Mercurial > hg > xemacs-beta
annotate man/lispref/strings.texi @ 5044:e84a30b0e4a2
remove duplicative code in change_frame_size()
-------------------- ChangeLog entries follow: --------------------
src/ChangeLog addition:
2010-02-15 Ben Wing <ben@xemacs.org>
* frame.c (change_frame_size_1):
Simplify the logic in this function.
(1) Don't allow 0 as the value of height or width. The old code
that tried to allow this was totally broken, anyway, so obviously
this never happens any more.
(2) Don't duplicate the code in frame_conversion_internal() that
converts displayable pixel size to total pixel size -- just call
that function.
| author | Ben Wing <ben@xemacs.org> |
|---|---|
| date | Mon, 15 Feb 2010 22:58:10 -0600 |
| parents | 6772ce4d982b |
| children | 99f8ebc082d9 |
| 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 | |
|
4885
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Fix hash tables, #'member*, #'assoc*, #'eql compiler macros if bignums
Aidan Kehoe <kehoea@parhasard.net>
parents:
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diff
changeset
|
148 non-negative fixnum. |
| 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 | |
|
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Aidan Kehoe <kehoea@parhasard.net>
parents:
4329
diff
changeset
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227 @var{end} is not a fixnum or @code{nil}. An @code{args-out-of-range} |
| 428 | 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" | |
|
4885
6772ce4d982b
Fix hash tables, #'member*, #'assoc*, #'eql compiler macros if bignums
Aidan Kehoe <kehoea@parhasard.net>
parents:
4329
diff
changeset
|
249 (equal (concat "abc" (list 120 (+ 256 121)) [122]) (format "abcx%cz" 377)) |
|
6772ce4d982b
Fix hash tables, #'member*, #'assoc*, #'eql compiler macros if bignums
Aidan Kehoe <kehoea@parhasard.net>
parents:
4329
diff
changeset
|
250 @result{} t |
| 428 | 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 @code{concat} function always constructs a new string that is | |
| 262 not @code{eq} to any existing string. | |
| 263 | |
| 264 For information about other concatenation functions, see the description | |
| 265 of @code{mapconcat} in @ref{Mapping Functions}, @code{vconcat} in | |
| 266 @ref{Vectors}, @code{bvconcat} in @ref{Bit Vectors}, and @code{append} | |
| 267 in @ref{Building Lists}. | |
| 268 @end defun | |
| 269 | |
| 1495 | 270 The function @code{split-string}, in @ref{Regexp Search}, generates a |
| 271 list of strings by splitting a string on occurances of a regular | |
| 272 expression. | |
| 273 | |
| 428 | 274 @node Predicates for Characters |
| 275 @section The Predicates for Characters | |
| 276 | |
| 277 @defun characterp object | |
| 278 This function returns @code{t} if @var{object} is a character. | |
| 279 | |
| 280 Some functions that work on integers (e.g. the comparison functions | |
| 281 <, <=, =, /=, etc. and the arithmetic functions +, -, *, etc.) | |
| 282 accept characters and implicitly convert them into integers. In | |
| 283 general, functions that work on characters also accept char-ints and | |
| 284 implicitly convert them into characters. WARNING: Neither of these | |
| 285 behaviors is very desirable, and they are maintained for backward | |
| 286 compatibility with old E-Lisp programs that confounded characters and | |
| 287 integers willy-nilly. These behaviors may change in the future; therefore, | |
| 288 do not rely on them. Instead, convert the characters explicitly | |
| 289 using @code{char-int}. | |
| 290 @end defun | |
| 291 | |
| 292 @defun integer-or-char-p object | |
| 293 This function returns @code{t} if @var{object} is an integer or character. | |
| 294 @end defun | |
| 295 | |
| 296 @node Character Codes | |
| 297 @section Character Codes | |
| 298 | |
| 444 | 299 @defun char-int character |
| 428 | 300 This function converts a character into an equivalent integer. |
| 301 The resulting integer will always be non-negative. The integers in | |
| 302 the range 0 - 255 map to characters as follows: | |
| 303 | |
| 304 @table @asis | |
| 305 @item 0 - 31 | |
| 306 Control set 0 | |
| 307 @item 32 - 127 | |
| 308 @sc{ascii} | |
| 309 @item 128 - 159 | |
| 310 Control set 1 | |
| 311 @item 160 - 255 | |
| 312 Right half of ISO-8859-1 | |
| 313 @end table | |
| 314 | |
| 315 If support for @sc{mule} does not exist, these are the only valid | |
| 316 character values. When @sc{mule} support exists, the values assigned to | |
| 317 other characters may vary depending on the particular version of XEmacs, | |
| 318 the order in which character sets were loaded, etc., and you should not | |
| 319 depend on them. | |
| 320 @end defun | |
| 321 | |
| 322 @defun int-char integer | |
| 323 This function converts an integer into the equivalent character. Not | |
| 324 all integers correspond to valid characters; use @code{char-int-p} to | |
| 325 determine whether this is the case. If the integer cannot be converted, | |
| 326 @code{nil} is returned. | |
| 327 @end defun | |
| 328 | |
| 329 @defun char-int-p object | |
| 330 This function returns @code{t} if @var{object} is an integer that can be | |
| 331 converted into a character. | |
| 332 @end defun | |
| 333 | |
| 334 @defun char-or-char-int-p object | |
| 335 This function returns @code{t} if @var{object} is a character or an | |
| 336 integer that can be converted into one. | |
| 337 @end defun | |
| 338 | |
| 339 @need 2000 | |
| 340 @node Text Comparison | |
| 341 @section Comparison of Characters and Strings | |
| 342 @cindex string equality | |
| 343 | |
| 444 | 344 @defun char-equal character1 character2 &optional buffer |
| 428 | 345 This function returns @code{t} if the arguments represent the same |
