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1 | @c -*-texinfo-*- |
2 | @c This is part of the GNU Emacs Lisp Reference Manual. | |
19cfd746 | 3 | @c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2004 |
177c0ea7 | 4 | @c Free Software Foundation, Inc. |
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5 | @c See the file elisp.texi for copying conditions. |
6 | @setfilename ../info/syntax | |
7 | @node Syntax Tables, Abbrevs, Searching and Matching, Top | |
8 | @chapter Syntax Tables | |
9 | @cindex parsing | |
10 | @cindex syntax table | |
11 | @cindex text parsing | |
12 | ||
13 | A @dfn{syntax table} specifies the syntactic textual function of each | |
a9f0a989 | 14 | character. This information is used by the @dfn{parsing functions}, the |
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15 | complex movement commands, and others to determine where words, symbols, |
16 | and other syntactic constructs begin and end. The current syntax table | |
17 | controls the meaning of the word motion functions (@pxref{Word Motion}) | |
f9f59935 | 18 | and the list motion functions (@pxref{List Motion}), as well as the |
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19 | functions in this chapter. |
20 | ||
21 | @menu | |
22 | * Basics: Syntax Basics. Basic concepts of syntax tables. | |
23 | * Desc: Syntax Descriptors. How characters are classified. | |
24 | * Syntax Table Functions:: How to create, examine and alter syntax tables. | |
f9f59935 | 25 | * Syntax Properties:: Overriding syntax with text properties. |
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26 | * Motion and Syntax:: Moving over characters with certain syntaxes. |
27 | * Parsing Expressions:: Parsing balanced expressions | |
28 | using the syntax table. | |
29 | * Standard Syntax Tables:: Syntax tables used by various major modes. | |
30 | * Syntax Table Internals:: How syntax table information is stored. | |
f9f59935 | 31 | * Categories:: Another way of classifying character syntax. |
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32 | @end menu |
33 | ||
34 | @node Syntax Basics | |
35 | @section Syntax Table Concepts | |
36 | ||
37680279 | 37 | @ifnottex |
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38 | A @dfn{syntax table} provides Emacs with the information that |
39 | determines the syntactic use of each character in a buffer. This | |
40 | information is used by the parsing commands, the complex movement | |
41 | commands, and others to determine where words, symbols, and other | |
42 | syntactic constructs begin and end. The current syntax table controls | |
43 | the meaning of the word motion functions (@pxref{Word Motion}) and the | |
44 | list motion functions (@pxref{List Motion}) as well as the functions in | |
45 | this chapter. | |
37680279 | 46 | @end ifnottex |
7015aca4 | 47 | |
969fe9b5 RS |
48 | A syntax table is a char-table (@pxref{Char-Tables}). The element at |
49 | index @var{c} describes the character with code @var{c}. The element's | |
50 | value should be a list that encodes the syntax of the character in | |
51 | question. | |
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52 | |
53 | Syntax tables are used only for moving across text, not for the Emacs | |
54 | Lisp reader. Emacs Lisp uses built-in syntactic rules when reading Lisp | |
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55 | expressions, and these rules cannot be changed. (Some Lisp systems |
56 | provide ways to redefine the read syntax, but we decided to leave this | |
57 | feature out of Emacs Lisp for simplicity.) | |
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58 | |
59 | Each buffer has its own major mode, and each major mode has its own | |
60 | idea of the syntactic class of various characters. For example, in Lisp | |
61 | mode, the character @samp{;} begins a comment, but in C mode, it | |
62 | terminates a statement. To support these variations, Emacs makes the | |
63 | choice of syntax table local to each buffer. Typically, each major | |
64 | mode has its own syntax table and installs that table in each buffer | |
7fd1911a | 65 | that uses that mode. Changing this table alters the syntax in all |
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66 | those buffers as well as in any buffers subsequently put in that mode. |
67 | Occasionally several similar modes share one syntax table. | |
68 | @xref{Example Major Modes}, for an example of how to set up a syntax | |
69 | table. | |
70 | ||
71 | A syntax table can inherit the data for some characters from the | |
72 | standard syntax table, while specifying other characters itself. The | |
73 | ``inherit'' syntax class means ``inherit this character's syntax from | |
f9f59935 | 74 | the standard syntax table.'' Just changing the standard syntax for a |
8241495d | 75 | character affects all syntax tables that inherit from it. |
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76 | |
77 | @defun syntax-table-p object | |
f9f59935 | 78 | This function returns @code{t} if @var{object} is a syntax table. |
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79 | @end defun |
80 | ||
81 | @node Syntax Descriptors | |
82 | @section Syntax Descriptors | |
83 | @cindex syntax classes | |
84 | ||
85 | This section describes the syntax classes and flags that denote the | |
86 | syntax of a character, and how they are represented as a @dfn{syntax | |
87 | descriptor}, which is a Lisp string that you pass to | |
969fe9b5 | 88 | @code{modify-syntax-entry} to specify the syntax you want. |
7015aca4 | 89 | |
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90 | The syntax table specifies a syntax class for each character. There |
91 | is no necessary relationship between the class of a character in one | |
92 | syntax table and its class in any other table. | |
7015aca4 | 93 | |
7fd1911a | 94 | Each class is designated by a mnemonic character, which serves as the |
7015aca4 | 95 | name of the class when you need to specify a class. Usually the |
8241495d | 96 | designator character is one that is often assigned that class; however, |
7fd1911a | 97 | its meaning as a designator is unvarying and independent of what syntax |
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98 | that character currently has. Thus, @samp{\} as a designator character |
99 | always gives ``escape character'' syntax, regardless of what syntax | |
100 | @samp{\} currently has. | |
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101 | |
102 | @cindex syntax descriptor | |
7fd1911a | 103 | A syntax descriptor is a Lisp string that specifies a syntax class, a |
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104 | matching character (used only for the parenthesis classes) and flags. |
105 | The first character is the designator for a syntax class. The second | |
106 | character is the character to match; if it is unused, put a space there. | |
107 | Then come the characters for any desired flags. If no matching | |
