xref: /vim-8.2.3635/runtime/doc/pattern.txt (revision e16b00a1)
1*pattern.txt*   For Vim version 8.0.  Last change: 2017 Jun 05
2
3
4		  VIM REFERENCE MANUAL    by Bram Moolenaar
5
6
7Patterns and search commands				*pattern-searches*
8
9The very basics can be found in section |03.9| of the user manual.  A few more
10explanations are in chapter 27 |usr_27.txt|.
11
121. Search commands		|search-commands|
132. The definition of a pattern	|search-pattern|
143. Magic			|/magic|
154. Overview of pattern items	|pattern-overview|
165. Multi items			|pattern-multi-items|
176. Ordinary atoms		|pattern-atoms|
187. Ignoring case in a pattern	|/ignorecase|
198. Composing characters		|patterns-composing|
209. Compare with Perl patterns	|perl-patterns|
2110. Highlighting matches	|match-highlight|
22
23==============================================================================
241. Search commands				*search-commands*
25
26							*/*
27/{pattern}[/]<CR>	Search forward for the [count]'th occurrence of
28			{pattern} |exclusive|.
29
30/{pattern}/{offset}<CR>	Search forward for the [count]'th occurrence of
31			{pattern} and go |{offset}| lines up or down.
32			|linewise|.
33
34							*/<CR>*
35/<CR>			Search forward for the [count]'th occurrence of the
36			latest used pattern |last-pattern| with latest used
37			|{offset}|.
38
39//{offset}<CR>		Search forward for the [count]'th occurrence of the
40			latest used pattern |last-pattern| with new
41			|{offset}|.  If {offset} is empty no offset is used.
42
43							*?*
44?{pattern}[?]<CR>	Search backward for the [count]'th previous
45			occurrence of {pattern} |exclusive|.
46
47?{pattern}?{offset}<CR>	Search backward for the [count]'th previous
48			occurrence of {pattern} and go |{offset}| lines up or
49			down |linewise|.
50
51							*?<CR>*
52?<CR>			Search backward for the [count]'th occurrence of the
53			latest used pattern |last-pattern| with latest used
54			|{offset}|.
55
56??{offset}<CR>		Search backward for the [count]'th occurrence of the
57			latest used pattern |last-pattern| with new
58			|{offset}|.  If {offset} is empty no offset is used.
59
60							*n*
61n			Repeat the latest "/" or "?" [count] times.
62			If the cursor doesn't move the search is repeated with
63			count + 1.
64			|last-pattern| {Vi: no count}
65
66							*N*
67N			Repeat the latest "/" or "?" [count] times in
68			opposite direction. |last-pattern| {Vi: no count}
69
70							*star* *E348* *E349*
71*			Search forward for the [count]'th occurrence of the
72			word nearest to the cursor.  The word used for the
73			search is the first of:
74				1. the keyword under the cursor |'iskeyword'|
75				2. the first keyword after the cursor, in the
76				   current line
77				3. the non-blank word under the cursor
78				4. the first non-blank word after the cursor,
79				   in the current line
80			Only whole keywords are searched for, like with the
81			command "/\<keyword\>".  |exclusive|  {not in Vi}
82			'ignorecase' is used, 'smartcase' is not.
83
84							*#*
85#			Same as "*", but search backward.  The pound sign
86			(character 163) also works.  If the "#" key works as
87			backspace, try using "stty erase <BS>" before starting
88			Vim (<BS> is CTRL-H or a real backspace).  {not in Vi}
89
90							*gstar*
91g*			Like "*", but don't put "\<" and "\>" around the word.
92			This makes the search also find matches that are not a
93			whole word.  {not in Vi}
94
95							*g#*
96g#			Like "#", but don't put "\<" and "\>" around the word.
97			This makes the search also find matches that are not a
98			whole word.  {not in Vi}
99
100							*gd*
101gd			Goto local Declaration.  When the cursor is on a local
102			variable, this command will jump to its declaration.
103			First Vim searches for the start of the current
104			function, just like "[[".  If it is not found the
105			search stops in line 1.  If it is found, Vim goes back
106			until a blank line is found.  From this position Vim
107			searches for the keyword under the cursor, like with
108			"*", but lines that look like a comment are ignored
109			(see 'comments' option).
110			Note that this is not guaranteed to work, Vim does not
111			really check the syntax, it only searches for a match
112			with the keyword.  If included files also need to be
113			searched use the commands listed in |include-search|.
