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1 | @c -*-texinfo-*- |
2 | @c This is part of the GNU Emacs Lisp Reference Manual. | |
f9f59935 | 3 | @c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998 Free Software Foundation, Inc. |
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4 | @c See the file elisp.texi for copying conditions. |
5 | @setfilename ../info/searching | |
f9f59935 | 6 | @node Searching and Matching, Syntax Tables, Non-ASCII Characters, Top |
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7 | @chapter Searching and Matching |
8 | @cindex searching | |
9 | ||
10 | GNU Emacs provides two ways to search through a buffer for specified | |
11 | text: exact string searches and regular expression searches. After a | |
12 | regular expression search, you can examine the @dfn{match data} to | |
13 | determine which text matched the whole regular expression or various | |
14 | portions of it. | |
15 | ||
16 | @menu | |
17 | * String Search:: Search for an exact match. | |
18 | * Regular Expressions:: Describing classes of strings. | |
19 | * Regexp Search:: Searching for a match for a regexp. | |
22697dac | 20 | * POSIX Regexps:: Searching POSIX-style for the longest match. |
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21 | * Search and Replace:: Internals of @code{query-replace}. |
22 | * Match Data:: Finding out which part of the text matched | |
23 | various parts of a regexp, after regexp search. | |
24 | * Searching and Case:: Case-independent or case-significant searching. | |
25 | * Standard Regexps:: Useful regexps for finding sentences, pages,... | |
26 | @end menu | |
27 | ||
28 | The @samp{skip-chars@dots{}} functions also perform a kind of searching. | |
29 | @xref{Skipping Characters}. | |
30 | ||
31 | @node String Search | |
32 | @section Searching for Strings | |
33 | @cindex string search | |
34 | ||
35 | These are the primitive functions for searching through the text in a | |
36 | buffer. They are meant for use in programs, but you may call them | |
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37 | interactively. If you do so, they prompt for the search string; the |
38 | arguments @var{limit} and @var{noerror} are @code{nil}, and @var{repeat} | |
39 | is 1. | |
7015aca4 | 40 | |
f9f59935 RS |
41 | These search functions convert the search string to multibyte if the |
42 | buffer is multibyte; they convert the search string to unibyte if the | |
43 | buffer is unibyte. @xref{Text Representations}. | |
44 | ||
7015aca4 | 45 | @deffn Command search-forward string &optional limit noerror repeat |
f9f59935 | 46 | This function searches forward from point for an exact match for |
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47 | @var{string}. If successful, it sets point to the end of the occurrence |
48 | found, and returns the new value of point. If no match is found, the | |
49 | value and side effects depend on @var{noerror} (see below). | |
50 | @c Emacs 19 feature | |
51 | ||
f9f59935 | 52 | In the following example, point is initially at the beginning of the |
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53 | line. Then @code{(search-forward "fox")} moves point after the last |
54 | letter of @samp{fox}: | |
55 | ||
56 | @example | |
57 | @group | |
58 | ---------- Buffer: foo ---------- | |
59 | @point{}The quick brown fox jumped over the lazy dog. | |
60 | ---------- Buffer: foo ---------- | |
61 | @end group | |
62 | ||
63 | @group | |
64 | (search-forward "fox") | |
65 | @result{} 20 | |
66 | ||
67 | ---------- Buffer: foo ---------- | |
68 | The quick brown fox@point{} jumped over the lazy dog. | |
69 | ---------- Buffer: foo ---------- | |
70 | @end group | |
71 | @end example | |
72 | ||
f9f59935 | 73 | The argument @var{limit} specifies the upper bound to the search. (It |
7015aca4 RS |
74 | must be a position in the current buffer.) No match extending after |
75 | that position is accepted. If @var{limit} is omitted or @code{nil}, it | |
76 | defaults to the end of the accessible portion of the buffer. | |
77 | ||
78 | @kindex search-failed | |
f9f59935 | 79 | What happens when the search fails depends on the value of |
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80 | @var{noerror}. If @var{noerror} is @code{nil}, a @code{search-failed} |
81 | error is signaled. If @var{noerror} is @code{t}, @code{search-forward} | |
82 | returns @code{nil} and does nothing. If @var{noerror} is neither | |
83 | @code{nil} nor @code{t}, then @code{search-forward} moves point to the | |
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84 | upper bound and returns @code{nil}. (It would be more consistent now to |
85 | return the new position of point in that case, but some existing | |
86 | programs may depend on a value of @code{nil}.) | |
7015aca4 | 87 | |
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88 | If @var{repeat} is supplied (it must be a positive number), then the |
89 | search is repeated that many times (each time starting at the end of the | |
90 | previous time's match). If these successive searches succeed, the | |
91 | function succeeds, moving point and returning its new value. Otherwise | |
92 | the search fails. | |
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93 | @end deffn |
94 | ||
95 | @deffn Command search-backward string &optional limit noerror repeat | |
96 | This function searches backward from point for @var{string}. It is | |
97 | just like @code{search-forward} except that it searches backwards and | |
98 | leaves point at the beginning of the match. | |
99 | @end deffn | |
100 | ||
101 | @deffn Command word-search-forward string &optional limit noerror repeat | |
102 | @cindex word search | |
103 | This function searches forward from point for a ``word'' match for | |
104 | @var{string}. If it finds a match, it sets point to the end of the | |
105 | match found, and returns the new value of point. | |
106 | @c Emacs 19 feature | |
107 | ||
108 | Word matching regards @var{string} as a sequence of words, disregarding | |
109 | punctuation that separates them. It searches the buffer for the same | |
110 | sequence of words. Each word must be distinct in the buffer (searching | |
111 | for the word @samp{ball} does not match the word @samp{balls}), but the | |
112 | details of punctuation and spacing are ignored (searching for @samp{ball | |
113 | boy} does match @samp{ball. Boy!}). | |
114 | ||
115 | In this example, point is initially at the beginning of the buffer; the | |
116 | search leaves it between the @samp{y} and the @samp{!}. | |
117 | ||
118 | @example | |
119 | @group | |
120 | ---------- Buffer: foo ---------- | |
121 | @point{}He said "Please! Find | |
122 | the ball boy!" | |
123 | ---------- Buffer: foo ---------- | |
124 | @end group | |
125 | ||
126 | @group | |
127 | (word-search-forward "Please find the ball, boy.") | |
128 | @result{} 35 | |
129 | ||
130 | ---------- Buffer: foo ---------- | |
131 | He said "Please! Find | |
132 | the ball boy@point{}!" | |
133 | ---------- Buffer: foo ---------- | |
134 | @end group | |
135 | @end example | |
136 | ||
137 | If @var{limit} is non-@code{nil} (it must be a position in the current | |
138 | buffer), then it is the upper bound to the search. The match found must | |
139 | not extend after that position. | |
140 | ||
141 | If @var{noerror} is @code{nil}, then @code{word-search-forward} signals | |
142 | an error if the search fails. If @var{noerror} is @code{t}, then it | |
143 | returns @code{nil} instead of signaling an error. If @var{noerror} is | |
144 | neither @code{nil} nor @code{t}, it moves point to @var{limit} (or the | |
145 | end of the buffer) and returns @code{nil}. | |
146 | ||
147 | If @var{repeat} is non-@code{nil}, then the search is repeated that many | |
148 | times. Point is positioned at the end of the last match. | |
149 | @end deffn | |
150 | ||
151 | @deffn Command word-search-backward string &optional limit noerror repeat | |
152 | This function searches backward from point for a word match to | |
153 | @var{string}. This function is just like @code{word-search-forward} | |
154 | except that it searches backward and normally leaves point at the | |
155 | beginning of the match. | |
156 | @end deffn | |
157 | ||
158 | @node Regular Expressions | |
159 | @section Regular Expressions | |
160 | @cindex regular expression | |
161 | @cindex regexp | |
162 | ||
163 | A @dfn{regular expression} (@dfn{regexp}, for short) is a pattern that | |
164 | denotes a (possibly infinite) set of strings. Searching for matches for | |
165 | a regexp is a very powerful operation. This section explains how to write | |
166 | regexps; the following section says how to search for them. | |
167 | ||
168 | @menu | |
169 | * Syntax of Regexps:: Rules for writing regular expressions. | |
8241495d | 170 | * Regexp Functions:: Functions for operating on regular expressions. |
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171 | * Regexp Example:: Illustrates regular expression syntax. |
172 | @end menu | |
173 | ||
174 | @node Syntax of Regexps | |
175 | @subsection Syntax of Regular Expressions | |
176 | ||
61cfa852 RS |
177 | Regular expressions have a syntax in which a few characters are |
178 | special constructs and the rest are @dfn{ordinary}. An ordinary | |
179 | character is a simple regular expression that matches that character and | |
180 | nothing else. The special characters are @samp{.}, @samp{*}, @samp{+}, | |