108 | character or flags are needed, one character is sufficient. | |
109 | ||
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110 | For example, the syntax descriptor for the character @samp{*} in C |
111 | mode is @samp{@w{. 23}} (i.e., punctuation, matching character slot | |
8241495d | 112 | unused, second character of a comment-starter, first character of a |
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113 | comment-ender), and the entry for @samp{/} is @samp{@w{. 14}} (i.e., |
114 | punctuation, matching character slot unused, first character of a | |
115 | comment-starter, second character of a comment-ender). | |
116 | ||
117 | @menu | |
118 | * Syntax Class Table:: Table of syntax classes. | |
119 | * Syntax Flags:: Additional flags each character can have. | |
120 | @end menu | |
121 | ||
122 | @node Syntax Class Table | |
123 | @subsection Table of Syntax Classes | |
124 | ||
7fd1911a | 125 | Here is a table of syntax classes, the characters that stand for them, |
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126 | their meanings, and examples of their use. |
127 | ||
128 | @deffn {Syntax class} @w{whitespace character} | |
f9f59935 | 129 | @dfn{Whitespace characters} (designated by @w{@samp{@ }} or @samp{-}) |
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130 | separate symbols and words from each other. Typically, whitespace |
131 | characters have no other syntactic significance, and multiple whitespace | |
132 | characters are syntactically equivalent to a single one. Space, tab, | |
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133 | newline and formfeed are classified as whitespace in almost all major |
134 | modes. | |
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135 | @end deffn |
136 | ||
137 | @deffn {Syntax class} @w{word constituent} | |
ca50933a RS |
138 | @dfn{Word constituents} (designated by @samp{w}) are parts of words in |
139 | human languages, and are typically used in variable and command names | |
140 | in programs. All upper- and lower-case letters, and the digits, are | |
141 | typically word constituents. | |
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142 | @end deffn |
143 | ||
144 | @deffn {Syntax class} @w{symbol constituent} | |
f9f59935 | 145 | @dfn{Symbol constituents} (designated by @samp{_}) are the extra |
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146 | characters that are used in variable and command names along with word |
147 | constituents. For example, the symbol constituents class is used in | |
148 | Lisp mode to indicate that certain characters may be part of symbol | |
149 | names even though they are not part of English words. These characters | |
150 | are @samp{$&*+-_<>}. In standard C, the only non-word-constituent | |
151 | character that is valid in symbols is underscore (@samp{_}). | |
152 | @end deffn | |
153 | ||
154 | @deffn {Syntax class} @w{punctuation character} | |
f9f59935 RS |
155 | @dfn{Punctuation characters} (designated by @samp{.}) are those |
156 | characters that are used as punctuation in English, or are used in some | |
157 | way in a programming language to separate symbols from one another. | |
8a2f014e | 158 | Some programming language modes, such as Emacs Lisp mode, have no |
f9f59935 | 159 | characters in this class since the few characters that are not symbol or |
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160 | word constituents all have other uses. Other programming language modes, |
161 | such as C mode, use punctuation syntax for operators. | |
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162 | @end deffn |
163 | ||
164 | @deffn {Syntax class} @w{open parenthesis character} | |
165 | @deffnx {Syntax class} @w{close parenthesis character} | |
166 | @cindex parenthesis syntax | |
167 | Open and close @dfn{parenthesis characters} are characters used in | |
168 | dissimilar pairs to surround sentences or expressions. Such a grouping | |
169 | is begun with an open parenthesis character and terminated with a close. | |
170 | Each open parenthesis character matches a particular close parenthesis | |
171 | character, and vice versa. Normally, Emacs indicates momentarily the | |
172 | matching open parenthesis when you insert a close parenthesis. | |
173 | @xref{Blinking}. | |
174 | ||
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175 | The class of open parentheses is designated by @samp{(}, and that of |
176 | close parentheses by @samp{)}. | |
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177 | |
178 | In English text, and in C code, the parenthesis pairs are @samp{()}, | |
179 | @samp{[]}, and @samp{@{@}}. In Emacs Lisp, the delimiters for lists and | |
180 | vectors (@samp{()} and @samp{[]}) are classified as parenthesis | |
181 | characters. | |
182 | @end deffn | |
183 | ||
184 | @deffn {Syntax class} @w{string quote} | |
f9f59935 | 185 | @dfn{String quote characters} (designated by @samp{"}) are used in |
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186 | many languages, including Lisp and C, to delimit string constants. The |
187 | same string quote character appears at the beginning and the end of a | |
188 | string. Such quoted strings do not nest. | |
189 | ||
190 | The parsing facilities of Emacs consider a string as a single token. | |
191 | The usual syntactic meanings of the characters in the string are | |
192 | suppressed. | |
193 | ||
194 | The Lisp modes have two string quote characters: double-quote (@samp{"}) | |
195 | and vertical bar (@samp{|}). @samp{|} is not used in Emacs Lisp, but it | |
196 | is used in Common Lisp. C also has two string quote characters: | |
197 | double-quote for strings, and single-quote (@samp{'}) for character | |
198 | constants. | |
199 | ||
200 | English text has no string quote characters because English is not a | |
201 | programming language. Although quotation marks are used in English, | |
202 | we do not want them to turn off the usual syntactic properties of | |
203 | other characters in the quotation. | |
204 | @end deffn | |
205 | ||
206 | @deffn {Syntax class} @w{escape} | |
f9f59935 | 207 | An @dfn{escape character} (designated by @samp{\}) starts an escape |
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208 | sequence such as is used in C string and character constants. The |
209 | character @samp{\} belongs to this class in both C and Lisp. (In C, it | |
210 | is used thus only inside strings, but it turns out to cause no trouble | |
211 | to treat it this way throughout C code.) | |
212 | ||
213 | Characters in this class count as part of words if | |
214 | @code{words-include-escapes} is non-@code{nil}. @xref{Word Motion}. | |
215 | @end deffn | |
216 | ||
217 | @deffn {Syntax class} @w{character quote} | |
f9f59935 | 218 | A @dfn{character quote character} (designated by @samp{/}) quotes the |
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219 | following character so that it loses its normal syntactic meaning. This |
220 | differs from an escape character in that only the character immediately | |
