |
| 2736 buffer are stored by the @code{point-to-register} function, this command | |
| 2737 can switch you to another buffer. | |
| 2738 | |
| 2739 If @var{register} contains a window configuration or a frame configuration. | |
| 428 | 2740 @code{jump-to-register} restores that configuration. |
| 2741 @end deffn | |
| 2742 @end ignore | |
| 2743 | |
| 444 | 2744 @deffn Command insert-register register &optional beforep |
| 2745 This command inserts contents of register @var{register} into the current | |
| 428 | 2746 buffer. |
| 2747 | |
| 2748 Normally, this command puts point before the inserted text, and the | |
| 2749 mark after it. However, if the optional second argument @var{beforep} | |
| 2750 is non-@code{nil}, it puts the mark before and point after. | |
| 2751 You can pass a non-@code{nil} second argument @var{beforep} to this | |
| 2752 function interactively by supplying any prefix argument. | |
| 2753 | |
| 2754 If the register contains a rectangle, then the rectangle is inserted | |
| 2755 with its upper left corner at point. This means that text is inserted | |
| 2756 in the current line and underneath it on successive lines. | |
| 2757 | |
| 2758 If the register contains something other than saved text (a string) or | |
| 2759 a rectangle (a list), currently useless things happen. This may be | |
| 2760 changed in the future. | |
| 2761 @end deffn | |
| 2762 | |
| 2763 @ignore | |
| 444 | 2764 @deffn Command copy-to-register register start end &optional delete-flag |
| 428 | 2765 This command copies the region from @var{start} to @var{end} into |
| 444 | 2766 register @var{register}. If @var{delete-flag} is non-@code{nil}, it deletes |
| 428 | 2767 the region from the buffer after copying it into the register. |
| 2768 @end deffn | |
| 2769 | |
| 444 | 2770 @deffn Command prepend-to-register register start end &optional delete-flag |
| 428 | 2771 This command prepends the region from @var{start} to @var{end} into |
| 444 | 2772 register @var{register}. If @var{delete-flag} is non-@code{nil}, it deletes |
| 428 | 2773 the region from the buffer after copying it to the register. |
| 2774 @end deffn | |
| 2775 | |
| 444 | 2776 @deffn Command append-to-register register start end &optional delete-flag |
| 428 | 2777 This command appends the region from @var{start} to @var{end} to the |
| 444 | 2778 text already in register @var{register}. If @var{delete-flag} is |
| 428 | 2779 non-@code{nil}, it deletes the region from the buffer after copying it |
| 2780 to the register. | |
| 2781 @end deffn | |
| 2782 | |
| 444 | 2783 @deffn Command copy-rectangle-to-register register start end &optional delete-flag |
| 428 | 2784 This command copies a rectangular region from @var{start} to @var{end} |
| 444 | 2785 into register @var{register}. If @var{delete-flag} is non-@code{nil}, it |
| 428 | 2786 deletes the region from the buffer after copying it to the register. |
| 2787 @end deffn | |
| 2788 | |
| 444 | 2789 @deffn Command window-configuration-to-register register |
| 428 | 2790 This function stores the window configuration of the selected frame in |
| 444 | 2791 register @var{register}. |
| 428 | 2792 @end deffn |
| 2793 | |
| 444 | 2794 @deffn Command frame-configuration-to-register register |
| 428 | 2795 This function stores the current frame configuration in register |
| 444 | 2796 @var{register}. |
| 428 | 2797 @end deffn |
| 2798 @end ignore | |
| 2799 | |
| 2800 @node Transposition | |
| 2801 @section Transposition of Text | |
| 2802 | |
| 2803 This subroutine is used by the transposition commands. | |
| 2804 | |
| 2805 @defun transpose-regions start1 end1 start2 end2 &optional leave-markers | |
| 2806 This function exchanges two nonoverlapping portions of the buffer. | |
| 2807 Arguments @var{start1} and @var{end1} specify the bounds of one portion | |
| 2808 and arguments @var{start2} and @var{end2} specify the bounds of the | |
| 2809 other portion. | |
| 2810 | |
| 2811 Normally, @code{transpose-regions} relocates markers with the transposed | |
| 2812 text; a marker previously positioned within one of the two transposed | |
| 2813 portions moves along with that portion, thus remaining between the same | |
| 2814 two characters in their new position. However, if @var{leave-markers} | |
| 2815 is non-@code{nil}, @code{transpose-regions} does not do this---it leaves | |
| 2816 all markers unrelocated. | |
| 2817 @end defun | |
| 2818 | |
| 2819 @node Change Hooks | |
| 2820 @section Change Hooks | |
| 2821 @cindex change hooks | |
| 2822 @cindex hooks for text changes | |
| 2823 | |
