Mercurial > hg > xemacs-beta
annotate man/lispref/strings.texi @ 4934:714f7c9fabb1
make it easier to debug staticpro crashes.
Add functions to print out the variable names saved during calls to
staticpro(), and change the order of enumerating staticpros to start
from 0 to make it easier to get a count to pass to the new functions.
| author | Ben Wing <ben@xemacs.org> |
|---|---|
| date | Tue, 19 Jan 2010 01:21:39 -0600 |
| parents | d9eb5ea14f65 |
| children | 6772ce4d982b |
| 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/strings.info | |
| 6 @node Strings and Characters, Lists, Numbers, Top | |
| 7 @chapter Strings and Characters | |
| 8 @cindex strings | |
| 9 @cindex character arrays | |
| 10 @cindex characters | |
| 11 @cindex bytes | |
| 12 | |
| 13 A string in XEmacs Lisp is an array that contains an ordered sequence | |
| 14 of characters. Strings are used as names of symbols, buffers, and | |
| 15 files, to send messages to users, to hold text being copied between | |
| 16 buffers, and for many other purposes. Because strings are so important, | |
| 17 XEmacs Lisp has many functions expressly for manipulating them. XEmacs | |
| 18 Lisp programs use strings more often than individual characters. | |
| 19 | |
| 20 @menu | |
| 440 | 21 * String Basics:: Basic properties of strings and characters. |
| 428 | 22 * Predicates for Strings:: Testing whether an object is a string or char. |
| 23 * Creating Strings:: Functions to allocate new strings. | |
| 24 * Predicates for Characters:: Testing whether an object is a character. | |
| 25 * Character Codes:: Each character has an equivalent integer. | |
| 26 * Text Comparison:: Comparing characters or strings. | |
| 27 * String Conversion:: Converting characters or strings and vice versa. | |
| 28 * Modifying Strings:: Changing characters in a string. | |
| 29 * String Properties:: Additional information attached to strings. | |
| 30 * Formatting Strings:: @code{format}: XEmacs's analog of @code{printf}. | |
| 31 * Character Case:: Case conversion functions. | |
| 32 * Case Tables:: Customizing case conversion. | |
| 33 * Char Tables:: Mapping from characters to Lisp objects. | |
| 34 @end menu | |
| 35 | |
| 36 @node String Basics | |
| 37 @section String and Character Basics | |
| 38 | |
| 39 Strings in XEmacs Lisp are arrays that contain an ordered sequence of | |
| 40 characters. Characters are their own primitive object type in XEmacs | |
| 41 20. However, in XEmacs 19, characters are represented in XEmacs Lisp as | |
| 42 integers; whether an integer was intended as a character or not is | |
| 43 determined only by how it is used. @xref{Character Type}. | |
| 44 | |
| 45 The length of a string (like any array) is fixed and independent of | |
| 46 the string contents, and cannot be altered. Strings in Lisp are | |
| 47 @emph{not} terminated by a distinguished character code. (By contrast, | |
| 48 strings in C are terminated by a character with @sc{ascii} code 0.) | |
| 49 This means that any character, including the null character (@sc{ascii} | |
| 50 code 0), is a valid element of a string.@refill | |
| 51 | |
| 52 Since strings are considered arrays, you can operate on them with the | |
| 53 general array functions. (@xref{Sequences Arrays Vectors}.) For | |
| 54 example, you can access or change individual characters in a string | |
| 55 using the functions @code{aref} and @code{aset} (@pxref{Array | |
| 56 Functions}). | |
| 57 | |
| 58 Strings use an efficient representation for storing the characters | |
| 59 in them, and thus take up much less memory than a vector of the same | |
| 60 length. | |
| 61 | |
| 62 Sometimes you will see strings used to hold key sequences. This | |
| 63 exists for backward compatibility with Emacs 18, but should @emph{not} | |
| 64 be used in new code, since many key chords can't be represented at | |
| 65 all and others (in particular meta key chords) are confused with | |
| 66 accented characters. | |
| 67 | |
| 68 @ignore @c Not accurate any more | |
| 69 Each character in a string is stored in a single byte. Therefore, | |
| 70 numbers not in the range 0 to 255 are truncated when stored into a | |
| 71 string. This means that a string takes up much less memory than a | |
| 72 vector of the same length. | |
| 73 | |
| 74 Sometimes key sequences are represented as strings. When a string is | |
| 75 a key sequence, string elements in the range 128 to 255 represent meta | |
| 76 characters (which are extremely large integers) rather than keyboard | |
| 77 events in the range 128 to 255. | |
| 78 | |
| 79 Strings cannot hold characters that have the hyper, super or alt | |
| 80 modifiers; they can hold @sc{ASCII} control characters, but no other | |
| 81 control characters. They do not distinguish case in @sc{ASCII} control | |
| 82 characters. @xref{Character Type}, for more information about | |
| 83 representation of meta and other modifiers for keyboard input | |
| 84 characters. | |
| 85 @end ignore | |
| 86 | |
| 87 Strings are useful for holding regular expressions. You can also | |
| 88 match regular expressions against strings (@pxref{Regexp Search}). The | |
| 89 functions @code{match-string} (@pxref{Simple Match Data}) and | |
| 90 @code{replace-match} (@pxref{Replacing Match}) are useful for | |
| 91 decomposing and modifying strings based on regular expression matching. | |
| 92 | |
| 93 Like a buffer, a string can contain extents in it. These extents are | |
| 94 created when a function such as @code{buffer-substring} is called on a | |
| 95 region with duplicable extents in it. When the string is inserted into | |
| 96 a buffer, the extents are inserted along with it. @xref{Duplicable | |
| 97 Extents}. | |
| 98 | |
| 99 @xref{Text}, for information about functions that display strings or | |
| 100 copy them into buffers. @xref{Character Type}, and @ref{String Type}, | |
| 101 for information about the syntax of characters and strings. | |
| 102 | |
| 103 @node Predicates for Strings | |
| 104 @section The Predicates for Strings | |
| 105 | |
| 106 For more information about general sequence and array predicates, | |
| 107 see @ref{Sequences Arrays Vectors}, and @ref{Arrays}. | |
| 108 | |
| 109 @defun stringp object | |
| 110 This function returns @code{t} if @var{object} is a string, @code{nil} | |
| 111 otherwise. | |
| 112 @end defun | |
| 113 | |
| 114 @defun char-or-string-p object | |
| 115 This function returns @code{t} if @var{object} is a string or a | |
| 116 character, @code{nil} otherwise. | |
| 117 | |
| 118 In XEmacs addition, this function also returns @code{t} if @var{object} | |
| 119 is an integer that can be represented as a character. This is because | |
| 120 of compatibility with previous XEmacs and should not be depended on. | |
| 121 @end defun | |
| 122 | |
| 123 @node Creating Strings | |
| 124 @section Creating Strings | |
| 125 | |
| 126 The following functions create strings, either from scratch, or by | |
| 127 putting strings together, or by taking them apart. | |
| 128 | |
| 129 @defun string &rest characters | |
| 130 This function returns a new string made up of @var{characters}. | |