114			After this command |n| searches forward for the next
115			match (not backward).
116			{not in Vi}
117
118							*gD*
119gD			Goto global Declaration.  When the cursor is on a
120			global variable that is defined in the file, this
121			command will jump to its declaration.  This works just
122			like "gd", except that the search for the keyword
123			always starts in line 1.  {not in Vi}
124
125							*1gd*
1261gd			Like "gd", but ignore matches inside a {} block that
127			ends before the cursor position. {not in Vi}
128
129							*1gD*
1301gD			Like "gD", but ignore matches inside a {} block that
131			ends before the cursor position. {not in Vi}
132
133							*CTRL-C*
134CTRL-C			Interrupt current (search) command.  Use CTRL-Break on
135			MS-DOS |dos-CTRL-Break|.
136			In Normal mode, any pending command is aborted.
137
138							*:noh* *:nohlsearch*
139:noh[lsearch]		Stop the highlighting for the 'hlsearch' option.  It
140			is automatically turned back on when using a search
141			command, or setting the 'hlsearch' option.
142			This command doesn't work in an autocommand, because
143			the highlighting state is saved and restored when
144			executing autocommands |autocmd-searchpat|.
145			Same thing for when invoking a user function.
146
147While typing the search pattern the current match will be shown if the
148'incsearch' option is on.  Remember that you still have to finish the search
149command with <CR> to actually position the cursor at the displayed match.  Or
150use <Esc> to abandon the search.
151
152All matches for the last used search pattern will be highlighted if you set
153the 'hlsearch' option.  This can be suspended with the |:nohlsearch| command.
154
155When no match is found you get the error: *E486* Pattern not found
156Note that for the |:global| command this behaves like a normal message, for Vi
157compatibility.  For the |:s| command the "e" flag can be used to avoid the
158error message |:s_flags|.
159
160					*search-offset* *{offset}*
161These commands search for the specified pattern.  With "/" and "?" an
162additional offset may be given.  There are two types of offsets: line offsets
163and character offsets.  {the character offsets are not in Vi}
164
165The offset gives the cursor position relative to the found match:
166    [num]	[num] lines downwards, in column 1
167    +[num]	[num] lines downwards, in column 1
168    -[num]	[num] lines upwards, in column 1
169    e[+num]	[num] characters to the right of the end of the match
170    e[-num]	[num] characters to the left of the end of the match
171    s[+num]	[num] characters to the right of the start of the match
172    s[-num]	[num] characters to the left of the start of the match
173    b[+num]	[num] identical to s[+num] above (mnemonic: begin)
174    b[-num]	[num] identical to s[-num] above (mnemonic: begin)
175    ;{pattern}  perform another search, see |//;|
176
177If a '-' or '+' is given but [num] is omitted, a count of one will be used.
178When including an offset with 'e', the search becomes inclusive (the
179character the cursor lands on is included in operations).
180
181Examples:
182
183pattern			cursor position	~
184/test/+1		one line below "test", in column 1
185/test/e			on the last t of "test"
186/test/s+2		on the 's' of "test"
187/test/b-3		three characters before "test"
188
189If one of these commands is used after an operator, the characters between
190the cursor position before and after the search is affected.  However, if a
191line offset is given, the whole lines between the two cursor positions are
192affected.
193
194An example of how to search for matches with a pattern and change the match
195with another word: >
196	/foo<CR>	find "foo"
197	c//e<CR>	change until end of match
198	bar<Esc>	type replacement
199	//<CR>		go to start of next match
200	c//e<CR>	change until end of match
201	beep<Esc>	type another replacement
202			etc.
203<
204							*//;* *E386*
205A very special offset is ';' followed by another search command.  For example: >
206
207   /test 1/;/test
208   /test.*/+1;?ing?
209
210The first one first finds the next occurrence of "test 1", and then the first
211occurrence of "test" after that.
212
213This is like executing two search commands after each other, except that:
214- It can be used as a single motion command after an operator.
215- The direction for a following "n" or "N" command comes from the first
216  search command.
217- When an error occurs the cursor is not moved at all.
218
219							*last-pattern*
220The last used pattern and offset are remembered.  They can be used to repeat
221the search, possibly in another direction or with another count.  Note that
222two patterns are remembered: One for 'normal' search commands and one for the
223substitute command ":s".  Each time an empty pattern is given, the previously
224used pattern is used.  However, if there is no previous search command, a
225previous substitute pattern is used, if possible.
