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1 | @c -*-texinfo-*- |
2 | @c This is part of the GNU Emacs Lisp Reference Manual. | |
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3 | @c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2002, 2003, |
4 | @c 2004, 2005 Free Software Foundation, Inc. | |
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5 | @c See the file elisp.texi for copying conditions. |
6 | @setfilename ../info/sequences | |
8241495d | 7 | @node Sequences Arrays Vectors, Hash Tables, Lists, Top |
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8 | @chapter Sequences, Arrays, and Vectors |
9 | @cindex sequence | |
10 | ||
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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. | |
4672ee8f | 15 | |
79d11238 | 16 | An @dfn{array} is a single primitive object that has a slot for each |
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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. | |
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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. | |
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26 | |
27 | The following diagram shows the relationship between these types: | |
28 | ||
29 | @example | |
30 | @group | |
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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 | |_____________________________________________| | |
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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. | |
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57 | * Vectors:: Special characteristics of Emacs Lisp vectors. |
58 | * Vector Functions:: Functions specifically for vectors. | |
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59 | * Char-Tables:: How to work with char-tables. |
60 | * Bool-Vectors:: How to work with bool-vectors. | |
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61 | @end menu |
62 | ||
63 | @node Sequence Functions | |
64 | @section Sequences | |
65 | ||
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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. | |
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70 | |
71 | @defun sequencep object | |
3a424014 LT |
72 | Returns @code{t} if @var{object} is a list, vector, string, |
73 | bool-vector, or char-table, @code{nil} otherwise. | |
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74 | @end defun |
75 | ||
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76 | @defun length sequence |
77 | @cindex string length | |
78 | @cindex list length | |
79 | @cindex vector length | |
80 | @cindex sequence length | |
d7f29ece | 81 | @cindex char-table length |
969fe9b5 | 82 | This function returns the number of elements in @var{sequence}. If |
3a424014 LT |
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. | |
969fe9b5 | 87 | |
3a424014 | 88 | @xref{Definition of safe-length}, for the related function @code{safe-length}. |
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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 | ||
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114 | @defun string-bytes string |
115 | @cindex string, number of bytes | |
116 | This function returns the number of bytes in @var{string}. | |
117 | If @var{string} is a multibyte string, this is greater than | |
118 | @code{(length @var{string})}. | |
119 | @end defun | |
120 | ||
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121 | @defun elt sequence index |
122 | @cindex elements of sequences | |
123 | This function returns the element of @var{sequence} indexed by | |
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124 | @var{index}. Legitimate values of @var{index} are integers ranging |
125 | from 0 up to one less than the length of @var{sequence}. If | |
126 | @var{sequence} is a list, out-of-range values behave as for | |
127 | @code{nth}. @xref{Definition of nth}. Otherwise, out-of-range values | |
128 | trigger an @code{args-out-of-range} error. | |
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129 | |
130 | @example | |
131 | @group | |
132 | (elt [1 2 3 4] 2) | |
133 | @result{} 3 | |
134 | @end group | |
135 | @group | |
136 | (elt '(1 2 3 4) 2) | |
137 | @result{} 3 | |
138 | @end group | |
139 | @group | |
140 | ;; @r{We use @code{string} to show clearly which character @code{elt} returns.} | |