| 131 | |
| 132 @example | |
| 133 (string ?X ?E ?m ?a ?c ?s) | |
| 134 @result{} "XEmacs" | |
| 135 (string) | |
| 136 @result{} "" | |
| 137 @end example | |
| 138 | |
| 139 Analogous functions operating on other data types include @code{list}, | |
| 140 @code{cons} (@pxref{Building Lists}), @code{vector} (@pxref{Vectors}) | |
| 444 | 141 and @code{bit-vector} (@pxref{Bit Vectors}). This function has not been |
| 428 | 142 available in XEmacs prior to 21.0 and FSF Emacs prior to 20.3. |
| 143 @end defun | |
| 144 | |
| 444 | 145 @defun make-string length character |
| 146 This function returns a new string consisting entirely of @var{length} | |
| 147 successive copies of @var{character}. @var{length} must be a | |
| 148 non-negative integer. | |
| 428 | 149 |
| 150 @example | |
| 151 (make-string 5 ?x) | |
| 152 @result{} "xxxxx" | |
| 153 (make-string 0 ?x) | |
| 154 @result{} "" | |
| 155 @end example | |
| 156 | |
| 157 Other functions to compare with this one include @code{char-to-string} | |
| 158 (@pxref{String Conversion}), @code{make-vector} (@pxref{Vectors}), and | |
| 159 @code{make-list} (@pxref{Building Lists}). | |
| 160 @end defun | |
| 161 | |
| 162 @defun substring string start &optional end | |
| 163 This function returns a new string which consists of those characters | |
| 164 from @var{string} in the range from (and including) the character at the | |
| 165 index @var{start} up to (but excluding) the character at the index | |
| 166 @var{end}. The first character is at index zero. | |
| 167 | |
| 168 @example | |
| 169 @group | |
| 170 (substring "abcdefg" 0 3) | |
| 171 @result{} "abc" | |
| 172 @end group | |
| 173 @end example | |
| 174 | |
| 175 @noindent | |
| 176 Here the index for @samp{a} is 0, the index for @samp{b} is 1, and the | |
| 177 index for @samp{c} is 2. Thus, three letters, @samp{abc}, are copied | |
| 178 from the string @code{"abcdefg"}. The index 3 marks the character | |
| 179 position up to which the substring is copied. The character whose index | |
| 180 is 3 is actually the fourth character in the string. | |
| 181 | |
| 182 A negative number counts from the end of the string, so that @minus{}1 | |
| 444 | 183 signifies the index of the last character of the string. For example: |
| 428 | 184 |
| 185 @example | |
| 186 @group | |
| 187 (substring "abcdefg" -3 -1) | |
| 188 @result{} "ef" | |
| 189 @end group | |
| 190 @end example | |
| 191 | |
| 192 @noindent | |
| 193 In this example, the index for @samp{e} is @minus{}3, the index for | |
| 194 @samp{f} is @minus{}2, and the index for @samp{g} is @minus{}1. | |
| 195 Therefore, @samp{e} and @samp{f} are included, and @samp{g} is excluded. | |
| 196 | |
| 197 When @code{nil} is used as an index, it stands for the length of the | |
| 198 string. Thus, | |
| 199 | |
| 200 @example | |
| 201 @group | |
| 202 (substring "abcdefg" -3 nil) | |
| 203 @result{} "efg" | |
| 204 @end group | |
| 205 @end example | |
| 206 | |
| 207 Omitting the argument @var{end} is equivalent to specifying @code{nil}. | |
| 208 It follows that @code{(substring @var{string} 0)} returns a copy of all | |
| 209 of @var{string}. | |
| 210 | |
| 211 @example | |
| 212 @group | |
| 213 (substring "abcdefg" 0) | |
| 214 @result{} "abcdefg" | |
| 215 @end group | |
| 216 @end example | |
| 217 | |
| 218 @noindent | |
| 219 But we recommend @code{copy-sequence} for this purpose (@pxref{Sequence | |
| 220 Functions}). | |
| 221 | |
| 222 If the characters copied from @var{string} have duplicable extents or | |
| 223 text properties, those are copied into the new string also. | |
| 224 @xref{Duplicable Extents}. | |
| 225 | |
| 226 A @code{wrong-type-argument} error is signaled if either @var{start} or | |
| 227 @var{end} is not an integer or @code{nil}. An @code{args-out-of-range} | |
| 228 error is signaled if @var{start} indicates a character following | |
| 229 @var{end}, or if either integer is out of range for @var{string}. | |
| 230 | |
| 231 Contrast this function with @code{buffer-substring} (@pxref{Buffer | |
| 232 Contents}), which returns a string containing a portion of the text in | |
| 233 the current buffer. The beginning of a string is at index 0, but the | |
| 234 beginning of a buffer is at index 1. | |
| 235 @end defun | |
| 236 | |
| 237 @defun concat &rest sequences | |
| 238 @cindex copying strings | |
| 239 @cindex concatenating strings | |
| 240 This function returns a new string consisting of the characters in the | |
| 241 arguments passed to it (along with their text properties, if any). The | |
| 242 arguments may be strings, lists of numbers, or vectors of numbers; they | |
| 243 are not themselves changed. If @code{concat} receives no arguments, it | |
| 244 returns an empty string. | |
| 245 | |
| 246 @example | |
| 247 (concat "abc" "-def") | |
| 248 @result{} "abc-def" | |
| 249 (concat "abc" (list 120 (+ 256 121)) [122]) | |
| 250 @result{} "abcxyz" | |
| 251 ;; @r{@code{nil} is an empty sequence.} | |
| 252 (concat "abc" nil "-def") | |
| 253 @result{} "abc-def" | |
| 254 (concat "The " "quick brown " "fox.") | |
| 255 @result{} "The quick brown fox." | |
| 256 (concat) | |
| 257 @result{} "" | |
| 258 @end example | |
| 259 | |
| 260 @noindent | |
| 261 The second example above shows how characters stored in strings are | |
| 262 taken modulo 256. In other words, each character in the string is | |
| 263 stored in one byte. | |
| 264 | |
| 265 The @code{concat} function always constructs a new string that is | |
| 266 not @code{eq} to any existing string. | |
| 267 | |
| 268 When an argument is an integer (not a sequence of integers), it is | |
| 269 converted to a string of digits making up the decimal printed | |
| 270 representation of the integer. @strong{Don't use this feature; we plan | |
| 271 to eliminate it. If you already use this feature, change your programs | |
| 272 now!} The proper way to convert an integer to a decimal number in this | |
| 273 way is with @code{format} (@pxref{Formatting Strings}) or | |
| 274 @code{number-to-string} (@pxref{String Conversion}). | |
| 275 | |
| 276 @example | |
| 277 @group | |
| 278 (concat 137) | |
| 279 @result{} "137" | |
| 280 (concat 54 321) | |
| 281 @result{} "54321" | |
| 282 @end group | |
| 283 @end example | |
| 284 | |
| 285 For information about other concatenation functions, see the description | |
| 286 of @code{mapconcat} in @ref{Mapping Functions}, @code{vconcat} in | |
| 287 @ref{Vectors}, @code{bvconcat} in @ref{Bit Vectors}, and @code{append} | |
| 288 in @ref{Building Lists}. | |
| 289 @end defun | |
| 290 | |
| 1495 | 291 The function @code{split-string}, in @ref{Regexp Search}, generates a |
| 292 list of strings by splitting a string on occurances of a regular | |
| 293 expression. | |
| 294 | |
| 428 | 295 @node Predicates for Characters |
| 296 @section The Predicates for Characters | |
| 297 | |
| 298 @defun characterp object | |
| 299 This function returns @code{t} if @var{object} is a character. | |
| 300 | |
| 301 Some functions that work on integers (e.g. the comparison functions | |
| 302 <, <=, =, /=, etc. and the arithmetic functions +, -, *, etc.) | |