226
227The 'magic' option sticks with the last used pattern.  If you change 'magic',
228this will not change how the last used pattern will be interpreted.
229The 'ignorecase' option does not do this.  When 'ignorecase' is changed, it
230will result in the pattern to match other text.
231
232All matches for the last used search pattern will be highlighted if you set
233the 'hlsearch' option.
234
235To clear the last used search pattern: >
236	:let @/ = ""
237This will not set the pattern to an empty string, because that would match
238everywhere.  The pattern is really cleared, like when starting Vim.
239
240The search usually skips matches that don't move the cursor.  Whether the next
241match is found at the next character or after the skipped match depends on the
242'c' flag in 'cpoptions'.  See |cpo-c|.
243	   with 'c' flag:   "/..." advances 1 to 3 characters
244	without 'c' flag:   "/..." advances 1 character
245The unpredictability with the 'c' flag is caused by starting the search in the
246first column, skipping matches until one is found past the cursor position.
247
248When searching backwards, searching starts at the start of the line, using the
249'c' flag in 'cpoptions' as described above.  Then the last match before the
250cursor position is used.
251
252In Vi the ":tag" command sets the last search pattern when the tag is searched
253for.  In Vim this is not done, the previous search pattern is still remembered,
254unless the 't' flag is present in 'cpoptions'.  The search pattern is always
255put in the search history.
256
257If the 'wrapscan' option is on (which is the default), searches wrap around
258the end of the buffer.  If 'wrapscan' is not set, the backward search stops
259at the beginning and the forward search stops at the end of the buffer.  If
260'wrapscan' is set and the pattern was not found the error message "pattern
261not found" is given, and the cursor will not be moved.  If 'wrapscan' is not
262set the message becomes "search hit BOTTOM without match" when searching
263forward, or "search hit TOP without match" when searching backward.  If
264wrapscan is set and the search wraps around the end of the file the message
265"search hit TOP, continuing at BOTTOM" or "search hit BOTTOM, continuing at
266TOP" is given when searching backwards or forwards respectively.  This can be
267switched off by setting the 's' flag in the 'shortmess' option.  The highlight
268method 'w' is used for this message (default: standout).
269
270							*search-range*
271You can limit the search command "/" to a certain range of lines by including
272\%>l items.  For example, to match the word "limit" below line 199 and above
273line 300: >
274	/\%>199l\%<300llimit
275Also see |/\%>l|.
276
277Another way is to use the ":substitute" command with the 'c' flag.  Example: >
278   :.,300s/Pattern//gc
279This command will search from the cursor position until line 300 for
280"Pattern".  At the match, you will be asked to type a character.  Type 'q' to
281stop at this match, type 'n' to find the next match.
282
283The "*", "#", "g*" and "g#" commands look for a word near the cursor in this
284order, the first one that is found is used:
285- The keyword currently under the cursor.
286- The first keyword to the right of the cursor, in the same line.
287- The WORD currently under the cursor.
288- The first WORD to the right of the cursor, in the same line.
289The keyword may only contain letters and characters in 'iskeyword'.
290The WORD may contain any non-blanks (<Tab>s and/or <Space>s).
291Note that if you type with ten fingers, the characters are easy to remember:
292the "#" is under your left hand middle finger (search to the left and up) and
293the "*" is under your right hand middle finger (search to the right and down).
294(this depends on your keyboard layout though).
295
296==============================================================================
2972. The definition of a pattern		*search-pattern* *pattern* *[pattern]*
298					*regular-expression* *regexp* *Pattern*
299					*E76* *E383* *E476*
300
301For starters, read chapter 27 of the user manual |usr_27.txt|.
302
303						*/bar* */\bar* */pattern*
3041. A pattern is one or more branches, separated by "\|".  It matches anything
305   that matches one of the branches.  Example: "foo\|beep" matches "foo" and
306   matches "beep".  If more than one branch matches, the first one is used.
307
308   pattern ::=	    branch
309		or  branch \| branch
310		or  branch \| branch \| branch
311		etc.
312
313						*/branch* */\&*
3142. A branch is one or more concats, separated by "\&".  It matches the last
315   concat, but only if all the preceding concats also match at the same
316   position.  Examples:
317	"foobeep\&..." matches "foo" in "foobeep".