| 346 character, @code{nil} otherwise. This function ignores differences | |
| 444 | 347 in case if the value of @code{case-fold-search} is non-@code{nil} in |
| 348 @var{buffer}, which defaults to the current buffer. | |
| 428 | 349 |
| 350 @example | |
| 351 (char-equal ?x ?x) | |
| 352 @result{} t | |
| 353 (let ((case-fold-search t)) | |
| 354 (char-equal ?x ?X)) | |
| 355 @result{} t | |
| 356 (let ((case-fold-search nil)) | |
| 357 (char-equal ?x ?X)) | |
| 358 @result{} nil | |
| 359 @end example | |
| 360 @end defun | |
| 361 | |
| 362 @defun char= character1 character2 | |
| 363 This function returns @code{t} if the arguments represent the same | |
| 364 character, @code{nil} otherwise. Case is significant. | |
| 365 | |
| 366 @example | |
| 367 (char= ?x ?x) | |
| 368 @result{} t | |
| 369 (char= ?x ?X) | |
| 370 @result{} nil | |
| 371 (let ((case-fold-search t)) | |
| 372 (char-equal ?x ?X)) | |
| 373 @result{} nil | |
| 374 (let ((case-fold-search nil)) | |
| 375 (char-equal ?x ?X)) | |
| 376 @result{} nil | |
| 377 @end example | |
| 378 @end defun | |
| 379 | |
| 380 @defun string= string1 string2 | |
| 381 This function returns @code{t} if the characters of the two strings | |
| 382 match exactly; case is significant. | |
| 383 | |
| 384 @example | |
| 385 (string= "abc" "abc") | |
| 386 @result{} t | |
| 387 (string= "abc" "ABC") | |
| 388 @result{} nil | |
| 389 (string= "ab" "ABC") | |
| 390 @result{} nil | |
| 391 @end example | |
| 392 | |
| 393 @ignore @c `equal' in XEmacs does not compare text properties | |
| 394 The function @code{string=} ignores the text properties of the | |
| 395 two strings. To compare strings in a way that compares their text | |
| 396 properties also, use @code{equal} (@pxref{Equality Predicates}). | |
| 397 @end ignore | |
| 398 @end defun | |
| 399 | |
| 400 @defun string-equal string1 string2 | |
| 401 @code{string-equal} is another name for @code{string=}. | |
| 402 @end defun | |
| 403 | |
| 404 @cindex lexical comparison | |
| 405 @defun string< string1 string2 | |
| 406 @c (findex string< causes problems for permuted index!!) | |
| 407 This function compares two strings a character at a time. First it | |
| 408 scans both the strings at once to find the first pair of corresponding | |
| 409 characters that do not match. If the lesser character of those two is | |
| 410 the character from @var{string1}, then @var{string1} is less, and this | |
| 411 function returns @code{t}. If the lesser character is the one from | |
| 412 @var{string2}, then @var{string1} is greater, and this function returns | |
| 413 @code{nil}. If the two strings match entirely, the value is @code{nil}. | |
| 414 | |
| 415 Pairs of characters are compared by their @sc{ascii} codes. Keep in | |
| 416 mind that lower case letters have higher numeric values in the | |
| 417 @sc{ascii} character set than their upper case counterparts; numbers and | |
| 418 many punctuation characters have a lower numeric value than upper case | |
| 419 letters. | |
| 420 | |
| 421 @example | |
| 422 @group | |
| 423 (string< "abc" "abd") | |
| 424 @result{} t | |
| 425 (string< "abd" "abc") | |
| 426 @result{} nil | |
| 427 (string< "123" "abc") | |
| 428 @result{} t | |
| 429 @end group | |
| 430 @end example | |
| 431 | |
| 432 When the strings have different lengths, and they match up to the | |
| 433 length of @var{string1}, then the result is @code{t}. If they match up | |
| 434 to the length of @var{string2}, the result is @code{nil}. A string of | |
| 435 no characters is less than any other string. | |
| 436 | |
| 437 @example | |
| 438 @group | |
| 439 (string< "" "abc") | |
| 440 @result{} t | |
| 441 (string< "ab" "abc") | |
| 442 @result{} t | |
| 443 (string< "abc" "") | |
| 444 @result{} nil | |
| 445 (string< "abc" "ab") | |
| 446 @result{} nil | |
| 447 (string< "" "") | |
| 444 | 448 @result{} nil |
| 428 | 449 @end group |
| 450 @end example | |
| 451 @end defun | |
| 452 | |
| 453 @defun string-lessp string1 string2 | |
| 454 @code{string-lessp} is another name for @code{string<}. | |
| 455 @end defun | |
| 456 | |
| 457 See also @code{compare-buffer-substrings} in @ref{Comparing Text}, for | |
| 458 a way to compare text in buffers. The function @code{string-match}, | |
| 459 which matches a regular expression against a string, can be used | |
| 460 for a kind of string comparison; see @ref{Regexp Search}. | |
| 461 | |
| 462 @node String Conversion | |
| 463 @section Conversion of Characters and Strings | |
| 464 @cindex conversion of strings | |
| 465 | |
| 466 This section describes functions for conversions between characters, | |
| 467 strings and integers. @code{format} and @code{prin1-to-string} | |
| 468 (@pxref{Output Functions}) can also convert Lisp objects into strings. | |
| 469 @code{read-from-string} (@pxref{Input Functions}) can ``convert'' a | |
| 470 string representation of a Lisp object into an object. | |
| 471 | |
| 472 @xref{Documentation}, for functions that produce textual descriptions | |
| 473 of text characters and general input events | |
| 474 (@code{single-key-description} and @code{text-char-description}). These | |
| 475 functions are used primarily for making help messages. | |
| 476 | |
| 477 @defun char-to-string character | |
| 478 @cindex character to string | |
| 479 This function returns a new string with a length of one character. | |
| 480 The value of @var{character}, modulo 256, is used to initialize the | |
| 481 element of the string. | |
| 482 | |
| 483 This function is similar to @code{make-string} with an integer argument | |
| 484 of 1. (@xref{Creating Strings}.) This conversion can also be done with | |
| 485 @code{format} using the @samp{%c} format specification. | |
| 486 (@xref{Formatting Strings}.) | |
| 487 | |