| 303 accept characters and implicitly convert them into integers. In | |
| 304 general, functions that work on characters also accept char-ints and | |
| 305 implicitly convert them into characters. WARNING: Neither of these | |
| 306 behaviors is very desirable, and they are maintained for backward | |
| 307 compatibility with old E-Lisp programs that confounded characters and | |
| 308 integers willy-nilly. These behaviors may change in the future; therefore, | |
| 309 do not rely on them. Instead, convert the characters explicitly | |
| 310 using @code{char-int}. | |
| 311 @end defun | |
| 312 | |
| 313 @defun integer-or-char-p object | |
| 314 This function returns @code{t} if @var{object} is an integer or character. | |
| 315 @end defun | |
| 316 | |
| 317 @node Character Codes | |
| 318 @section Character Codes | |
| 319 | |
| 444 | 320 @defun char-int character |
| 428 | 321 This function converts a character into an equivalent integer. |
| 322 The resulting integer will always be non-negative. The integers in | |
| 323 the range 0 - 255 map to characters as follows: | |
| 324 | |
| 325 @table @asis | |
| 326 @item 0 - 31 | |
| 327 Control set 0 | |
| 328 @item 32 - 127 | |
| 329 @sc{ascii} | |
| 330 @item 128 - 159 | |
| 331 Control set 1 | |
| 332 @item 160 - 255 | |
| 333 Right half of ISO-8859-1 | |
| 334 @end table | |
| 335 | |
| 336 If support for @sc{mule} does not exist, these are the only valid | |
| 337 character values. When @sc{mule} support exists, the values assigned to | |
| 338 other characters may vary depending on the particular version of XEmacs, | |
| 339 the order in which character sets were loaded, etc., and you should not | |
| 340 depend on them. | |
| 341 @end defun | |
| 342 | |
| 343 @defun int-char integer | |
| 344 This function converts an integer into the equivalent character. Not | |
| 345 all integers correspond to valid characters; use @code{char-int-p} to | |
| 346 determine whether this is the case. If the integer cannot be converted, | |
| 347 @code{nil} is returned. | |
| 348 @end defun | |
| 349 | |
| 350 @defun char-int-p object | |
| 351 This function returns @code{t} if @var{object} is an integer that can be | |
| 352 converted into a character. | |
| 353 @end defun | |
| 354 | |
| 355 @defun char-or-char-int-p object | |
| 356 This function returns @code{t} if @var{object} is a character or an | |
| 357 integer that can be converted into one. | |
| 358 @end defun | |
| 359 | |
| 360 @need 2000 | |
| 361 @node Text Comparison | |
| 362 @section Comparison of Characters and Strings | |
| 363 @cindex string equality | |
| 364 | |
| 444 | 365 @defun char-equal character1 character2 &optional buffer |
| 428 | 366 This function returns @code{t} if the arguments represent the same |
| 367 character, @code{nil} otherwise. This function ignores differences | |
| 444 | 368 in case if the value of @code{case-fold-search} is non-@code{nil} in |
| 369 @var{buffer}, which defaults to the current buffer. | |
| 428 | 370 |
| 371 @example | |
| 372 (char-equal ?x ?x) | |
| 373 @result{} t | |
| 374 (let ((case-fold-search t)) | |
| 375 (char-equal ?x ?X)) | |
| 376 @result{} t | |
| 377 (let ((case-fold-search nil)) | |
| 378 (char-equal ?x ?X)) | |
| 379 @result{} nil | |
| 380 @end example | |
| 381 @end defun | |
| 382 | |
| 383 @defun char= character1 character2 | |
| 384 This function returns @code{t} if the arguments represent the same | |
| 385 character, @code{nil} otherwise. Case is significant. | |
| 386 | |
| 387 @example | |
| 388 (char= ?x ?x) | |
| 389 @result{} t | |
| 390 (char= ?x ?X) | |
| 391 @result{} nil | |
| 392 (let ((case-fold-search t)) | |
| 393 (char-equal ?x ?X)) | |
| 394 @result{} nil | |
| 395 (let ((case-fold-search nil)) | |
| 396 (char-equal ?x ?X)) | |
| 397 @result{} nil | |
| 398 @end example | |
| 399 @end defun | |
| 400 | |
| 401 @defun string= string1 string2 | |
| 402 This function returns @code{t} if the characters of the two strings | |
| 403 match exactly; case is significant. | |
| 404 | |
| 405 @example | |
| 406 (string= "abc" "abc") | |
| 407 @result{} t | |
| 408 (string= "abc" "ABC") | |
| 409 @result{} nil | |
| 410 (string= "ab" "ABC") | |
| 411 @result{} nil | |
| 412 @end example | |
| 413 | |
| 414 @ignore @c `equal' in XEmacs does not compare text properties | |
| 415 The function @code{string=} ignores the text properties of the | |
| 416 two strings. To compare strings in a way that compares their text | |
| 417 properties also, use @code{equal} (@pxref{Equality Predicates}). | |
| 418 @end ignore | |
| 419 @end defun | |
| 420 | |
| 421 @defun string-equal string1 string2 | |
| 422 @code{string-equal} is another name for @code{string=}. | |
| 423 @end defun | |
| 424 | |
| 425 @cindex lexical comparison | |
| 426 @defun string< string1 string2 | |
| 427 @c (findex string< causes problems for permuted index!!) | |
| 428 This function compares two strings a character at a time. First it | |
| 429 scans both the strings at once to find the first pair of corresponding | |
| 430 characters that do not match. If the lesser character of those two is | |
| 431 the character from @var{string1}, then @var{string1} is less, and this | |
| 432 function returns @code{t}. If the lesser character is the one from | |
| 433 @var{string2}, then @var{string1} is greater, and this function returns | |
| 434 @code{nil}. If the two strings match entirely, the value is @code{nil}. | |
| 435 | |
| 436 Pairs of characters are compared by their @sc{ascii} codes. Keep in | |
| 437 mind that lower case letters have higher numeric values in the | |
| 438 @sc{ascii} character set than their upper case counterparts; numbers and | |
| 439 many punctuation characters have a lower numeric value than upper case | |
| 440 letters. | |
| 441 | |
| 442 @example | |
| 443 @group | |
| 444 (string< "abc" "abd") | |
| 445 @result{} t | |
| 446 (string< "abd" "abc") | |
| 447 @result{} nil | |
| 448 (string< "123" "abc") | |
| 449 @result{} t | |
| 450 @end group | |
| 451 @end example | |
| 452 | |
| 453 When the strings have different lengths, and they match up to the | |
| 454 length of @var{string1}, then the result is @code{t}. If they match up | |
| 455 to the length of @var{string2}, the result is @code{nil}. A string of | |
| 456 no characters is less than any other string. | |
| 457 | |
| 458 @example | |
| 459 @group | |
| 460 (string< "" "abc") | |
| 461 @result{} t | |
| 462 (string< "ab" "abc") | |
| 463 @result{} t | |
| 464 (string< "abc" "") | |
| 465 @result{} nil | |
| 466 (string< "abc" "ab") | |
| 467 @result{} nil | |
| 468 (string< "" "") | |
| 444 | 469 @result{} nil |
| 428 | 470 @end group |
| 471 @end example | |
| 472 @end defun | |
| 473 | |
| 474 @defun string-lessp string1 string2 | |
| 475 @code{string-lessp} is another name for @code{string<}. | |
| 476 @end defun | |
| 477 | |
| 478 See also @code{compare-buffer-substrings} in @ref{Comparing Text}, for | |
| 479 a way to compare text in buffers. The function @code{string-match}, | |
| 480 which matches a regular expression against a string, can be used | |