141 | (string (elt "1234" 2)) | |
142 | @result{} "3" | |
143 | @end group | |
144 | @group | |
145 | (elt [1 2 3 4] 4) | |
a9f0a989 | 146 | @error{} Args out of range: [1 2 3 4], 4 |
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147 | @end group |
148 | @group | |
149 | (elt [1 2 3 4] -1) | |
a9f0a989 | 150 | @error{} Args out of range: [1 2 3 4], -1 |
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151 | @end group |
152 | @end example | |
153 | ||
154 | This function generalizes @code{aref} (@pxref{Array Functions}) and | |
3a424014 | 155 | @code{nth} (@pxref{Definition of nth}). |
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156 | @end defun |
157 | ||
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158 | @defun copy-sequence sequence |
159 | @cindex copying sequences | |
160 | Returns a copy of @var{sequence}. The copy is the same type of object | |
161 | as the original sequence, and it has the same elements in the same order. | |
162 | ||
163 | Storing a new element into the copy does not affect the original | |
164 | @var{sequence}, and vice versa. However, the elements of the new | |
165 | sequence are not copies; they are identical (@code{eq}) to the elements | |
166 | of the original. Therefore, changes made within these elements, as | |
167 | found via the copied sequence, are also visible in the original | |
168 | sequence. | |
169 | ||
170 | If the sequence is a string with text properties, the property list in | |
171 | the copy is itself a copy, not shared with the original's property | |
172 | list. However, the actual values of the properties are shared. | |
173 | @xref{Text Properties}. | |
174 | ||
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175 | This function does not work for dotted lists. Trying to copy a |
176 | circular list may cause an infinite loop. | |
177 | ||
4672ee8f | 178 | See also @code{append} in @ref{Building Lists}, @code{concat} in |
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179 | @ref{Creating Strings}, and @code{vconcat} in @ref{Vector Functions}, |
180 | for other ways to copy sequences. | |
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181 | |
182 | @example | |
183 | @group | |
184 | (setq bar '(1 2)) | |
185 | @result{} (1 2) | |
186 | @end group | |
187 | @group | |
188 | (setq x (vector 'foo bar)) | |
189 | @result{} [foo (1 2)] | |
190 | @end group | |
191 | @group | |
192 | (setq y (copy-sequence x)) | |
193 | @result{} [foo (1 2)] | |
194 | @end group | |
195 | ||
196 | @group | |
197 | (eq x y) | |
198 | @result{} nil | |
199 | @end group | |
200 | @group | |
201 | (equal x y) | |
202 | @result{} t | |
203 | @end group | |
204 | @group | |
205 | (eq (elt x 1) (elt y 1)) | |
206 | @result{} t | |
207 | @end group | |
208 | ||
209 | @group | |
210 | ;; @r{Replacing an element of one sequence.} | |
211 | (aset x 0 'quux) | |
212 | x @result{} [quux (1 2)] | |
213 | y @result{} [foo (1 2)] | |
214 | @end group | |
215 | ||
216 | @group | |
217 | ;; @r{Modifying the inside of a shared element.} | |
218 | (setcar (aref x 1) 69) | |
219 | x @result{} [quux (69 2)] | |
220 | y @result{} [foo (69 2)] | |
221 | @end group | |
222 | @end example | |
223 | @end defun | |
224 | ||
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225 | @node Arrays |
226 | @section Arrays | |
227 | @cindex array | |
228 | ||
79d11238 | 229 | An @dfn{array} object has slots that hold a number of other Lisp |
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230 | objects, called the elements of the array. Any element of an array may |
231 | be accessed in constant time. In contrast, an element of a list | |
232 | requires access time that is proportional to the position of the element | |
233 | in the list. | |
234 | ||
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235 | Emacs defines four types of array, all one-dimensional: @dfn{strings}, |
236 | @dfn{vectors}, @dfn{bool-vectors} and @dfn{char-tables}. A vector is a | |
237 | general array; its elements can be any Lisp objects. A string is a | |
177c0ea7 | 238 | specialized array; its elements must be characters. Each type of array |
2bdedac1 | 239 | has its own read syntax. |
a9f0a989 | 240 | @xref{String Type}, and @ref{Vector Type}. |
4672ee8f | 241 | |
969fe9b5 | 242 | All four kinds of array share these characteristics: |
