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1 | @c -*-texinfo-*- |
2 | @c This is part of the GNU Emacs Lisp Reference Manual. | |
3 | @c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2001, | |
57ebf0be | 4 | @c 2002, 2003, 2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc. |
b8d4c8d0 | 5 | @c See the file elisp.texi for copying conditions. |
6336d8c3 | 6 | @setfilename ../../info/sequences |
b8d4c8d0 GM |
7 | @node Sequences Arrays Vectors, Hash Tables, Lists, Top |
8 | @chapter Sequences, Arrays, and Vectors | |
9 | @cindex sequence | |
10 | ||
11 | Recall that the @dfn{sequence} type is the union of two other Lisp | |
12 | types: lists and arrays. In other words, any list is a sequence, and | |
13 | any array is a sequence. The common property that all sequences have is | |
14 | that each is an ordered collection of elements. | |
15 | ||
16 | An @dfn{array} is a single primitive object that has a slot for each | |
17 | of its elements. All the elements are accessible in constant time, but | |
18 | the length of an existing array cannot be changed. Strings, vectors, | |
19 | char-tables and bool-vectors are the four types of arrays. | |
20 | ||
21 | A list is a sequence of elements, but it is not a single primitive | |
22 | object; it is made of cons cells, one cell per element. Finding the | |
23 | @var{n}th element requires looking through @var{n} cons cells, so | |
24 | elements farther from the beginning of the list take longer to access. | |
25 | But it is possible to add elements to the list, or remove elements. | |
26 | ||
27 | The following diagram shows the relationship between these types: | |
28 | ||
29 | @example | |
30 | @group | |
31 | _____________________________________________ | |
32 | | | | |
33 | | Sequence | | |
34 | | ______ ________________________________ | | |
35 | | | | | | | | |
36 | | | List | | Array | | | |
37 | | | | | ________ ________ | | | |
38 | | |______| | | | | | | | | |
39 | | | | Vector | | String | | | | |
40 | | | |________| |________| | | | |
41 | | | ____________ _____________ | | | |
42 | | | | | | | | | | |
43 | | | | Char-table | | Bool-vector | | | | |
44 | | | |____________| |_____________| | | | |
45 | | |________________________________| | | |
46 | |_____________________________________________| | |
47 | @end group | |
48 | @end example | |
49 | ||
50 | The elements of vectors and lists may be any Lisp objects. The | |
51 | elements of strings are all characters. | |
52 | ||
53 | @menu | |
54 | * Sequence Functions:: Functions that accept any kind of sequence. | |
55 | * Arrays:: Characteristics of arrays in Emacs Lisp. | |
56 | * Array Functions:: Functions specifically for arrays. | |
57 | * Vectors:: Special characteristics of Emacs Lisp vectors. | |
58 | * Vector Functions:: Functions specifically for vectors. | |
59 | * Char-Tables:: How to work with char-tables. | |
60 | * Bool-Vectors:: How to work with bool-vectors. | |
61 | @end menu | |
62 | ||
63 | @node Sequence Functions | |
64 | @section Sequences | |
65 | ||
66 | In Emacs Lisp, a @dfn{sequence} is either a list or an array. The | |
67 | common property of all sequences is that they are ordered collections of | |
68 | elements. This section describes functions that accept any kind of | |
69 | sequence. | |
70 | ||
71 | @defun sequencep object | |
72 | Returns @code{t} if @var{object} is a list, vector, string, | |
73 | bool-vector, or char-table, @code{nil} otherwise. | |
74 | @end defun | |
75 | ||
76 | @defun length sequence | |
77 | @cindex string length | |
78 | @cindex list length | |
79 | @cindex vector length | |
80 | @cindex sequence length | |
81 | @cindex char-table length | |
82 | This function returns the number of elements in @var{sequence}. If | |
83 | @var{sequence} is a dotted list, a @code{wrong-type-argument} error is | |
84 | signaled. Circular lists may cause an infinite loop. For a | |
85 | char-table, the value returned is always one more than the maximum | |
86 | Emacs character code. | |
87 | ||
88 | @xref{Definition of safe-length}, for the related function @code{safe-length}. | |
89 | ||