| 488 @example | |
| 489 (char-to-string ?x) | |
| 490 @result{} "x" | |
| 491 (char-to-string (+ 256 ?x)) | |
| 492 @result{} "x" | |
| 493 (make-string 1 ?x) | |
| 494 @result{} "x" | |
| 495 @end example | |
| 496 @end defun | |
| 497 | |
| 498 @defun string-to-char string | |
| 499 @cindex string to character | |
| 500 This function returns the first character in @var{string}. If the | |
| 501 string is empty, the function returns 0. (Under XEmacs 19, the value is | |
| 502 also 0 when the first character of @var{string} is the null character, | |
| 503 @sc{ascii} code 0.) | |
| 504 | |
| 505 @example | |
| 506 (string-to-char "ABC") | |
| 507 @result{} ?A ;; @r{Under XEmacs 20.} | |
| 508 @result{} 65 ;; @r{Under XEmacs 19.} | |
| 509 (string-to-char "xyz") | |
| 510 @result{} ?x ;; @r{Under XEmacs 20.} | |
| 511 @result{} 120 ;; @r{Under XEmacs 19.} | |
| 512 (string-to-char "") | |
| 513 @result{} 0 | |
| 514 (string-to-char "\000") | |
| 515 @result{} ?\^@ ;; @r{Under XEmacs 20.} | |
| 516 @result{} 0 ;; @r{Under XEmacs 20.} | |
| 517 @end example | |
| 518 | |
| 519 This function may be eliminated in the future if it does not seem useful | |
| 520 enough to retain. | |
| 521 @end defun | |
| 522 | |
| 523 @defun number-to-string number | |
| 524 @cindex integer to string | |
| 525 @cindex integer to decimal | |
| 526 This function returns a string consisting of the printed | |
| 527 representation of @var{number}, which may be an integer or a floating | |
| 528 point number. The value starts with a sign if the argument is | |
| 529 negative. | |
| 530 | |
| 531 @example | |
| 532 (number-to-string 256) | |
| 533 @result{} "256" | |
| 534 (number-to-string -23) | |
| 535 @result{} "-23" | |
| 536 (number-to-string -23.5) | |
| 537 @result{} "-23.5" | |
| 538 @end example | |
| 539 | |
| 540 @cindex int-to-string | |
| 541 @code{int-to-string} is a semi-obsolete alias for this function. | |
| 542 | |
| 543 See also the function @code{format} in @ref{Formatting Strings}. | |
| 544 @end defun | |
| 545 | |
| 546 @defun string-to-number string &optional base | |
| 547 @cindex string to number | |
| 444 | 548 This function returns the numeric value represented by @var{string}, |
| 549 read in @var{base}. It skips spaces and tabs at the beginning of | |
| 550 @var{string}, then reads as much of @var{string} as it can interpret as | |
| 551 a number. (On some systems it ignores other whitespace at the | |
| 552 beginning, not just spaces and tabs.) If the first character after the | |
| 553 ignored whitespace is not a digit or a minus sign, this function returns | |
| 554 0. | |
| 428 | 555 |
| 556 If @var{base} is not specified, it defaults to ten. With @var{base} | |
| 557 other than ten, only integers can be read. | |
| 558 | |
| 559 @example | |
| 560 (string-to-number "256") | |
| 561 @result{} 256 | |
| 562 (string-to-number "25 is a perfect square.") | |
| 563 @result{} 25 | |
| 564 (string-to-number "X256") | |
| 565 @result{} 0 | |
| 566 (string-to-number "-4.5") | |
| 567 @result{} -4.5 | |
| 568 (string-to-number "ffff" 16) | |
| 569 @result{} 65535 | |
| 570 @end example | |
| 571 | |
| 572 @findex string-to-int | |
| 573 @code{string-to-int} is an obsolete alias for this function. | |
| 574 @end defun | |
| 575 | |
| 576 @node Modifying Strings | |
| 577 @section Modifying Strings | |
| 578 @cindex strings, modifying | |
| 579 | |
| 580 You can modify a string using the general array-modifying primitives. | |
| 581 @xref{Arrays}. The function @code{aset} modifies a single character; | |
| 582 the function @code{fillarray} sets all characters in the string to | |
| 583 a specified character. | |
| 584 | |
| 585 Each string has a tick counter that starts out at zero (when the string | |
| 586 is created) and is incremented each time a change is made to that | |
| 587 string. | |
| 588 | |
| 589 @defun string-modified-tick string | |
| 590 This function returns the tick counter for @samp{string}. | |
| 591 @end defun | |
| 592 | |
| 593 @node String Properties | |
| 594 @section String Properties | |
| 595 @cindex string properties | |
| 596 @cindex properties of strings | |
| 597 | |
| 442 | 598 Just as with symbols, extents, faces, and glyphs, you can attach |
| 428 | 599 additional information to strings in the form of @dfn{string |
| 600 properties}. These differ from text properties, which are logically | |
| 601 attached to particular characters in the string. | |
| 602 | |
| 603 To attach a property to a string, use @code{put}. To retrieve a property | |
| 604 from a string, use @code{get}. You can also use @code{remprop} to remove | |
| 442 | 605 a property from a string and @code{object-plist} to retrieve a list of |
| 428 | 606 all the properties in a string. |
| 607 | |
| 608 @node Formatting Strings | |
| 609 @section Formatting Strings | |
| 610 @cindex formatting strings | |
| 611 @cindex strings, formatting them | |
| 612 | |
| 613 @dfn{Formatting} means constructing a string by substitution of | |
| 614 computed values at various places in a constant string. This string | |
| 615 controls how the other values are printed as well as where they appear; | |
| 616 it is called a @dfn{format string}. | |
| 617 | |
| 618 Formatting is often useful for computing messages to be displayed. In | |
| 619 fact, the functions @code{message} and @code{error} provide the same | |
| 620 formatting feature described here; they differ from @code{format} only | |
| 621 in how they use the result of formatting. | |
| 622 | |
| 623 @defun format string &rest objects | |
| 624 This function returns a new string that is made by copying | |
| 444 | 625 @var{string} and then replacing any format specification |
| 428 | 626 in the copy with encodings of the corresponding @var{objects}. The |