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243 | |
244 | @itemize @bullet | |
245 | @item | |
246 | The first element of an array has index zero, the second element has | |
247 | index 1, and so on. This is called @dfn{zero-origin} indexing. For | |
248 | example, an array of four elements has indices 0, 1, 2, @w{and 3}. | |
249 | ||
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250 | @item |
251 | The length of the array is fixed once you create it; you cannot | |
252 | change the length of an existing array. | |
253 | ||
254 | @item | |
bdd78d05 | 255 | For purposes of evaluation, the array is a constant---in other words, |
a87ffdbc | 256 | it evaluates to itself. |
969fe9b5 | 257 | |
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258 | @item |
259 | The elements of an array may be referenced or changed with the functions | |
260 | @code{aref} and @code{aset}, respectively (@pxref{Array Functions}). | |
261 | @end itemize | |
262 | ||
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263 | When you create an array, other than a char-table, you must specify |
264 | its length. You cannot specify the length of a char-table, because that | |
265 | is determined by the range of character codes. | |
266 | ||
267 | In principle, if you want an array of text characters, you could use | |
268 | either a string or a vector. In practice, we always choose strings for | |
269 | such applications, for four reasons: | |
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270 | |
271 | @itemize @bullet | |
272 | @item | |
273 | They occupy one-fourth the space of a vector of the same elements. | |
274 | ||
275 | @item | |
276 | Strings are printed in a way that shows the contents more clearly | |
f9f59935 | 277 | as text. |
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278 | |
279 | @item | |
280 | Strings can hold text properties. @xref{Text Properties}. | |
281 | ||
282 | @item | |
283 | Many of the specialized editing and I/O facilities of Emacs accept only | |
284 | strings. For example, you cannot insert a vector of characters into a | |
285 | buffer the way you can insert a string. @xref{Strings and Characters}. | |
286 | @end itemize | |
287 | ||
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288 | By contrast, for an array of keyboard input characters (such as a key |
289 | sequence), a vector may be necessary, because many keyboard input | |
290 | characters are outside the range that will fit in a string. @xref{Key | |
291 | Sequence Input}. | |
292 | ||
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293 | @node Array Functions |
294 | @section Functions that Operate on Arrays | |
295 | ||
f9f59935 RS |
296 | In this section, we describe the functions that accept all types of |
297 | arrays. | |
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298 | |
299 | @defun arrayp object | |
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300 | This function returns @code{t} if @var{object} is an array (i.e., a |
301 | vector, a string, a bool-vector or a char-table). | |
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302 | |
303 | @example | |
304 | @group | |
305 | (arrayp [a]) | |
969fe9b5 | 306 | @result{} t |
4672ee8f | 307 | (arrayp "asdf") |
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308 | @result{} t |
309 | (arrayp (syntax-table)) ;; @r{A char-table.} | |
310 | @result{} t | |
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311 | @end group |
312 | @end example | |
313 | @end defun | |
314 | ||
315 | @defun aref array index | |
316 | @cindex array elements | |
317 | This function returns the @var{index}th element of @var{array}. The | |
318 | first element is at index zero. | |
319 | ||
320 | @example | |
321 | @group | |
322 | (setq primes [2 3 5 7 11 13]) | |
323 | @result{} [2 3 5 7 11 13] | |
324 | (aref primes 4) | |
325 | @result{} 11 | |
4672ee8f | 326 | @end group |
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327 | @group |
328 | (aref "abcdefg" 1) | |
ad800164 | 329 | @result{} 98 ; @r{@samp{b} is @acronym{ASCII} code 98.} |
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330 | @end group |
331 | @end example | |
332 | ||
333 | See also the function @code{elt}, in @ref{Sequence Functions}. | |
334 | @end defun | |
335 | ||
336 | @defun aset array index object | |
337 | This function sets the @var{index}th element of @var{array} to be | |