90 | @example | |
91 | @group | |
92 | (length '(1 2 3)) | |
93 | @result{} 3 | |
94 | @end group | |
95 | @group | |
96 | (length ()) | |
97 | @result{} 0 | |
98 | @end group | |
99 | @group | |
100 | (length "foobar") | |
101 | @result{} 6 | |
102 | @end group | |
103 | @group | |
104 | (length [1 2 3]) | |
105 | @result{} 3 | |
106 | @end group | |
107 | @group | |
108 | (length (make-bool-vector 5 nil)) | |
109 | @result{} 5 | |
110 | @end group | |
111 | @end example | |
112 | @end defun | |
113 | ||
114 | @noindent | |
115 | See also @code{string-bytes}, in @ref{Text Representations}. | |
116 | ||
117 | @defun elt sequence index | |
118 | @cindex elements of sequences | |
119 | This function returns the element of @var{sequence} indexed by | |
120 | @var{index}. Legitimate values of @var{index} are integers ranging | |
121 | from 0 up to one less than the length of @var{sequence}. If | |
122 | @var{sequence} is a list, out-of-range values behave as for | |
123 | @code{nth}. @xref{Definition of nth}. Otherwise, out-of-range values | |
124 | trigger an @code{args-out-of-range} error. | |
125 | ||
126 | @example | |
127 | @group | |
128 | (elt [1 2 3 4] 2) | |
129 | @result{} 3 | |
130 | @end group | |
131 | @group | |
132 | (elt '(1 2 3 4) 2) | |
133 | @result{} 3 | |
134 | @end group | |
135 | @group | |
136 | ;; @r{We use @code{string} to show clearly which character @code{elt} returns.} | |
137 | (string (elt "1234" 2)) | |
138 | @result{} "3" | |
139 | @end group | |
140 | @group | |
141 | (elt [1 2 3 4] 4) | |
142 | @error{} Args out of range: [1 2 3 4], 4 | |
143 | @end group | |
144 | @group | |
145 | (elt [1 2 3 4] -1) | |
146 | @error{} Args out of range: [1 2 3 4], -1 | |
147 | @end group | |
148 | @end example | |
149 | ||
150 | This function generalizes @code{aref} (@pxref{Array Functions}) and | |
151 | @code{nth} (@pxref{Definition of nth}). | |
152 | @end defun | |
153 | ||
154 | @defun copy-sequence sequence | |
155 | @cindex copying sequences | |
156 | Returns a copy of @var{sequence}. The copy is the same type of object | |
157 | as the original sequence, and it has the same elements in the same order. | |
158 | ||
159 | Storing a new element into the copy does not affect the original | |
160 | @var{sequence}, and vice versa. However, the elements of the new | |
161 | sequence are not copies; they are identical (@code{eq}) to the elements | |
162 | of the original. Therefore, changes made within these elements, as | |
163 | found via the copied sequence, are also visible in the original | |
164 | sequence. | |
165 | ||
166 | If the sequence is a string with text properties, the property list in | |
167 | the copy is itself a copy, not shared with the original's property | |
168 | list. However, the actual values of the properties are shared. | |
169 | @xref{Text Properties}. | |
170 | ||
171 | This function does not work for dotted lists. Trying to copy a | |
172 | circular list may cause an infinite loop. | |
173 | ||
174 | See also @code{append} in @ref{Building Lists}, @code{concat} in | |
175 | @ref{Creating Strings}, and @code{vconcat} in @ref{Vector Functions}, | |
176 | for other ways to copy sequences. | |
177 | ||
178 | @example | |
179 | @group | |
180 | (setq bar '(1 2)) | |
181 | @result{} (1 2) | |
182 | @end group | |
183 | @group | |
184 | (setq x (vector 'foo bar)) | |
185 | @result{} [foo (1 2)] | |
186 | @end group | |
187 | @group | |
188 | (setq y (copy-sequence x)) | |
189 | @result{} [foo (1 2)] | |
190 | @end group | |
191 | ||
192 | @group | |
193 | (eq x y) | |
194 | @result{} nil | |
195 | @end group | |
196 | @group | |
197 | (equal x y) | |
198 | @result{} t | |
199 | @end group | |
200 | @group | |
201 | (eq (elt x 1) (elt y 1)) | |
202 | @result{} t | |
203 | @end group | |
204 | ||
205 | @group | |
206 | ;; @r{Replacing an element of one sequence.} | |
207 | (aset x 0 'quux) | |
208 | x @result{} [quux (1 2)] | |
209 | y @result{} [foo (1 2)] | |
210 | @end group | |
211 | ||
212 | @group | |
213 | ;; @r{Modifying the inside of a shared element.} | |
214 | (setcar (aref x 1) 69) | |
