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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, | |
6ed161e1 | 4 | @c 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 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 | ||
c19ac817 CY |
16 | An @dfn{array} is a fixed-length object with a slot for each of its |
17 | elements. All the elements are accessible in constant time. The four | |
18 | types of arrays are strings, vectors, char-tables and bool-vectors. | |
b8d4c8d0 GM |
19 | |
20 | A list is a sequence of elements, but it is not a single primitive | |
21 | object; it is made of cons cells, one cell per element. Finding the | |
22 | @var{n}th element requires looking through @var{n} cons cells, so | |
23 | elements farther from the beginning of the list take longer to access. | |
24 | But it is possible to add elements to the list, or remove elements. | |
25 | ||
26 | The following diagram shows the relationship between these types: | |
27 | ||
28 | @example | |
29 | @group | |
30 | _____________________________________________ | |
31 | | | | |
32 | | Sequence | | |
33 | | ______ ________________________________ | | |
34 | | | | | | | | |
35 | | | List | | Array | | | |
36 | | | | | ________ ________ | | | |
37 | | |______| | | | | | | | | |
38 | | | | Vector | | String | | | | |
39 | | | |________| |________| | | | |
40 | | | ____________ _____________ | | | |
41 | | | | | | | | | | |
42 | | | | Char-table | | Bool-vector | | | | |
43 | | | |____________| |_____________| | | | |
44 | | |________________________________| | | |
45 | |_____________________________________________| | |
46 | @end group | |
47 | @end example | |
48 | ||
b8d4c8d0 GM |
49 | @menu |
50 | * Sequence Functions:: Functions that accept any kind of sequence. | |
51 | * Arrays:: Characteristics of arrays in Emacs Lisp. | |
52 | * Array Functions:: Functions specifically for arrays. | |
53 | * Vectors:: Special characteristics of Emacs Lisp vectors. | |
54 | * Vector Functions:: Functions specifically for vectors. | |
55 | * Char-Tables:: How to work with char-tables. | |
56 | * Bool-Vectors:: How to work with bool-vectors. | |
57 | @end menu | |
58 | ||
59 | @node Sequence Functions | |
60 | @section Sequences | |
61 | ||
62 | In Emacs Lisp, a @dfn{sequence} is either a list or an array. The | |
63 | common property of all sequences is that they are ordered collections of | |
64 | elements. This section describes functions that accept any kind of | |
65 | sequence. | |
66 | ||
67 | @defun sequencep object | |
68 | Returns @code{t} if @var{object} is a list, vector, string, | |
69 | bool-vector, or char-table, @code{nil} otherwise. | |
70 | @end defun | |
71 | ||
72 | @defun length sequence | |
73 | @cindex string length | |
74 | @cindex list length | |
75 | @cindex vector length | |
76 | @cindex sequence length | |
77 | @cindex char-table length | |
78 | This function returns the number of elements in @var{sequence}. If | |
79 | @var{sequence} is a dotted list, a @code{wrong-type-argument} error is | |
80 | signaled. Circular lists may cause an infinite loop. For a | |
81 | char-table, the value returned is always one more than the maximum | |
82 | Emacs character code. | |
83 | ||
84 | @xref{Definition of safe-length}, for the related function @code{safe-length}. | |
85 | ||
86 | @example | |
87 | @group | |
88 | (length '(1 2 3)) | |
89 | @result{} 3 | |
90 | @end group | |
91 | @group | |
92 | (length ()) | |
93 | @result{} 0 | |
94 | @end group | |
95 | @group | |
96 | (length "foobar") | |
97 | @result{} 6 | |
98 | @end group | |
99 | @group | |
100 | (length [1 2 3]) | |
101 | @result{} 3 | |
102 | @end group | |
103 | @group | |
104 | (length (make-bool-vector 5 nil)) | |
105 | @result{} 5 | |
106 | @end group | |
107 | @end example | |
108 | @end defun | |
109 | ||
110 | @noindent | |
111 | See also @code{string-bytes}, in @ref{Text Representations}. | |
112 | ||
113 | @defun elt sequence index | |
114 | @cindex elements of sequences | |
115 | This function returns the element of @var{sequence} indexed by | |