| 627 arguments @var{objects} are the computed values to be formatted. | |
| 628 @end defun | |
| 629 | |
| 630 @cindex @samp{%} in format | |
| 631 @cindex format specification | |
| 632 A format specification is a sequence of characters beginning with a | |
| 633 @samp{%}. Thus, if there is a @samp{%d} in @var{string}, the | |
| 634 @code{format} function replaces it with the printed representation of | |
| 635 one of the values to be formatted (one of the arguments @var{objects}). | |
| 636 For example: | |
| 637 | |
| 638 @example | |
| 639 @group | |
| 640 (format "The value of fill-column is %d." fill-column) | |
| 641 @result{} "The value of fill-column is 72." | |
| 642 @end group | |
| 643 @end example | |
| 644 | |
| 645 If @var{string} contains more than one format specification, the | |
| 646 format specifications correspond with successive values from | |
| 647 @var{objects}. Thus, the first format specification in @var{string} | |
| 648 uses the first such value, the second format specification uses the | |
| 649 second such value, and so on. Any extra format specifications (those | |
| 650 for which there are no corresponding values) cause unpredictable | |
| 651 behavior. Any extra values to be formatted are ignored. | |
| 652 | |
| 653 Certain format specifications require values of particular types. | |
| 654 However, no error is signaled if the value actually supplied fails to | |
| 655 have the expected type. Instead, the output is likely to be | |
| 656 meaningless. | |
| 657 | |
| 658 Here is a table of valid format specifications: | |
| 659 | |
| 660 @table @samp | |
| 661 @item %s | |
| 662 Replace the specification with the printed representation of the object, | |
| 663 made without quoting. Thus, strings are represented by their contents | |
| 664 alone, with no @samp{"} characters, and symbols appear without @samp{\} | |
| 665 characters. This is equivalent to printing the object with @code{princ}. | |
| 666 | |
| 667 If there is no corresponding object, the empty string is used. | |
| 668 | |
| 669 @item %S | |
| 670 Replace the specification with the printed representation of the object, | |
| 671 made with quoting. Thus, strings are enclosed in @samp{"} characters, | |
| 672 and @samp{\} characters appear where necessary before special characters. | |
| 673 This is equivalent to printing the object with @code{prin1}. | |
| 674 | |
| 675 If there is no corresponding object, the empty string is used. | |
| 676 | |
| 677 @item %o | |
| 678 @cindex integer to octal | |
| 679 Replace the specification with the base-eight representation of an | |
| 680 integer. | |
| 681 | |
| 682 @item %d | |
| 683 @itemx %i | |
| 684 Replace the specification with the base-ten representation of an | |
| 685 integer. | |
| 686 | |
| 687 @item %x | |
| 688 @cindex integer to hexadecimal | |
| 689 Replace the specification with the base-sixteen representation of an | |
| 690 integer, using lowercase letters. | |
| 691 | |
| 692 @item %X | |
| 693 @cindex integer to hexadecimal | |
| 694 Replace the specification with the base-sixteen representation of an | |
| 695 integer, using uppercase letters. | |
| 696 | |
|
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697 @item %b |
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698 @cindex integer to binary |
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699 Replace the specification with the base-two representation of an |
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700 integer. |
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701 |
| 428 | 702 @item %c |
| 703 Replace the specification with the character which is the value given. | |
| 704 | |
| 705 @item %e | |
| 706 Replace the specification with the exponential notation for a floating | |
| 707 point number (e.g. @samp{7.85200e+03}). | |
| 708 | |
| 709 @item %f | |
| 710 Replace the specification with the decimal-point notation for a floating | |
| 711 point number. | |
| 712 | |
| 713 @item %g | |
| 714 Replace the specification with notation for a floating point number, | |
| 715 using a ``pretty format''. Either exponential notation or decimal-point | |
| 716 notation will be used (usually whichever is shorter), and trailing | |
| 717 zeroes are removed from the fractional part. | |
| 718 | |
| 719 @item %% | |
| 720 A single @samp{%} is placed in the string. This format specification is | |
| 721 unusual in that it does not use a value. For example, @code{(format "%% | |
| 722 %d" 30)} returns @code{"% 30"}. | |
| 723 @end table | |
| 724 | |
| 725 Any other format character results in an @samp{Invalid format | |
| 726 operation} error. | |
| 727 | |
| 728 Here are several examples: | |
| 729 | |
| 730 @example | |
| 731 @group | |
| 732 (format "The name of this buffer is %s." (buffer-name)) | |
| 733 @result{} "The name of this buffer is strings.texi." | |
| 734 | |
| 735 (format "The buffer object prints as %s." (current-buffer)) | |
| 736 @result{} "The buffer object prints as #<buffer strings.texi>." | |
| 737 | |
| 444 | 738 (format "The octal value of %d is %o, |
| 428 | 739 and the hex value is %x." 18 18 18) |
| 444 | 740 @result{} "The octal value of 18 is 22, |
| 428 | 741 and the hex value is 12." |
| 742 @end group | |
| 743 @end example | |
| 744 | |
| 745 There are many additional flags and specifications that can occur | |
| 746 between the @samp{%} and the format character, in the following order: | |
| 747 | |
| 748 @enumerate | |
| 749 @item | |
| 750 An optional repositioning specification, which is a positive | |
| 751 integer followed by a @samp{$}. | |
| 752 | |
| 753 @item | |
| 754 Zero or more of the optional flag characters @samp{-}, @samp{+}, | |