| 481 for a kind of string comparison; see @ref{Regexp Search}. | |
| 482 | |
| 483 @node String Conversion | |
| 484 @section Conversion of Characters and Strings | |
| 485 @cindex conversion of strings | |
| 486 | |
| 487 This section describes functions for conversions between characters, | |
| 488 strings and integers. @code{format} and @code{prin1-to-string} | |
| 489 (@pxref{Output Functions}) can also convert Lisp objects into strings. | |
| 490 @code{read-from-string} (@pxref{Input Functions}) can ``convert'' a | |
| 491 string representation of a Lisp object into an object. | |
| 492 | |
| 493 @xref{Documentation}, for functions that produce textual descriptions | |
| 494 of text characters and general input events | |
| 495 (@code{single-key-description} and @code{text-char-description}). These | |
| 496 functions are used primarily for making help messages. | |
| 497 | |
| 498 @defun char-to-string character | |
| 499 @cindex character to string | |
| 500 This function returns a new string with a length of one character. | |
| 501 The value of @var{character}, modulo 256, is used to initialize the | |
| 502 element of the string. | |
| 503 | |
| 504 This function is similar to @code{make-string} with an integer argument | |
| 505 of 1. (@xref{Creating Strings}.) This conversion can also be done with | |
| 506 @code{format} using the @samp{%c} format specification. | |
| 507 (@xref{Formatting Strings}.) | |
| 508 | |
| 509 @example | |
| 510 (char-to-string ?x) | |
| 511 @result{} "x" | |
| 512 (char-to-string (+ 256 ?x)) | |
| 513 @result{} "x" | |
| 514 (make-string 1 ?x) | |
| 515 @result{} "x" | |
| 516 @end example | |
| 517 @end defun | |
| 518 | |
| 519 @defun string-to-char string | |
| 520 @cindex string to character | |
| 521 This function returns the first character in @var{string}. If the | |
| 522 string is empty, the function returns 0. (Under XEmacs 19, the value is | |
| 523 also 0 when the first character of @var{string} is the null character, | |
| 524 @sc{ascii} code 0.) | |
| 525 | |
| 526 @example | |
| 527 (string-to-char "ABC") | |
| 528 @result{} ?A ;; @r{Under XEmacs 20.} | |
| 529 @result{} 65 ;; @r{Under XEmacs 19.} | |
| 530 (string-to-char "xyz") | |
| 531 @result{} ?x ;; @r{Under XEmacs 20.} | |
| 532 @result{} 120 ;; @r{Under XEmacs 19.} | |
| 533 (string-to-char "") | |
| 534 @result{} 0 | |
| 535 (string-to-char "\000") | |
| 536 @result{} ?\^@ ;; @r{Under XEmacs 20.} | |
| 537 @result{} 0 ;; @r{Under XEmacs 20.} | |
| 538 @end example | |
| 539 | |
| 540 This function may be eliminated in the future if it does not seem useful | |
| 541 enough to retain. | |
| 542 @end defun | |
| 543 | |
| 544 @defun number-to-string number | |
| 545 @cindex integer to string | |
| 546 @cindex integer to decimal | |
| 547 This function returns a string consisting of the printed | |
| 548 representation of @var{number}, which may be an integer or a floating | |
| 549 point number. The value starts with a sign if the argument is | |
| 550 negative. | |
| 551 | |
| 552 @example | |
| 553 (number-to-string 256) | |
| 554 @result{} "256" | |
| 555 (number-to-string -23) | |
| 556 @result{} "-23" | |
| 557 (number-to-string -23.5) | |
| 558 @result{} "-23.5" | |
| 559 @end example | |
| 560 | |
| 561 @cindex int-to-string | |
| 562 @code{int-to-string} is a semi-obsolete alias for this function. | |
| 563 | |
| 564 See also the function @code{format} in @ref{Formatting Strings}. | |
| 565 @end defun | |
| 566 | |
| 567 @defun string-to-number string &optional base | |
| 568 @cindex string to number | |
| 444 | 569 This function returns the numeric value represented by @var{string}, |
| 570 read in @var{base}. It skips spaces and tabs at the beginning of | |
| 571 @var{string}, then reads as much of @var{string} as it can interpret as | |
| 572 a number. (On some systems it ignores other whitespace at the | |
| 573 beginning, not just spaces and tabs.) If the first character after the | |
| 574 ignored whitespace is not a digit or a minus sign, this function returns | |
| 575 0. | |
| 428 | 576 |
| 577 If @var{base} is not specified, it defaults to ten. With @var{base} | |
| 578 other than ten, only integers can be read. | |
| 579 | |
| 580 @example | |
| 581 (string-to-number "256") | |
| 582 @result{} 256 | |
| 583 (string-to-number "25 is a perfect square.") | |
| 584 @result{} 25 | |
| 585 (string-to-number "X256") | |
| 586 @result{} 0 | |
| 587 (string-to-number "-4.5") | |
| 588 @result{} -4.5 | |
| 589 (string-to-number "ffff" 16) | |
| 590 @result{} 65535 | |
| 591 @end example | |
| 592 | |
| 593 @findex string-to-int | |
| 594 @code{string-to-int} is an obsolete alias for this function. | |
| 595 @end defun | |
| 596 | |
| 597 @node Modifying Strings | |
| 598 @section Modifying Strings | |
| 599 @cindex strings, modifying | |
| 600 | |
| 601 You can modify a string using the general array-modifying primitives. | |
| 602 @xref{Arrays}. The function @code{aset} modifies a single character; | |
| 603 the function @code{fillarray} sets all characters in the string to | |
| 604 a specified character. | |
| 605 | |
| 606 Each string has a tick counter that starts out at zero (when the string | |
| 607 is created) and is incremented each time a change is made to that | |
| 608 string. | |
| 609 | |
| 610 @defun string-modified-tick string | |
| 611 This function returns the tick counter for @samp{string}. | |
| 612 @end defun | |
| 613 | |
| 614 @node String Properties | |
| 615 @section String Properties | |
| 616 @cindex string properties | |
| 617 @cindex properties of strings | |
| 618 | |
| 442 | 619 Just as with symbols, extents, faces, and glyphs, you can attach |
| 428 | 620 additional information to strings in the form of @dfn{string |
| 621 properties}. These differ from text properties, which are logically | |
| 622 attached to particular characters in the string. | |
| 623 | |
| 624 To attach a property to a string, use @code{put}. To retrieve a property | |
| 625 from a string, use @code{get}. You can also use @code{remprop} to remove | |
| 442 | 626 a property from a string and @code{object-plist} to retrieve a list of |
| 428 | 627 all the properties in a string. |
| 628 | |
| 629 @node Formatting Strings | |
| 630 @section Formatting Strings | |
| 631 @cindex formatting strings | |
| 632 @cindex strings, formatting them | |
| 633 | |
| 634 @dfn{Formatting} means constructing a string by substitution of | |
| 635 computed values at various places in a constant string. This string | |
| 636 controls how the other values are printed as well as where they appear; | |
| 637 it is called a @dfn{format string}. | |
| 638 | |
| 639 Formatting is often useful for computing messages to be displayed. In | |
| 640 fact, the functions @code{message} and @code{error} provide the same | |
| 641 formatting feature described here; they differ from @code{format} only | |
| 642 in how they use the result of formatting. | |
| 643 | |
| 644 @defun format string &rest objects | |
| 645 This function returns a new string that is made by copying | |
| 444 | 646 @var{string} and then replacing any format specification |