| 2824 These hook variables let you arrange to take notice of all changes in | |
| 2825 all buffers (or in a particular buffer, if you make them buffer-local). | |
| 2826 @ignore Not in XEmacs | |
| 2827 See also @ref{Special Properties}, for how to detect changes to specific | |
| 2828 parts of the text. | |
| 2829 @end ignore | |
| 2830 | |
| 2831 The functions you use in these hooks should save and restore the match | |
| 2832 data if they do anything that uses regular expressions; otherwise, they | |
| 2833 will interfere in bizarre ways with the editing operations that call | |
| 2834 them. | |
| 2835 | |
| 2836 Buffer changes made while executing the following hooks don't | |
| 2837 themselves cause any change hooks to be invoked. | |
| 2838 | |
| 2839 @defvar before-change-functions | |
| 2840 This variable holds a list of a functions to call before any buffer | |
| 2841 modification. Each function gets two arguments, the beginning and end | |
| 2842 of the region that is about to change, represented as integers. The | |
| 2843 buffer that is about to change is always the current buffer. | |
| 2844 @end defvar | |
| 2845 | |
| 2846 @defvar after-change-functions | |
| 2847 This variable holds a list of a functions to call after any buffer | |
| 2848 modification. Each function receives three arguments: the beginning and | |
| 2849 end of the region just changed, and the length of the text that existed | |
| 2850 before the change. (To get the current length, subtract the region | |
| 2851 beginning from the region end.) All three arguments are integers. The | |
| 2852 buffer that's about to change is always the current buffer. | |
| 2853 @end defvar | |
| 2854 | |
| 2855 @defvar before-change-function | |
| 2856 This obsolete variable holds one function to call before any buffer | |
| 2857 modification (or @code{nil} for no function). It is called just like | |
| 2858 the functions in @code{before-change-functions}. | |
| 2859 @end defvar | |
| 2860 | |
| 2861 @defvar after-change-function | |
| 2862 This obsolete variable holds one function to call after any buffer modification | |
| 2863 (or @code{nil} for no function). It is called just like the functions in | |
| 2864 @code{after-change-functions}. | |
| 2865 @end defvar | |
| 2866 | |
| 2867 @defvar first-change-hook | |
| 2868 This variable is a normal hook that is run whenever a buffer is changed | |
| 2869 that was previously in the unmodified state. | |
| 2870 @end defvar | |
| 2871 | |
| 2872 @node Transformations | |
| 2873 @section Textual transformations---MD5 and base64 support | |
| 2874 @cindex MD5 digests | |
| 2875 @cindex base64 | |
| 2876 | |
| 2877 Some textual operations inherently require examining each character in | |
| 2878 turn, and performing arithmetic operations on them. Such operations | |
| 2879 can, of course, be implemented in Emacs Lisp, but tend to be very slow | |
| 2880 for large portions of text or data. This is why some of them are | |
| 2881 implemented in C, with an appropriate interface for Lisp programmers. | |
| 2882 Examples of algorithms thus provided are MD5 and base64 support. | |
| 2883 | |
| 2884 MD5 is an algorithm for calculating message digests, as described in | |
| 901 | 2885 rfc1321. Given a message of arbitrary length, MD5 produces a 128-bit |
| 428 | 2886 ``fingerprint'' (``message digest'') corresponding to that message. It |
| 2887 is considered computationally infeasible to produce two messages having | |
| 2888 the same MD5 digest, or to produce a message having a prespecified | |
| 2889 target digest. MD5 is used heavily by various authentication schemes. | |
| 2890 | |
| 2891 Emacs Lisp interface to MD5 consists of a single function @code{md5}: | |
| 2892 | |
| 444 | 2893 @defun md5 object &optional start end coding noerror |
| 428 | 2894 This function returns the MD5 message digest of @var{object}, a buffer |
| 2895 or string. | |
| 2896 | |
| 2897 Optional arguments @var{start} and @var{end} denote positions for | |
| 2898 computing the digest of a portion of @var{object}. | |
| 2899 | |
| 444 | 2900 The optional @var{coding} argument specifies the coding system the text |
| 2901 is to be represented in while computing the digest. If unspecified, it | |
| 2902 defaults to the current format of the data, or is guessed. | |
| 2903 | |
| 2904 If @var{noerror} is non-@code{nil}, silently assume binary coding if the | |
| 2905 guesswork fails. Normally, an error is signaled in such case. | |
| 2906 | |
| 2907 @var{coding} and @var{noerror} arguments are meaningful only in XEmacsen | |
| 2908 with file-coding or Mule support. Otherwise, they are ignored. Some | |