181 | @samp{?}, @samp{[}, @samp{]}, @samp{^}, @samp{$}, and @samp{\}; no new | |
182 | special characters will be defined in the future. Any other character | |
183 | appearing in a regular expression is ordinary, unless a @samp{\} | |
184 | precedes it. | |
7015aca4 | 185 | |
8241495d | 186 | For example, @samp{f} is not a special character, so it is ordinary, and |
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187 | therefore @samp{f} is a regular expression that matches the string |
188 | @samp{f} and no other string. (It does @emph{not} match the string | |
8241495d RS |
189 | @samp{fg}, but it does match a @emph{part} of that string.) Likewise, |
190 | @samp{o} is a regular expression that matches only @samp{o}.@refill | |
7015aca4 | 191 | |
8241495d | 192 | Any two regular expressions @var{a} and @var{b} can be concatenated. The |
61cfa852 | 193 | result is a regular expression that matches a string if @var{a} matches |
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194 | some amount of the beginning of that string and @var{b} matches the rest of |
195 | the string.@refill | |
196 | ||
8241495d | 197 | As a simple example, we can concatenate the regular expressions @samp{f} |
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198 | and @samp{o} to get the regular expression @samp{fo}, which matches only |
199 | the string @samp{fo}. Still trivial. To do something more powerful, you | |
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200 | need to use one of the special regular expression constructs. |
201 | ||
202 | @menu | |
203 | * Regexp Special:: Special characters in regular expressions. | |
204 | * Char Classes:: Character classes used in regular expressions. | |
205 | * Regexp Backslash:: Backslash-sequences in regular expressions. | |
206 | @end menu | |
207 | ||
208 | @node Regexp Special | |
209 | @subsubsection Special Characters in Regular Expressions | |
210 | ||
211 | Here is a list of the characters that are special in a regular | |
212 | expression. | |
7015aca4 | 213 | |
7dd3d99f | 214 | @need 800 |
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215 | @table @asis |
216 | @item @samp{.}@: @r{(Period)} | |
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217 | @cindex @samp{.} in regexp |
218 | is a special character that matches any single character except a newline. | |
219 | Using concatenation, we can make regular expressions like @samp{a.b}, which | |
220 | matches any three-character string that begins with @samp{a} and ends with | |
221 | @samp{b}.@refill | |
222 | ||
969fe9b5 | 223 | @item @samp{*} |
7015aca4 | 224 | @cindex @samp{*} in regexp |
1cd71ce0 RS |
225 | is not a construct by itself; it is a postfix operator that means to |
226 | match the preceding regular expression repetitively as many times as | |
227 | possible. Thus, @samp{o*} matches any number of @samp{o}s (including no | |
228 | @samp{o}s). | |
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229 | |
230 | @samp{*} always applies to the @emph{smallest} possible preceding | |
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231 | expression. Thus, @samp{fo*} has a repeating @samp{o}, not a repeating |
232 | @samp{fo}. It matches @samp{f}, @samp{fo}, @samp{foo}, and so on. | |
7015aca4 | 233 | |
f9f59935 RS |
234 | The matcher processes a @samp{*} construct by matching, immediately, as |
235 | many repetitions as can be found. Then it continues with the rest of | |
236 | the pattern. If that fails, backtracking occurs, discarding some of the | |
237 | matches of the @samp{*}-modified construct in the hope that that will | |
238 | make it possible to match the rest of the pattern. For example, in | |
239 | matching @samp{ca*ar} against the string @samp{caaar}, the @samp{a*} | |
240 | first tries to match all three @samp{a}s; but the rest of the pattern is | |
7015aca4 | 241 | @samp{ar} and there is only @samp{r} left to match, so this try fails. |
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242 | The next alternative is for @samp{a*} to match only two @samp{a}s. With |
243 | this choice, the rest of the regexp matches successfully.@refill | |
7015aca4 | 244 | |
73031603 | 245 | Nested repetition operators can be extremely slow if they specify |
22697dac | 246 | backtracking loops. For example, it could take hours for the regular |
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247 | expression @samp{\(x+y*\)*a} to try to match the sequence |
248 | @samp{xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxz}, before it ultimately fails. | |
249 | The slowness is because Emacs must try each imaginable way of grouping | |
1911e6e5 | 250 | the 35 @samp{x}s before concluding that none of them can work. To make |
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251 | sure your regular expressions run fast, check nested repetitions |
252 | carefully. | |
73031603 | 253 | |
969fe9b5 | 254 | @item @samp{+} |
7015aca4 | 255 | @cindex @samp{+} in regexp |
1cd71ce0 RS |
256 | is a postfix operator, similar to @samp{*} except that it must match |
257 | the preceding expression at least once. So, for example, @samp{ca+r} | |
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258 | matches the strings @samp{car} and @samp{caaaar} but not the string |
259 | @samp{cr}, whereas @samp{ca*r} matches all three strings. | |
260 | ||
969fe9b5 | 261 | @item @samp{?} |
7015aca4 | 262 | @cindex @samp{?} in regexp |
f9f59935 | 263 | is a postfix operator, similar to @samp{*} except that it must match the |
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264 | preceding expression either once or not at all. For example, |
265 | @samp{ca?r} matches @samp{car} or @samp{cr}; nothing else. | |
7015aca4 | 266 | |
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267 | @item @samp{[ @dots{} ]} |
268 | @cindex character alternative (in regexp) | |
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269 | @cindex @samp{[} in regexp |
270 | @cindex @samp{]} in regexp | |
969fe9b5 RS |
271 | is a @dfn{character alternative}, which begins with @samp{[} and is |
272 | terminated by @samp{]}. In the simplest case, the characters between | |
273 | the two brackets are what this character alternative can match. | |
1cd71ce0 RS |
274 | |
275 | Thus, @samp{[ad]} matches either one @samp{a} or one @samp{d}, and | |
276 | @samp{[ad]*} matches any string composed of just @samp{a}s and @samp{d}s | |
277 | (including the empty string), from which it follows that @samp{c[ad]*r} | |
278 | matches @samp{cr}, @samp{car}, @samp{cdr}, @samp{caddaar}, etc. | |
279 | ||
969fe9b5 RS |
280 | You can also include character ranges in a character alternative, by |
281 | writing the starting and ending characters with a @samp{-} between them. | |
8241495d | 282 | Thus, @samp{[a-z]} matches any lower-case @sc{ascii} letter. Ranges may be |
1cd71ce0 | 283 | intermixed freely with individual characters, as in @samp{[a-z$%.]}, |
8241495d | 284 | which matches any lower case @sc{ascii} letter or @samp{$}, @samp{%} or |
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285 | period. |
286 | ||
287 | Note that the usual regexp special characters are not special inside a | |
86494bd5 | 288 | character alternative. A completely different set of characters is |
969fe9b5 | 289 | special inside character alternatives: @samp{]}, @samp{-} and @samp{^}. |
1cd71ce0 | 290 | |
969fe9b5 RS |
291 | To include a @samp{]} in a character alternative, you must make it the |
292 | first character. For example, @samp{[]a]} matches @samp{]} or @samp{a}. | |
293 | To include a @samp{-}, write @samp{-} as the first or last character of | |
294 | the character alternative, or put it after a range. Thus, @samp{[]-]} | |
295 | matches both @samp{]} and @samp{-}. | |
7015aca4 | 296 | |
969fe9b5 RS |
297 | To include @samp{^} in a character alternative, put it anywhere but at |
298 | the beginning. | |
7015aca4 | 299 | |
8241495d RS |
300 | The beginning and end of a range must be in the same character set |
301 | (@pxref{Character Sets}). Thus, @samp{[a-\x8e0]} is invalid because | |
302 | @samp{a} is in the @sc{ascii} character set but the character 0x8e0 | |
303 | (@samp{a} with grave accent) is in the Emacs character set for Latin-1. | |
304 | ||
305 | You cannot always match all non-@sc{ascii} characters with the regular | |
306 | expression @samp{[\200-\377]}. This works when searching a unibyte | |
307 | buffer or string (@pxref{Text Representations}), but not in a multibyte | |
308 | buffer or string, because many non-@sc{ascii} characters have codes | |
309 | above octal 0377. However, the regular expression @samp{[^\000-\177]} | |
310 | does match all non-@sc{ascii} characters (see below regarding @samp{^}), | |
311 | in both multibyte and unibyte representations, because only the | |
312 | @sc{ascii} characters are excluded. | |
313 | ||
314 | Starting in Emacs 21, a character alternative can also specify named | |
315 | character classes (@pxref{Char Classes}). This is a POSIX feature whose | |
316 | syntax is @samp{[:@var{class}:]}. Using a character class is equivalent | |
317 | to mentioning each of the characters in that class; but the latter is | |
318 | not feasible in practice, since some classes include thousands of | |
319 | different characters. | |
320 | ||
969fe9b5 | 321 | @item @samp{[^ @dots{} ]} |
7015aca4 | 322 | @cindex @samp{^} in regexp |
969fe9b5 | 323 | @samp{[^} begins a @dfn{complemented character alternative}, which matches any |
1cd71ce0 RS |
324 | character except the ones specified. Thus, @samp{[^a-z0-9A-Z]} matches |