215 | x @result{} [quux (69 2)] | |
216 | y @result{} [foo (69 2)] | |
217 | @end group | |
218 | @end example | |
219 | @end defun | |
220 | ||
221 | @node Arrays | |
222 | @section Arrays | |
223 | @cindex array | |
224 | ||
225 | An @dfn{array} object has slots that hold a number of other Lisp | |
226 | objects, called the elements of the array. Any element of an array may | |
227 | be accessed in constant time. In contrast, an element of a list | |
228 | requires access time that is proportional to the position of the element | |
229 | in the list. | |
230 | ||
231 | Emacs defines four types of array, all one-dimensional: @dfn{strings}, | |
232 | @dfn{vectors}, @dfn{bool-vectors} and @dfn{char-tables}. A vector is a | |
233 | general array; its elements can be any Lisp objects. A string is a | |
234 | specialized array; its elements must be characters. Each type of array | |
235 | has its own read syntax. | |
236 | @xref{String Type}, and @ref{Vector Type}. | |
237 | ||
238 | All four kinds of array share these characteristics: | |
239 | ||
240 | @itemize @bullet | |
241 | @item | |
242 | The first element of an array has index zero, the second element has | |
243 | index 1, and so on. This is called @dfn{zero-origin} indexing. For | |
244 | example, an array of four elements has indices 0, 1, 2, @w{and 3}. | |
245 | ||
246 | @item | |
247 | The length of the array is fixed once you create it; you cannot | |
248 | change the length of an existing array. | |
249 | ||
250 | @item | |
251 | For purposes of evaluation, the array is a constant---in other words, | |
252 | it evaluates to itself. | |
253 | ||
254 | @item | |
255 | The elements of an array may be referenced or changed with the functions | |
256 | @code{aref} and @code{aset}, respectively (@pxref{Array Functions}). | |
257 | @end itemize | |
258 | ||
259 | When you create an array, other than a char-table, you must specify | |
260 | its length. You cannot specify the length of a char-table, because that | |
261 | is determined by the range of character codes. | |
262 | ||
263 | In principle, if you want an array of text characters, you could use | |
264 | either a string or a vector. In practice, we always choose strings for | |
265 | such applications, for four reasons: | |
266 | ||
267 | @itemize @bullet | |
268 | @item | |
269 | They occupy one-fourth the space of a vector of the same elements. | |
270 | ||
271 | @item | |
272 | Strings are printed in a way that shows the contents more clearly | |
273 | as text. | |
274 | ||
275 | @item | |
276 | Strings can hold text properties. @xref{Text Properties}. | |
277 | ||
278 | @item | |
279 | Many of the specialized editing and I/O facilities of Emacs accept only | |
280 | strings. For example, you cannot insert a vector of characters into a | |
281 | buffer the way you can insert a string. @xref{Strings and Characters}. | |
282 | @end itemize | |
283 | ||
284 | By contrast, for an array of keyboard input characters (such as a key | |
285 | sequence), a vector may be necessary, because many keyboard input | |
286 | characters are outside the range that will fit in a string. @xref{Key | |
287 | Sequence Input}. | |
288 | ||
289 | @node Array Functions | |
290 | @section Functions that Operate on Arrays | |
291 | ||
292 | In this section, we describe the functions that accept all types of | |
293 | arrays. | |
294 | ||
295 | @defun arrayp object | |
296 | This function returns @code{t} if @var{object} is an array (i.e., a | |
297 | vector, a string, a bool-vector or a char-table). | |
298 | ||
299 | @example | |
300 | @group | |
301 | (arrayp [a]) | |
302 | @result{} t | |
303 | (arrayp "asdf") | |
304 | @result{} t | |
305 | (arrayp (syntax-table)) ;; @r{A char-table.} | |
306 | @result{} t | |
307 | @end group | |
308 | @end example | |
309 | @end defun | |
310 | ||
311 | @defun aref array index | |
312 | @cindex array elements | |
313 | This function returns the @var{index}th element of @var{array}. The | |
314 | first element is at index zero. | |
315 | ||
316 | @example | |
317 | @group | |
318 | (setq primes [2 3 5 7 11 13]) | |