116 | @var{index}. Legitimate values of @var{index} are integers ranging | |
117 | from 0 up to one less than the length of @var{sequence}. If | |
118 | @var{sequence} is a list, out-of-range values behave as for | |
119 | @code{nth}. @xref{Definition of nth}. Otherwise, out-of-range values | |
120 | trigger an @code{args-out-of-range} error. | |
121 | ||
122 | @example | |
123 | @group | |
124 | (elt [1 2 3 4] 2) | |
125 | @result{} 3 | |
126 | @end group | |
127 | @group | |
128 | (elt '(1 2 3 4) 2) | |
129 | @result{} 3 | |
130 | @end group | |
131 | @group | |
132 | ;; @r{We use @code{string} to show clearly which character @code{elt} returns.} | |
133 | (string (elt "1234" 2)) | |
134 | @result{} "3" | |
135 | @end group | |
136 | @group | |
137 | (elt [1 2 3 4] 4) | |
138 | @error{} Args out of range: [1 2 3 4], 4 | |
139 | @end group | |
140 | @group | |
141 | (elt [1 2 3 4] -1) | |
142 | @error{} Args out of range: [1 2 3 4], -1 | |
143 | @end group | |
144 | @end example | |
145 | ||
146 | This function generalizes @code{aref} (@pxref{Array Functions}) and | |
147 | @code{nth} (@pxref{Definition of nth}). | |
148 | @end defun | |
149 | ||
150 | @defun copy-sequence sequence | |
151 | @cindex copying sequences | |
152 | Returns a copy of @var{sequence}. The copy is the same type of object | |
153 | as the original sequence, and it has the same elements in the same order. | |
154 | ||
155 | Storing a new element into the copy does not affect the original | |
156 | @var{sequence}, and vice versa. However, the elements of the new | |
157 | sequence are not copies; they are identical (@code{eq}) to the elements | |
158 | of the original. Therefore, changes made within these elements, as | |
159 | found via the copied sequence, are also visible in the original | |
160 | sequence. | |
161 | ||
162 | If the sequence is a string with text properties, the property list in | |
163 | the copy is itself a copy, not shared with the original's property | |
164 | list. However, the actual values of the properties are shared. | |
165 | @xref{Text Properties}. | |
166 | ||
167 | This function does not work for dotted lists. Trying to copy a | |
168 | circular list may cause an infinite loop. | |
169 | ||
170 | See also @code{append} in @ref{Building Lists}, @code{concat} in | |
171 | @ref{Creating Strings}, and @code{vconcat} in @ref{Vector Functions}, | |
172 | for other ways to copy sequences. | |
173 | ||
174 | @example | |
175 | @group | |
176 | (setq bar '(1 2)) | |
177 | @result{} (1 2) | |
178 | @end group | |
179 | @group | |
180 | (setq x (vector 'foo bar)) | |
181 | @result{} [foo (1 2)] | |
182 | @end group | |
183 | @group | |
184 | (setq y (copy-sequence x)) | |
185 | @result{} [foo (1 2)] | |
186 | @end group | |
187 | ||
188 | @group | |
189 | (eq x y) | |
190 | @result{} nil | |
191 | @end group | |
192 | @group | |
193 | (equal x y) | |
194 | @result{} t | |
195 | @end group | |
196 | @group | |
197 | (eq (elt x 1) (elt y 1)) | |
198 | @result{} t | |
199 | @end group | |
200 | ||
201 | @group | |
202 | ;; @r{Replacing an element of one sequence.} | |
203 | (aset x 0 'quux) | |
204 | x @result{} [quux (1 2)] | |
205 | y @result{} [foo (1 2)] | |
206 | @end group | |
207 | ||
208 | @group | |
209 | ;; @r{Modifying the inside of a shared element.} | |
210 | (setcar (aref x 1) 69) | |
211 | x @result{} [quux (69 2)] | |
212 | y @result{} [foo (69 2)] | |
213 | @end group | |
214 | @end example | |
215 | @end defun | |
216 | ||
217 | @node Arrays | |
218 | @section Arrays | |
219 | @cindex array | |
220 | ||
221 | An @dfn{array} object has slots that hold a number of other Lisp | |
c19ac817 CY |
222 | objects, called the elements of the array. Any element of an array |
223 | may be accessed in constant time. In contrast, the time to access an | |
224 | element of a list is proportional to the position of that element in | |
225 | the list. | |
226 | ||
227 | Emacs defines four types of array, all one-dimensional: | |
228 | @dfn{strings} (@pxref{String Type}), @dfn{vectors} (@pxref{Vector | |