325 | all characters @emph{except} letters and digits. | |
7015aca4 | 326 | |
969fe9b5 | 327 | @samp{^} is not special in a character alternative unless it is the first |
7015aca4 | 328 | character. The character following the @samp{^} is treated as if it |
1cd71ce0 | 329 | were first (in other words, @samp{-} and @samp{]} are not special there). |
7015aca4 | 330 | |
969fe9b5 | 331 | A complemented character alternative can match a newline, unless newline is |
1cd71ce0 RS |
332 | mentioned as one of the characters not to match. This is in contrast to |
333 | the handling of regexps in programs such as @code{grep}. | |
7015aca4 | 334 | |
969fe9b5 | 335 | @item @samp{^} |
7015aca4 | 336 | @cindex beginning of line in regexp |
61cfa852 RS |
337 | is a special character that matches the empty string, but only at the |
338 | beginning of a line in the text being matched. Otherwise it fails to | |
339 | match anything. Thus, @samp{^foo} matches a @samp{foo} that occurs at | |
340 | the beginning of a line. | |
7015aca4 | 341 | |
61cfa852 RS |
342 | When matching a string instead of a buffer, @samp{^} matches at the |
343 | beginning of the string or after a newline character @samp{\n}. | |
7015aca4 | 344 | |
8241495d RS |
345 | For historical compatibility reasons, @samp{^} can be used only at the |
346 | beginning of the regular expression, or after @samp{\(} or @samp{\|}. | |
347 | ||
969fe9b5 | 348 | @item @samp{$} |
7015aca4 | 349 | @cindex @samp{$} in regexp |
8241495d | 350 | @cindex end of line in regexp |
7015aca4 RS |
351 | is similar to @samp{^} but matches only at the end of a line. Thus, |
352 | @samp{x+$} matches a string of one @samp{x} or more at the end of a line. | |
353 | ||
61cfa852 RS |
354 | When matching a string instead of a buffer, @samp{$} matches at the end |
355 | of the string or before a newline character @samp{\n}. | |
7015aca4 | 356 | |
8241495d RS |
357 | For historical compatibility reasons, @samp{$} can be used only at the |
358 | end of the regular expression, or before @samp{\)} or @samp{\|}. | |
359 | ||
969fe9b5 | 360 | @item @samp{\} |
7015aca4 RS |
361 | @cindex @samp{\} in regexp |
362 | has two functions: it quotes the special characters (including | |
363 | @samp{\}), and it introduces additional special constructs. | |
364 | ||
365 | Because @samp{\} quotes special characters, @samp{\$} is a regular | |
61cfa852 RS |
366 | expression that matches only @samp{$}, and @samp{\[} is a regular |
367 | expression that matches only @samp{[}, and so on. | |
7015aca4 RS |
368 | |
369 | Note that @samp{\} also has special meaning in the read syntax of Lisp | |
370 | strings (@pxref{String Type}), and must be quoted with @samp{\}. For | |
371 | example, the regular expression that matches the @samp{\} character is | |
372 | @samp{\\}. To write a Lisp string that contains the characters | |
373 | @samp{\\}, Lisp syntax requires you to quote each @samp{\} with another | |
374 | @samp{\}. Therefore, the read syntax for a regular expression matching | |
375 | @samp{\} is @code{"\\\\"}.@refill | |
376 | @end table | |
377 | ||
b22f3a19 | 378 | @strong{Please note:} For historical compatibility, special characters |
7015aca4 RS |
379 | are treated as ordinary ones if they are in contexts where their special |
380 | meanings make no sense. For example, @samp{*foo} treats @samp{*} as | |
381 | ordinary since there is no preceding expression on which the @samp{*} | |
61cfa852 RS |
382 | can act. It is poor practice to depend on this behavior; quote the |
383 | special character anyway, regardless of where it appears.@refill | |
7015aca4 | 384 | |
8241495d RS |
385 | @node Char Classes |
386 | @subsubsection Character Classes | |
387 | @cindex character classes in regexp | |
388 | ||
389 | Here is a table of the classes you can use in a character alternative, | |
390 | in Emacs 21, and what they mean: | |
391 | ||
392 | @table @samp | |
393 | @item [:ascii:] | |
394 | This matches any ASCII (unibyte) character. | |
395 | @item [:alnum:] | |
396 | This matches any letter or digit. (At present, for multibyte | |
397 | characters, it matches anything that has word syntax.) | |
398 | @item [:alpha:] | |
399 | This matches any letter. (At present, for multibyte characters, it | |
400 | matches anything that has word syntax.) | |
401 | @item [:blank:] | |
402 | This matches space and tab only. | |
403 | @item [:cntrl:] | |
404 | This matches any ASCII control character. | |
405 | @item [:digit:] | |
406 | This matches @samp{0} through @samp{9}. Thus, @samp{[-+[:digit:]]} | |
407 | matches any digit, as well as @samp{+} and @samp{-}. | |
408 | @item [:graph:] | |
409 | This matches graphic characters---everything except ASCII control characters, | |
410 | space, and DEL. | |
411 | @item [:lower:] | |
412 | This matches any lower-case letter, as determined by | |
413 | the current case table (@pxref{Case Tables}). | |
414 | @item [:nonascii:] | |
415 | This matches any non-ASCII (multibyte) character. | |
416 | @item [:print:] | |
417 | This matches printing characters---everything except ASCII control | |
418 | characters and DEL. | |
419 | @item [:punct:] | |
420 | This matches any punctuation character. (At present, for multibyte | |
421 | characters, it matches anything that has non-word syntax.) | |
422 | @item [:space:] | |
423 | This matches any character that has whitespace syntax | |
424 | (@pxref{Syntax Class Table}). | |
425 | @item [:upper:] | |
426 | This matches any upper-case letter, as determined by | |
427 | the current case table (@pxref{Case Tables}). | |
428 | @item [:word:] | |
429 | This matches any character that has word syntax (@pxref{Syntax Class | |
430 | Table}). | |
431 | @item [:xdigit:] | |
432 | This matches the hexadecimal digits: @samp{0} through @samp{9}, @samp{a} | |
433 | through @samp{f} and @samp{A} through @samp{F}. | |
434 | @end table | |
435 | ||
436 | @node Regexp Backslash | |
437 | @subsubsection Backslash Constructs in Regular Expressions | |
438 | ||
439 | For the most part, @samp{\} followed by any character matches only | |
440 | that character. However, there are several exceptions: certain | |
441 | two-character sequences starting with @samp{\} that have special | |
442 | meanings. (The character after the @samp{\} in such a sequence is | |
443 | always ordinary when used on its own.) Here is a table of the special | |
444 | @samp{\} constructs. | |
7015aca4 | 445 | |
969fe9b5 | 446 | @table @samp |
7015aca4 RS |
447 | @item \| |
448 | @cindex @samp{|} in regexp | |
449 | @cindex regexp alternative | |
450 | specifies an alternative. | |
451 | Two regular expressions @var{a} and @var{b} with @samp{\|} in | |
452 | between form an expression that matches anything that either @var{a} or | |
453 | @var{b} matches.@refill | |
454 | ||
455 | Thus, @samp{foo\|bar} matches either @samp{foo} or @samp{bar} | |
456 | but no other string.@refill | |
457 | ||
458 | @samp{\|} applies to the largest possible surrounding expressions. Only a | |
459 | surrounding @samp{\( @dots{} \)} grouping can limit the grouping power of | |
460 | @samp{\|}.@refill | |
461 | ||
8241495d RS |
462 | Full backtracking capability exists to handle multiple uses of |
463 | @samp{\|}, if you use the POSIX regular expression functions | |
464 | (@pxref{POSIX Regexps}). | |
7015aca4 RS |
465 | |
466 | @item \( @dots{} \) | |
467 | @cindex @samp{(} in regexp | |
468 | @cindex @samp{)} in regexp | |
469 | @cindex regexp grouping | |
470 | is a grouping construct that serves three purposes: | |
471 | ||
472 | @enumerate | |
473 | @item | |
9e2b495b RS |
474 | To enclose a set of @samp{\|} alternatives for other operations. Thus, |
475 | the regular expression @samp{\(foo\|bar\)x} matches either @samp{foox} | |
476 | or @samp{barx}. | |
7015aca4 RS |
477 | |
478 | @item | |
1cd71ce0 RS |
479 | To enclose a complicated expression for the postfix operators @samp{*}, |
480 | @samp{+} and @samp{?} to operate on. Thus, @samp{ba\(na\)*} matches | |
a9f0a989 RS |
481 | @samp{ba}, @samp{bana}, @samp{banana}, @samp{bananana}, etc., with any |
482 | number (zero or more) of @samp{na} strings. | |
7015aca4 RS |
483 | |
484 | @item | |
485 | To record a matched substring for future reference. | |
486 | @end enumerate | |
487 | ||
488 | This last application is not a consequence of the idea of a | |
61cfa852 | 489 | parenthetical grouping; it is a separate feature that happens to be |
7015aca4 RS |
490 | assigned as a second meaning to the same @samp{\( @dots{} \)} construct |
491 | because there is no conflict in practice between the two meanings. | |
492 | Here is an explanation of this feature: | |
493 | ||
494 | @item \@var{digit} | |
61cfa852 | 495 | matches the same text that matched the @var{digit}th occurrence of a |
7015aca4 RS |
496 | @samp{\( @dots{} \)} construct. |
497 | ||
1cd71ce0 | 498 | In other words, after the end of a @samp{\( @dots{} \)} construct, the |
7015aca4 RS |
499 | matcher remembers the beginning and end of the text matched by that |
500 | construct. Then, later on in the regular expression, you can use | |
501 | @samp{\} followed by @var{digit} to match that same text, whatever it | |
502 | may have been. | |
503 | ||
504 | The strings matching the first nine @samp{\( @dots{} \)} constructs | |
505 | appearing in a regular expression are assigned numbers 1 through 9 in | |
506 | the order that the open parentheses appear in the regular expression. | |
507 | So you can use @samp{\1} through @samp{\9} to refer to the text matched | |