319 | @result{} [2 3 5 7 11 13] | |
320 | (aref primes 4) | |
321 | @result{} 11 | |
322 | @end group | |
323 | @group | |
324 | (aref "abcdefg" 1) | |
325 | @result{} 98 ; @r{@samp{b} is @acronym{ASCII} code 98.} | |
326 | @end group | |
327 | @end example | |
328 | ||
329 | See also the function @code{elt}, in @ref{Sequence Functions}. | |
330 | @end defun | |
331 | ||
332 | @defun aset array index object | |
333 | This function sets the @var{index}th element of @var{array} to be | |
334 | @var{object}. It returns @var{object}. | |
335 | ||
336 | @example | |
337 | @group | |
338 | (setq w [foo bar baz]) | |
339 | @result{} [foo bar baz] | |
340 | (aset w 0 'fu) | |
341 | @result{} fu | |
342 | w | |
343 | @result{} [fu bar baz] | |
344 | @end group | |
345 | ||
346 | @group | |
347 | (setq x "asdfasfd") | |
348 | @result{} "asdfasfd" | |
349 | (aset x 3 ?Z) | |
350 | @result{} 90 | |
351 | x | |
352 | @result{} "asdZasfd" | |
353 | @end group | |
354 | @end example | |
355 | ||
356 | If @var{array} is a string and @var{object} is not a character, a | |
357 | @code{wrong-type-argument} error results. The function converts a | |
358 | unibyte string to multibyte if necessary to insert a character. | |
359 | @end defun | |
360 | ||
361 | @defun fillarray array object | |
362 | This function fills the array @var{array} with @var{object}, so that | |
363 | each element of @var{array} is @var{object}. It returns @var{array}. | |
364 | ||
365 | @example | |
366 | @group | |
367 | (setq a [a b c d e f g]) | |
368 | @result{} [a b c d e f g] | |
369 | (fillarray a 0) | |
370 | @result{} [0 0 0 0 0 0 0] | |
371 | a | |
372 | @result{} [0 0 0 0 0 0 0] | |
373 | @end group | |
374 | @group | |
375 | (setq s "When in the course") | |
376 | @result{} "When in the course" | |
377 | (fillarray s ?-) | |
378 | @result{} "------------------" | |
379 | @end group | |
380 | @end example | |
381 | ||
382 | If @var{array} is a string and @var{object} is not a character, a | |
383 | @code{wrong-type-argument} error results. | |
384 | @end defun | |
385 | ||
386 | The general sequence functions @code{copy-sequence} and @code{length} | |
387 | are often useful for objects known to be arrays. @xref{Sequence Functions}. | |
388 | ||
389 | @node Vectors | |
390 | @section Vectors | |
391 | @cindex vector (type) | |
392 | ||
393 | Arrays in Lisp, like arrays in most languages, are blocks of memory | |
394 | whose elements can be accessed in constant time. A @dfn{vector} is a | |
395 | general-purpose array of specified length; its elements can be any Lisp | |
396 | objects. (By contrast, a string can hold only characters as elements.) | |
397 | Vectors in Emacs are used for obarrays (vectors of symbols), and as part | |
398 | of keymaps (vectors of commands). They are also used internally as part | |
399 | of the representation of a byte-compiled function; if you print such a | |
400 | function, you will see a vector in it. | |
401 | ||
402 | In Emacs Lisp, the indices of the elements of a vector start from zero | |
403 | and count up from there. | |
404 | ||
405 | Vectors are printed with square brackets surrounding the elements. | |
406 | Thus, a vector whose elements are the symbols @code{a}, @code{b} and | |
407 | @code{a} is printed as @code{[a b a]}. You can write vectors in the | |
408 | same way in Lisp input. | |
409 | ||
410 | A vector, like a string or a number, is considered a constant for | |
411 | evaluation: the result of evaluating it is the same vector. This does | |
412 | not evaluate or even examine the elements of the vector. | |
413 | @xref{Self-Evaluating Forms}. | |
414 | ||
415 | Here are examples illustrating these principles: | |
416 | ||
417 | @example | |
418 | @group | |
419 | (setq avector [1 two '(three) "four" [five]]) | |
420 | @result{} [1 two (quote (three)) "four" [five]] | |
421 | (eval avector) | |
422 | @result{} [1 two (quote (three)) "four" [five]] | |
423 | (eq avector (eval avector)) | |
424 | @result{} t | |
425 | @end group | |
426 | @end example | |
427 | ||
428 | @node Vector Functions | |
429 | @section Functions for Vectors | |
430 | ||