229 | Type}), @dfn{bool-vectors} (@pxref{Bool-Vector Type}), and | |
230 | @dfn{char-tables} (@pxref{Char-Table Type}). Vectors and char-tables | |
231 | can hold elements of any type, but strings can only hold characters, | |
232 | and bool-vectors can only hold @code{t} and @code{nil}. | |
b8d4c8d0 GM |
233 | |
234 | All four kinds of array share these characteristics: | |
235 | ||
236 | @itemize @bullet | |
237 | @item | |
238 | The first element of an array has index zero, the second element has | |
239 | index 1, and so on. This is called @dfn{zero-origin} indexing. For | |
240 | example, an array of four elements has indices 0, 1, 2, @w{and 3}. | |
241 | ||
242 | @item | |
243 | The length of the array is fixed once you create it; you cannot | |
244 | change the length of an existing array. | |
245 | ||
246 | @item | |
247 | For purposes of evaluation, the array is a constant---in other words, | |
248 | it evaluates to itself. | |
249 | ||
250 | @item | |
251 | The elements of an array may be referenced or changed with the functions | |
252 | @code{aref} and @code{aset}, respectively (@pxref{Array Functions}). | |
253 | @end itemize | |
254 | ||
255 | When you create an array, other than a char-table, you must specify | |
256 | its length. You cannot specify the length of a char-table, because that | |
257 | is determined by the range of character codes. | |
258 | ||
259 | In principle, if you want an array of text characters, you could use | |
260 | either a string or a vector. In practice, we always choose strings for | |
261 | such applications, for four reasons: | |
262 | ||
263 | @itemize @bullet | |
264 | @item | |
265 | They occupy one-fourth the space of a vector of the same elements. | |
266 | ||
267 | @item | |
268 | Strings are printed in a way that shows the contents more clearly | |
269 | as text. | |
270 | ||
271 | @item | |
272 | Strings can hold text properties. @xref{Text Properties}. | |
273 | ||
274 | @item | |
275 | Many of the specialized editing and I/O facilities of Emacs accept only | |
276 | strings. For example, you cannot insert a vector of characters into a | |
277 | buffer the way you can insert a string. @xref{Strings and Characters}. | |
278 | @end itemize | |
279 | ||
280 | By contrast, for an array of keyboard input characters (such as a key | |
281 | sequence), a vector may be necessary, because many keyboard input | |
282 | characters are outside the range that will fit in a string. @xref{Key | |
283 | Sequence Input}. | |
284 | ||
285 | @node Array Functions | |
286 | @section Functions that Operate on Arrays | |
287 | ||
288 | In this section, we describe the functions that accept all types of | |
289 | arrays. | |
290 | ||
291 | @defun arrayp object | |
292 | This function returns @code{t} if @var{object} is an array (i.e., a | |
293 | vector, a string, a bool-vector or a char-table). | |
294 | ||
295 | @example | |
296 | @group | |
297 | (arrayp [a]) | |
298 | @result{} t | |
299 | (arrayp "asdf") | |
300 | @result{} t | |
301 | (arrayp (syntax-table)) ;; @r{A char-table.} | |
302 | @result{} t | |
303 | @end group | |
304 | @end example | |
305 | @end defun | |
306 | ||
307 | @defun aref array index | |
308 | @cindex array elements | |
309 | This function returns the @var{index}th element of @var{array}. The | |
310 | first element is at index zero. | |
311 | ||
312 | @example | |
313 | @group | |
314 | (setq primes [2 3 5 7 11 13]) | |
315 | @result{} [2 3 5 7 11 13] | |
316 | (aref primes 4) | |
317 | @result{} 11 | |
318 | @end group | |
319 | @group | |
320 | (aref "abcdefg" 1) | |
321 | @result{} 98 ; @r{@samp{b} is @acronym{ASCII} code 98.} | |
322 | @end group | |
323 | @end example | |
324 | ||
325 | See also the function @code{elt}, in @ref{Sequence Functions}. | |
326 | @end defun | |
327 | ||
328 | @defun aset array index object | |
329 | This function sets the @var{index}th element of @var{array} to be | |
330 | @var{object}. It returns @var{object}. | |
331 | ||
332 | @example | |
333 | @group | |
334 | (setq w [foo bar baz]) | |
335 | @result{} [foo bar baz] | |
336 | (aset w 0 'fu) | |