508 | by the corresponding @samp{\( @dots{} \)} constructs. | |
509 | ||
510 | For example, @samp{\(.*\)\1} matches any newline-free string that is | |
511 | composed of two identical halves. The @samp{\(.*\)} matches the first | |
512 | half, which may be anything, but the @samp{\1} that follows must match | |
513 | the same exact text. | |
514 | ||
515 | @item \w | |
516 | @cindex @samp{\w} in regexp | |
517 | matches any word-constituent character. The editor syntax table | |
518 | determines which characters these are. @xref{Syntax Tables}. | |
519 | ||
520 | @item \W | |
521 | @cindex @samp{\W} in regexp | |
61cfa852 | 522 | matches any character that is not a word constituent. |
7015aca4 RS |
523 | |
524 | @item \s@var{code} | |
525 | @cindex @samp{\s} in regexp | |
526 | matches any character whose syntax is @var{code}. Here @var{code} is a | |
61cfa852 | 527 | character that represents a syntax code: thus, @samp{w} for word |
7015aca4 | 528 | constituent, @samp{-} for whitespace, @samp{(} for open parenthesis, |
f9f59935 RS |
529 | etc. To represent whitespace syntax, use either @samp{-} or a space |
530 | character. @xref{Syntax Class Table}, for a list of syntax codes and | |
531 | the characters that stand for them. | |
7015aca4 RS |
532 | |
533 | @item \S@var{code} | |
534 | @cindex @samp{\S} in regexp | |
535 | matches any character whose syntax is not @var{code}. | |
536 | @end table | |
537 | ||
61cfa852 | 538 | The following regular expression constructs match the empty string---that is, |
7015aca4 RS |
539 | they don't use up any characters---but whether they match depends on the |
540 | context. | |
541 | ||
969fe9b5 | 542 | @table @samp |
7015aca4 RS |
543 | @item \` |
544 | @cindex @samp{\`} in regexp | |
545 | matches the empty string, but only at the beginning | |
546 | of the buffer or string being matched against. | |
547 | ||
548 | @item \' | |
549 | @cindex @samp{\'} in regexp | |
550 | matches the empty string, but only at the end of | |
551 | the buffer or string being matched against. | |
552 | ||
553 | @item \= | |
554 | @cindex @samp{\=} in regexp | |
555 | matches the empty string, but only at point. | |
556 | (This construct is not defined when matching against a string.) | |
557 | ||
558 | @item \b | |
559 | @cindex @samp{\b} in regexp | |
560 | matches the empty string, but only at the beginning or | |
561 | end of a word. Thus, @samp{\bfoo\b} matches any occurrence of | |
562 | @samp{foo} as a separate word. @samp{\bballs?\b} matches | |
563 | @samp{ball} or @samp{balls} as a separate word.@refill | |
564 | ||
1cd71ce0 RS |
565 | @samp{\b} matches at the beginning or end of the buffer |
566 | regardless of what text appears next to it. | |
567 | ||
7015aca4 RS |
568 | @item \B |
569 | @cindex @samp{\B} in regexp | |
570 | matches the empty string, but @emph{not} at the beginning or | |
571 | end of a word. | |
572 | ||
573 | @item \< | |
574 | @cindex @samp{\<} in regexp | |
575 | matches the empty string, but only at the beginning of a word. | |
1cd71ce0 RS |
576 | @samp{\<} matches at the beginning of the buffer only if a |
577 | word-constituent character follows. | |
7015aca4 RS |
578 | |
579 | @item \> | |
580 | @cindex @samp{\>} in regexp | |
1cd71ce0 RS |
581 | matches the empty string, but only at the end of a word. @samp{\>} |
582 | matches at the end of the buffer only if the contents end with a | |
583 | word-constituent character. | |
7015aca4 RS |
584 | @end table |
585 | ||
586 | @kindex invalid-regexp | |
587 | Not every string is a valid regular expression. For example, a string | |
588 | with unbalanced square brackets is invalid (with a few exceptions, such | |
61cfa852 | 589 | as @samp{[]]}), and so is a string that ends with a single @samp{\}. If |
7015aca4 RS |
590 | an invalid regular expression is passed to any of the search functions, |
591 | an @code{invalid-regexp} error is signaled. | |
592 | ||
7015aca4 RS |
593 | @node Regexp Example |
594 | @comment node-name, next, previous, up | |
595 | @subsection Complex Regexp Example | |
596 | ||
597 | Here is a complicated regexp, used by Emacs to recognize the end of a | |
598 | sentence together with any whitespace that follows. It is the value of | |
599 | the variable @code{sentence-end}. | |
600 | ||
601 | First, we show the regexp as a string in Lisp syntax to distinguish | |
602 | spaces from tab characters. The string constant begins and ends with a | |
603 | double-quote. @samp{\"} stands for a double-quote as part of the | |
604 | string, @samp{\\} for a backslash as part of the string, @samp{\t} for a | |
605 | tab and @samp{\n} for a newline. | |
606 | ||
607 | @example | |
608 | "[.?!][]\"')@}]*\\($\\| $\\|\t\\| \\)[ \t\n]*" | |
609 | @end example | |
610 | ||
969fe9b5 RS |
611 | @noindent |
612 | In contrast, if you evaluate the variable @code{sentence-end}, you | |
7015aca4 RS |
613 | will see the following: |
614 | ||
615 | @example | |
616 | @group | |
617 | sentence-end | |
969fe9b5 | 618 | @result{} "[.?!][]\"')@}]*\\($\\| $\\| \\| \\)[ |
7015aca4 RS |
619 | ]*" |
620 | @end group | |
621 | @end example | |
622 | ||
623 | @noindent | |
624 | In this output, tab and newline appear as themselves. | |
625 | ||
626 | This regular expression contains four parts in succession and can be | |
627 | deciphered as follows: | |
628 | ||
629 | @table @code | |
630 | @item [.?!] | |
969fe9b5 RS |
631 | The first part of the pattern is a character alternative that matches |
632 | any one of three characters: period, question mark, and exclamation | |
633 | mark. The match must begin with one of these three characters. | |
7015aca4 RS |
634 | |
635 | @item []\"')@}]* | |
636 | The second part of the pattern matches any closing braces and quotation | |
637 | marks, zero or more of them, that may follow the period, question mark | |
638 | or exclamation mark. The @code{\"} is Lisp syntax for a double-quote in | |
639 | a string. The @samp{*} at the end indicates that the immediately | |
969fe9b5 | 640 | preceding regular expression (a character alternative, in this case) may be |
7015aca4 RS |
641 | repeated zero or more times. |
642 | ||
7fd1911a | 643 | @item \\($\\|@ $\\|\t\\|@ @ \\) |
7015aca4 | 644 | The third part of the pattern matches the whitespace that follows the |
f9f59935 RS |
645 | end of a sentence: the end of a line (optionally with a space), or a |
646 | tab, or two spaces. The double backslashes mark the parentheses and | |
647 | vertical bars as regular expression syntax; the parentheses delimit a | |
648 | group and the vertical bars separate alternatives. The dollar sign is | |
649 | used to match the end of a line. | |
7015aca4 RS |
650 | |
651 | @item [ \t\n]* | |
652 | Finally, the last part of the pattern matches any additional whitespace | |
653 | beyond the minimum needed to end a sentence. | |
654 | @end table | |
655 | ||
8241495d RS |
656 | @node Regexp Functions |
657 | @subsection Regular Expression Functions | |
658 | ||
659 | These functions operate on regular expressions. | |
660 | ||
661 | @defun regexp-quote string | |
662 | This function returns a regular expression whose only exact match is | |
663 | @var{string}. Using this regular expression in @code{looking-at} will | |
664 | succeed only if the next characters in the buffer are @var{string}; | |
665 | using it in a search function will succeed if the text being searched | |
666 | contains @var{string}. | |
667 | ||
668 | This allows you to request an exact string match or search when calling | |
669 | a function that wants a regular expression. | |
670 | ||
671 | @example | |
672 | @group | |
673 | (regexp-quote "^The cat$") | |
674 | @result{} "\\^The cat\\$" | |
675 | @end group | |
676 | @end example | |
677 | ||
678 | One use of @code{regexp-quote} is to combine an exact string match with | |
679 | context described as a regular expression. For example, this searches | |
680 | for the string that is the value of @var{string}, surrounded by | |
681 | whitespace: | |
682 | ||
683 | @example | |
684 | @group | |
685 | (re-search-forward | |
686 | (concat "\\s-" (regexp-quote string) "\\s-")) | |
687 | @end group | |
688 | @end example | |
689 | @end defun | |
690 | ||
691 | @defun regexp-opt strings &optional paren | |
692 | @tindex regexp-opt | |
693 | This function returns an efficient regular expression that will match | |
694 | any of the strings @var{strings}. This is useful when you need to make | |
695 | matching or searching as fast as possible---for example, for Font Lock | |
696 | mode. | |
697 | ||
698 | If the optional argument @var{paren} is non-@code{nil}, then the | |
699 | returned regular expression is always enclosed by at least one | |
700 | parentheses-grouping construct. | |
701 | ||
702 | This simplified definition of @code{regexp-opt} produces a | |
703 | regular expression which is equivalent to the actual value | |
704 | (but not as efficient): | |
705 | ||
706 | @example | |
707 | (defun regexp-opt (strings paren) | |
708 | (let ((open-paren (if paren "\\(" "")) | |
709 | (close-paren (if paren "\\)" ""))) | |
710 | (concat open-paren | |
711 | (mapconcat 'regexp-quote strings "\\|") | |
712 | close-paren))) | |
713 | @end example | |
714 | @end defun | |
715 | ||
716 | @defun regexp-opt-depth regexp | |
717 | @tindex regexp-opt-depth | |
718 | This function returns the total number of grouping constructs | |
719 | (parenthesized expressions) in @var{regexp}. | |
720 | @end defun | |
721 | ||
7015aca4 RS |