431 | Here are some functions that relate to vectors: | |
432 | ||
433 | @defun vectorp object | |
434 | This function returns @code{t} if @var{object} is a vector. | |
435 | ||
436 | @example | |
437 | @group | |
438 | (vectorp [a]) | |
439 | @result{} t | |
440 | (vectorp "asdf") | |
441 | @result{} nil | |
442 | @end group | |
443 | @end example | |
444 | @end defun | |
445 | ||
446 | @defun vector &rest objects | |
447 | This function creates and returns a vector whose elements are the | |
448 | arguments, @var{objects}. | |
449 | ||
450 | @example | |
451 | @group | |
452 | (vector 'foo 23 [bar baz] "rats") | |
453 | @result{} [foo 23 [bar baz] "rats"] | |
454 | (vector) | |
455 | @result{} [] | |
456 | @end group | |
457 | @end example | |
458 | @end defun | |
459 | ||
460 | @defun make-vector length object | |
461 | This function returns a new vector consisting of @var{length} elements, | |
462 | each initialized to @var{object}. | |
463 | ||
464 | @example | |
465 | @group | |
466 | (setq sleepy (make-vector 9 'Z)) | |
467 | @result{} [Z Z Z Z Z Z Z Z Z] | |
468 | @end group | |
469 | @end example | |
470 | @end defun | |
471 | ||
472 | @defun vconcat &rest sequences | |
473 | @cindex copying vectors | |
474 | This function returns a new vector containing all the elements of the | |
475 | @var{sequences}. The arguments @var{sequences} may be true lists, | |
476 | vectors, strings or bool-vectors. If no @var{sequences} are given, an | |
477 | empty vector is returned. | |
478 | ||
479 | The value is a newly constructed vector that is not @code{eq} to any | |
480 | existing vector. | |
481 | ||
482 | @example | |
483 | @group | |
484 | (setq a (vconcat '(A B C) '(D E F))) | |
485 | @result{} [A B C D E F] | |
486 | (eq a (vconcat a)) | |
487 | @result{} nil | |
488 | @end group | |
489 | @group | |
490 | (vconcat) | |
491 | @result{} [] | |
492 | (vconcat [A B C] "aa" '(foo (6 7))) | |
493 | @result{} [A B C 97 97 foo (6 7)] | |
494 | @end group | |
495 | @end example | |
496 | ||
497 | The @code{vconcat} function also allows byte-code function objects as | |
498 | arguments. This is a special feature to make it easy to access the entire | |
499 | contents of a byte-code function object. @xref{Byte-Code Objects}. | |
500 | ||
501 | In Emacs versions before 21, the @code{vconcat} function allowed | |
502 | integers as arguments, converting them to strings of digits, but that | |
503 | feature has been eliminated. The proper way to convert an integer to | |
504 | a decimal number in this way is with @code{format} (@pxref{Formatting | |
505 | Strings}) or @code{number-to-string} (@pxref{String Conversion}). | |
506 | ||
507 | For other concatenation functions, see @code{mapconcat} in @ref{Mapping | |
508 | Functions}, @code{concat} in @ref{Creating Strings}, and @code{append} | |
509 | in @ref{Building Lists}. | |
510 | @end defun | |
511 | ||
512 | The @code{append} function also provides a way to convert a vector into a | |
513 | list with the same elements: | |
514 | ||
515 | @example | |
516 | @group | |
517 | (setq avector [1 two (quote (three)) "four" [five]]) | |
518 | @result{} [1 two (quote (three)) "four" [five]] | |
519 | (append avector nil) | |
520 | @result{} (1 two (quote (three)) "four" [five]) | |
521 | @end group | |
522 | @end example | |
523 | ||
524 | @node Char-Tables | |
525 | @section Char-Tables | |
526 | @cindex char-tables | |
527 | @cindex extra slots of char-table | |
528 | ||
529 | A char-table is much like a vector, except that it is indexed by | |
530 | character codes. Any valid character code, without modifiers, can be | |
531 | used as an index in a char-table. You can access a char-table's | |
532 | elements with @code{aref} and @code{aset}, as with any array. In | |
533 | addition, a char-table can have @dfn{extra slots} to hold additional | |
534 | data not associated with particular character codes. Char-tables are | |
535 | constants when evaluated. | |
536 | ||
537 | @cindex subtype of char-table | |
538 | Each char-table has a @dfn{subtype} which is a symbol. The subtype | |