| 428 | 647 in the copy with encodings of the corresponding @var{objects}. The |
| 648 arguments @var{objects} are the computed values to be formatted. | |
| 649 @end defun | |
| 650 | |
| 651 @cindex @samp{%} in format | |
| 652 @cindex format specification | |
| 653 A format specification is a sequence of characters beginning with a | |
| 654 @samp{%}. Thus, if there is a @samp{%d} in @var{string}, the | |
| 655 @code{format} function replaces it with the printed representation of | |
| 656 one of the values to be formatted (one of the arguments @var{objects}). | |
| 657 For example: | |
| 658 | |
| 659 @example | |
| 660 @group | |
| 661 (format "The value of fill-column is %d." fill-column) | |
| 662 @result{} "The value of fill-column is 72." | |
| 663 @end group | |
| 664 @end example | |
| 665 | |
| 666 If @var{string} contains more than one format specification, the | |
| 667 format specifications correspond with successive values from | |
| 668 @var{objects}. Thus, the first format specification in @var{string} | |
| 669 uses the first such value, the second format specification uses the | |
| 670 second such value, and so on. Any extra format specifications (those | |
| 671 for which there are no corresponding values) cause unpredictable | |
| 672 behavior. Any extra values to be formatted are ignored. | |
| 673 | |
| 674 Certain format specifications require values of particular types. | |
| 675 However, no error is signaled if the value actually supplied fails to | |
| 676 have the expected type. Instead, the output is likely to be | |
| 677 meaningless. | |
| 678 | |
| 679 Here is a table of valid format specifications: | |
| 680 | |
| 681 @table @samp | |
| 682 @item %s | |
| 683 Replace the specification with the printed representation of the object, | |
| 684 made without quoting. Thus, strings are represented by their contents | |
| 685 alone, with no @samp{"} characters, and symbols appear without @samp{\} | |
| 686 characters. This is equivalent to printing the object with @code{princ}. | |
| 687 | |
| 688 If there is no corresponding object, the empty string is used. | |
| 689 | |
| 690 @item %S | |
| 691 Replace the specification with the printed representation of the object, | |
| 692 made with quoting. Thus, strings are enclosed in @samp{"} characters, | |
| 693 and @samp{\} characters appear where necessary before special characters. | |
| 694 This is equivalent to printing the object with @code{prin1}. | |
| 695 | |
| 696 If there is no corresponding object, the empty string is used. | |
| 697 | |
| 698 @item %o | |
| 699 @cindex integer to octal | |
| 700 Replace the specification with the base-eight representation of an | |
| 701 integer. | |
| 702 | |
| 703 @item %d | |
| 704 @itemx %i | |
| 705 Replace the specification with the base-ten representation of an | |
| 706 integer. | |
| 707 | |
| 708 @item %x | |
| 709 @cindex integer to hexadecimal | |
| 710 Replace the specification with the base-sixteen representation of an | |
| 711 integer, using lowercase letters. | |
| 712 | |
| 713 @item %X | |
| 714 @cindex integer to hexadecimal | |
| 715 Replace the specification with the base-sixteen representation of an | |
| 716 integer, using uppercase letters. | |
| 717 | |
|
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718 @item %b |
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719 @cindex integer to binary |
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720 Replace the specification with the base-two representation of an |
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721 integer. |
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722 |
| 428 | 723 @item %c |
| 724 Replace the specification with the character which is the value given. | |
| 725 | |
| 726 @item %e | |
| 727 Replace the specification with the exponential notation for a floating | |
| 728 point number (e.g. @samp{7.85200e+03}). | |
| 729 | |
| 730 @item %f | |
| 731 Replace the specification with the decimal-point notation for a floating | |
| 732 point number. | |
| 733 | |
| 734 @item %g | |
| 735 Replace the specification with notation for a floating point number, | |
| 736 using a ``pretty format''. Either exponential notation or decimal-point | |
| 737 notation will be used (usually whichever is shorter), and trailing | |
| 738 zeroes are removed from the fractional part. | |
| 739 | |
| 740 @item %% | |
| 741 A single @samp{%} is placed in the string. This format specification is | |
| 742 unusual in that it does not use a value. For example, @code{(format "%% | |
| 743 %d" 30)} returns @code{"% 30"}. | |
| 744 @end table | |
| 745 | |
| 746 Any other format character results in an @samp{Invalid format | |
| 747 operation} error. | |
| 748 | |
| 749 Here are several examples: | |
| 750 | |
| 751 @example | |
| 752 @group | |
| 753 (format "The name of this buffer is %s." (buffer-name)) | |
| 754 @result{} "The name of this buffer is strings.texi." | |
| 755 | |
| 756 (format "The buffer object prints as %s." (current-buffer)) | |
| 757 @result{} "The buffer object prints as #<buffer strings.texi>." | |
| 758 | |
| 444 | 759 (format "The octal value of %d is %o, |
| 428 | 760 and the hex value is %x." 18 18 18) |
| 444 | 761 @result{} "The octal value of 18 is 22, |
| 428 | 762 and the hex value is 12." |
| 763 @end group | |
| 764 @end example | |
| 765 | |
| 766 There are many additional flags and specifications that can occur | |
| 767 between the @samp{%} and the format character, in the following order: | |
| 768 | |
| 769 @enumerate | |
| 770 @item | |
| 771 An optional repositioning specification, which is a positive | |
| 772 integer followed by a @samp{$}. | |
| 773 | |
| 774 @item | |
| 775 Zero or more of the optional flag characters @samp{-}, @samp{+}, | |
| 776 @samp{ }, @samp{0}, and @samp{#}. | |
| 777 | |
| 778 @item | |
| 779 An asterisk (@samp{*}, meaning that the field width is now assumed to | |
| 780 have been specified as an argument. | |
| 781 | |
| 782 @item | |
| 783 An optional minimum field width. | |
| 784 | |
| 785 @item | |
| 786 An optional precision, preceded by a @samp{.} character. | |
| 787 @end enumerate | |
| 788 | |
| 789 @cindex repositioning format arguments | |
| 790 @cindex multilingual string formatting | |
| 791 A @dfn{repositioning} specification changes which argument to | |
| 792 @code{format} is used by the current and all following format | |
| 793 specifications. Normally the first specification uses the first | |
| 794 argument, the second specification uses the second argument, etc. Using | |
| 795 a repositioning specification, you can change this. By placing a number | |
| 444 | 796 @var{n} followed by a @samp{$} between the @samp{%} and the format |
| 797 character, you cause the specification to use the @var{n}th argument. | |
| 798 The next specification will use the @var{n}+1'th argument, etc. | |
| 428 | 799 |
| 800 For example: | |
| 801 | |
| 802 @example | |
| 803 @group | |
| 804 (format "Can't find file `%s' in directory `%s'." | |
| 805 "ignatius.c" "loyola/") | |
| 806 @result{} "Can't find file `ignatius.c' in directory `loyola/'." | |
| 807 | |