337 | @result{} fu | |
338 | w | |
339 | @result{} [fu bar baz] | |
340 | @end group | |
341 | ||
342 | @group | |
343 | (setq x "asdfasfd") | |
344 | @result{} "asdfasfd" | |
345 | (aset x 3 ?Z) | |
346 | @result{} 90 | |
347 | x | |
348 | @result{} "asdZasfd" | |
349 | @end group | |
350 | @end example | |
351 | ||
352 | If @var{array} is a string and @var{object} is not a character, a | |
353 | @code{wrong-type-argument} error results. The function converts a | |
354 | unibyte string to multibyte if necessary to insert a character. | |
355 | @end defun | |
356 | ||
357 | @defun fillarray array object | |
358 | This function fills the array @var{array} with @var{object}, so that | |
359 | each element of @var{array} is @var{object}. It returns @var{array}. | |
360 | ||
361 | @example | |
362 | @group | |
363 | (setq a [a b c d e f g]) | |
364 | @result{} [a b c d e f g] | |
365 | (fillarray a 0) | |
366 | @result{} [0 0 0 0 0 0 0] | |
367 | a | |
368 | @result{} [0 0 0 0 0 0 0] | |
369 | @end group | |
370 | @group | |
371 | (setq s "When in the course") | |
372 | @result{} "When in the course" | |
373 | (fillarray s ?-) | |
374 | @result{} "------------------" | |
375 | @end group | |
376 | @end example | |
377 | ||
378 | If @var{array} is a string and @var{object} is not a character, a | |
379 | @code{wrong-type-argument} error results. | |
380 | @end defun | |
381 | ||
382 | The general sequence functions @code{copy-sequence} and @code{length} | |
383 | are often useful for objects known to be arrays. @xref{Sequence Functions}. | |
384 | ||
385 | @node Vectors | |
386 | @section Vectors | |
387 | @cindex vector (type) | |
388 | ||
c19ac817 CY |
389 | A @dfn{vector} is a general-purpose array whose elements can be any |
390 | Lisp objects. (By contrast, the elements of a string can only be | |
391 | characters. @xref{Strings and Characters}.) Vectors are used in | |
392 | Emacs for many purposes: as key sequences (@pxref{Key Sequences}), as | |
393 | symbol-lookup tables (@pxref{Creating Symbols}), as part of the | |
394 | representation of a byte-compiled function (@pxref{Byte Compilation}), | |
395 | and more. | |
b8d4c8d0 GM |
396 | |
397 | In Emacs Lisp, the indices of the elements of a vector start from zero | |
398 | and count up from there. | |
399 | ||
400 | Vectors are printed with square brackets surrounding the elements. | |
401 | Thus, a vector whose elements are the symbols @code{a}, @code{b} and | |
402 | @code{a} is printed as @code{[a b a]}. You can write vectors in the | |
403 | same way in Lisp input. | |
404 | ||
405 | A vector, like a string or a number, is considered a constant for | |
406 | evaluation: the result of evaluating it is the same vector. This does | |
407 | not evaluate or even examine the elements of the vector. | |
408 | @xref{Self-Evaluating Forms}. | |
409 | ||
410 | Here are examples illustrating these principles: | |
411 | ||
412 | @example | |
413 | @group | |
414 | (setq avector [1 two '(three) "four" [five]]) | |
415 | @result{} [1 two (quote (three)) "four" [five]] | |
416 | (eval avector) | |
417 | @result{} [1 two (quote (three)) "four" [five]] | |
418 | (eq avector (eval avector)) | |
419 | @result{} t | |
420 | @end group | |
421 | @end example | |
422 | ||
423 | @node Vector Functions | |
424 | @section Functions for Vectors | |
425 | ||
426 | Here are some functions that relate to vectors: | |
427 | ||
428 | @defun vectorp object | |
429 | This function returns @code{t} if @var{object} is a vector. | |
430 | ||
431 | @example | |
432 | @group | |
433 | (vectorp [a]) | |
434 | @result{} t | |
435 | (vectorp "asdf") | |
436 | @result{} nil | |
437 | @end group | |
438 | @end example | |
439 | @end defun | |
440 | ||
441 | @defun vector &rest objects | |
442 | This function creates and returns a vector whose elements are the | |
443 | arguments, @var{objects}. | |
444 | ||
445 | @example | |
446 | @group | |
447 | (vector 'foo 23 [bar baz] "rats") | |
448 | @result{} [foo 23 [bar baz] "rats"] | |
449 | (vector) | |
450 | @result{} [] | |
451 | @end group | |
452 | @end example | |