221 | following is ever affected. | |
222 | ||
223 | Characters in this class count as part of words if | |
224 | @code{words-include-escapes} is non-@code{nil}. @xref{Word Motion}. | |
225 | ||
e30ab160 | 226 | This class is used for backslash in @TeX{} mode. |
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227 | @end deffn |
228 | ||
229 | @deffn {Syntax class} @w{paired delimiter} | |
f9f59935 | 230 | @dfn{Paired delimiter characters} (designated by @samp{$}) are like |
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231 | string quote characters except that the syntactic properties of the |
232 | characters between the delimiters are not suppressed. Only @TeX{} mode | |
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233 | uses a paired delimiter presently---the @samp{$} that both enters and |
234 | leaves math mode. | |
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235 | @end deffn |
236 | ||
237 | @deffn {Syntax class} @w{expression prefix} | |
f9f59935 RS |
238 | An @dfn{expression prefix operator} (designated by @samp{'}) is used for |
239 | syntactic operators that are considered as part of an expression if they | |
240 | appear next to one. In Lisp modes, these characters include the | |
241 | apostrophe, @samp{'} (used for quoting), the comma, @samp{,} (used in | |
242 | macros), and @samp{#} (used in the read syntax for certain data types). | |
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243 | @end deffn |
244 | ||
245 | @deffn {Syntax class} @w{comment starter} | |
246 | @deffnx {Syntax class} @w{comment ender} | |
247 | @cindex comment syntax | |
248 | The @dfn{comment starter} and @dfn{comment ender} characters are used in | |
249 | various languages to delimit comments. These classes are designated | |
f9f59935 | 250 | by @samp{<} and @samp{>}, respectively. |
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251 | |
252 | English text has no comment characters. In Lisp, the semicolon | |
253 | (@samp{;}) starts a comment and a newline or formfeed ends one. | |
254 | @end deffn | |
255 | ||
256 | @deffn {Syntax class} @w{inherit} | |
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257 | This syntax class does not specify a particular syntax. It says to look |
258 | in the standard syntax table to find the syntax of this character. The | |
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259 | designator for this syntax code is @samp{@@}. |
260 | @end deffn | |
261 | ||
f9f59935 | 262 | @deffn {Syntax class} @w{generic comment delimiter} |
d1f08d85 SM |
263 | A @dfn{generic comment delimiter} (designated by @samp{!}) starts |
264 | or ends a special kind of comment. @emph{Any} generic comment delimiter | |
265 | matches @emph{any} generic comment delimiter, but they cannot match | |
266 | a comment starter or comment ender; generic comment delimiters can only | |
267 | match each other. | |
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268 | |
269 | This syntax class is primarily meant for use with the | |
270 | @code{syntax-table} text property (@pxref{Syntax Properties}). You can | |
271 | mark any range of characters as forming a comment, by giving the first | |
272 | and last characters of the range @code{syntax-table} properties | |
273 | identifying them as generic comment delimiters. | |
274 | @end deffn | |
275 | ||
276 | @deffn {Syntax class} @w{generic string delimiter} | |
d1f08d85 SM |
277 | A @dfn{generic string delimiter} (designated by @samp{|}) starts or ends |
278 | a string. This class differs from the string quote class in that @emph{any} | |
279 | generic string delimiter can match any other generic string delimiter; but | |
280 | they do not match ordinary string quote characters. | |
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281 | |
282 | This syntax class is primarily meant for use with the | |
283 | @code{syntax-table} text property (@pxref{Syntax Properties}). You can | |
284 | mark any range of characters as forming a string constant, by giving the | |
285 | first and last characters of the range @code{syntax-table} properties | |
286 | identifying them as generic string delimiters. | |
287 | @end deffn | |
288 | ||
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289 | @node Syntax Flags |
290 | @subsection Syntax Flags | |
291 | @cindex syntax flags | |
292 | ||
293 | In addition to the classes, entries for characters in a syntax table | |
79ddc9c9 GM |
294 | can specify flags. There are seven possible flags, represented by the |
295 | characters @samp{1}, @samp{2}, @samp{3}, @samp{4}, @samp{b}, @samp{n}, | |
296 | and @samp{p}. | |
297 | ||
298 | All the flags except @samp{n} and @samp{p} are used to describe | |
299 | multi-character comment delimiters. The digit flags indicate that a | |
300 | character can @emph{also} be part of a comment sequence, in addition to | |
301 | the syntactic properties associated with its character class. The flags | |
302 | are independent of the class and each other for the sake of characters | |
303 | such as @samp{*} in C mode, which is a punctuation character, @emph{and} | |
304 | the second character of a start-of-comment sequence (@samp{/*}), | |
305 | @emph{and} the first character of an end-of-comment sequence | |
306 | (@samp{*/}). | |
7015aca4 | 307 | |
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308 | Here is a table of the possible flags for a character @var{c}, |
309 | and what they mean: | |
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310 | |
311 | @itemize @bullet | |
312 | @item | |
7fd1911a | 313 | @samp{1} means @var{c} is the start of a two-character comment-start |
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314 | sequence. |
315 | ||
316 | @item | |
317 | @samp{2} means @var{c} is the second character of such a sequence. | |
318 | ||
319 | @item | |
7fd1911a | 320 | @samp{3} means @var{c} is the start of a two-character comment-end |
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321 | sequence. |
322 | ||
323 | @item | |
324 | @samp{4} means @var{c} is the second character of such a sequence. | |
325 | ||
326 | @item | |
327 | @c Emacs 19 feature | |
328 | @samp{b} means that @var{c} as a comment delimiter belongs to the | |
329 | alternative ``b'' comment style. | |
330 | ||
331 | Emacs supports two comment styles simultaneously in any one syntax | |
332 | table. This is for the sake of C++. Each style of comment syntax has | |
333 | its own comment-start sequence and its own comment-end sequence. Each | |
334 | comment must stick to one style or the other; thus, if it starts with | |
335 | the comment-start sequence of style ``b'', it must also end with the | |
336 | comment-end sequence of style ``b''. | |
337 | ||
338 | The two comment-start sequences must begin with the same character; only | |
339 | the second character may differ. Mark the second character of the | |
7fd1911a | 340 | ``b''-style comment-start sequence with the @samp{b} flag. |
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341 | |