338 | @var{object}. It returns @var{object}. | |
339 | ||
340 | @example | |
341 | @group | |
342 | (setq w [foo bar baz]) | |
343 | @result{} [foo bar baz] | |
344 | (aset w 0 'fu) | |
345 | @result{} fu | |
346 | w | |
347 | @result{} [fu bar baz] | |
348 | @end group | |
349 | ||
350 | @group | |
351 | (setq x "asdfasfd") | |
352 | @result{} "asdfasfd" | |
353 | (aset x 3 ?Z) | |
354 | @result{} 90 | |
355 | x | |
356 | @result{} "asdZasfd" | |
357 | @end group | |
358 | @end example | |
359 | ||
360 | If @var{array} is a string and @var{object} is not a character, a | |
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361 | @code{wrong-type-argument} error results. The function converts a |
362 | unibyte string to multibyte if necessary to insert a character. | |
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363 | @end defun |
364 | ||
365 | @defun fillarray array object | |
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366 | This function fills the array @var{array} with @var{object}, so that |
367 | each element of @var{array} is @var{object}. It returns @var{array}. | |
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368 | |
369 | @example | |
370 | @group | |
371 | (setq a [a b c d e f g]) | |
372 | @result{} [a b c d e f g] | |
373 | (fillarray a 0) | |
374 | @result{} [0 0 0 0 0 0 0] | |
375 | a | |
376 | @result{} [0 0 0 0 0 0 0] | |
377 | @end group | |
378 | @group | |
379 | (setq s "When in the course") | |
380 | @result{} "When in the course" | |
381 | (fillarray s ?-) | |
382 | @result{} "------------------" | |
383 | @end group | |
384 | @end example | |
385 | ||
386 | If @var{array} is a string and @var{object} is not a character, a | |
387 | @code{wrong-type-argument} error results. | |
388 | @end defun | |
389 | ||
390 | The general sequence functions @code{copy-sequence} and @code{length} | |
391 | are often useful for objects known to be arrays. @xref{Sequence Functions}. | |
392 | ||
393 | @node Vectors | |
394 | @section Vectors | |
395 | @cindex vector | |
396 | ||
397 | Arrays in Lisp, like arrays in most languages, are blocks of memory | |
398 | whose elements can be accessed in constant time. A @dfn{vector} is a | |
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399 | general-purpose array of specified length; its elements can be any Lisp |
400 | objects. (By contrast, a string can hold only characters as elements.) | |
401 | Vectors in Emacs are used for obarrays (vectors of symbols), and as part | |
402 | of keymaps (vectors of commands). They are also used internally as part | |
403 | of the representation of a byte-compiled function; if you print such a | |
f9f59935 | 404 | function, you will see a vector in it. |
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405 | |
406 | In Emacs Lisp, the indices of the elements of a vector start from zero | |
407 | and count up from there. | |
408 | ||
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409 | Vectors are printed with square brackets surrounding the elements. |
410 | Thus, a vector whose elements are the symbols @code{a}, @code{b} and | |
411 | @code{a} is printed as @code{[a b a]}. You can write vectors in the | |
412 | same way in Lisp input. | |
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413 | |
414 | A vector, like a string or a number, is considered a constant for | |
415 | evaluation: the result of evaluating it is the same vector. This does | |
416 | not evaluate or even examine the elements of the vector. | |
417 | @xref{Self-Evaluating Forms}. | |
418 | ||
f9f59935 | 419 | Here are examples illustrating these principles: |
4672ee8f RS |
420 | |
421 | @example | |
422 | @group | |
423 | (setq avector [1 two '(three) "four" [five]]) | |
424 | @result{} [1 two (quote (three)) "four" [five]] | |
425 | (eval avector) | |
426 | @result{} [1 two (quote (three)) "four" [five]] | |
427 | (eq avector (eval avector)) | |
428 | @result{} t | |
429 | @end group | |
430 | @end example | |
431 | ||
79d11238 | 432 | @node Vector Functions |
969fe9b5 | 433 | @section Functions for Vectors |
79d11238 | 434 | |
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435 | Here are some functions that relate to vectors: |
436 | ||
437 | @defun vectorp object | |
438 | This function returns @code{t} if @var{object} is a vector. | |
439 | ||
440 | @example | |
441 | @group | |
442 | (vectorp [a]) | |
443 | @result{} t | |