722 | @node Regexp Search |
723 | @section Regular Expression Searching | |
724 | @cindex regular expression searching | |
725 | @cindex regexp searching | |
726 | @cindex searching for regexp | |
727 | ||
969fe9b5 RS |
728 | In GNU Emacs, you can search for the next match for a regular |
729 | expression either incrementally or not. For incremental search | |
730 | commands, see @ref{Regexp Search, , Regular Expression Search, emacs, | |
731 | The GNU Emacs Manual}. Here we describe only the search functions | |
732 | useful in programs. The principal one is @code{re-search-forward}. | |
7015aca4 | 733 | |
f9f59935 RS |
734 | These search functions convert the regular expression to multibyte if |
735 | the buffer is multibyte; they convert the regular expression to unibyte | |
736 | if the buffer is unibyte. @xref{Text Representations}. | |
737 | ||
7015aca4 RS |
738 | @deffn Command re-search-forward regexp &optional limit noerror repeat |
739 | This function searches forward in the current buffer for a string of | |
740 | text that is matched by the regular expression @var{regexp}. The | |
741 | function skips over any amount of text that is not matched by | |
742 | @var{regexp}, and leaves point at the end of the first match found. | |
743 | It returns the new value of point. | |
744 | ||
745 | If @var{limit} is non-@code{nil} (it must be a position in the current | |
746 | buffer), then it is the upper bound to the search. No match extending | |
747 | after that position is accepted. | |
748 | ||
f9f59935 RS |
749 | If @var{repeat} is supplied (it must be a positive number), then the |
750 | search is repeated that many times (each time starting at the end of the | |
751 | previous time's match). If all these successive searches succeed, the | |
752 | function succeeds, moving point and returning its new value. Otherwise | |
753 | the function fails. | |
754 | ||
755 | What happens when the function fails depends on the value of | |
7015aca4 RS |
756 | @var{noerror}. If @var{noerror} is @code{nil}, a @code{search-failed} |
757 | error is signaled. If @var{noerror} is @code{t}, | |
758 | @code{re-search-forward} does nothing and returns @code{nil}. If | |
759 | @var{noerror} is neither @code{nil} nor @code{t}, then | |
760 | @code{re-search-forward} moves point to @var{limit} (or the end of the | |
761 | buffer) and returns @code{nil}. | |
762 | ||
7015aca4 RS |
763 | In the following example, point is initially before the @samp{T}. |
764 | Evaluating the search call moves point to the end of that line (between | |
765 | the @samp{t} of @samp{hat} and the newline). | |
766 | ||
767 | @example | |
768 | @group | |
769 | ---------- Buffer: foo ---------- | |
770 | I read "@point{}The cat in the hat | |
771 | comes back" twice. | |
772 | ---------- Buffer: foo ---------- | |
773 | @end group | |
774 | ||
775 | @group | |
776 | (re-search-forward "[a-z]+" nil t 5) | |
777 | @result{} 27 | |
778 | ||
779 | ---------- Buffer: foo ---------- | |
780 | I read "The cat in the hat@point{} | |
781 | comes back" twice. | |
782 | ---------- Buffer: foo ---------- | |
783 | @end group | |
784 | @end example | |
785 | @end deffn | |
786 | ||
787 | @deffn Command re-search-backward regexp &optional limit noerror repeat | |
788 | This function searches backward in the current buffer for a string of | |
789 | text that is matched by the regular expression @var{regexp}, leaving | |
790 | point at the beginning of the first text found. | |
791 | ||
7fd1911a RS |
792 | This function is analogous to @code{re-search-forward}, but they are not |
793 | simple mirror images. @code{re-search-forward} finds the match whose | |
794 | beginning is as close as possible to the starting point. If | |
795 | @code{re-search-backward} were a perfect mirror image, it would find the | |
796 | match whose end is as close as possible. However, in fact it finds the | |
3f63de1e | 797 | match whose beginning is as close as possible. The reason for this is that |
7fd1911a RS |
798 | matching a regular expression at a given spot always works from |
799 | beginning to end, and starts at a specified beginning position. | |
7015aca4 RS |
800 | |
801 | A true mirror-image of @code{re-search-forward} would require a special | |
969fe9b5 RS |
802 | feature for matching regular expressions from end to beginning. It's |
803 | not worth the trouble of implementing that. | |
7015aca4 RS |
804 | @end deffn |
805 | ||
806 | @defun string-match regexp string &optional start | |
807 | This function returns the index of the start of the first match for | |
808 | the regular expression @var{regexp} in @var{string}, or @code{nil} if | |
809 | there is no match. If @var{start} is non-@code{nil}, the search starts | |
810 | at that index in @var{string}. | |
811 | ||
812 | For example, | |
813 | ||
814 | @example | |
815 | @group | |
816 | (string-match | |
817 | "quick" "The quick brown fox jumped quickly.") | |
818 | @result{} 4 | |
819 | @end group | |
820 | @group | |
821 | (string-match | |
822 | "quick" "The quick brown fox jumped quickly." 8) | |
823 | @result{} 27 | |
824 | @end group | |
825 | @end example | |
826 | ||
827 | @noindent | |
828 | The index of the first character of the | |
829 | string is 0, the index of the second character is 1, and so on. | |
830 | ||
831 | After this function returns, the index of the first character beyond | |
832 | the match is available as @code{(match-end 0)}. @xref{Match Data}. | |
833 | ||
834 | @example | |
835 | @group | |
836 | (string-match | |
837 | "quick" "The quick brown fox jumped quickly." 8) | |
838 | @result{} 27 | |
839 | @end group | |
840 | ||
841 | @group | |
842 | (match-end 0) | |
843 | @result{} 32 | |
844 | @end group | |
845 | @end example | |
846 | @end defun | |
847 | ||
848 | @defun looking-at regexp | |
849 | This function determines whether the text in the current buffer directly | |
850 | following point matches the regular expression @var{regexp}. ``Directly | |
851 | following'' means precisely that: the search is ``anchored'' and it can | |
852 | succeed only starting with the first character following point. The | |
853 | result is @code{t} if so, @code{nil} otherwise. | |
854 | ||
855 | This function does not move point, but it updates the match data, which | |
856 | you can access using @code{match-beginning} and @code{match-end}. | |
857 | @xref{Match Data}. | |
858 | ||
859 | In this example, point is located directly before the @samp{T}. If it | |
860 | were anywhere else, the result would be @code{nil}. | |
861 | ||
862 | @example | |
863 | @group | |
864 | ---------- Buffer: foo ---------- | |
865 | I read "@point{}The cat in the hat | |
866 | comes back" twice. | |
867 | ---------- Buffer: foo ---------- | |
868 | ||
869 | (looking-at "The cat in the hat$") | |
870 | @result{} t | |
871 | @end group | |
872 | @end example | |
873 | @end defun | |
874 | ||
22697dac KH |
875 | @node POSIX Regexps |
876 | @section POSIX Regular Expression Searching | |
877 | ||
878 | The usual regular expression functions do backtracking when necessary | |
879 | to handle the @samp{\|} and repetition constructs, but they continue | |
880 | this only until they find @emph{some} match. Then they succeed and | |
881 | report the first match found. | |
882 | ||
883 | This section describes alternative search functions which perform the | |
884 | full backtracking specified by the POSIX standard for regular expression | |
885 | matching. They continue backtracking until they have tried all | |
886 | possibilities and found all matches, so they can report the longest | |
887 | match, as required by POSIX. This is much slower, so use these | |
888 | functions only when you really need the longest match. | |
889 | ||
22697dac KH |
890 | @defun posix-search-forward regexp &optional limit noerror repeat |
891 | This is like @code{re-search-forward} except that it performs the full | |
892 | backtracking specified by the POSIX standard for regular expression | |
893 | matching. | |
894 | @end defun | |
895 | ||
896 | @defun posix-search-backward regexp &optional limit noerror repeat | |
897 | This is like @code{re-search-backward} except that it performs the full | |
898 | backtracking specified by the POSIX standard for regular expression | |
899 | matching. | |
900 | @end defun | |
901 | ||
902 | @defun posix-looking-at regexp | |
903 | This is like @code{looking-at} except that it performs the full | |
904 | backtracking specified by the POSIX standard for regular expression | |
905 | matching. | |
906 | @end defun | |
907 | ||
908 | @defun posix-string-match regexp string &optional start | |
909 | This is like @code{string-match} except that it performs the full | |
910 | backtracking specified by the POSIX standard for regular expression | |
911 | matching. | |
912 | @end defun | |
913 | ||
7015aca4 RS |
914 | @ignore |
915 | @deffn Command delete-matching-lines regexp | |
916 | This function is identical to @code{delete-non-matching-lines}, save | |
917 | that it deletes what @code{delete-non-matching-lines} keeps. | |
918 | ||
919 | In the example below, point is located on the first line of text. | |
920 | ||
921 | @example | |
922 | @group | |
923 | ---------- Buffer: foo ---------- | |
924 | We hold these truths | |
925 | to be self-evident, | |
926 | that all men are created | |
927 | equal, and that they are | |
928 | ---------- Buffer: foo ---------- | |
929 | @end group | |
930 | ||
931 | @group | |
932 | (delete-matching-lines "the") | |
933 | @result{} nil | |