453 | @end defun | |
454 | ||
455 | @defun make-vector length object | |
456 | This function returns a new vector consisting of @var{length} elements, | |
457 | each initialized to @var{object}. | |
458 | ||
459 | @example | |
460 | @group | |
461 | (setq sleepy (make-vector 9 'Z)) | |
462 | @result{} [Z Z Z Z Z Z Z Z Z] | |
463 | @end group | |
464 | @end example | |
465 | @end defun | |
466 | ||
467 | @defun vconcat &rest sequences | |
468 | @cindex copying vectors | |
c19ac817 | 469 | This function returns a new vector containing all the elements of |
b8d4c8d0 GM |
470 | @var{sequences}. The arguments @var{sequences} may be true lists, |
471 | vectors, strings or bool-vectors. If no @var{sequences} are given, an | |
472 | empty vector is returned. | |
473 | ||
474 | The value is a newly constructed vector that is not @code{eq} to any | |
475 | existing vector. | |
476 | ||
477 | @example | |
478 | @group | |
479 | (setq a (vconcat '(A B C) '(D E F))) | |
480 | @result{} [A B C D E F] | |
481 | (eq a (vconcat a)) | |
482 | @result{} nil | |
483 | @end group | |
484 | @group | |
485 | (vconcat) | |
486 | @result{} [] | |
487 | (vconcat [A B C] "aa" '(foo (6 7))) | |
488 | @result{} [A B C 97 97 foo (6 7)] | |
489 | @end group | |
490 | @end example | |
491 | ||
492 | The @code{vconcat} function also allows byte-code function objects as | |
493 | arguments. This is a special feature to make it easy to access the entire | |
494 | contents of a byte-code function object. @xref{Byte-Code Objects}. | |
495 | ||
b8d4c8d0 GM |
496 | For other concatenation functions, see @code{mapconcat} in @ref{Mapping |
497 | Functions}, @code{concat} in @ref{Creating Strings}, and @code{append} | |
498 | in @ref{Building Lists}. | |
499 | @end defun | |
500 | ||
501 | The @code{append} function also provides a way to convert a vector into a | |
502 | list with the same elements: | |
503 | ||
504 | @example | |
505 | @group | |
506 | (setq avector [1 two (quote (three)) "four" [five]]) | |
507 | @result{} [1 two (quote (three)) "four" [five]] | |
508 | (append avector nil) | |
509 | @result{} (1 two (quote (three)) "four" [five]) | |
510 | @end group | |
511 | @end example | |
512 | ||
513 | @node Char-Tables | |
514 | @section Char-Tables | |
515 | @cindex char-tables | |
516 | @cindex extra slots of char-table | |
517 | ||
518 | A char-table is much like a vector, except that it is indexed by | |
519 | character codes. Any valid character code, without modifiers, can be | |
520 | used as an index in a char-table. You can access a char-table's | |
521 | elements with @code{aref} and @code{aset}, as with any array. In | |
522 | addition, a char-table can have @dfn{extra slots} to hold additional | |
c19ac817 CY |
523 | data not associated with particular character codes. Like vectors, |
524 | char-tables are constants when evaluated, and can hold elements of any | |
525 | type. | |
b8d4c8d0 GM |
526 | |
527 | @cindex subtype of char-table | |
c19ac817 CY |
528 | Each char-table has a @dfn{subtype}, a symbol, which serves two |
529 | purposes: | |
530 | ||
531 | @itemize @bullet | |
532 | @item | |
533 | The subtype provides an easy way to tell what the char-table is for. | |
534 | For instance, display tables are char-tables with @code{display-table} | |
535 | as the subtype, and syntax tables are char-tables with | |
536 | @code{syntax-table} as the subtype. The subtype can be queried using | |
537 | the function @code{char-table-subtype}, described below. | |
538 | ||
539 | @item | |
540 | The subtype controls the number of @dfn{extra slots} in the | |
541 | char-table. This number is specified by the subtype's | |
542 | @code{char-table-extra-slots} symbol property, which should be an | |
543 | integer between 0 and 10. If the subtype has no such symbol property, | |
a61bc6e2 CY |
544 | the char-table has no extra slots. @xref{Property Lists}, for |
545 | information about symbol properties. | |
c19ac817 | 546 | @end itemize |
b8d4c8d0 GM |
547 | |
548 | @cindex parent of char-table | |
549 | A char-table can have a @dfn{parent}, which is another char-table. If | |