539 | has two purposes: to distinguish char-tables meant for different uses, | |
540 | and to control the number of extra slots. For example, display tables | |
541 | are char-tables with @code{display-table} as the subtype, and syntax | |
542 | tables are char-tables with @code{syntax-table} as the subtype. A valid | |
543 | subtype must have a @code{char-table-extra-slots} property which is an | |
544 | integer between 0 and 10. This integer specifies the number of | |
545 | @dfn{extra slots} in the char-table. | |
546 | ||
547 | @cindex parent of char-table | |
548 | A char-table can have a @dfn{parent}, which is another char-table. If | |
549 | it does, then whenever the char-table specifies @code{nil} for a | |
550 | particular character @var{c}, it inherits the value specified in the | |
551 | parent. In other words, @code{(aref @var{char-table} @var{c})} returns | |
552 | the value from the parent of @var{char-table} if @var{char-table} itself | |
553 | specifies @code{nil}. | |
554 | ||
555 | @cindex default value of char-table | |
556 | A char-table can also have a @dfn{default value}. If so, then | |
557 | @code{(aref @var{char-table} @var{c})} returns the default value | |
558 | whenever the char-table does not specify any other non-@code{nil} value. | |
559 | ||
560 | @defun make-char-table subtype &optional init | |
561 | Return a newly created char-table, with subtype @var{subtype}. Each | |
562 | element is initialized to @var{init}, which defaults to @code{nil}. You | |
563 | cannot alter the subtype of a char-table after the char-table is | |
564 | created. | |
565 | ||
566 | There is no argument to specify the length of the char-table, because | |
567 | all char-tables have room for any valid character code as an index. | |
568 | @end defun | |
569 | ||
570 | @defun char-table-p object | |
571 | This function returns @code{t} if @var{object} is a char-table, | |
572 | otherwise @code{nil}. | |
573 | @end defun | |
574 | ||
575 | @defun char-table-subtype char-table | |
576 | This function returns the subtype symbol of @var{char-table}. | |
577 | @end defun | |
578 | ||
b8d4c8d0 GM |
579 | There is no special function to access default values in a char-table. |
580 | To do that, use @code{char-table-range} (see below). | |
b8d4c8d0 GM |
581 | |
582 | @defun char-table-parent char-table | |
583 | This function returns the parent of @var{char-table}. The parent is | |
584 | always either @code{nil} or another char-table. | |
585 | @end defun | |
586 | ||
587 | @defun set-char-table-parent char-table new-parent | |
588 | This function sets the parent of @var{char-table} to @var{new-parent}. | |
589 | @end defun | |
590 | ||
591 | @defun char-table-extra-slot char-table n | |
592 | This function returns the contents of extra slot @var{n} of | |
593 | @var{char-table}. The number of extra slots in a char-table is | |
594 | determined by its subtype. | |
595 | @end defun | |
596 | ||
597 | @defun set-char-table-extra-slot char-table n value | |
598 | This function stores @var{value} in extra slot @var{n} of | |
599 | @var{char-table}. | |
600 | @end defun | |
601 | ||
602 | A char-table can specify an element value for a single character code; | |
603 | it can also specify a value for an entire character set. | |
604 | ||
605 | @defun char-table-range char-table range | |
606 | This returns the value specified in @var{char-table} for a range of | |
607 | characters @var{range}. Here are the possibilities for @var{range}: | |
608 | ||
609 | @table @asis | |
610 | @item @code{nil} | |
611 | Refers to the default value. | |
612 | ||
613 | @item @var{char} | |
614 | Refers to the element for character @var{char} | |
615 | (supposing @var{char} is a valid character code). | |
616 | ||
2724b26a EZ |
617 | @item @code{(@var{from} . @var{to})} |
618 | A cons cell refers to all the characters in the inclusive range | |
619 | @samp{[@var{from}..@var{to}]}. | |
b8d4c8d0 GM |
620 | @end table |
621 | @end defun | |
622 | ||
623 | @defun set-char-table-range char-table range value | |
624 | This function sets the value in @var{char-table} for a range of | |