934 | ||
935 | ---------- Buffer: foo ---------- | |
936 | to be self-evident, | |
937 | that all men are created | |
938 | ---------- Buffer: foo ---------- | |
939 | @end group | |
940 | @end example | |
941 | @end deffn | |
942 | ||
943 | @deffn Command flush-lines regexp | |
944 | This function is the same as @code{delete-matching-lines}. | |
945 | @end deffn | |
946 | ||
947 | @defun delete-non-matching-lines regexp | |
948 | This function deletes all lines following point which don't | |
949 | contain a match for the regular expression @var{regexp}. | |
950 | @end defun | |
951 | ||
952 | @deffn Command keep-lines regexp | |
953 | This function is the same as @code{delete-non-matching-lines}. | |
954 | @end deffn | |
955 | ||
956 | @deffn Command how-many regexp | |
957 | This function counts the number of matches for @var{regexp} there are in | |
958 | the current buffer following point. It prints this number in | |
959 | the echo area, returning the string printed. | |
960 | @end deffn | |
961 | ||
962 | @deffn Command count-matches regexp | |
963 | This function is a synonym of @code{how-many}. | |
964 | @end deffn | |
965 | ||
966 | @deffn Command list-matching-lines regexp nlines | |
967 | This function is a synonym of @code{occur}. | |
968 | Show all lines following point containing a match for @var{regexp}. | |
969 | Display each line with @var{nlines} lines before and after, | |
970 | or @code{-}@var{nlines} before if @var{nlines} is negative. | |
971 | @var{nlines} defaults to @code{list-matching-lines-default-context-lines}. | |
972 | Interactively it is the prefix arg. | |
973 | ||
974 | The lines are shown in a buffer named @samp{*Occur*}. | |
975 | It serves as a menu to find any of the occurrences in this buffer. | |
86494bd5 | 976 | @kbd{C-h m} (@code{describe-mode}) in that buffer gives help. |
7015aca4 RS |
977 | @end deffn |
978 | ||
979 | @defopt list-matching-lines-default-context-lines | |
980 | Default value is 0. | |
981 | Default number of context lines to include around a @code{list-matching-lines} | |
982 | match. A negative number means to include that many lines before the match. | |
983 | A positive number means to include that many lines both before and after. | |
984 | @end defopt | |
985 | @end ignore | |
986 | ||
987 | @node Search and Replace | |
988 | @section Search and Replace | |
989 | @cindex replacement | |
990 | ||
991 | @defun perform-replace from-string replacements query-flag regexp-flag delimited-flag &optional repeat-count map | |
992 | This function is the guts of @code{query-replace} and related commands. | |
993 | It searches for occurrences of @var{from-string} and replaces some or | |
994 | all of them. If @var{query-flag} is @code{nil}, it replaces all | |
995 | occurrences; otherwise, it asks the user what to do about each one. | |
996 | ||
997 | If @var{regexp-flag} is non-@code{nil}, then @var{from-string} is | |
998 | considered a regular expression; otherwise, it must match literally. If | |
999 | @var{delimited-flag} is non-@code{nil}, then only replacements | |
1000 | surrounded by word boundaries are considered. | |
1001 | ||
1002 | The argument @var{replacements} specifies what to replace occurrences | |
1003 | with. If it is a string, that string is used. It can also be a list of | |
1004 | strings, to be used in cyclic order. | |
1005 | ||
8241495d RS |
1006 | If @var{replacements} is a cons cell, @var{(@var{function} |
1007 | . @var{data})}, this means to call @var{function} after each match to | |
1008 | get the replacement text. This function is called with two arguments: | |
1009 | @var{data}, and the number of replacements already made. | |
1010 | ||
bda144f4 MW |
1011 | If @var{repeat-count} is non-@code{nil}, it should be an integer. Then |
1012 | it specifies how many times to use each of the strings in the | |
1013 | @var{replacements} list before advancing cyclicly to the next one. | |
7015aca4 | 1014 | |
8241495d RS |
1015 | If @var{from-string} contains upper-case letters, then |
1016 | @code{perform-replace} binds @code{case-fold-search} to @code{nil}, and | |
1017 | it uses the @code{replacements} without altering the case of them. | |
1018 | ||
7015aca4 | 1019 | Normally, the keymap @code{query-replace-map} defines the possible user |
7fd1911a RS |
1020 | responses for queries. The argument @var{map}, if non-@code{nil}, is a |
1021 | keymap to use instead of @code{query-replace-map}. | |
7015aca4 RS |
1022 | @end defun |
1023 | ||
1024 | @defvar query-replace-map | |
1025 | This variable holds a special keymap that defines the valid user | |
1026 | responses for @code{query-replace} and related functions, as well as | |
1027 | @code{y-or-n-p} and @code{map-y-or-n-p}. It is unusual in two ways: | |
1028 | ||
1029 | @itemize @bullet | |
1030 | @item | |
1031 | The ``key bindings'' are not commands, just symbols that are meaningful | |
1032 | to the functions that use this map. | |
1033 | ||
1034 | @item | |
f9f59935 RS |
1035 | Prefix keys are not supported; each key binding must be for a |
1036 | single-event key sequence. This is because the functions don't use | |
1037 | @code{read-key-sequence} to get the input; instead, they read a single | |
1038 | event and look it up ``by hand.'' | |
7015aca4 RS |
1039 | @end itemize |
1040 | @end defvar | |
1041 | ||
1042 | Here are the meaningful ``bindings'' for @code{query-replace-map}. | |
1043 | Several of them are meaningful only for @code{query-replace} and | |
1044 | friends. | |
1045 | ||
1046 | @table @code | |
1047 | @item act | |
1048 | Do take the action being considered---in other words, ``yes.'' | |
1049 | ||
1050 | @item skip | |
1051 | Do not take action for this question---in other words, ``no.'' | |
1052 | ||
1053 | @item exit | |
7fd1911a RS |
1054 | Answer this question ``no,'' and give up on the entire series of |
1055 | questions, assuming that the answers will be ``no.'' | |
7015aca4 RS |
1056 | |
1057 | @item act-and-exit | |
7fd1911a RS |
1058 | Answer this question ``yes,'' and give up on the entire series of |
1059 | questions, assuming that subsequent answers will be ``no.'' | |
7015aca4 RS |
1060 | |
1061 | @item act-and-show | |
1062 | Answer this question ``yes,'' but show the results---don't advance yet | |
1063 | to the next question. | |
1064 | ||
1065 | @item automatic | |
1066 | Answer this question and all subsequent questions in the series with | |
1067 | ``yes,'' without further user interaction. | |
1068 | ||
1069 | @item backup | |
1070 | Move back to the previous place that a question was asked about. | |
1071 | ||
1072 | @item edit | |
1073 | Enter a recursive edit to deal with this question---instead of any | |
1074 | other action that would normally be taken. | |
1075 | ||
1076 | @item delete-and-edit | |
1077 | Delete the text being considered, then enter a recursive edit to replace | |
1078 | it. | |
1079 | ||
1080 | @item recenter | |
1081 | Redisplay and center the window, then ask the same question again. | |
1082 | ||
1083 | @item quit | |
1084 | Perform a quit right away. Only @code{y-or-n-p} and related functions | |
1085 | use this answer. | |
1086 | ||
1087 | @item help | |
1088 | Display some help, then ask again. | |
1089 | @end table | |
1090 | ||
1091 | @node Match Data | |
1092 | @section The Match Data | |
1093 | @cindex match data | |
1094 | ||
3f63de1e | 1095 | Emacs keeps track of the start and end positions of the segments of |
7015aca4 RS |
1096 | text found during a regular expression search. This means, for example, |
1097 | that you can search for a complex pattern, such as a date in an Rmail | |
1098 | message, and then extract parts of the match under control of the | |
1099 | pattern. | |
1100 | ||
1101 | Because the match data normally describe the most recent search only, | |
1102 | you must be careful not to do another search inadvertently between the | |
1103 | search you wish to refer back to and the use of the match data. If you | |
1104 | can't avoid another intervening search, you must save and restore the | |
1105 | match data around it, to prevent it from being overwritten. | |
1106 | ||
1107 | @menu | |
969fe9b5 | 1108 | * Replacing Match:: Replacing a substring that was matched. |
7015aca4 RS |
1109 | * Simple Match Data:: Accessing single items of match data, |
1110 | such as where a particular subexpression started. | |
7015aca4 RS |
1111 | * Entire Match Data:: Accessing the entire match data at once, as a list. |
1112 | * Saving Match Data:: Saving and restoring the match data. | |
1113 | @end menu | |
1114 | ||
969fe9b5 | 1115 | @node Replacing Match |
8241495d | 1116 | @subsection Replacing the Text that Matched |
969fe9b5 RS |
1117 | |
1118 | This function replaces the text matched by the last search with | |
1119 | @var{replacement}. | |
1120 | ||
1121 | @cindex case in replacements | |
1122 | @defun replace-match replacement &optional fixedcase literal string subexp | |
1123 | This function replaces the text in the buffer (or in @var{string}) that | |
1124 | was matched by the last search. It replaces that text with | |
1125 | @var{replacement}. | |
1126 | ||
1127 | If you did the last search in a buffer, you should specify @code{nil} | |
1128 | for @var{string}. Then @code{replace-match} does the replacement by | |
1129 | editing the buffer; it leaves point at the end of the replacement text, | |
1130 | and returns @code{t}. | |
1131 | ||
1132 | If you did the search in a string, pass the same string as @var{string}. | |