550 | it does, then whenever the char-table specifies @code{nil} for a | |
551 | particular character @var{c}, it inherits the value specified in the | |
552 | parent. In other words, @code{(aref @var{char-table} @var{c})} returns | |
553 | the value from the parent of @var{char-table} if @var{char-table} itself | |
554 | specifies @code{nil}. | |
555 | ||
556 | @cindex default value of char-table | |
557 | A char-table can also have a @dfn{default value}. If so, then | |
558 | @code{(aref @var{char-table} @var{c})} returns the default value | |
559 | whenever the char-table does not specify any other non-@code{nil} value. | |
560 | ||
561 | @defun make-char-table subtype &optional init | |
c19ac817 CY |
562 | Return a newly-created char-table, with subtype @var{subtype} (a |
563 | symbol). Each element is initialized to @var{init}, which defaults to | |
564 | @code{nil}. You cannot alter the subtype of a char-table after the | |
565 | char-table is created. | |
b8d4c8d0 GM |
566 | |
567 | There is no argument to specify the length of the char-table, because | |
568 | all char-tables have room for any valid character code as an index. | |
c19ac817 CY |
569 | |
570 | If @var{subtype} has the @code{char-table-extra-slots} symbol | |
571 | property, that specifies the number of extra slots in the char-table. | |
572 | This should be an integer between 0 and 10; otherwise, | |
573 | @code{make-char-table} raises an error. If @var{subtype} has no | |
a61bc6e2 CY |
574 | @code{char-table-extra-slots} symbol property (@pxref{Property |
575 | Lists}), the char-table has no extra slots. | |
b8d4c8d0 GM |
576 | @end defun |
577 | ||
578 | @defun char-table-p object | |
c19ac817 CY |
579 | This function returns @code{t} if @var{object} is a char-table, and |
580 | @code{nil} otherwise. | |
b8d4c8d0 GM |
581 | @end defun |
582 | ||
583 | @defun char-table-subtype char-table | |
584 | This function returns the subtype symbol of @var{char-table}. | |
585 | @end defun | |
586 | ||
b8d4c8d0 GM |
587 | There is no special function to access default values in a char-table. |
588 | To do that, use @code{char-table-range} (see below). | |
b8d4c8d0 GM |
589 | |
590 | @defun char-table-parent char-table | |
591 | This function returns the parent of @var{char-table}. The parent is | |
592 | always either @code{nil} or another char-table. | |
593 | @end defun | |
594 | ||
595 | @defun set-char-table-parent char-table new-parent | |
596 | This function sets the parent of @var{char-table} to @var{new-parent}. | |
597 | @end defun | |
598 | ||
599 | @defun char-table-extra-slot char-table n | |
600 | This function returns the contents of extra slot @var{n} of | |
601 | @var{char-table}. The number of extra slots in a char-table is | |
602 | determined by its subtype. | |
603 | @end defun | |
604 | ||
605 | @defun set-char-table-extra-slot char-table n value | |
606 | This function stores @var{value} in extra slot @var{n} of | |
607 | @var{char-table}. | |
608 | @end defun | |
609 | ||
610 | A char-table can specify an element value for a single character code; | |
611 | it can also specify a value for an entire character set. | |
612 | ||
613 | @defun char-table-range char-table range | |
614 | This returns the value specified in @var{char-table} for a range of | |
615 | characters @var{range}. Here are the possibilities for @var{range}: | |
616 | ||
617 | @table @asis | |
618 | @item @code{nil} | |
619 | Refers to the default value. | |
620 | ||
621 | @item @var{char} | |
622 | Refers to the element for character @var{char} | |
623 | (supposing @var{char} is a valid character code). | |
624 | ||
2724b26a EZ |
625 | @item @code{(@var{from} . @var{to})} |
626 | A cons cell refers to all the characters in the inclusive range | |
627 | @samp{[@var{from}..@var{to}]}. | |
b8d4c8d0 GM |
628 | @end table |
629 | @end defun | |
630 | ||
631 | @defun set-char-table-range char-table range value | |
632 | This function sets the value in @var{char-table} for a range of | |
633 | characters @var{range}. Here are the possibilities for @var{range}: | |