444 | (vectorp "asdf") | |
445 | @result{} nil | |
446 | @end group | |
447 | @end example | |
448 | @end defun | |
449 | ||
450 | @defun vector &rest objects | |
451 | This function creates and returns a vector whose elements are the | |
452 | arguments, @var{objects}. | |
453 | ||
454 | @example | |
455 | @group | |
456 | (vector 'foo 23 [bar baz] "rats") | |
457 | @result{} [foo 23 [bar baz] "rats"] | |
458 | (vector) | |
459 | @result{} [] | |
460 | @end group | |
461 | @end example | |
462 | @end defun | |
463 | ||
464 | @defun make-vector length object | |
465 | This function returns a new vector consisting of @var{length} elements, | |
466 | each initialized to @var{object}. | |
467 | ||
468 | @example | |
469 | @group | |
470 | (setq sleepy (make-vector 9 'Z)) | |
471 | @result{} [Z Z Z Z Z Z Z Z Z] | |
472 | @end group | |
473 | @end example | |
474 | @end defun | |
475 | ||
476 | @defun vconcat &rest sequences | |
477 | @cindex copying vectors | |
478 | This function returns a new vector containing all the elements of the | |
3a424014 LT |
479 | @var{sequences}. The arguments @var{sequences} may be true lists, |
480 | vectors, strings or bool-vectors. If no @var{sequences} are given, an | |
481 | empty vector is returned. | |
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482 | |
483 | The value is a newly constructed vector that is not @code{eq} to any | |
484 | existing vector. | |
485 | ||
486 | @example | |
487 | @group | |
488 | (setq a (vconcat '(A B C) '(D E F))) | |
489 | @result{} [A B C D E F] | |
490 | (eq a (vconcat a)) | |
491 | @result{} nil | |
492 | @end group | |
493 | @group | |
494 | (vconcat) | |
495 | @result{} [] | |
496 | (vconcat [A B C] "aa" '(foo (6 7))) | |
497 | @result{} [A B C 97 97 foo (6 7)] | |
498 | @end group | |
499 | @end example | |
500 | ||
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501 | The @code{vconcat} function also allows byte-code function objects as |
502 | arguments. This is a special feature to make it easy to access the entire | |
503 | contents of a byte-code function object. @xref{Byte-Code Objects}. | |
504 | ||
2d9c2502 RS |
505 | In Emacs versions before 21, the @code{vconcat} function allowed |
506 | integers as arguments, converting them to strings of digits, but that | |
507 | feature has been eliminated. The proper way to convert an integer to | |
508 | a decimal number in this way is with @code{format} (@pxref{Formatting | |
509 | Strings}) or @code{number-to-string} (@pxref{String Conversion}). | |
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510 | |
511 | For other concatenation functions, see @code{mapconcat} in @ref{Mapping | |
512 | Functions}, @code{concat} in @ref{Creating Strings}, and @code{append} | |
513 | in @ref{Building Lists}. | |
514 | @end defun | |
515 | ||
516 | The @code{append} function provides a way to convert a vector into a | |
517 | list with the same elements (@pxref{Building Lists}): | |
518 | ||
519 | @example | |
520 | @group | |
521 | (setq avector [1 two (quote (three)) "four" [five]]) | |
522 | @result{} [1 two (quote (three)) "four" [five]] | |
523 | (append avector nil) | |
524 | @result{} (1 two (quote (three)) "four" [five]) | |
525 | @end group | |
526 | @end example | |
f9f59935 RS |
527 | |
528 | @node Char-Tables | |
529 | @section Char-Tables | |
530 | @cindex char-tables | |
a9f0a989 | 531 | @cindex extra slots of char-table |
f9f59935 RS |
532 | |
533 | A char-table is much like a vector, except that it is indexed by | |
534 | character codes. Any valid character code, without modifiers, can be | |
969fe9b5 | 535 | used as an index in a char-table. You can access a char-table's |
a9f0a989 RS |
536 | elements with @code{aref} and @code{aset}, as with any array. In |
537 | addition, a char-table can have @dfn{extra slots} to hold additional | |
538 | data not associated with particular character codes. Char-tables are | |
539 | constants when evaluated. | |
f9f59935 | 540 | |
f9f59935 | 541 | @cindex subtype of char-table |
a9f0a989 RS |
542 | Each char-table has a @dfn{subtype} which is a symbol. The subtype |
543 | has two purposes: to distinguish char-tables meant for different uses, | |
544 | and to control the number of extra slots. For example, display tables | |
545 | are char-tables with @code{display-table} as the subtype, and syntax | |