342 | A comment-end sequence (one or two characters) applies to the ``b'' | |
343 | style if its first character has the @samp{b} flag set; otherwise, it | |
344 | applies to the ``a'' style. | |
345 | ||
346 | The appropriate comment syntax settings for C++ are as follows: | |
347 | ||
348 | @table @asis | |
349 | @item @samp{/} | |
350 | @samp{124b} | |
351 | @item @samp{*} | |
352 | @samp{23} | |
353 | @item newline | |
354 | @samp{>b} | |
355 | @end table | |
356 | ||
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357 | This defines four comment-delimiting sequences: |
358 | ||
359 | @table @asis | |
360 | @item @samp{/*} | |
361 | This is a comment-start sequence for ``a'' style because the | |
362 | second character, @samp{*}, does not have the @samp{b} flag. | |
363 | ||
364 | @item @samp{//} | |
365 | This is a comment-start sequence for ``b'' style because the second | |
366 | character, @samp{/}, does have the @samp{b} flag. | |
367 | ||
368 | @item @samp{*/} | |
369 | This is a comment-end sequence for ``a'' style because the first | |
1911e6e5 | 370 | character, @samp{*}, does not have the @samp{b} flag. |
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371 | |
372 | @item newline | |
373 | This is a comment-end sequence for ``b'' style, because the newline | |
374 | character has the @samp{b} flag. | |
375 | @end table | |
7015aca4 | 376 | |
79ddc9c9 GM |
377 | @item |
378 | @samp{n} on a comment delimiter character specifies | |
379 | that this kind of comment can be nested. For a two-character | |
380 | comment delimiter, @samp{n} on either character makes it | |
381 | nestable. | |
382 | ||
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383 | @item |
384 | @c Emacs 19 feature | |
385 | @samp{p} identifies an additional ``prefix character'' for Lisp syntax. | |
386 | These characters are treated as whitespace when they appear between | |
387 | expressions. When they appear within an expression, they are handled | |
388 | according to their usual syntax codes. | |
389 | ||
390 | The function @code{backward-prefix-chars} moves back over these | |
391 | characters, as well as over characters whose primary syntax class is | |
392 | prefix (@samp{'}). @xref{Motion and Syntax}. | |
393 | @end itemize | |
394 | ||
395 | @node Syntax Table Functions | |
396 | @section Syntax Table Functions | |
397 | ||
398 | In this section we describe functions for creating, accessing and | |
399 | altering syntax tables. | |
400 | ||
9c5609e8 LT |
401 | @defun make-syntax-table &optional table |
402 | This function creates a new syntax table, with all values initialized | |
403 | to @code{nil}. If @var{table} is non-@code{nil}, it becomes the | |
404 | parent of the new syntax table, otherwise the standard syntax table is | |
405 | the parent. Like all char-tables, a syntax table inherits from its | |
406 | parent. Thus the original syntax of all characters in the returned | |
407 | syntax table is determined by the parent. @xref{Char-Tables}. | |
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408 | |
409 | Most major mode syntax tables are created in this way. | |
410 | @end defun | |
411 | ||
412 | @defun copy-syntax-table &optional table | |
413 | This function constructs a copy of @var{table} and returns it. If | |
414 | @var{table} is not supplied (or is @code{nil}), it returns a copy of the | |
9c5609e8 | 415 | standard syntax table. Otherwise, an error is signaled if @var{table} is |
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416 | not a syntax table. |
417 | @end defun | |
418 | ||
419 | @deffn Command modify-syntax-entry char syntax-descriptor &optional table | |
420 | This function sets the syntax entry for @var{char} according to | |
421 | @var{syntax-descriptor}. The syntax is changed only for @var{table}, | |
422 | which defaults to the current buffer's syntax table, and not in any | |
423 | other syntax table. The argument @var{syntax-descriptor} specifies the | |
424 | desired syntax; this is a string beginning with a class designator | |
425 | character, and optionally containing a matching character and flags as | |
426 | well. @xref{Syntax Descriptors}. | |
427 | ||
428 | This function always returns @code{nil}. The old syntax information in | |
429 | the table for this character is discarded. | |
430 | ||
431 | An error is signaled if the first character of the syntax descriptor is not | |
9c5609e8 | 432 | one of the seventeen syntax class designator characters. An error is also |
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433 | signaled if @var{char} is not a character. |
434 | ||
435 | @example | |
436 | @group | |
437 | @exdent @r{Examples:} | |
438 | ||
439 | ;; @r{Put the space character in class whitespace.} | |
2b01bb55 | 440 | (modify-syntax-entry ?\s " ") |
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441 | @result{} nil |
442 | @end group | |
443 | ||
444 | @group | |
445 | ;; @r{Make @samp{$} an open parenthesis character,} | |
446 | ;; @r{with @samp{^} as its matching close.} | |
447 | (modify-syntax-entry ?$ "(^") | |
448 | @result{} nil | |
449 | @end group | |
450 | ||
451 | @group | |
452 | ;; @r{Make @samp{^} a close parenthesis character,} | |
453 | ;; @r{with @samp{$} as its matching open.} | |
454 | (modify-syntax-entry ?^ ")$") | |
455 | @result{} nil | |
456 | @end group | |
457 | ||
458 | @group | |
459 | ;; @r{Make @samp{/} a punctuation character,} | |
460 | ;; @r{the first character of a start-comment sequence,} | |
461 | ;; @r{and the second character of an end-comment sequence.} | |
462 | ;; @r{This is used in C mode.} | |
7fd1911a | 463 | (modify-syntax-entry ?/ ". 14") |
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464 | @result{} nil |
465 | @end group | |
466 | @end example | |
467 | @end deffn | |
468 | ||
469 | @defun char-syntax character | |
470 | This function returns the syntax class of @var{character}, represented | |
f9f59935 | 471 | by its mnemonic designator character. This returns @emph{only} the |
7015aca4 RS |
472 | class, not any matching parenthesis or flags. |
473 | ||
474 | An error is signaled if @var{char} is not a character. | |
475 | ||
476 | The following examples apply to C mode. The first example shows that | |
477 | the syntax class of space is whitespace (represented by a space). The | |
478 | second example shows that the syntax of @samp{/} is punctuation. This | |
7fd1911a RS |
479 | does not show the fact that it is also part of comment-start and -end |
480 | sequences. The third example shows that open parenthesis is in the class | |
7015aca4 RS |
481 | of open parentheses. This does not show the fact that it has a matching |
482 | character, @samp{)}. | |
483 | ||
484 | @example | |
485 | @group | |
2b01bb55 | 486 | (string (char-syntax ?\s)) |
7015aca4 RS |
487 | @result{} " " |
488 | @end group | |
489 | ||
490 | @group | |
969fe9b5 | 491 | (string (char-syntax ?/)) |
7015aca4 RS |
492 | @result{} "." |
493 | @end group | |
494 | ||
495 | @group | |
969fe9b5 | 496 | (string (char-syntax ?\()) |