| 808 (format "In directory `%2$s', the file `%1$s' was not found." | |
| 809 "ignatius.c" "loyola/") | |
| 810 @result{} "In directory `loyola/', the file `ignatius.c' was not found." | |
| 811 | |
| 812 (format | |
| 813 "The numbers %d and %d are %1$x and %x in hex and %1$o and %o in octal." | |
| 814 37 12) | |
| 815 @result{} "The numbers 37 and 12 are 25 and c in hex and 45 and 14 in octal." | |
| 816 @end group | |
| 817 @end example | |
| 818 | |
| 819 As you can see, this lets you reprocess arguments more than once or | |
| 820 reword a format specification (thereby moving the arguments around) | |
| 821 without having to actually reorder the arguments. This is especially | |
| 822 useful in translating messages from one language to another: Different | |
| 823 languages use different word orders, and this sometimes entails changing | |
| 824 the order of the arguments. By using repositioning specifications, | |
| 825 this can be accomplished without having to embed knowledge of particular | |
| 826 languages into the location in the program's code where the message is | |
| 827 displayed. | |
| 828 | |
| 829 @cindex numeric prefix | |
| 830 @cindex field width | |
| 831 @cindex padding | |
| 832 All the specification characters allow an optional numeric prefix | |
| 833 between the @samp{%} and the character, and following any repositioning | |
| 834 specification or flag. The optional numeric prefix defines the minimum | |
| 835 width for the object. If the printed representation of the object | |
| 836 contains fewer characters than this, then it is padded. The padding is | |
| 837 normally on the left, but will be on the right if the @samp{-} flag | |
| 838 character is given. The padding character is normally a space, but if | |
| 839 the @samp{0} flag character is given, zeros are used for padding. | |
| 840 | |
| 841 @example | |
| 842 (format "%06d is padded on the left with zeros" 123) | |
| 843 @result{} "000123 is padded on the left with zeros" | |
| 844 | |
| 845 (format "%-6d is padded on the right" 123) | |
| 846 @result{} "123 is padded on the right" | |
| 847 @end example | |
| 848 | |
| 849 @code{format} never truncates an object's printed representation, no | |
| 850 matter what width you specify. Thus, you can use a numeric prefix to | |
| 851 specify a minimum spacing between columns with no risk of losing | |
| 852 information. | |
| 853 | |
| 854 In the following three examples, @samp{%7s} specifies a minimum width | |
| 855 of 7. In the first case, the string inserted in place of @samp{%7s} has | |
| 856 only 3 letters, so 4 blank spaces are inserted for padding. In the | |
| 857 second case, the string @code{"specification"} is 13 letters wide but is | |
| 858 not truncated. In the third case, the padding is on the right. | |
| 859 | |
| 444 | 860 @smallexample |
| 428 | 861 @group |
| 862 (format "The word `%7s' actually has %d letters in it." | |
| 863 "foo" (length "foo")) | |
| 444 | 864 @result{} "The word ` foo' actually has 3 letters in it." |
| 428 | 865 @end group |
| 866 | |
| 867 @group | |
| 868 (format "The word `%7s' actually has %d letters in it." | |
| 444 | 869 "specification" (length "specification")) |
| 870 @result{} "The word `specification' actually has 13 letters in it." | |
| 428 | 871 @end group |
| 872 | |
| 873 @group | |
| 874 (format "The word `%-7s' actually has %d letters in it." | |
| 875 "foo" (length "foo")) | |
| 444 | 876 @result{} "The word `foo ' actually has 3 letters in it." |
| 428 | 877 @end group |
| 878 @end smallexample | |
| 879 | |
| 880 @cindex format precision | |
| 881 @cindex precision of formatted numbers | |
| 882 After any minimum field width, a precision may be specified by | |
| 883 preceding it with a @samp{.} character. The precision specifies the | |
| 884 minimum number of digits to appear in @samp{%d}, @samp{%i}, @samp{%o}, | |
| 885 @samp{%x}, and @samp{%X} conversions (the number is padded on the left | |
| 886 with zeroes as necessary); the number of digits printed after the | |
| 887 decimal point for @samp{%f}, @samp{%e}, and @samp{%E} conversions; the | |
| 888 number of significant digits printed in @samp{%g} and @samp{%G} | |
| 889 conversions; and the maximum number of non-padding characters printed in | |
| 890 @samp{%s} and @samp{%S} conversions. The default precision for | |
| 891 floating-point conversions is six. | |
| 892 | |
| 893 The other flag characters have the following meanings: | |
| 894 | |
| 895 @itemize @bullet | |
| 896 @item | |
| 897 The @samp{ } flag means prefix non-negative numbers with a space. | |
| 898 | |
| 899 @item | |
| 900 The @samp{+} flag means prefix non-negative numbers with a plus sign. | |
| 901 | |
| 902 @item | |
| 903 The @samp{#} flag means print numbers in an alternate, more verbose | |
| 904 format: octal numbers begin with zero; hex numbers begin with a | |
| 905 @samp{0x} or @samp{0X}; a decimal point is printed in @samp{%f}, | |
| 906 @samp{%e}, and @samp{%E} conversions even if no numbers are printed | |
| 907 after it; and trailing zeroes are not omitted in @samp{%g} and @samp{%G} | |
| 908 conversions. | |
| 909 @end itemize | |
| 910 | |
| 911 @node Character Case | |
| 912 @section Character Case | |
| 444 | 913 @cindex upper case |
| 914 @cindex lower case | |
| 915 @cindex character case | |
| 428 | 916 |
| 917 The character case functions change the case of single characters or | |
| 918 of the contents of strings. The functions convert only alphabetic | |
| 919 characters (the letters @samp{A} through @samp{Z} and @samp{a} through | |
| 920 @samp{z}); other characters are not altered. The functions do not | |
| 921 modify the strings that are passed to them as arguments. | |
| 922 | |
| 923 The examples below use the characters @samp{X} and @samp{x} which have | |
| 924 @sc{ascii} codes 88 and 120 respectively. | |
| 925 | |
| 444 | 926 @defun downcase string-or-char &optional buffer |
| 428 | 927 This function converts a character or a string to lower case. |
| 928 | |
| 929 When the argument to @code{downcase} is a string, the function creates | |
| 930 and returns a new string in which each letter in the argument that is | |
| 931 upper case is converted to lower case. When the argument to | |
| 932 @code{downcase} is a character, @code{downcase} returns the | |
| 933 corresponding lower case character. (This value is actually an integer | |
| 934 under XEmacs 19.) If the original character is lower case, or is not a | |
| 935 letter, then the value equals the original character. | |
| 936 | |
| 444 | 937 Optional second arg @var{buffer} specifies which buffer's case tables to |
| 938 use, and defaults to the current buffer. | |
| 939 | |
| 428 | 940 @example |
| 941 (downcase "The cat in the hat") | |
| 942 @result{} "the cat in the hat" | |
| 943 | |
| 944 (downcase ?X) | |
| 945 @result{} ?x ;; @r{Under XEmacs 20.} | |
| 946 @result{} 120 ;; @r{Under XEmacs 19.} | |
| 947 | |
| 948 @end example | |
| 949 @end defun | |
| 950 | |
| 444 | 951 @defun upcase string-or-char &optional buffer |
| 428 | 952 This function converts a character or a string to upper case. |
| 953 | |