625 | characters @var{range}. Here are the possibilities for @var{range}: | |
626 | ||
627 | @table @asis | |
628 | @item @code{nil} | |
629 | Refers to the default value. | |
630 | ||
631 | @item @code{t} | |
632 | Refers to the whole range of character codes. | |
633 | ||
634 | @item @var{char} | |
635 | Refers to the element for character @var{char} | |
636 | (supposing @var{char} is a valid character code). | |
637 | ||
2724b26a EZ |
638 | @item @code{(@var{from} . @var{to})} |
639 | A cons cell refers to all the characters in the inclusive range | |
640 | @samp{[@var{from}..@var{to}]}. | |
b8d4c8d0 GM |
641 | @end table |
642 | @end defun | |
643 | ||
644 | @defun map-char-table function char-table | |
22526bc4 EZ |
645 | This function calls the specified @var{function} for each element of |
646 | @var{char-table} that has a non-@code{nil} value. | |
b8d4c8d0 GM |
647 | @var{function} is called with two arguments, a key and a value. The key |
648 | is a possible @var{range} argument for @code{char-table-range}---either | |
22526bc4 EZ |
649 | a valid character or a cons cell @code{(@var{from} . @var{to})}, |
650 | specifying a range of characters that share the same value. The value is | |
651 | what @code{(char-table-range @var{char-table} @var{key})} returns. | |
b8d4c8d0 GM |
652 | |
653 | Overall, the key-value pairs passed to @var{function} describe all the | |
654 | values stored in @var{char-table}. | |
655 | ||
22526bc4 EZ |
656 | The return value is always @code{nil}; to make calls to |
657 | @code{map-char-table} useful, @var{function} should have side effects. | |
658 | For example, here is how to examine the elements of the syntax table: | |
b8d4c8d0 GM |
659 | |
660 | @example | |
661 | (let (accumulator) | |
22526bc4 EZ |
662 | (map-char-table |
663 | #'(lambda (key value) | |
664 | (setq accumulator | |
665 | (cons (list | |
666 | (if (consp key) | |
667 | (list (car key) (cdr key)) | |
668 | key) | |
669 | value) | |
670 | accumulator))) | |
671 | (syntax-table)) | |
672 | accumulator) | |
b8d4c8d0 | 673 | @result{} |
22526bc4 EZ |
674 | (((2597602 4194303) (2)) ((2597523 2597601) (3)) |
675 | ... (65379 (5 . 65378)) (65378 (4 . 65379)) (65377 (1)) | |
676 | ... (12 (0)) (11 (3)) (10 (12)) (9 (0)) ((0 8) (3))) | |
b8d4c8d0 GM |
677 | @end example |
678 | @end defun | |
679 | ||
680 | @node Bool-Vectors | |
681 | @section Bool-vectors | |
682 | @cindex Bool-vectors | |
683 | ||
684 | A bool-vector is much like a vector, except that it stores only the | |
685 | values @code{t} and @code{nil}. If you try to store any non-@code{nil} | |
686 | value into an element of the bool-vector, the effect is to store | |
687 | @code{t} there. As with all arrays, bool-vector indices start from 0, | |
688 | and the length cannot be changed once the bool-vector is created. | |
689 | Bool-vectors are constants when evaluated. | |
690 | ||
691 | There are two special functions for working with bool-vectors; aside | |
692 | from that, you manipulate them with same functions used for other kinds | |
693 | of arrays. | |
694 | ||
695 | @defun make-bool-vector length initial | |
696 | Return a new bool-vector of @var{length} elements, | |
697 | each one initialized to @var{initial}. | |
698 | @end defun | |
699 | ||
700 | @defun bool-vector-p object | |
701 | This returns @code{t} if @var{object} is a bool-vector, | |
702 | and @code{nil} otherwise. | |
703 | @end defun | |
704 | ||
705 | Here is an example of creating, examining, and updating a | |
706 | bool-vector. Note that the printed form represents up to 8 boolean | |
707 | values as a single character. | |
708 | ||
709 | @example | |
710 | (setq bv (make-bool-vector 5 t)) | |
711 | @result{} #&5"^_" | |
712 | (aref bv 1) | |
713 | @result{} t | |
714 | (aset bv 3 nil) | |
715 | @result{} nil | |
716 | bv | |
717 | @result{} #&5"^W" | |
718 | @end example | |
719 | ||
720 | @noindent | |
721 | These results make sense because the binary codes for control-_ and | |
722 | control-W are 11111 and 10111, respectively. | |
723 | ||
724 | @ignore | |
725 | arch-tag: fcf1084a-cd29-4adc-9f16-68586935b386 | |
726 | @end ignore |