7015aca4 RS |
497 | @result{} "(" |
498 | @end group | |
499 | @end example | |
969fe9b5 RS |
500 | |
501 | We use @code{string} to make it easier to see the character returned by | |
502 | @code{char-syntax}. | |
7015aca4 RS |
503 | @end defun |
504 | ||
505 | @defun set-syntax-table table | |
506 | This function makes @var{table} the syntax table for the current buffer. | |
507 | It returns @var{table}. | |
508 | @end defun | |
509 | ||
510 | @defun syntax-table | |
511 | This function returns the current syntax table, which is the table for | |
512 | the current buffer. | |
513 | @end defun | |
514 | ||
2468d0c0 DL |
515 | @defmac with-syntax-table @var{table} @var{body}... |
516 | @tindex with-syntax-table | |
517 | This macro executes @var{body} using @var{table} as the current syntax | |
518 | table. It returns the value of the last form in @var{body}, after | |
519 | restoring the old current syntax table. | |
520 | ||
521 | Since each buffer has its own current syntax table, we should make that | |
522 | more precise: @code{with-syntax-table} temporarily alters the current | |
523 | syntax table of whichever buffer is current at the time the macro | |
524 | execution starts. Other buffers are not affected. | |
525 | @end defmac | |
526 | ||
f9f59935 RS |
527 | @node Syntax Properties |
528 | @section Syntax Properties | |
529 | @kindex syntax-table @r{(text property)} | |
530 | ||
531 | When the syntax table is not flexible enough to specify the syntax of a | |
532 | language, you can use @code{syntax-table} text properties to override | |
533 | the syntax table for specific character occurrences in the buffer. | |
534 | @xref{Text Properties}. | |
535 | ||
969fe9b5 | 536 | The valid values of @code{syntax-table} text property are: |
f9f59935 RS |
537 | |
538 | @table @asis | |
539 | @item @var{syntax-table} | |
540 | If the property value is a syntax table, that table is used instead of | |
541 | the current buffer's syntax table to determine the syntax for this | |
542 | occurrence of the character. | |
543 | ||
544 | @item @code{(@var{syntax-code} . @var{matching-char})} | |
545 | A cons cell of this format specifies the syntax for this | |
d1f08d85 | 546 | occurrence of the character. (@pxref{Syntax Table Internals}) |
f9f59935 RS |
547 | |
548 | @item @code{nil} | |
549 | If the property is @code{nil}, the character's syntax is determined from | |
550 | the current syntax table in the usual way. | |
551 | @end table | |
552 | ||
f9f59935 RS |
553 | @defvar parse-sexp-lookup-properties |
554 | If this is non-@code{nil}, the syntax scanning functions pay attention | |
555 | to syntax text properties. Otherwise they use only the current syntax | |
556 | table. | |
557 | @end defvar | |
558 | ||
7015aca4 RS |
559 | @node Motion and Syntax |
560 | @section Motion and Syntax | |
561 | ||
969fe9b5 RS |
562 | This section describes functions for moving across characters that |
563 | have certain syntax classes. | |
7015aca4 RS |
564 | |
565 | @defun skip-syntax-forward syntaxes &optional limit | |
9c5609e8 LT |
566 | This function moves point forward across characters having syntax |
567 | classes mentioned in @var{syntaxes} (a string of syntax code | |
568 | characters). It stops when it encounters the end of the buffer, or | |
569 | position @var{limit} (if specified), or a character it is not supposed | |
570 | to skip. | |
8241495d RS |
571 | |
572 | If @var{syntaxes} starts with @samp{^}, then the function skips | |
573 | characters whose syntax is @emph{not} in @var{syntaxes}. | |
574 | ||
7015aca4 RS |
575 | The return value is the distance traveled, which is a nonnegative |
576 | integer. | |
7015aca4 RS |
577 | @end defun |
578 | ||
579 | @defun skip-syntax-backward syntaxes &optional limit | |
580 | This function moves point backward across characters whose syntax | |
581 | classes are mentioned in @var{syntaxes}. It stops when it encounters | |
8241495d RS |
582 | the beginning of the buffer, or position @var{limit} (if specified), or |
583 | a character it is not supposed to skip. | |
584 | ||
585 | If @var{syntaxes} starts with @samp{^}, then the function skips | |
586 | characters whose syntax is @emph{not} in @var{syntaxes}. | |
1911e6e5 | 587 | |
7015aca4 RS |
588 | The return value indicates the distance traveled. It is an integer that |
589 | is zero or less. | |
7015aca4 RS |
590 | @end defun |
591 | ||
592 | @defun backward-prefix-chars | |
593 | This function moves point backward over any number of characters with | |
594 | expression prefix syntax. This includes both characters in the | |
595 | expression prefix syntax class, and characters with the @samp{p} flag. | |
596 | @end defun | |
597 | ||
598 | @node Parsing Expressions | |
599 | @section Parsing Balanced Expressions | |
600 | ||
601 | Here are several functions for parsing and scanning balanced | |
6cbdd38b RS |
602 | expressions, also known as @dfn{sexps}. Basically, a sexp is either a |
603 | balanced parenthetical grouping, or a symbol name (a sequence of | |
604 | characters whose syntax is either word constituent or symbol | |
605 | constituent). However, characters whose syntax is expression prefix | |
606 | are treated as part of the sexp if they appear next to it. | |
607 | ||
608 | The syntax table controls the interpretation of characters, so these | |
609 | functions can be used for Lisp expressions when in Lisp mode and for C | |
610 | expressions when in C mode. @xref{List Motion}, for convenient | |
7015aca4 RS |
611 | higher-level functions for moving over balanced expressions. |
612 | ||
6cbdd38b RS |
613 | A syntax table only describes how each character changes the state |
614 | of the parser, rather than describing the state itself. For example, | |
615 | a string delimiter character toggles the parser state between | |
616 | ``in-string'' and ``in-code'' but the characters inside the string do | |
617 | not have any particular syntax to identify them as such. For example | |
618 | (note that 15 is the syntax code for generic string delimiters), | |
45493fb7 SM |
619 | |
620 | @example | |
621 | (put-text-property 1 9 'syntax-table '(15 . nil)) | |
622 | @end example | |
623 | ||
6cbdd38b | 624 | @noindent |
45493fb7 | 625 | does not tell Emacs that the first eight chars of the current buffer |
6cbdd38b RS |
626 | are a string, but rather that they are all string delimiters. As a |
627 | result, Emacs treats them as four consecutive empty string constants. | |
628 | ||
629 | Every time you use the parser, you specify it a starting state as | |
630 | well as a starting position. If you omit the starting state, the | |
631 | default is ``top level in parenthesis structure,'' as it would be at | |
632 | the beginning of a function definition. (This is the case for | |
633 | @code{forward-sexp}, which blindly assumes that the starting point is | |
634 | in such a state.) | |
45493fb7 | 635 | |
7015aca4 RS |
636 | @defun parse-partial-sexp start limit &optional target-depth stop-before state stop-comment |