546 | tables are char-tables with @code{syntax-table} as the subtype. A valid | |
547 | subtype must have a @code{char-table-extra-slots} property which is an | |
548 | integer between 0 and 10. This integer specifies the number of | |
549 | @dfn{extra slots} in the char-table. | |
f9f59935 RS |
550 | |
551 | @cindex parent of char-table | |
4f790472 | 552 | A char-table can have a @dfn{parent}, which is another char-table. If |
f9f59935 RS |
553 | it does, then whenever the char-table specifies @code{nil} for a |
554 | particular character @var{c}, it inherits the value specified in the | |
555 | parent. In other words, @code{(aref @var{char-table} @var{c})} returns | |
556 | the value from the parent of @var{char-table} if @var{char-table} itself | |
557 | specifies @code{nil}. | |
558 | ||
559 | @cindex default value of char-table | |
560 | A char-table can also have a @dfn{default value}. If so, then | |
561 | @code{(aref @var{char-table} @var{c})} returns the default value | |
562 | whenever the char-table does not specify any other non-@code{nil} value. | |
563 | ||
f9f59935 RS |
564 | @defun make-char-table subtype &optional init |
565 | Return a newly created char-table, with subtype @var{subtype}. Each | |
566 | element is initialized to @var{init}, which defaults to @code{nil}. You | |
567 | cannot alter the subtype of a char-table after the char-table is | |
568 | created. | |
969fe9b5 RS |
569 | |
570 | There is no argument to specify the length of the char-table, because | |
571 | all char-tables have room for any valid character code as an index. | |
f9f59935 RS |
572 | @end defun |
573 | ||
f9f59935 | 574 | @defun char-table-p object |
969fe9b5 | 575 | This function returns @code{t} if @var{object} is a char-table, |
f9f59935 RS |
576 | otherwise @code{nil}. |
577 | @end defun | |
578 | ||
f9f59935 RS |
579 | @defun char-table-subtype char-table |
580 | This function returns the subtype symbol of @var{char-table}. | |
581 | @end defun | |
582 | ||
a87ffdbc RS |
583 | @defun set-char-table-default char-table char new-default |
584 | This function sets the default value of generic character @var{char} | |
585 | in @var{char-table} to @var{new-default}. | |
f9f59935 | 586 | |
a87ffdbc RS |
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). | |
f9f59935 RS |
589 | @end defun |
590 | ||
f9f59935 RS |
591 | @defun char-table-parent char-table |
592 | This function returns the parent of @var{char-table}. The parent is | |
593 | always either @code{nil} or another char-table. | |
594 | @end defun | |
595 | ||
f9f59935 RS |
596 | @defun set-char-table-parent char-table new-parent |
597 | This function sets the parent of @var{char-table} to @var{new-parent}. | |
598 | @end defun | |
599 | ||
f9f59935 RS |
600 | @defun char-table-extra-slot char-table n |
601 | This function returns the contents of extra slot @var{n} of | |
602 | @var{char-table}. The number of extra slots in a char-table is | |
603 | determined by its subtype. | |
604 | @end defun | |
605 | ||
f9f59935 RS |
606 | @defun set-char-table-extra-slot char-table n value |
607 | This function stores @var{value} in extra slot @var{n} of | |
608 | @var{char-table}. | |
609 | @end defun | |
610 | ||
611 | A char-table can specify an element value for a single character code; | |
612 | it can also specify a value for an entire character set. | |
613 | ||
f9f59935 RS |
614 | @defun char-table-range char-table range |
615 | This returns the value specified in @var{char-table} for a range of | |
a9f0a989 | 616 | characters @var{range}. Here are the possibilities for @var{range}: |
f9f59935 RS |
617 | |
618 | @table @asis | |
619 | @item @code{nil} | |
620 | Refers to the default value. | |
621 | ||
622 | @item @var{char} | |
a9f0a989 RS |
623 | Refers to the element for character @var{char} |
624 | (supposing @var{char} is a valid character code). | |
f9f59935 RS |
625 | |
626 | @item @var{charset} | |
627 | Refers to the value specified for the whole character set | |
628 | @var{charset} (@pxref{Character Sets}). | |
a9f0a989 RS |
629 | |
630 | @item @var{generic-char} | |
a87ffdbc RS |
631 | A generic character stands for a character set, or a row of a |
632 | character set; specifying the generic character as argument is | |
633 | equivalent to specifying the character set name. @xref{Splitting | |
634 | Characters}, for a description of generic characters. | |
f9f59935 RS |