| 954 When the argument to @code{upcase} is a string, the function creates | |
| 955 and returns a new string in which each letter in the argument that is | |
| 956 lower case is converted to upper case. | |
| 957 | |
| 958 When the argument to @code{upcase} is a character, @code{upcase} returns | |
| 959 the corresponding upper case character. (This value is actually an | |
| 960 integer under XEmacs 19.) If the original character is upper case, or | |
| 961 is not a letter, then the value equals the original character. | |
| 962 | |
| 444 | 963 Optional second arg @var{buffer} specifies which buffer's case tables to |
| 964 use, and defaults to the current buffer. | |
| 965 | |
| 428 | 966 @example |
| 967 (upcase "The cat in the hat") | |
| 968 @result{} "THE CAT IN THE HAT" | |
| 969 | |
| 970 (upcase ?x) | |
| 971 @result{} ?X ;; @r{Under XEmacs 20.} | |
| 972 @result{} 88 ;; @r{Under XEmacs 19.} | |
| 973 @end example | |
| 974 @end defun | |
| 975 | |
| 444 | 976 @defun capitalize string-or-char &optional buffer |
| 428 | 977 @cindex capitalization |
| 978 This function capitalizes strings or characters. If | |
| 979 @var{string-or-char} is a string, the function creates and returns a new | |
| 980 string, whose contents are a copy of @var{string-or-char} in which each | |
| 981 word has been capitalized. This means that the first character of each | |
| 982 word is converted to upper case, and the rest are converted to lower | |
| 983 case. | |
| 984 | |
| 985 The definition of a word is any sequence of consecutive characters that | |
| 986 are assigned to the word constituent syntax class in the current syntax | |
| 987 table (@pxref{Syntax Class Table}). | |
| 988 | |
| 989 When the argument to @code{capitalize} is a character, @code{capitalize} | |
| 990 has the same result as @code{upcase}. | |
| 991 | |
| 444 | 992 Optional second arg @var{buffer} specifies which buffer's case tables to |
| 993 use, and defaults to the current buffer. | |
| 994 | |
| 428 | 995 @example |
| 996 (capitalize "The cat in the hat") | |
| 997 @result{} "The Cat In The Hat" | |
| 998 | |
| 999 (capitalize "THE 77TH-HATTED CAT") | |
| 1000 @result{} "The 77th-Hatted Cat" | |
| 1001 | |
| 1002 @group | |
| 1003 (capitalize ?x) | |
| 1004 @result{} ?X ;; @r{Under XEmacs 20.} | |
| 1005 @result{} 88 ;; @r{Under XEmacs 19.} | |
| 1006 @end group | |
| 1007 @end example | |
| 1008 @end defun | |
| 1009 | |
| 1010 @node Case Tables | |
| 1011 @section The Case Table | |
| 1012 | |
| 1013 You can customize case conversion by installing a special @dfn{case | |
| 1014 table}. A case table specifies the mapping between upper case and lower | |
| 1015 case letters. It affects both the string and character case conversion | |
| 1016 functions (see the previous section) and those that apply to text in the | |
| 1017 buffer (@pxref{Case Changes}). You need a case table if you are using a | |
| 1018 language which has letters other than the standard @sc{ascii} letters. | |
| 1019 | |
| 1020 A case table is a list of this form: | |
| 1021 | |
| 1022 @example | |
| 1023 (@var{downcase} @var{upcase} @var{canonicalize} @var{equivalences}) | |
| 1024 @end example | |
| 1025 | |
| 1026 @noindent | |
| 1027 where each element is either @code{nil} or a string of length 256. The | |
| 1028 element @var{downcase} says how to map each character to its lower-case | |
| 1029 equivalent. The element @var{upcase} maps each character to its | |
| 1030 upper-case equivalent. If lower and upper case characters are in | |
| 1031 one-to-one correspondence, use @code{nil} for @var{upcase}; then XEmacs | |
| 1032 deduces the upcase table from @var{downcase}. | |
| 1033 | |
| 1034 For some languages, upper and lower case letters are not in one-to-one | |
| 1035 correspondence. There may be two different lower case letters with the | |
| 1036 same upper case equivalent. In these cases, you need to specify the | |
| 1037 maps for both directions. | |
| 1038 | |
| 1039 The element @var{canonicalize} maps each character to a canonical | |
| 1040 equivalent; any two characters that are related by case-conversion have | |
| 1041 the same canonical equivalent character. | |
| 1042 | |
| 1043 The element @var{equivalences} is a map that cyclicly permutes each | |
| 1044 equivalence class (of characters with the same canonical equivalent). | |
| 1045 (For ordinary @sc{ascii}, this would map @samp{a} into @samp{A} and | |
| 1046 @samp{A} into @samp{a}, and likewise for each set of equivalent | |
| 1047 characters.) | |
| 1048 | |
| 1049 When you construct a case table, you can provide @code{nil} for | |
| 1050 @var{canonicalize}; then Emacs fills in this string from @var{upcase} | |
| 1051 and @var{downcase}. You can also provide @code{nil} for | |
| 1052 @var{equivalences}; then Emacs fills in this string from | |
| 1053 @var{canonicalize}. In a case table that is actually in use, those | |
| 1054 components are non-@code{nil}. Do not try to specify @var{equivalences} | |
| 1055 without also specifying @var{canonicalize}. | |
| 1056 | |
| 1057 Each buffer has a case table. XEmacs also has a @dfn{standard case | |
| 1058 table} which is copied into each buffer when you create the buffer. | |
| 1059 Changing the standard case table doesn't affect any existing buffers. | |
| 1060 | |
| 1061 Here are the functions for working with case tables: | |
| 1062 | |
| 1063 @defun case-table-p object | |
| 1064 This predicate returns non-@code{nil} if @var{object} is a valid case | |
| 1065 table. | |
| 1066 @end defun | |
| 1067 | |
| 444 | 1068 @defun set-standard-case-table case-table |
| 1069 This function makes @var{case-table} the standard case table, so that it | |
| 1070 will apply to any buffers created subsequently. | |
| 428 | 1071 @end defun |
| 1072 | |
| 1073 @defun standard-case-table | |
| 1074 This returns the standard case table. | |
| 1075 @end defun | |
| 1076 | |
| 444 | 1077 @defun current-case-table &optional buffer |
| 1078 This function returns the case table of @var{buffer}, which defaults to | |
| 1079 the current buffer. | |
| 428 | 1080 @end defun |
| 1081 | |
| 444 | 1082 @defun set-case-table case-table |
| 1083 This sets the current buffer's case table to @var{case-table}. | |
| 428 | 1084 @end defun |
| 1085 | |
| 1086 The following three functions are convenient subroutines for packages | |
| 1087 that define non-@sc{ascii} character sets. They modify a string | |
| 1088 @var{downcase-table} provided as an argument; this should be a string to | |
| 1089 be used as the @var{downcase} part of a case table. They also modify | |
| 1090 the standard syntax table. @xref{Syntax Tables}. | |
| 1091 | |
| 1092 @defun set-case-syntax-pair uc lc downcase-table | |
| 1093 This function specifies a pair of corresponding letters, one upper case | |
| 1094 and one lower case. | |
| 1095 @end defun | |
| 1096 | |
| 1097 @defun set-case-syntax-delims l r downcase-table | |
| 1098 This function makes characters @var{l} and @var{r} a matching pair of | |
| 1099 case-invariant delimiters. | |
| 1100 @end defun | |
| 1101 | |
| 1102 @defun set-case-syntax char syntax downcase-table | |