1133 | Then @code{replace-match} does the replacement by constructing and | |
1134 | returning a new string. | |
1135 | ||
1136 | If @var{fixedcase} is non-@code{nil}, then the case of the replacement | |
1137 | text is not changed; otherwise, the replacement text is converted to a | |
1138 | different case depending upon the capitalization of the text to be | |
1139 | replaced. If the original text is all upper case, the replacement text | |
1140 | is converted to upper case. If the first word of the original text is | |
1141 | capitalized, then the first word of the replacement text is capitalized. | |
1142 | If the original text contains just one word, and that word is a capital | |
1143 | letter, @code{replace-match} considers this a capitalized first word | |
1144 | rather than all upper case. | |
1145 | ||
969fe9b5 RS |
1146 | If @var{literal} is non-@code{nil}, then @var{replacement} is inserted |
1147 | exactly as it is, the only alterations being case changes as needed. | |
1148 | If it is @code{nil} (the default), then the character @samp{\} is treated | |
1149 | specially. If a @samp{\} appears in @var{replacement}, then it must be | |
1150 | part of one of the following sequences: | |
1151 | ||
1152 | @table @asis | |
1153 | @item @samp{\&} | |
1154 | @cindex @samp{&} in replacement | |
1155 | @samp{\&} stands for the entire text being replaced. | |
1156 | ||
1157 | @item @samp{\@var{n}} | |
1158 | @cindex @samp{\@var{n}} in replacement | |
1159 | @samp{\@var{n}}, where @var{n} is a digit, stands for the text that | |
1160 | matched the @var{n}th subexpression in the original regexp. | |
1161 | Subexpressions are those expressions grouped inside @samp{\(@dots{}\)}. | |
1162 | ||
1163 | @item @samp{\\} | |
1164 | @cindex @samp{\} in replacement | |
1165 | @samp{\\} stands for a single @samp{\} in the replacement text. | |
1166 | @end table | |
1167 | ||
1168 | If @var{subexp} is non-@code{nil}, that says to replace just | |
1169 | subexpression number @var{subexp} of the regexp that was matched, not | |
1170 | the entire match. For example, after matching @samp{foo \(ba*r\)}, | |
1171 | calling @code{replace-match} with 1 as @var{subexp} means to replace | |
1172 | just the text that matched @samp{\(ba*r\)}. | |
1173 | @end defun | |
1174 | ||
7015aca4 RS |
1175 | @node Simple Match Data |
1176 | @subsection Simple Match Data Access | |
1177 | ||
22697dac KH |
1178 | This section explains how to use the match data to find out what was |
1179 | matched by the last search or match operation. | |
1180 | ||
1181 | You can ask about the entire matching text, or about a particular | |
1182 | parenthetical subexpression of a regular expression. The @var{count} | |
1183 | argument in the functions below specifies which. If @var{count} is | |
1184 | zero, you are asking about the entire match. If @var{count} is | |
1185 | positive, it specifies which subexpression you want. | |
1186 | ||
1187 | Recall that the subexpressions of a regular expression are those | |
1188 | expressions grouped with escaped parentheses, @samp{\(@dots{}\)}. The | |
1189 | @var{count}th subexpression is found by counting occurrences of | |
1190 | @samp{\(} from the beginning of the whole regular expression. The first | |
1191 | subexpression is numbered 1, the second 2, and so on. Only regular | |
1192 | expressions can have subexpressions---after a simple string search, the | |
1193 | only information available is about the entire match. | |
1194 | ||
a9f0a989 RS |
1195 | A search which fails may or may not alter the match data. In the |
1196 | past, a failing search did not do this, but we may change it in the | |
1197 | future. | |
1198 | ||
22697dac KH |
1199 | @defun match-string count &optional in-string |
1200 | This function returns, as a string, the text matched in the last search | |
1201 | or match operation. It returns the entire text if @var{count} is zero, | |
1202 | or just the portion corresponding to the @var{count}th parenthetical | |
1203 | subexpression, if @var{count} is positive. If @var{count} is out of | |
bfe721d1 KH |
1204 | range, or if that subexpression didn't match anything, the value is |
1205 | @code{nil}. | |
22697dac KH |
1206 | |
1207 | If the last such operation was done against a string with | |
1208 | @code{string-match}, then you should pass the same string as the | |
969fe9b5 | 1209 | argument @var{in-string}. After a buffer search or match, |
22697dac KH |
1210 | you should omit @var{in-string} or pass @code{nil} for it; but you |
1211 | should make sure that the current buffer when you call | |
1212 | @code{match-string} is the one in which you did the searching or | |
1213 | matching. | |
1214 | @end defun | |
7015aca4 | 1215 | |
f9f59935 RS |
1216 | @defun match-string-no-properties count |
1217 | This function is like @code{match-string} except that the result | |
1218 | has no text properties. | |
1219 | @end defun | |
1220 | ||
7015aca4 RS |
1221 | @defun match-beginning count |
1222 | This function returns the position of the start of text matched by the | |
1223 | last regular expression searched for, or a subexpression of it. | |
1224 | ||
7fd1911a | 1225 | If @var{count} is zero, then the value is the position of the start of |
eaac2be1 | 1226 | the entire match. Otherwise, @var{count} specifies a subexpression in |
969fe9b5 | 1227 | the regular expression, and the value of the function is the starting |
22697dac KH |
1228 | position of the match for that subexpression. |
1229 | ||
1230 | The value is @code{nil} for a subexpression inside a @samp{\|} | |
1231 | alternative that wasn't used in the match. | |
7015aca4 RS |
1232 | @end defun |
1233 | ||
1234 | @defun match-end count | |
22697dac KH |
1235 | This function is like @code{match-beginning} except that it returns the |
1236 | position of the end of the match, rather than the position of the | |
1237 | beginning. | |
7015aca4 RS |
1238 | @end defun |
1239 | ||
1240 | Here is an example of using the match data, with a comment showing the | |
1241 | positions within the text: | |
1242 | ||
1243 | @example | |
1244 | @group | |
1245 | (string-match "\\(qu\\)\\(ick\\)" | |
1246 | "The quick fox jumped quickly.") | |
1247 | ;0123456789 | |
1248 | @result{} 4 | |
1249 | @end group | |
1250 | ||
22697dac KH |
1251 | @group |
1252 | (match-string 0 "The quick fox jumped quickly.") | |
1253 | @result{} "quick" | |
1254 | (match-string 1 "The quick fox jumped quickly.") | |
1255 | @result{} "qu" | |
1256 | (match-string 2 "The quick fox jumped quickly.") | |
1257 | @result{} "ick" | |
1258 | @end group | |
1259 | ||
7015aca4 RS |
1260 | @group |
1261 | (match-beginning 1) ; @r{The beginning of the match} | |
1262 | @result{} 4 ; @r{with @samp{qu} is at index 4.} | |
1263 | @end group | |
1264 | ||
1265 | @group | |
1266 | (match-beginning 2) ; @r{The beginning of the match} | |
1267 | @result{} 6 ; @r{with @samp{ick} is at index 6.} | |
1268 | @end group | |
1269 | ||
1270 | @group | |
1271 | (match-end 1) ; @r{The end of the match} | |
1272 | @result{} 6 ; @r{with @samp{qu} is at index 6.} | |
1273 | ||
1274 | (match-end 2) ; @r{The end of the match} | |
1275 | @result{} 9 ; @r{with @samp{ick} is at index 9.} | |
1276 | @end group | |
1277 | @end example | |
1278 | ||
1279 | Here is another example. Point is initially located at the beginning | |
1280 | of the line. Searching moves point to between the space and the word | |
1281 | @samp{in}. The beginning of the entire match is at the 9th character of | |
1282 | the buffer (@samp{T}), and the beginning of the match for the first | |
1283 | subexpression is at the 13th character (@samp{c}). | |
1284 | ||
1285 | @example | |
1286 | @group | |
1287 | (list | |
1288 | (re-search-forward "The \\(cat \\)") | |
1289 | (match-beginning 0) | |
1290 | (match-beginning 1)) | |
7fd1911a | 1291 | @result{} (9 9 13) |
7015aca4 RS |
1292 | @end group |
1293 | ||
1294 | @group | |
1295 | ---------- Buffer: foo ---------- | |
1296 | I read "The cat @point{}in the hat comes back" twice. | |
1297 | ^ ^ | |
1298 | 9 13 | |
1299 | ---------- Buffer: foo ---------- | |
1300 | @end group | |
1301 | @end example | |
1302 | ||
1303 | @noindent | |
1304 | (In this case, the index returned is a buffer position; the first | |
1305 | character of the buffer counts as 1.) | |
1306 | ||
7015aca4 RS |
1307 | @node Entire Match Data |
1308 | @subsection Accessing the Entire Match Data | |
1309 | ||
1310 | The functions @code{match-data} and @code{set-match-data} read or | |
1311 | write the entire match data, all at once. | |
1312 | ||
1313 | @defun match-data | |
1314 | This function returns a newly constructed list containing all the | |
1315 | information on what text the last search matched. Element zero is the | |
1316 | position of the beginning of the match for the whole expression; element | |
1317 | one is the position of the end of the match for the expression. The | |
1318 | next two elements are the positions of the beginning and end of the | |
1319 | match for the first subexpression, and so on. In general, element | |
1320 | @ifinfo | |
1321 | number 2@var{n} | |
1322 | @end ifinfo | |
1323 | @tex | |
1324 | number {\mathsurround=0pt $2n$} | |
1325 | @end tex | |
1326 | corresponds to @code{(match-beginning @var{n})}; and | |
1327 | element | |
1328 | @ifinfo | |
1329 | number 2@var{n} + 1 | |
1330 | @end ifinfo | |
1331 | @tex | |
1332 | number {\mathsurround=0pt $2n+1$} | |
1333 | @end tex | |
1334 | corresponds to @code{(match-end @var{n})}. | |
1335 | ||