637 | This function parses a sexp in the current buffer starting at | |
7fd1911a RS |
638 | @var{start}, not scanning past @var{limit}. It stops at position |
639 | @var{limit} or when certain criteria described below are met, and sets | |
640 | point to the location where parsing stops. It returns a value | |
641 | describing the status of the parse at the point where it stops. | |
7015aca4 RS |
642 | |
643 | If @var{state} is @code{nil}, @var{start} is assumed to be at the top | |
644 | level of parenthesis structure, such as the beginning of a function | |
645 | definition. Alternatively, you might wish to resume parsing in the | |
646 | middle of the structure. To do this, you must provide a @var{state} | |
647 | argument that describes the initial status of parsing. | |
648 | ||
649 | @cindex parenthesis depth | |
650 | If the third argument @var{target-depth} is non-@code{nil}, parsing | |
651 | stops if the depth in parentheses becomes equal to @var{target-depth}. | |
652 | The depth starts at 0, or at whatever is given in @var{state}. | |
653 | ||
654 | If the fourth argument @var{stop-before} is non-@code{nil}, parsing | |
655 | stops when it comes to any character that starts a sexp. If | |
656 | @var{stop-comment} is non-@code{nil}, parsing stops when it comes to the | |
f9f59935 RS |
657 | start of a comment. If @var{stop-comment} is the symbol |
658 | @code{syntax-table}, parsing stops after the start of a comment or a | |
1911e6e5 | 659 | string, or the end of a comment or a string, whichever comes first. |
7015aca4 RS |
660 | |
661 | @cindex parse state | |
8a2f014e | 662 | The fifth argument @var{state} is a ten-element list of the same form |
969fe9b5 | 663 | as the value of this function, described below. (It is OK to omit the |
8a2f014e RS |
664 | last two elements of this list.) The return value of one call may be |
665 | used to initialize the state of the parse on another call to | |
f9f59935 | 666 | @code{parse-partial-sexp}. |
7015aca4 | 667 | |
8a2f014e | 668 | The result is a list of ten elements describing the final state of |
7015aca4 RS |
669 | the parse: |
670 | ||
671 | @enumerate 0 | |
177c0ea7 | 672 | @item |
7015aca4 RS |
673 | The depth in parentheses, counting from 0. |
674 | ||
177c0ea7 | 675 | @item |
7015aca4 | 676 | @cindex innermost containing parentheses |
7fd1911a RS |
677 | The character position of the start of the innermost parenthetical |
678 | grouping containing the stopping point; @code{nil} if none. | |
7015aca4 | 679 | |
177c0ea7 | 680 | @item |
7015aca4 RS |
681 | @cindex previous complete subexpression |
682 | The character position of the start of the last complete subexpression | |
683 | terminated; @code{nil} if none. | |
684 | ||
177c0ea7 | 685 | @item |
7015aca4 RS |
686 | @cindex inside string |
687 | Non-@code{nil} if inside a string. More precisely, this is the | |
f9f59935 RS |
688 | character that will terminate the string, or @code{t} if a generic |
689 | string delimiter character should terminate it. | |
7015aca4 | 690 | |
177c0ea7 | 691 | @item |
7015aca4 | 692 | @cindex inside comment |
79ddc9c9 GM |
693 | @code{t} if inside a comment (of either style), |
694 | or the comment nesting level if inside a kind of comment | |
695 | that can be nested. | |
7015aca4 | 696 | |
177c0ea7 | 697 | @item |
7015aca4 RS |
698 | @cindex quote character |
699 | @code{t} if point is just after a quote character. | |
700 | ||
177c0ea7 | 701 | @item |
7015aca4 RS |
702 | The minimum parenthesis depth encountered during this scan. |
703 | ||
704 | @item | |
9c5609e8 LT |
705 | What kind of comment is active: @code{nil} for a comment of style |
706 | ``a'' or when not inside a comment, @code{t} for a comment of style | |
707 | ``b'', and @code{syntax-table} for a comment that should be ended by a | |
708 | generic comment delimiter character. | |
f9f59935 RS |
709 | |
710 | @item | |
711 | The string or comment start position. While inside a comment, this is | |
712 | the position where the comment began; while inside a string, this is the | |
713 | position where the string began. When outside of strings and comments, | |
714 | this element is @code{nil}. | |
7015aca4 | 715 | |
8a2f014e RS |
716 | @item |
717 | Internal data for continuing the parsing. The meaning of this | |
718 | data is subject to change; it is used if you pass this list | |
719 | as the @var{state} argument to another call. | |
720 | ||
721 | @end enumerate | |
7015aca4 | 722 | |
8a2f014e RS |
723 | Elements 0, 3, 4, 5, 7 and 9 are significant in the argument |
724 | @var{state}. | |
9c5609e8 | 725 | |
7015aca4 RS |
726 | @cindex indenting with parentheses |
727 | This function is most often used to compute indentation for languages | |
728 | that have nested parentheses. | |
729 | @end defun | |
730 | ||
731 | @defun scan-lists from count depth | |
732 | This function scans forward @var{count} balanced parenthetical groupings | |
f9f59935 RS |
733 | from position @var{from}. It returns the position where the scan stops. |
734 | If @var{count} is negative, the scan moves backwards. | |
7015aca4 RS |
735 | |
736 | If @var{depth} is nonzero, parenthesis depth counting begins from that | |
737 | value. The only candidates for stopping are places where the depth in | |
738 | parentheses becomes zero; @code{scan-lists} counts @var{count} such | |
739 | places and then stops. Thus, a positive value for @var{depth} means go | |
7fd1911a | 740 | out @var{depth} levels of parenthesis. |
7015aca4 RS |
741 | |
742 | Scanning ignores comments if @code{parse-sexp-ignore-comments} is | |
743 | non-@code{nil}. | |
744 | ||
7fd1911a RS |
745 | If the scan reaches the beginning or end of the buffer (or its |
746 | accessible portion), and the depth is not zero, an error is signaled. | |
747 | If the depth is zero but the count is not used up, @code{nil} is | |
748 | returned. | |
7015aca4 RS |
749 | @end defun |
750 | ||
751 | @defun scan-sexps from count | |
f9f59935 RS |
752 | This function scans forward @var{count} sexps from position @var{from}. |
753 | It returns the position where the scan stops. If @var{count} is | |
754 | negative, the scan moves backwards. | |
7015aca4 RS |
755 | |
756 | Scanning ignores comments if @code{parse-sexp-ignore-comments} is | |
757 | non-@code{nil}. | |
758 | ||
7fd1911a | 759 | If the scan reaches the beginning or end of (the accessible part of) the |
f9f59935 RS |
760 | buffer while in the middle of a parenthetical grouping, an error is |
761 | signaled. If it reaches the beginning or end between groupings but | |
762 | before count is used up, @code{nil} is returned. | |
7015aca4 RS |
763 | @end defun |
764 | ||
3357a32f RS |
765 | @defvar multibyte-syntax-as-symbol |
766 | @tindex multibyte-syntax-as-symbol | |
767 | If this variable is non-@code{nil}, @code{scan-sexps} treats all | |
ad800164 | 768 | non-@acronym{ASCII} characters as symbol constituents regardless |
3357a32f RS |
769 | of what the syntax table says about them. (However, text properties |