| 755 @samp{ }, @samp{0}, and @samp{#}. | |
| 756 | |
| 757 @item | |
| 758 An asterisk (@samp{*}, meaning that the field width is now assumed to | |
| 759 have been specified as an argument. | |
| 760 | |
| 761 @item | |
| 762 An optional minimum field width. | |
| 763 | |
| 764 @item | |
| 765 An optional precision, preceded by a @samp{.} character. | |
| 766 @end enumerate | |
| 767 | |
| 768 @cindex repositioning format arguments | |
| 769 @cindex multilingual string formatting | |
| 770 A @dfn{repositioning} specification changes which argument to | |
| 771 @code{format} is used by the current and all following format | |
| 772 specifications. Normally the first specification uses the first | |
| 773 argument, the second specification uses the second argument, etc. Using | |
| 774 a repositioning specification, you can change this. By placing a number | |
| 444 | 775 @var{n} followed by a @samp{$} between the @samp{%} and the format |
| 776 character, you cause the specification to use the @var{n}th argument. | |
| 777 The next specification will use the @var{n}+1'th argument, etc. | |
| 428 | 778 |
| 779 For example: | |
| 780 | |
| 781 @example | |
| 782 @group | |
| 783 (format "Can't find file `%s' in directory `%s'." | |
| 784 "ignatius.c" "loyola/") | |
| 785 @result{} "Can't find file `ignatius.c' in directory `loyola/'." | |
| 786 | |
| 787 (format "In directory `%2$s', the file `%1$s' was not found." | |
| 788 "ignatius.c" "loyola/") | |
| 789 @result{} "In directory `loyola/', the file `ignatius.c' was not found." | |
| 790 | |
| 791 (format | |
| 792 "The numbers %d and %d are %1$x and %x in hex and %1$o and %o in octal." | |
| 793 37 12) | |
| 794 @result{} "The numbers 37 and 12 are 25 and c in hex and 45 and 14 in octal." | |
| 795 @end group | |
| 796 @end example | |
| 797 | |
| 798 As you can see, this lets you reprocess arguments more than once or | |
| 799 reword a format specification (thereby moving the arguments around) | |
| 800 without having to actually reorder the arguments. This is especially | |
| 801 useful in translating messages from one language to another: Different | |
| 802 languages use different word orders, and this sometimes entails changing | |
| 803 the order of the arguments. By using repositioning specifications, | |
| 804 this can be accomplished without having to embed knowledge of particular | |
| 805 languages into the location in the program's code where the message is | |
| 806 displayed. | |
| 807 | |
| 808 @cindex numeric prefix | |
| 809 @cindex field width | |
| 810 @cindex padding | |
| 811 All the specification characters allow an optional numeric prefix | |
| 812 between the @samp{%} and the character, and following any repositioning | |
| 813 specification or flag. The optional numeric prefix defines the minimum | |
| 814 width for the object. If the printed representation of the object | |
| 815 contains fewer characters than this, then it is padded. The padding is | |
| 816 normally on the left, but will be on the right if the @samp{-} flag | |
| 817 character is given. The padding character is normally a space, but if | |
| 818 the @samp{0} flag character is given, zeros are used for padding. | |
| 819 | |
| 820 @example | |
| 821 (format "%06d is padded on the left with zeros" 123) | |
| 822 @result{} "000123 is padded on the left with zeros" | |
| 823 | |
| 824 (format "%-6d is padded on the right" 123) | |
| 825 @result{} "123 is padded on the right" | |
| 826 @end example | |
| 827 | |
| 828 @code{format} never truncates an object's printed representation, no | |
| 829 matter what width you specify. Thus, you can use a numeric prefix to | |
| 830 specify a minimum spacing between columns with no risk of losing | |
| 831 information. | |
| 832 | |
| 833 In the following three examples, @samp{%7s} specifies a minimum width | |
| 834 of 7. In the first case, the string inserted in place of @samp{%7s} has | |
| 835 only 3 letters, so 4 blank spaces are inserted for padding. In the | |
| 836 second case, the string @code{"specification"} is 13 letters wide but is | |
| 837 not truncated. In the third case, the padding is on the right. | |
| 838 | |
| 444 | 839 @smallexample |
| 428 | 840 @group |
| 841 (format "The word `%7s' actually has %d letters in it." | |
| 842 "foo" (length "foo")) | |
| 444 | 843 @result{} "The word ` foo' actually has 3 letters in it." |
| 428 | 844 @end group |
| 845 | |
| 846 @group | |
| 847 (format "The word `%7s' actually has %d letters in it." | |
| 444 | 848 "specification" (length "specification")) |
| 849 @result{} "The word `specification' actually has 13 letters in it." | |
| 428 | 850 @end group |
| 851 | |
| 852 @group | |
| 853 (format "The word `%-7s' actually has %d letters in it." | |
| 854 "foo" (length "foo")) | |
| 444 | 855 @result{} "The word `foo ' actually has 3 letters in it." |
| 428 | 856 @end group |
| 857 @end smallexample | |
| 858 | |
| 859 @cindex format precision | |
| 860 @cindex precision of formatted numbers | |
| 861 After any minimum field width, a precision may be specified by | |
| 862 preceding it with a @samp{.} character. The precision specifies the | |
| 863 minimum number of digits to appear in @samp{%d}, @samp{%i}, @samp{%o}, | |
| 864 @samp{%x}, and @samp{%X} conversions (the number is padded on the left | |
| 865 with zeroes as necessary); the number of digits printed after the | |
| 866 decimal point for @samp{%f}, @samp{%e}, and @samp{%E} conversions; the | |
| 867 number of significant digits printed in @samp{%g} and @samp{%G} | |
| 868 conversions; and the maximum number of non-padding characters printed in | |
| 869 @samp{%s} and @samp{%S} conversions. The default precision for | |
| 870 floating-point conversions is six. | |