| 1103 This function makes @var{char} case-invariant, with syntax | |
| 1104 @var{syntax}. | |
| 1105 @end defun | |
| 1106 | |
| 1107 @deffn Command describe-buffer-case-table | |
| 1108 This command displays a description of the contents of the current | |
| 1109 buffer's case table. | |
| 1110 @end deffn | |
| 1111 | |
| 1112 @cindex ISO Latin 1 | |
| 1113 @pindex iso-syntax | |
| 1114 You can load the library @file{iso-syntax} to set up the standard syntax | |
| 1115 table and define a case table for the 8-bit ISO Latin 1 character set. | |
| 1116 | |
| 1117 @node Char Tables | |
| 1118 @section The Char Table | |
| 1119 | |
| 1120 A char table is a table that maps characters (or ranges of characters) | |
| 1121 to values. Char tables are specialized for characters, only allowing | |
| 1122 particular sorts of ranges to be assigned values. Although this | |
| 1123 loses in generality, it makes for extremely fast (constant-time) | |
| 1124 lookups, and thus is feasible for applications that do an extremely | |
| 1125 large number of lookups (e.g. scanning a buffer for a character in | |
| 1126 a particular syntax, where a lookup in the syntax table must occur | |
| 1127 once per character). | |
| 1128 | |
| 1129 Note that char tables as a primitive type, and all of the functions in | |
| 1130 this section, exist only in XEmacs 20. In XEmacs 19, char tables are | |
| 1131 generally implemented using a vector of 256 elements. | |
| 1132 | |
| 1133 When @sc{mule} support exists, the types of ranges that can be assigned | |
| 1134 values are | |
| 1135 | |
| 1136 @itemize @bullet | |
| 1137 @item | |
| 1138 all characters | |
| 1139 @item | |
| 1140 an entire charset | |
| 1141 @item | |
| 1142 a single row in a two-octet charset | |
| 1143 @item | |
| 1144 a single character | |
| 1145 @end itemize | |
| 1146 | |
| 1147 When @sc{mule} support is not present, the types of ranges that can be | |
| 1148 assigned values are | |
| 1149 | |
| 1150 @itemize @bullet | |
| 1151 @item | |
| 1152 all characters | |
| 1153 @item | |
| 1154 a single character | |
| 1155 @end itemize | |
| 1156 | |
| 1157 @defun char-table-p object | |
| 1158 This function returns non-@code{nil} if @var{object} is a char table. | |
| 1159 @end defun | |
| 1160 | |
| 1161 @menu | |
| 1162 * Char Table Types:: Char tables have different uses. | |
| 1163 * Working With Char Tables:: Creating and working with char tables. | |
| 1164 @end menu | |
| 1165 | |
| 1166 @node Char Table Types | |
| 1167 @subsection Char Table Types | |
| 1168 | |
| 1169 Each char table type is used for a different purpose and allows different | |
| 1170 sorts of values. The different char table types are | |
| 1171 | |
| 1172 @table @code | |
| 1173 @item category | |
| 1174 Used for category tables, which specify the regexp categories | |
| 1175 that a character is in. The valid values are @code{nil} or a | |
| 1176 bit vector of 95 elements. Higher-level Lisp functions are | |
| 1177 provided for working with category tables. Currently categories | |
| 1178 and category tables only exist when @sc{mule} support is present. | |
| 1179 @item char | |
| 1180 A generalized char table, for mapping from one character to | |
| 1181 another. Used for case tables, syntax matching tables, | |
| 1182 @code{keyboard-translate-table}, etc. The valid values are characters. | |
| 1183 @item generic | |
| 1184 An even more generalized char table, for mapping from a | |
| 1185 character to anything. | |
| 1186 @item display | |
| 1187 Used for display tables, which specify how a particular character | |
| 1188 is to appear when displayed. #### Not yet implemented. | |
| 1189 @item syntax | |
| 1190 Used for syntax tables, which specify the syntax of a particular | |
| 1191 character. Higher-level Lisp functions are provided for | |
| 1192 working with syntax tables. The valid values are integers. | |
| 1193 @end table | |
| 1194 | |
| 444 | 1195 @defun char-table-type char-table |
| 1196 This function returns the type of char table @var{char-table}. | |
| 428 | 1197 @end defun |
| 1198 | |
| 1199 @defun char-table-type-list | |
| 1200 This function returns a list of the recognized char table types. | |
| 1201 @end defun | |
| 1202 | |
| 1203 @defun valid-char-table-type-p type | |
| 1204 This function returns @code{t} if @var{type} if a recognized char table type. | |
| 1205 @end defun | |
| 1206 | |
| 1207 @node Working With Char Tables | |
| 1208 @subsection Working With Char Tables | |
| 1209 | |
| 1210 @defun make-char-table type | |
| 1211 This function makes a new, empty char table of type @var{type}. | |
| 1212 @var{type} should be a symbol, one of @code{char}, @code{category}, | |
| 1213 @code{display}, @code{generic}, or @code{syntax}. | |
| 1214 @end defun | |
| 1215 | |
| 444 | 1216 @defun put-char-table range value char-table |
| 1217 This function sets the value for chars in @var{range} to be @var{value} in | |
| 1218 @var{char-table}. | |
| 428 | 1219 |
| 1220 @var{range} specifies one or more characters to be affected and should be | |
| 1221 one of the following: | |
| 1222 | |
| 1223 @itemize @bullet | |
| 1224 @item | |
| 1225 @code{t} (all characters are affected) | |
| 1226 @item | |
| 1227 A charset (only allowed when @sc{mule} support is present) | |
| 1228 @item | |
| 1229 A vector of two elements: a two-octet charset and a row number | |
| 1230 (only allowed when @sc{mule} support is present) | |
| 1231 @item | |
| 1232 A single character | |
| 1233 @end itemize | |
| 1234 | |
| 444 | 1235 @var{value} must be a value appropriate for the type of @var{char-table}. |
| 428 | 1236 @end defun |
| 1237 | |
| 444 | 1238 @defun get-char-table character char-table |
| 1239 This function finds the value for @var{character} in @var{char-table}. | |
| 428 | 1240 @end defun |
| 1241 | |
| 444 | 1242 @defun get-range-char-table range char-table &optional multi |
| 1243 This function finds the value for a range in @var{char-table}. If there is | |
| 428 | 1244 more than one value, @var{multi} is returned (defaults to @code{nil}). |
| 1245 @end defun | |
| 1246 | |
| 444 | 1247 @defun reset-char-table char-table |
| 1248 This function resets @var{char-table} to its default state. | |
| 428 | 1249 @end defun |
| 1250 | |
| 444 | 1251 @defun map-char-table function char-table &optional range |
| 1252 This function maps @var{function} over entries in @var{char-table}, calling | |
| 428 | 1253 it with two args, each key and value in the table. |
| 1254 | |
| 1255 @var{range} specifies a subrange to map over and is in the same format | |
| 1256 as the @var{range} argument to @code{put-range-table}. If omitted or | |
| 1257 @code{t}, it defaults to the entire table. | |
| 1258 @end defun | |
| 1259 | |
| 1260 @defun valid-char-table-value-p value char-table-type | |
| 1261 This function returns non-@code{nil} if @var{value} is a valid value for | |
| 1262 @var{char-table-type}. | |
| 1263 @end defun | |
| 1264 | |
| 1265 @defun check-valid-char-table-value value char-table-type | |
| 1266 This function signals an error if @var{value} is not a valid value for | |
| 1267 @var{char-table-type}. | |
| 1268 @end defun |