634 | ||
635 | @table @asis | |
636 | @item @code{nil} | |
637 | Refers to the default value. | |
638 | ||
639 | @item @code{t} | |
640 | Refers to the whole range of character codes. | |
641 | ||
642 | @item @var{char} | |
643 | Refers to the element for character @var{char} | |
644 | (supposing @var{char} is a valid character code). | |
645 | ||
2724b26a EZ |
646 | @item @code{(@var{from} . @var{to})} |
647 | A cons cell refers to all the characters in the inclusive range | |
648 | @samp{[@var{from}..@var{to}]}. | |
b8d4c8d0 GM |
649 | @end table |
650 | @end defun | |
651 | ||
652 | @defun map-char-table function char-table | |
b2fe54ae EZ |
653 | This function calls its argument @var{function} for each element of |
654 | @var{char-table} that has a non-@code{nil} value. The call to | |
655 | @var{function} is with two arguments, a key and a value. The key | |
b8d4c8d0 | 656 | is a possible @var{range} argument for @code{char-table-range}---either |
22526bc4 EZ |
657 | a valid character or a cons cell @code{(@var{from} . @var{to})}, |
658 | specifying a range of characters that share the same value. The value is | |
659 | what @code{(char-table-range @var{char-table} @var{key})} returns. | |
b8d4c8d0 GM |
660 | |
661 | Overall, the key-value pairs passed to @var{function} describe all the | |
662 | values stored in @var{char-table}. | |
663 | ||
22526bc4 EZ |
664 | The return value is always @code{nil}; to make calls to |
665 | @code{map-char-table} useful, @var{function} should have side effects. | |
666 | For example, here is how to examine the elements of the syntax table: | |
b8d4c8d0 GM |
667 | |
668 | @example | |
669 | (let (accumulator) | |
22526bc4 EZ |
670 | (map-char-table |
671 | #'(lambda (key value) | |
672 | (setq accumulator | |
673 | (cons (list | |
674 | (if (consp key) | |
675 | (list (car key) (cdr key)) | |
676 | key) | |
677 | value) | |
678 | accumulator))) | |
679 | (syntax-table)) | |
680 | accumulator) | |
b8d4c8d0 | 681 | @result{} |
22526bc4 EZ |
682 | (((2597602 4194303) (2)) ((2597523 2597601) (3)) |
683 | ... (65379 (5 . 65378)) (65378 (4 . 65379)) (65377 (1)) | |
684 | ... (12 (0)) (11 (3)) (10 (12)) (9 (0)) ((0 8) (3))) | |
b8d4c8d0 GM |
685 | @end example |
686 | @end defun | |
687 | ||
688 | @node Bool-Vectors | |
689 | @section Bool-vectors | |
690 | @cindex Bool-vectors | |
691 | ||
692 | A bool-vector is much like a vector, except that it stores only the | |
693 | values @code{t} and @code{nil}. If you try to store any non-@code{nil} | |
694 | value into an element of the bool-vector, the effect is to store | |
695 | @code{t} there. As with all arrays, bool-vector indices start from 0, | |
696 | and the length cannot be changed once the bool-vector is created. | |
697 | Bool-vectors are constants when evaluated. | |
698 | ||
699 | There are two special functions for working with bool-vectors; aside | |
700 | from that, you manipulate them with same functions used for other kinds | |
701 | of arrays. | |
702 | ||
703 | @defun make-bool-vector length initial | |
704 | Return a new bool-vector of @var{length} elements, | |
705 | each one initialized to @var{initial}. | |
706 | @end defun | |
707 | ||
708 | @defun bool-vector-p object | |
709 | This returns @code{t} if @var{object} is a bool-vector, | |
710 | and @code{nil} otherwise. | |
711 | @end defun | |
712 | ||
713 | Here is an example of creating, examining, and updating a | |
714 | bool-vector. Note that the printed form represents up to 8 boolean | |
715 | values as a single character. | |
716 | ||
717 | @example | |
718 | (setq bv (make-bool-vector 5 t)) | |
719 | @result{} #&5"^_" | |
720 | (aref bv 1) | |
721 | @result{} t | |
722 | (aset bv 3 nil) | |
723 | @result{} nil | |
724 | bv | |
725 | @result{} #&5"^W" | |
726 | @end example | |
727 | ||
728 | @noindent | |
729 | These results make sense because the binary codes for control-_ and | |
730 | control-W are 11111 and 10111, respectively. | |
731 | ||
732 | @ignore | |
733 | arch-tag: fcf1084a-cd29-4adc-9f16-68586935b386 | |
734 | @end ignore |