| 871 | |
| 872 The other flag characters have the following meanings: | |
| 873 | |
| 874 @itemize @bullet | |
| 875 @item | |
| 876 The @samp{ } flag means prefix non-negative numbers with a space. | |
| 877 | |
| 878 @item | |
| 879 The @samp{+} flag means prefix non-negative numbers with a plus sign. | |
| 880 | |
| 881 @item | |
| 882 The @samp{#} flag means print numbers in an alternate, more verbose | |
| 883 format: octal numbers begin with zero; hex numbers begin with a | |
| 884 @samp{0x} or @samp{0X}; a decimal point is printed in @samp{%f}, | |
| 885 @samp{%e}, and @samp{%E} conversions even if no numbers are printed | |
| 886 after it; and trailing zeroes are not omitted in @samp{%g} and @samp{%G} | |
| 887 conversions. | |
| 888 @end itemize | |
| 889 | |
| 890 @node Character Case | |
| 891 @section Character Case | |
| 444 | 892 @cindex upper case |
| 893 @cindex lower case | |
| 894 @cindex character case | |
| 428 | 895 |
| 896 The character case functions change the case of single characters or | |
| 897 of the contents of strings. The functions convert only alphabetic | |
| 898 characters (the letters @samp{A} through @samp{Z} and @samp{a} through | |
| 899 @samp{z}); other characters are not altered. The functions do not | |
| 900 modify the strings that are passed to them as arguments. | |
| 901 | |
| 902 The examples below use the characters @samp{X} and @samp{x} which have | |
| 903 @sc{ascii} codes 88 and 120 respectively. | |
| 904 | |
| 444 | 905 @defun downcase string-or-char &optional buffer |
| 428 | 906 This function converts a character or a string to lower case. |
| 907 | |
| 908 When the argument to @code{downcase} is a string, the function creates | |
| 909 and returns a new string in which each letter in the argument that is | |
| 910 upper case is converted to lower case. When the argument to | |
| 911 @code{downcase} is a character, @code{downcase} returns the | |
| 912 corresponding lower case character. (This value is actually an integer | |
| 913 under XEmacs 19.) If the original character is lower case, or is not a | |
| 914 letter, then the value equals the original character. | |
| 915 | |
| 444 | 916 Optional second arg @var{buffer} specifies which buffer's case tables to |
| 917 use, and defaults to the current buffer. | |
| 918 | |
| 428 | 919 @example |
| 920 (downcase "The cat in the hat") | |
| 921 @result{} "the cat in the hat" | |
| 922 | |
| 923 (downcase ?X) | |
| 924 @result{} ?x ;; @r{Under XEmacs 20.} | |
| 925 @result{} 120 ;; @r{Under XEmacs 19.} | |
| 926 | |
| 927 @end example | |
| 928 @end defun | |
| 929 | |
| 444 | 930 @defun upcase string-or-char &optional buffer |
| 428 | 931 This function converts a character or a string to upper case. |
| 932 | |
| 933 When the argument to @code{upcase} is a string, the function creates | |
| 934 and returns a new string in which each letter in the argument that is | |
| 935 lower case is converted to upper case. | |
| 936 | |
| 937 When the argument to @code{upcase} is a character, @code{upcase} returns | |
| 938 the corresponding upper case character. (This value is actually an | |
| 939 integer under XEmacs 19.) If the original character is upper case, or | |
| 940 is not a letter, then the value equals the original character. | |
| 941 | |
| 444 | 942 Optional second arg @var{buffer} specifies which buffer's case tables to |
| 943 use, and defaults to the current buffer. | |
| 944 | |
| 428 | 945 @example |
| 946 (upcase "The cat in the hat") | |
| 947 @result{} "THE CAT IN THE HAT" | |
| 948 | |
| 949 (upcase ?x) | |
| 950 @result{} ?X ;; @r{Under XEmacs 20.} | |
| 951 @result{} 88 ;; @r{Under XEmacs 19.} | |
| 952 @end example | |
| 953 @end defun | |
| 954 | |
| 444 | 955 @defun capitalize string-or-char &optional buffer |
| 428 | 956 @cindex capitalization |
| 957 This function capitalizes strings or characters. If | |
| 958 @var{string-or-char} is a string, the function creates and returns a new | |
| 959 string, whose contents are a copy of @var{string-or-char} in which each | |
| 960 word has been capitalized. This means that the first character of each | |
| 961 word is converted to upper case, and the rest are converted to lower | |
| 962 case. | |
| 963 | |
| 964 The definition of a word is any sequence of consecutive characters that | |
| 965 are assigned to the word constituent syntax class in the current syntax | |
| 966 table (@pxref{Syntax Class Table}). | |
| 967 | |
| 968 When the argument to @code{capitalize} is a character, @code{capitalize} | |
| 969 has the same result as @code{upcase}. | |
| 970 | |
| 444 | 971 Optional second arg @var{buffer} specifies which buffer's case tables to |
| 972 use, and defaults to the current buffer. | |
| 973 | |
| 428 | 974 @example |
| 975 (capitalize "The cat in the hat") | |
| 976 @result{} "The Cat In The Hat" | |
| 977 | |
| 978 (capitalize "THE 77TH-HATTED CAT") | |
| 979 @result{} "The 77th-Hatted Cat" | |
| 980 | |
| 981 @group | |
| 982 (capitalize ?x) | |
| 983 @result{} ?X ;; @r{Under XEmacs 20.} | |
| 984 @result{} 88 ;; @r{Under XEmacs 19.} | |
| 985 @end group | |
| 986 @end example | |
| 987 @end defun | |
| 988 | |
| 989 @node Case Tables | |
| 990 @section The Case Table | |
| 991 | |
| 992 You can customize case conversion by installing a special @dfn{case | |
| 993 table}. A case table specifies the mapping between upper case and lower | |
| 994 case letters. It affects both the string and character case conversion | |
| 995 functions (see the previous section) and those that apply to text in the | |
| 996 buffer (@pxref{Case Changes}). You need a case table if you are using a | |
| 997 language which has letters other than the standard @sc{ascii} letters. | |
| 998 | |