770 | can still override the syntax.) | |
771 | @end defvar | |
772 | ||
9c5609e8 | 773 | @defopt parse-sexp-ignore-comments |
7015aca4 RS |
774 | @cindex skipping comments |
775 | If the value is non-@code{nil}, then comments are treated as | |
776 | whitespace by the functions in this section and by @code{forward-sexp}. | |
9c5609e8 | 777 | @end defopt |
7015aca4 | 778 | |
cf4ccadb DL |
779 | @vindex parse-sexp-lookup-properties |
780 | The behaviour of @code{parse-partial-sexp} is also affected by | |
075ec3c4 | 781 | @code{parse-sexp-lookup-properties} (@pxref{Syntax Properties}). |
cf4ccadb | 782 | |
7015aca4 RS |
783 | You can use @code{forward-comment} to move forward or backward over |
784 | one comment or several comments. | |
785 | ||
786 | @defun forward-comment count | |
47eda1bd RS |
787 | This function moves point forward across @var{count} complete comments |
788 | (that is, including the starting delimiter and the terminating | |
37778b63 RS |
789 | delimiter if any), plus any whitespace encountered on the way. It |
790 | moves backward if @var{count} is negative. If it encounters anything | |
791 | other than a comment or whitespace, it stops, leaving point at the | |
792 | place where it stopped. This includes (for instance) finding the end | |
793 | of a comment when moving forward and expecting the beginning of one. | |
794 | The function also stops immediately after moving over the specified | |
cf4ccadb | 795 | number of complete comments. If @var{count} comments are found as |
075ec3c4 RS |
796 | expected, with nothing except whitespace between them, it returns |
797 | @code{t}; otherwise it returns @code{nil}. | |
47eda1bd RS |
798 | |
799 | This function cannot tell whether the ``comments'' it traverses are | |
800 | embedded within a string. If they look like comments, it treats them | |
801 | as comments. | |
7015aca4 RS |
802 | @end defun |
803 | ||
804 | To move forward over all comments and whitespace following point, use | |
805 | @code{(forward-comment (buffer-size))}. @code{(buffer-size)} is a good | |
7fd1911a | 806 | argument to use, because the number of comments in the buffer cannot |
7015aca4 RS |
807 | exceed that many. |
808 | ||
809 | @node Standard Syntax Tables | |
810 | @section Some Standard Syntax Tables | |
811 | ||
bfe721d1 KH |
812 | Most of the major modes in Emacs have their own syntax tables. Here |
813 | are several of them: | |
7015aca4 RS |
814 | |
815 | @defun standard-syntax-table | |
816 | This function returns the standard syntax table, which is the syntax | |
817 | table used in Fundamental mode. | |
818 | @end defun | |
819 | ||
820 | @defvar text-mode-syntax-table | |
821 | The value of this variable is the syntax table used in Text mode. | |
822 | @end defvar | |
823 | ||
824 | @defvar c-mode-syntax-table | |
825 | The value of this variable is the syntax table for C-mode buffers. | |
826 | @end defvar | |
827 | ||
828 | @defvar emacs-lisp-mode-syntax-table | |
829 | The value of this variable is the syntax table used in Emacs Lisp mode | |
830 | by editing commands. (It has no effect on the Lisp @code{read} | |
831 | function.) | |
832 | @end defvar | |
833 | ||
834 | @node Syntax Table Internals | |
835 | @section Syntax Table Internals | |
836 | @cindex syntax table internals | |
837 | ||
f9f59935 | 838 | Lisp programs don't usually work with the elements directly; the |
7015aca4 | 839 | Lisp-level syntax table functions usually work with syntax descriptors |
f9f59935 | 840 | (@pxref{Syntax Descriptors}). Nonetheless, here we document the |
d1f08d85 SM |
841 | internal format. This format is used mostly when manipulating |
842 | syntax properties. | |
f9f59935 RS |
843 | |
844 | Each element of a syntax table is a cons cell of the form | |
845 | @code{(@var{syntax-code} . @var{matching-char})}. The @sc{car}, | |
846 | @var{syntax-code}, is an integer that encodes the syntax class, and any | |
847 | flags. The @sc{cdr}, @var{matching-char}, is non-@code{nil} if | |
848 | a character to match was specified. | |
7015aca4 | 849 | |
f9f59935 RS |
850 | This table gives the value of @var{syntax-code} which corresponds |
851 | to each syntactic type. | |
7015aca4 | 852 | |
969fe9b5 | 853 | @multitable @columnfractions .05 .3 .3 .3 |
a9f0a989 RS |
854 | @item |
855 | @tab | |
969fe9b5 RS |
856 | @i{Integer} @i{Class} |
857 | @tab | |
858 | @i{Integer} @i{Class} | |
859 | @tab | |
860 | @i{Integer} @i{Class} | |
a9f0a989 RS |
861 | @item |
862 | @tab | |
969fe9b5 RS |
863 | 0 @ @ whitespace |
864 | @tab | |
865 | 5 @ @ close parenthesis | |
866 | @tab | |
867 | 10 @ @ character quote | |
a9f0a989 RS |
868 | @item |
869 | @tab | |
969fe9b5 RS |
870 | 1 @ @ punctuation |
871 | @tab | |
872 | 6 @ @ expression prefix | |
873 | @tab | |
874 | 11 @ @ comment-start | |
a9f0a989 RS |
875 | @item |
876 | @tab | |
969fe9b5 RS |
877 | 2 @ @ word |
878 | @tab | |
879 | 7 @ @ string quote | |
880 | @tab | |
881 | 12 @ @ comment-end | |
a9f0a989 RS |
882 | @item |
883 | @tab | |
969fe9b5 RS |
884 | 3 @ @ symbol |
885 | @tab | |
886 | 8 @ @ paired delimiter | |
887 | @tab | |
888 | 13 @ @ inherit | |
a9f0a989 RS |
889 | @item |
890 | @tab | |
969fe9b5 RS |
891 | 4 @ @ open parenthesis |
892 | @tab | |
893 | 9 @ @ escape | |
894 | @tab | |
85c7ceaa | 895 | 14 @ @ generic comment |
a9f0a989 RS |
896 | @item |
897 | @tab | |
85c7ceaa | 898 | 15 @ generic string |
969fe9b5 | 899 | @end multitable |
7015aca4 | 900 | |
f9f59935 RS |
901 | For example, the usual syntax value for @samp{(} is @code{(4 . 41)}. |
902 | (41 is the character code for @samp{)}.) | |
903 | ||
904 | The flags are encoded in higher order bits, starting 16 bits from the | |
905 | least significant bit. This table gives the power of two which | |
906 | corresponds to each syntax flag. | |
907 | ||
969fe9b5 | 908 | @multitable @columnfractions .05 .3 .3 .3 |
a9f0a989 RS |
909 | @item |
910 | @tab | |
969fe9b5 RS |
911 | @i{Prefix} @i{Flag} |
912 | @tab | |
913 | @i{Prefix} @i{Flag} | |
914 | @tab | |
915 | @i{Prefix} @i{Flag} | |
a9f0a989 RS |
916 | @item |
917 | @tab | |
969fe9b5 RS |
918 | @samp{1} @ @ @code{(lsh 1 16)} |
919 | @tab | |
79ddc9c9 | 920 | @samp{4} @ @ @code{(lsh 1 19)} |
969fe9b5 | 921 | @tab |
79ddc9c9 | 922 | @samp{b} @ @ @code{(lsh 1 21)} |
a9f0a989 RS |
923 | @item |
924 | @tab | |
969fe9b5 RS |
925 | @samp{2} @ @ @code{(lsh 1 17)} |
926 | @tab | |
79ddc9c9 | 927 | @samp{p} @ @ @code{(lsh 1 20)} |
969fe9b5 | 928 | @tab |
79ddc9c9 GM |
929 | @samp{n} @ @ @code{(lsh 1 22)} |
930 | @item | |
931 | @tab | |
932 | @samp{3} @ @ @code{(lsh 1 18)} | |
969fe9b5 | 933 | @end multitable |
f9f59935 | 934 | |
d1f08d85 SM |
935 | @defun string-to-syntax @var{desc} |
936 | This function returns the internal form @code{(@var{syntax-code} . | |
937 | @var{matching-char})} corresponding to the syntax descriptor @var{desc}. | |
40153606 | 938 | @end defun |
d1f08d85 | 939 | |
8a2f014e RS |
940 | @defun syntax-after pos |
941 | This function returns the syntax code of the character in the buffer | |