| 2909 examples of usage: | |
| 428 | 2910 |
| 2911 @example | |
| 2912 @group | |
| 2913 ;; @r{Calculate the digest of the entire buffer} | |
| 2914 (md5 (current-buffer)) | |
| 2915 @result{} "8842b04362899b1cda8d2d126dc11712" | |
| 2916 @end group | |
| 2917 | |
| 2918 @group | |
| 2919 ;; @r{Calculate the digest of the current line} | |
| 2920 (md5 (current-buffer) (point-at-bol) (point-at-eol)) | |
| 2921 @result{} "60614d21e9dee27dfdb01fa4e30d6d00" | |
| 2922 @end group | |
| 2923 | |
| 2924 @group | |
| 2925 ;; @r{Calculate the digest of your name and email address} | |
| 2926 (md5 (concat (format "%s <%s>" (user-full-name) user-mail-address))) | |
| 2927 @result{} "0a2188c40fd38922d941fe6032fce516" | |
| 2928 @end group | |
| 2929 @end example | |
| 2930 @end defun | |
| 2931 | |
| 2932 Base64 is a portable encoding for arbitrary sequences of octets, in a | |
| 2933 form that need not be readable by humans. It uses a 65-character subset | |
| 2934 of US-ASCII, as described in rfc2045. Base64 is used by MIME to encode | |
| 2935 binary bodies, and to encode binary characters in message headers. | |
| 2936 | |
| 2937 The Lisp interface to base64 consists of four functions: | |
| 2938 | |
| 444 | 2939 @deffn Command base64-encode-region start end &optional no-line-break |
| 2940 This function encodes the region between @var{start} and @var{end} of the | |
| 2941 current buffer to base64 format. This means that the original region is | |
| 428 | 2942 deleted, and replaced with its base64 equivalent. |
| 2943 | |
| 2944 Normally, encoded base64 output is multi-line, with 76-character lines. | |
| 444 | 2945 If @var{no-line-break} is non-@code{nil}, newlines will not be inserted, |
| 428 | 2946 resulting in single-line output. |
| 2947 | |
| 2948 Mule note: you should make sure that you convert the multibyte | |
| 2949 characters (those that do not fit into 0--255 range) to something else, | |
| 2950 because they cannot be meaningfully converted to base64. If the | |
| 2951 @code{base64-encode-region} encounters such characters, it will signal | |
| 2952 an error. | |
| 2953 | |
| 2954 @code{base64-encode-region} returns the length of the encoded text. | |
| 2955 | |
| 2956 @example | |
| 2957 @group | |
| 2958 ;; @r{Encode the whole buffer in base64} | |
| 2959 (base64-encode-region (point-min) (point-max)) | |
| 2960 @end group | |
| 2961 @end example | |
| 2962 | |
| 2963 The function can also be used interactively, in which case it works on | |
| 2964 the currently active region. | |
| 444 | 2965 @end deffn |
| 2966 | |
| 2967 @defun base64-encode-string string &optional no-line-break | |
| 428 | 2968 This function encodes @var{string} to base64, and returns the encoded |
| 2969 string. | |
| 2970 | |
| 444 | 2971 Normally, encoded base64 output is multi-line, with 76-character lines. |
| 2972 If @var{no-line-break} is non-@code{nil}, newlines will not be inserted, | |
| 2973 resulting in single-line output. | |
| 2974 | |
| 428 | 2975 For Mule, the same considerations apply as for |
| 2976 @code{base64-encode-region}. | |
| 2977 | |
| 2978 @example | |
| 2979 @group | |
| 2980 (base64-encode-string "fubar") | |
| 2981 @result{} "ZnViYXI=" | |
| 2982 @end group | |
| 2983 @end example | |
| 2984 @end defun | |
| 2985 | |
| 444 | 2986 @deffn Command base64-decode-region start end |
| 2987 This function decodes the region between @var{start} and @var{end} of the | |
| 428 | 2988 current buffer. The region should be in base64 encoding. |
| 2989 | |
| 2990 If the region was decoded correctly, @code{base64-decode-region} returns | |
| 444 | 2991 the length of the decoded region. If the decoding failed, @code{nil} is |
| 428 | 2992 returned. |
| 2993 | |
| 2994 @example | |
| 2995 @group | |
| 2996 ;; @r{Decode a base64 buffer, and replace it with the decoded version} | |
| 2997 (base64-decode-region (point-min) (point-max)) | |
| 2998 @end group | |
| 2999 @end example | |
| 444 | 3000 @end deffn |
| 428 | 3001 |
| 3002 @defun base64-decode-string string | |
| 3003 This function decodes @var{string} to base64, and returns the decoded | |
| 3004 string. @var{string} should be valid base64-encoded text. | |
| 3005 | |
| 3006 If encoding was not possible, @code{nil} is returned. | |
| 3007 | |
| 3008 @example | |
| 3009 @group | |
| 3010 (base64-decode-string "ZnViYXI=") | |
| 3011 @result{} "fubar" | |
| 3012 @end group | |
| 3013 | |
| 3014 @group | |
| 3015 (base64-decode-string "totally bogus") | |
| 3016 @result{} nil | |
| 3017 @end group | |
| 3018 @end example | |
| 3019 @end defun |