| 999 A case table is a list of this form: | |
| 1000 | |
| 1001 @example | |
| 1002 (@var{downcase} @var{upcase} @var{canonicalize} @var{equivalences}) | |
| 1003 @end example | |
| 1004 | |
| 1005 @noindent | |
| 1006 where each element is either @code{nil} or a string of length 256. The | |
| 1007 element @var{downcase} says how to map each character to its lower-case | |
| 1008 equivalent. The element @var{upcase} maps each character to its | |
| 1009 upper-case equivalent. If lower and upper case characters are in | |
| 1010 one-to-one correspondence, use @code{nil} for @var{upcase}; then XEmacs | |
| 1011 deduces the upcase table from @var{downcase}. | |
| 1012 | |
| 1013 For some languages, upper and lower case letters are not in one-to-one | |
| 1014 correspondence. There may be two different lower case letters with the | |
| 1015 same upper case equivalent. In these cases, you need to specify the | |
| 1016 maps for both directions. | |
| 1017 | |
| 1018 The element @var{canonicalize} maps each character to a canonical | |
| 1019 equivalent; any two characters that are related by case-conversion have | |
| 1020 the same canonical equivalent character. | |
| 1021 | |
| 1022 The element @var{equivalences} is a map that cyclicly permutes each | |
| 1023 equivalence class (of characters with the same canonical equivalent). | |
| 1024 (For ordinary @sc{ascii}, this would map @samp{a} into @samp{A} and | |
| 1025 @samp{A} into @samp{a}, and likewise for each set of equivalent | |
| 1026 characters.) | |
| 1027 | |
| 1028 When you construct a case table, you can provide @code{nil} for | |
| 1029 @var{canonicalize}; then Emacs fills in this string from @var{upcase} | |
| 1030 and @var{downcase}. You can also provide @code{nil} for | |
| 1031 @var{equivalences}; then Emacs fills in this string from | |
| 1032 @var{canonicalize}. In a case table that is actually in use, those | |
| 1033 components are non-@code{nil}. Do not try to specify @var{equivalences} | |
| 1034 without also specifying @var{canonicalize}. | |
| 1035 | |
| 1036 Each buffer has a case table. XEmacs also has a @dfn{standard case | |
| 1037 table} which is copied into each buffer when you create the buffer. | |
| 1038 Changing the standard case table doesn't affect any existing buffers. | |
| 1039 | |
| 1040 Here are the functions for working with case tables: | |
| 1041 | |
| 1042 @defun case-table-p object | |
| 1043 This predicate returns non-@code{nil} if @var{object} is a valid case | |
| 1044 table. | |
| 1045 @end defun | |
| 1046 | |
| 444 | 1047 @defun set-standard-case-table case-table |
| 1048 This function makes @var{case-table} the standard case table, so that it | |
| 1049 will apply to any buffers created subsequently. | |
| 428 | 1050 @end defun |
| 1051 | |
| 1052 @defun standard-case-table | |
| 1053 This returns the standard case table. | |
| 1054 @end defun | |
| 1055 | |
| 444 | 1056 @defun current-case-table &optional buffer |
| 1057 This function returns the case table of @var{buffer}, which defaults to | |
| 1058 the current buffer. | |
| 428 | 1059 @end defun |
| 1060 | |
| 444 | 1061 @defun set-case-table case-table |
| 1062 This sets the current buffer's case table to @var{case-table}. | |
| 428 | 1063 @end defun |
| 1064 | |
| 1065 The following three functions are convenient subroutines for packages | |
| 1066 that define non-@sc{ascii} character sets. They modify a string | |
| 1067 @var{downcase-table} provided as an argument; this should be a string to | |
| 1068 be used as the @var{downcase} part of a case table. They also modify | |
| 1069 the standard syntax table. @xref{Syntax Tables}. | |
| 1070 | |
| 1071 @defun set-case-syntax-pair uc lc downcase-table | |
| 1072 This function specifies a pair of corresponding letters, one upper case | |
| 1073 and one lower case. | |
| 1074 @end defun | |
| 1075 | |
| 1076 @defun set-case-syntax-delims l r downcase-table | |
| 1077 This function makes characters @var{l} and @var{r} a matching pair of | |
| 1078 case-invariant delimiters. | |
| 1079 @end defun | |
| 1080 | |
| 1081 @defun set-case-syntax char syntax downcase-table | |
| 1082 This function makes @var{char} case-invariant, with syntax | |
| 1083 @var{syntax}. | |
| 1084 @end defun | |
| 1085 | |
| 1086 @deffn Command describe-buffer-case-table | |
| 1087 This command displays a description of the contents of the current | |
| 1088 buffer's case table. | |
| 1089 @end deffn | |
| 1090 | |
| 1091 @cindex ISO Latin 1 | |
| 1092 @pindex iso-syntax | |
| 1093 You can load the library @file{iso-syntax} to set up the standard syntax | |
| 1094 table and define a case table for the 8-bit ISO Latin 1 character set. | |
| 1095 | |
| 1096 @node Char Tables | |
| 1097 @section The Char Table | |
| 1098 | |
| 1099 A char table is a table that maps characters (or ranges of characters) | |
| 1100 to values. Char tables are specialized for characters, only allowing | |
| 1101 particular sorts of ranges to be assigned values. Although this | |
| 1102 loses in generality, it makes for extremely fast (constant-time) | |
| 1103 lookups, and thus is feasible for applications that do an extremely | |
| 1104 large number of lookups (e.g. scanning a buffer for a character in | |
| 1105 a particular syntax, where a lookup in the syntax table must occur | |
| 1106 once per character). | |
| 1107 | |
| 1108 Note that char tables as a primitive type, and all of the functions in | |
| 1109 this section, exist only in XEmacs 20. In XEmacs 19, char tables are | |
| 1110 generally implemented using a vector of 256 elements. | |
| 1111 | |
| 1112 When @sc{mule} support exists, the types of ranges that can be assigned | |
| 1113 values are | |
| 1114 | |
| 1115 @itemize @bullet | |
| 1116 @item | |