942 | after position @var{pos}, taking account of syntax properties as well | |
943 | as the syntax table. | |
944 | @end defun | |
945 | ||
f9f59935 RS |
946 | @node Categories |
947 | @section Categories | |
948 | @cindex categories of characters | |
949 | ||
950 | @dfn{Categories} provide an alternate way of classifying characters | |
969fe9b5 RS |
951 | syntactically. You can define several categories as needed, then |
952 | independently assign each character to one or more categories. Unlike | |
f9f59935 RS |
953 | syntax classes, categories are not mutually exclusive; it is normal for |
954 | one character to belong to several categories. | |
955 | ||
956 | Each buffer has a @dfn{category table} which records which categories | |
957 | are defined and also which characters belong to each category. Each | |
969fe9b5 RS |
958 | category table defines its own categories, but normally these are |
959 | initialized by copying from the standard categories table, so that the | |
960 | standard categories are available in all modes. | |
961 | ||
ad800164 | 962 | Each category has a name, which is an @acronym{ASCII} printing character in |
969fe9b5 RS |
963 | the range @w{@samp{ }} to @samp{~}. You specify the name of a category |
964 | when you define it with @code{define-category}. | |
f9f59935 RS |
965 | |
966 | The category table is actually a char-table (@pxref{Char-Tables}). | |
967 | The element of the category table at index @var{c} is a @dfn{category | |
968 | set}---a bool-vector---that indicates which categories character @var{c} | |
969 | belongs to. In this category set, if the element at index @var{cat} is | |
970 | @code{t}, that means category @var{cat} is a member of the set, and that | |
971 | character @var{c} belongs to category @var{cat}. | |
972 | ||
9c5609e8 LT |
973 | For the next three functions, the optional argument @var{table} |
974 | defaults to the current buffer's category table. | |
975 | ||
f9f59935 RS |
976 | @defun define-category char docstring &optional table |
977 | This function defines a new category, with name @var{char} and | |
8a2f014e | 978 | documentation @var{docstring}, for the category table @var{table}. |
f9f59935 RS |
979 | @end defun |
980 | ||
981 | @defun category-docstring category &optional table | |
982 | This function returns the documentation string of category @var{category} | |
983 | in category table @var{table}. | |
984 | ||
985 | @example | |
986 | (category-docstring ?a) | |
987 | @result{} "ASCII" | |
988 | (category-docstring ?l) | |
989 | @result{} "Latin" | |
990 | @end example | |
991 | @end defun | |
992 | ||
9c5609e8 | 993 | @defun get-unused-category &optional table |
f9f59935 | 994 | This function returns a category name (a character) which is not |
969fe9b5 | 995 | currently defined in @var{table}. If all possible categories are in use |
1911e6e5 | 996 | in @var{table}, it returns @code{nil}. |
f9f59935 RS |
997 | @end defun |
998 | ||
999 | @defun category-table | |
1000 | This function returns the current buffer's category table. | |
1001 | @end defun | |
1002 | ||
1003 | @defun category-table-p object | |
1004 | This function returns @code{t} if @var{object} is a category table, | |
1005 | otherwise @code{nil}. | |
1006 | @end defun | |
1007 | ||
1008 | @defun standard-category-table | |
1009 | This function returns the standard category table. | |
1010 | @end defun | |
1011 | ||
1012 | @defun copy-category-table &optional table | |
1013 | This function constructs a copy of @var{table} and returns it. If | |
1014 | @var{table} is not supplied (or is @code{nil}), it returns a copy of the | |
9c5609e8 | 1015 | standard category table. Otherwise, an error is signaled if @var{table} |
f9f59935 RS |
1016 | is not a category table. |
1017 | @end defun | |
1018 | ||
1019 | @defun set-category-table table | |
1020 | This function makes @var{table} the category table for the current | |
1021 | buffer. It returns @var{table}. | |
1022 | @end defun | |
1023 | ||
3f26d1e6 | 1024 | @defun make-category-table |
2468d0c0 | 1025 | @tindex make-category-table |
3f26d1e6 GM |
1026 | This creates and returns an empty category table. In an empty category |
1027 | table, no categories have been allocated, and no characters belong to | |
1028 | any categories. | |
2468d0c0 DL |
1029 | @end defun |
1030 | ||
f9f59935 RS |
1031 | @defun make-category-set categories |
1032 | This function returns a new category set---a bool-vector---whose initial | |
1033 | contents are the categories listed in the string @var{categories}. The | |
1034 | elements of @var{categories} should be category names; the new category | |
1035 | set has @code{t} for each of those categories, and @code{nil} for all | |
1036 | other categories. | |
1037 | ||
1038 | @example | |
1039 | (make-category-set "al") | |
1040 | @result{} #&128"\0\0\0\0\0\0\0\0\0\0\0\0\2\20\0\0" | |
1041 | @end example | |
1042 | @end defun | |
1043 | ||
1044 | @defun char-category-set char | |
9c5609e8 LT |
1045 | This function returns the category set for character @var{char} in the |
1046 | current buffer's category table. This is the bool-vector which | |
1047 | records which categories the character @var{char} belongs to. The | |
1048 | function @code{char-category-set} does not allocate storage, because | |
1049 | it returns the same bool-vector that exists in the category table. | |
f9f59935 RS |
1050 | |
1051 | @example | |
1052 | (char-category-set ?a) | |
1053 | @result{} #&128"\0\0\0\0\0\0\0\0\0\0\0\0\2\20\0\0" | |
1054 | @end example | |
1055 | @end defun | |
1056 | ||
1057 | @defun category-set-mnemonics category-set | |
1058 | This function converts the category set @var{category-set} into a string | |
2468d0c0 DL |
1059 | containing the characters that designate the categories that are members |
1060 | of the set. | |
f9f59935 RS |
1061 | |
1062 | @example | |
1063 | (category-set-mnemonics (char-category-set ?a)) | |
1064 | @result{} "al" | |
1065 | @end example | |
1066 | @end defun | |
1067 | ||
1068 | @defun modify-category-entry character category &optional table reset | |
1069 | This function modifies the category set of @var{character} in category | |
1070 | table @var{table} (which defaults to the current buffer's category | |
1071 | table). | |
1072 | ||
1073 | Normally, it modifies the category set by adding @var{category} to it. | |
1074 | But if @var{reset} is non-@code{nil}, then it deletes @var{category} | |
1075 | instead. | |
1076 | @end defun | |
a57092e8 | 1077 | |
9c5609e8 | 1078 | @deffn Command describe-categories &optional buffer-or-name |
a57092e8 | 1079 | This function describes the category specifications in the current |
9c5609e8 LT |
1080 | category table. It inserts the descriptions in a buffer, and then |
1081 | displays that buffer. If @var{buffer-or-name} is non-@code{nil}, it | |
1082 | describes the category table of that buffer instead. | |
a57092e8 | 1083 | @end deffn |
ab5796a9 MB |
1084 | |
1085 | @ignore | |
1086 | arch-tag: 4d914e96-0283-445c-9233-75d33662908c | |
1087 | @end ignore |