1336 | All the elements are markers or @code{nil} if matching was done on a | |
1337 | buffer, and all are integers or @code{nil} if matching was done on a | |
969fe9b5 | 1338 | string with @code{string-match}. |
7015aca4 RS |
1339 | |
1340 | As always, there must be no possibility of intervening searches between | |
1341 | the call to a search function and the call to @code{match-data} that is | |
1342 | intended to access the match data for that search. | |
1343 | ||
1344 | @example | |
1345 | @group | |
1346 | (match-data) | |
1347 | @result{} (#<marker at 9 in foo> | |
1348 | #<marker at 17 in foo> | |
1349 | #<marker at 13 in foo> | |
1350 | #<marker at 17 in foo>) | |
1351 | @end group | |
1352 | @end example | |
1353 | @end defun | |
1354 | ||
1355 | @defun set-match-data match-list | |
1356 | This function sets the match data from the elements of @var{match-list}, | |
1357 | which should be a list that was the value of a previous call to | |
1358 | @code{match-data}. | |
1359 | ||
1360 | If @var{match-list} refers to a buffer that doesn't exist, you don't get | |
1361 | an error; that sets the match data in a meaningless but harmless way. | |
1362 | ||
1363 | @findex store-match-data | |
969fe9b5 | 1364 | @code{store-match-data} is a semi-obsolete alias for @code{set-match-data}. |
7015aca4 RS |
1365 | @end defun |
1366 | ||
1367 | @node Saving Match Data | |
1368 | @subsection Saving and Restoring the Match Data | |
1369 | ||
d1280259 RS |
1370 | When you call a function that may do a search, you may need to save |
1371 | and restore the match data around that call, if you want to preserve the | |
1372 | match data from an earlier search for later use. Here is an example | |
1373 | that shows the problem that arises if you fail to save the match data: | |
7015aca4 RS |
1374 | |
1375 | @example | |
1376 | @group | |
1377 | (re-search-forward "The \\(cat \\)") | |
1378 | @result{} 48 | |
1379 | (foo) ; @r{Perhaps @code{foo} does} | |
1380 | ; @r{more searching.} | |
1381 | (match-end 0) | |
1382 | @result{} 61 ; @r{Unexpected result---not 48!} | |
1383 | @end group | |
1384 | @end example | |
1385 | ||
d1280259 | 1386 | You can save and restore the match data with @code{save-match-data}: |
7015aca4 | 1387 | |
bfe721d1 | 1388 | @defmac save-match-data body@dots{} |
1911e6e5 | 1389 | This macro executes @var{body}, saving and restoring the match |
d1280259 | 1390 | data around it. |
bfe721d1 | 1391 | @end defmac |
7015aca4 | 1392 | |
969fe9b5 RS |
1393 | You could use @code{set-match-data} together with @code{match-data} to |
1394 | imitate the effect of the special form @code{save-match-data}. Here is | |
1395 | how: | |
7015aca4 RS |
1396 | |
1397 | @example | |
1398 | @group | |
1399 | (let ((data (match-data))) | |
1400 | (unwind-protect | |
f9f59935 | 1401 | @dots{} ; @r{Ok to change the original match data.} |
7015aca4 RS |
1402 | (set-match-data data))) |
1403 | @end group | |
1404 | @end example | |
1405 | ||
d1280259 RS |
1406 | Emacs automatically saves and restores the match data when it runs |
1407 | process filter functions (@pxref{Filter Functions}) and process | |
1408 | sentinels (@pxref{Sentinels}). | |
1409 | ||
7015aca4 RS |
1410 | @ignore |
1411 | Here is a function which restores the match data provided the buffer | |
1412 | associated with it still exists. | |
1413 | ||
1414 | @smallexample | |
1415 | @group | |
1416 | (defun restore-match-data (data) | |
1417 | @c It is incorrect to split the first line of a doc string. | |
1418 | @c If there's a problem here, it should be solved in some other way. | |
1419 | "Restore the match data DATA unless the buffer is missing." | |
1420 | (catch 'foo | |
1421 | (let ((d data)) | |
1422 | @end group | |
1423 | (while d | |
1424 | (and (car d) | |
1425 | (null (marker-buffer (car d))) | |
1426 | @group | |
1427 | ;; @file{match-data} @r{buffer is deleted.} | |
1428 | (throw 'foo nil)) | |
1429 | (setq d (cdr d))) | |
1430 | (set-match-data data)))) | |
1431 | @end group | |
1432 | @end smallexample | |
1433 | @end ignore | |
1434 | ||
1435 | @node Searching and Case | |
1436 | @section Searching and Case | |
1437 | @cindex searching and case | |
1438 | ||
1439 | By default, searches in Emacs ignore the case of the text they are | |
1440 | searching through; if you specify searching for @samp{FOO}, then | |
f9f59935 RS |
1441 | @samp{Foo} or @samp{foo} is also considered a match. This applies to |
1442 | regular expressions, too; thus, @samp{[aB]} would match @samp{a} or | |
1443 | @samp{A} or @samp{b} or @samp{B}. | |
7015aca4 RS |
1444 | |
1445 | If you do not want this feature, set the variable | |
1446 | @code{case-fold-search} to @code{nil}. Then all letters must match | |
7fd1911a RS |
1447 | exactly, including case. This is a buffer-local variable; altering the |
1448 | variable affects only the current buffer. (@xref{Intro to | |
7015aca4 RS |
1449 | Buffer-Local}.) Alternatively, you may change the value of |
1450 | @code{default-case-fold-search}, which is the default value of | |
1451 | @code{case-fold-search} for buffers that do not override it. | |
1452 | ||
1453 | Note that the user-level incremental search feature handles case | |
1454 | distinctions differently. When given a lower case letter, it looks for | |
1455 | a match of either case, but when given an upper case letter, it looks | |
1456 | for an upper case letter only. But this has nothing to do with the | |
f9f59935 | 1457 | searching functions used in Lisp code. |
7015aca4 RS |
1458 | |
1459 | @defopt case-replace | |
7fd1911a RS |
1460 | This variable determines whether the replacement functions should |
1461 | preserve case. If the variable is @code{nil}, that means to use the | |
1462 | replacement text verbatim. A non-@code{nil} value means to convert the | |
1463 | case of the replacement text according to the text being replaced. | |
1464 | ||
8241495d RS |
1465 | This variable is used by passing it as an argument to the function |
1466 | @code{replace-match}. @xref{Replacing Match}. | |
7015aca4 RS |
1467 | @end defopt |
1468 | ||
1469 | @defopt case-fold-search | |
1470 | This buffer-local variable determines whether searches should ignore | |
1471 | case. If the variable is @code{nil} they do not ignore case; otherwise | |
1472 | they do ignore case. | |
1473 | @end defopt | |
1474 | ||
1475 | @defvar default-case-fold-search | |
1476 | The value of this variable is the default value for | |
1477 | @code{case-fold-search} in buffers that do not override it. This is the | |
1478 | same as @code{(default-value 'case-fold-search)}. | |
1479 | @end defvar | |
1480 | ||
1481 | @node Standard Regexps | |
1482 | @section Standard Regular Expressions Used in Editing | |
1483 | @cindex regexps used standardly in editing | |
1484 | @cindex standard regexps used in editing | |
1485 | ||
1486 | This section describes some variables that hold regular expressions | |
1487 | used for certain purposes in editing: | |
1488 | ||
1489 | @defvar page-delimiter | |
969fe9b5 RS |
1490 | This is the regular expression describing line-beginnings that separate |
1491 | pages. The default value is @code{"^\014"} (i.e., @code{"^^L"} or | |
1492 | @code{"^\C-l"}); this matches a line that starts with a formfeed | |
1493 | character. | |
7015aca4 RS |
1494 | @end defvar |
1495 | ||
22697dac KH |
1496 | The following two regular expressions should @emph{not} assume the |
1497 | match always starts at the beginning of a line; they should not use | |
1498 | @samp{^} to anchor the match. Most often, the paragraph commands do | |
1499 | check for a match only at the beginning of a line, which means that | |
bfe721d1 KH |
1500 | @samp{^} would be superfluous. When there is a nonzero left margin, |
1501 | they accept matches that start after the left margin. In that case, a | |
1502 | @samp{^} would be incorrect. However, a @samp{^} is harmless in modes | |
1503 | where a left margin is never used. | |
22697dac | 1504 | |
7015aca4 RS |
1505 | @defvar paragraph-separate |
1506 | This is the regular expression for recognizing the beginning of a line | |
1507 | that separates paragraphs. (If you change this, you may have to | |
7fd1911a | 1508 | change @code{paragraph-start} also.) The default value is |
22697dac KH |
1509 | @w{@code{"[@ \t\f]*$"}}, which matches a line that consists entirely of |
1510 | spaces, tabs, and form feeds (after its left margin). | |
7015aca4 RS |
1511 | @end defvar |
1512 | ||
1513 | @defvar paragraph-start | |
1514 | This is the regular expression for recognizing the beginning of a line | |
1515 | that starts @emph{or} separates paragraphs. The default value is | |
22697dac KH |
1516 | @w{@code{"[@ \t\n\f]"}}, which matches a line starting with a space, tab, |
1517 | newline, or form feed (after its left margin). | |
7015aca4 RS |
1518 | @end defvar |
1519 | ||
1520 | @defvar sentence-end | |
1521 | This is the regular expression describing the end of a sentence. (All | |
1522 | paragraph boundaries also end sentences, regardless.) The default value | |
1523 | is: | |
1524 | ||
1525 | @example | |
7fd1911a | 1526 | "[.?!][]\"')@}]*\\($\\| $\\|\t\\| \\)[ \t\n]*" |
7015aca4 RS |
1527 | @end example |
1528 | ||
7fd1911a RS |
1529 | This means a period, question mark or exclamation mark, followed |
1530 | optionally by a closing parenthetical character, followed by tabs, | |
1531 | spaces or new lines. | |
7015aca4 RS |
1532 | |
1533 | For a detailed explanation of this regular expression, see @ref{Regexp | |
1534 | Example}. | |
1535 | @end defvar |