| 1117 all characters | |
| 1118 @item | |
| 1119 an entire charset | |
| 1120 @item | |
| 1121 a single row in a two-octet charset | |
| 1122 @item | |
| 1123 a single character | |
| 1124 @end itemize | |
| 1125 | |
| 1126 When @sc{mule} support is not present, the types of ranges that can be | |
| 1127 assigned values are | |
| 1128 | |
| 1129 @itemize @bullet | |
| 1130 @item | |
| 1131 all characters | |
| 1132 @item | |
| 1133 a single character | |
| 1134 @end itemize | |
| 1135 | |
| 1136 @defun char-table-p object | |
| 1137 This function returns non-@code{nil} if @var{object} is a char table. | |
| 1138 @end defun | |
| 1139 | |
| 1140 @menu | |
| 1141 * Char Table Types:: Char tables have different uses. | |
| 1142 * Working With Char Tables:: Creating and working with char tables. | |
| 1143 @end menu | |
| 1144 | |
| 1145 @node Char Table Types | |
| 1146 @subsection Char Table Types | |
| 1147 | |
| 1148 Each char table type is used for a different purpose and allows different | |
| 1149 sorts of values. The different char table types are | |
| 1150 | |
| 1151 @table @code | |
| 1152 @item category | |
| 1153 Used for category tables, which specify the regexp categories | |
| 1154 that a character is in. The valid values are @code{nil} or a | |
| 1155 bit vector of 95 elements. Higher-level Lisp functions are | |
| 1156 provided for working with category tables. Currently categories | |
| 1157 and category tables only exist when @sc{mule} support is present. | |
| 1158 @item char | |
| 1159 A generalized char table, for mapping from one character to | |
| 1160 another. Used for case tables, syntax matching tables, | |
| 1161 @code{keyboard-translate-table}, etc. The valid values are characters. | |
| 1162 @item generic | |
| 1163 An even more generalized char table, for mapping from a | |
| 1164 character to anything. | |
| 1165 @item display | |
| 1166 Used for display tables, which specify how a particular character | |
| 1167 is to appear when displayed. #### Not yet implemented. | |
| 1168 @item syntax | |
| 1169 Used for syntax tables, which specify the syntax of a particular | |
| 1170 character. Higher-level Lisp functions are provided for | |
|
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6772ce4d982b
Fix hash tables, #'member*, #'assoc*, #'eql compiler macros if bignums
Aidan Kehoe <kehoea@parhasard.net>
parents:
4329
diff
changeset
|
1171 working with syntax tables. The valid values are fixnums. |
| 428 | 1172 @end table |
| 1173 | |
| 444 | 1174 @defun char-table-type char-table |
| 1175 This function returns the type of char table @var{char-table}. | |
| 428 | 1176 @end defun |
| 1177 | |
| 1178 @defun char-table-type-list | |
| 1179 This function returns a list of the recognized char table types. | |
| 1180 @end defun | |
| 1181 | |
| 1182 @defun valid-char-table-type-p type | |
| 1183 This function returns @code{t} if @var{type} if a recognized char table type. | |
| 1184 @end defun | |
| 1185 | |
| 1186 @node Working With Char Tables | |
| 1187 @subsection Working With Char Tables | |
| 1188 | |
| 1189 @defun make-char-table type | |
| 1190 This function makes a new, empty char table of type @var{type}. | |
| 1191 @var{type} should be a symbol, one of @code{char}, @code{category}, | |
| 1192 @code{display}, @code{generic}, or @code{syntax}. | |
| 1193 @end defun | |
| 1194 | |
| 444 | 1195 @defun put-char-table range value char-table |
| 1196 This function sets the value for chars in @var{range} to be @var{value} in | |
| 1197 @var{char-table}. | |
| 428 | 1198 |
| 1199 @var{range} specifies one or more characters to be affected and should be | |
| 1200 one of the following: | |
| 1201 | |
| 1202 @itemize @bullet | |
| 1203 @item | |
| 1204 @code{t} (all characters are affected) | |
| 1205 @item | |
| 1206 A charset (only allowed when @sc{mule} support is present) | |
| 1207 @item | |
| 1208 A vector of two elements: a two-octet charset and a row number | |
| 1209 (only allowed when @sc{mule} support is present) | |
| 1210 @item | |
| 1211 A single character | |
| 1212 @end itemize | |
| 1213 | |
| 444 | 1214 @var{value} must be a value appropriate for the type of @var{char-table}. |
| 428 | 1215 @end defun |
| 1216 | |
| 444 | 1217 @defun get-char-table character char-table |
| 1218 This function finds the value for @var{character} in @var{char-table}. | |
| 428 | 1219 @end defun |
| 1220 | |
| 444 | 1221 @defun get-range-char-table range char-table &optional multi |
| 1222 This function finds the value for a range in @var{char-table}. If there is | |
| 428 | 1223 more than one value, @var{multi} is returned (defaults to @code{nil}). |
| 1224 @end defun | |
| 1225 | |
| 444 | 1226 @defun reset-char-table char-table |
| 1227 This function resets @var{char-table} to its default state. | |
| 428 | 1228 @end defun |
| 1229 | |
| 444 | 1230 @defun map-char-table function char-table &optional range |
| 1231 This function maps @var{function} over entries in @var{char-table}, calling | |
| 428 | 1232 it with two args, each key and value in the table. |
| 1233 | |
| 1234 @var{range} specifies a subrange to map over and is in the same format | |
| 1235 as the @var{range} argument to @code{put-range-table}. If omitted or | |
| 1236 @code{t}, it defaults to the entire table. | |
| 1237 @end defun | |
| 1238 | |
| 1239 @defun valid-char-table-value-p value char-table-type | |
| 1240 This function returns non-@code{nil} if @var{value} is a valid value for | |
| 1241 @var{char-table-type}. | |
| 1242 @end defun | |
| 1243 | |
| 1244 @defun check-valid-char-table-value value char-table-type | |
| 1245 This function signals an error if @var{value} is not a valid value for | |
| 1246 @var{char-table-type}. | |
| 1247 @end defun |