635 | @end table |
636 | @end defun | |
637 | ||
f9f59935 | 638 | @defun set-char-table-range char-table range value |
1911e6e5 | 639 | This function sets the value in @var{char-table} for a range of |
a9f0a989 | 640 | characters @var{range}. Here are the possibilities for @var{range}: |
f9f59935 RS |
641 | |
642 | @table @asis | |
643 | @item @code{nil} | |
644 | Refers to the default value. | |
645 | ||
646 | @item @code{t} | |
647 | Refers to the whole range of character codes. | |
648 | ||
649 | @item @var{char} | |
a9f0a989 RS |
650 | Refers to the element for character @var{char} |
651 | (supposing @var{char} is a valid character code). | |
f9f59935 RS |
652 | |
653 | @item @var{charset} | |
654 | Refers to the value specified for the whole character set | |
655 | @var{charset} (@pxref{Character Sets}). | |
a9f0a989 RS |
656 | |
657 | @item @var{generic-char} | |
658 | A generic character stands for a character set; specifying the generic | |
659 | character as argument is equivalent to specifying the character set | |
660 | name. @xref{Splitting Characters}, for a description of generic characters. | |
f9f59935 RS |
661 | @end table |
662 | @end defun | |
663 | ||
f9f59935 RS |
664 | @defun map-char-table function char-table |
665 | This function calls @var{function} for each element of @var{char-table}. | |
666 | @var{function} is called with two arguments, a key and a value. The key | |
a9f0a989 RS |
667 | is a possible @var{range} argument for @code{char-table-range}---either |
668 | a valid character or a generic character---and the value is | |
669 | @code{(char-table-range @var{char-table} @var{key})}. | |
f9f59935 | 670 | |
969fe9b5 | 671 | Overall, the key-value pairs passed to @var{function} describe all the |
f9f59935 | 672 | values stored in @var{char-table}. |
a9f0a989 RS |
673 | |
674 | The return value is always @code{nil}; to make this function useful, | |
675 | @var{function} should have side effects. For example, | |
676 | here is how to examine each element of the syntax table: | |
677 | ||
678 | @example | |
1911e6e5 RS |
679 | (let (accumulator) |
680 | (map-char-table | |
681 | #'(lambda (key value) | |
682 | (setq accumulator | |
683 | (cons (list key value) accumulator))) | |
684 | (syntax-table)) | |
685 | accumulator) | |
a9f0a989 RS |
686 | @result{} |
687 | ((475008 nil) (474880 nil) (474752 nil) (474624 nil) | |
688 | ... (5 (3)) (4 (3)) (3 (3)) (2 (3)) (1 (3)) (0 (3))) | |
689 | @end example | |
f9f59935 RS |
690 | @end defun |
691 | ||
692 | @node Bool-Vectors | |
693 | @section Bool-vectors | |
694 | @cindex Bool-vectors | |
695 | ||
696 | A bool-vector is much like a vector, except that it stores only the | |
697 | values @code{t} and @code{nil}. If you try to store any non-@code{nil} | |
969fe9b5 RS |
698 | value into an element of the bool-vector, the effect is to store |
699 | @code{t} there. As with all arrays, bool-vector indices start from 0, | |
700 | and the length cannot be changed once the bool-vector is created. | |
701 | Bool-vectors are constants when evaluated. | |
f9f59935 RS |
702 | |
703 | There are two special functions for working with bool-vectors; aside | |
704 | from that, you manipulate them with same functions used for other kinds | |
705 | of arrays. | |
706 | ||
f9f59935 | 707 | @defun make-bool-vector length initial |
db4413be | 708 | Return a new bool-vector of @var{length} elements, |
f9f59935 RS |
709 | each one initialized to @var{initial}. |
710 | @end defun | |
711 | ||
712 | @defun bool-vector-p object | |
713 | This returns @code{t} if @var{object} is a bool-vector, | |
714 | and @code{nil} otherwise. | |
715 | @end defun | |
716 | ||
5785f550 RS |
717 | Here is an example of creating, examining, and updating a |
718 | bool-vector. Note that the printed form represents up to 8 boolean | |
719 | values as a single character. | |
720 | ||
721 | @example | |
722 | (setq bv (make-bool-vector 5 t)) | |
723 | @result{} #&5"^_" | |
724 | (aref bv 1) | |
725 | @result{} t | |
726 | (aset bv 3 nil) | |
727 | @result{} nil | |
728 | bv | |
729 | @result{} #&5"^W" | |
730 | @end example | |
731 | ||
732 | @noindent | |
733 | These results make sense because the binary codes for control-_ and | |
734 | control-W are 11111 and 10111, respectively. | |
735 | ||
ab5796a9 MB |
736 | @ignore |
737 | arch-tag: fcf1084a-cd29-4adc-9f16-68586935b386 | |
738 | @end ignore |