318	".*Peter\&.*Bob" matches in a line containing both "Peter" and "Bob"
319
320   branch ::=	    concat
321		or  concat \& concat
322		or  concat \& concat \& concat
323		etc.
324
325						*/concat*
3263. A concat is one or more pieces, concatenated.  It matches a match for the
327   first piece, followed by a match for the second piece, etc.  Example:
328   "f[0-9]b", first matches "f", then a digit and then "b".
329
330   concat  ::=	    piece
331		or  piece piece
332		or  piece piece piece
333		etc.
334
335						*/piece*
3364. A piece is an atom, possibly followed by a multi, an indication of how many
337   times the atom can be matched.  Example: "a*" matches any sequence of "a"
338   characters: "", "a", "aa", etc.  See |/multi|.
339
340   piece   ::=	    atom
341		or  atom  multi
342
343						*/atom*
3445. An atom can be one of a long list of items.  Many atoms match one character
345   in the text.  It is often an ordinary character or a character class.
346   Braces can be used to make a pattern into an atom.  The "\z(\)" construct
347   is only for syntax highlighting.
348
349   atom    ::=	    ordinary-atom		|/ordinary-atom|
350		or  \( pattern \)		|/\(|
351		or  \%( pattern \)		|/\%(|
352		or  \z( pattern \)		|/\z(|
353
354
355				*/\%#=* *two-engines* *NFA*
356Vim includes two regexp engines:
3571. An old, backtracking engine that supports everything.
3582. A new, NFA engine that works much faster on some patterns, possibly slower
359   on some patterns.
360
361Vim will automatically select the right engine for you.  However, if you run
362into a problem or want to specifically select one engine or the other, you can
363prepend one of the following to the pattern:
364
365	\%#=0	Force automatic selection.  Only has an effect when
366	        'regexpengine' has been set to a non-zero value.
367	\%#=1	Force using the old engine.
368	\%#=2	Force using the NFA engine.
369
370You can also use the 'regexpengine' option to change the default.
371
372			 *E864* *E868* *E874* *E875* *E876* *E877* *E878*
373If selecting the NFA engine and it runs into something that is not implemented
374the pattern will not match.  This is only useful when debugging Vim.
375
376==============================================================================
3773. Magic							*/magic*
378
379Some characters in the pattern are taken literally.  They match with the same
380character in the text.  When preceded with a backslash however, these
381characters get a special meaning.
382
383Other characters have a special meaning without a backslash.  They need to be
384preceded with a backslash to match literally.
385
386If a character is taken literally or not depends on the 'magic' option and the
387items mentioned next.
388							*/\m* */\M*
389Use of "\m" makes the pattern after it be interpreted as if 'magic' is set,
390ignoring the actual value of the 'magic' option.
391Use of "\M" makes the pattern after it be interpreted as if 'nomagic' is used.
392							*/\v* */\V*
393Use of "\v" means that in the pattern after it all ASCII characters except
394'0'-'9', 'a'-'z', 'A'-'Z' and '_' have a special meaning.  "very magic"
395
396Use of "\V" means that in the pattern after it only the backslash and the
397terminating character (/ or ?) has a special meaning.  "very nomagic"
398
399Examples:
400after:	  \v	   \m	    \M	     \V		matches ~
401		'magic' 'nomagic'
402	  $	   $	    $	     \$		matches end-of-line
403	  .	   .	    \.	     \.		matches any character
404	  *	   *	    \*	     \*		any number of the previous atom
405	  ~	   ~	    \~	     \~		latest substitute string
406	  ()	   \(\)     \(\)     \(\)	grouping into an atom
407	  |	   \|	    \|	     \|		separating alternatives
408	  \a	   \a	    \a	     \a		alphabetic character
409	  \\	   \\	    \\	     \\		literal backslash
410	  \.	   \.	    .	     .		literal dot
411	  \{	   {	    {	     {		literal '{'
412	  a	   a	    a	     a		literal 'a'
413
414{only Vim supports \m, \M, \v and \V}
415
416It is recommended to always keep the 'magic' option at the default setting,
417which is 'magic'.  This avoids portability problems.  To make a pattern immune
418to the 'magic' option being set or not, put "\m" or "\M" at the start of the
419pattern.
420
421==============================================================================
4224. Overview of pattern items				*pattern-overview*
423						*E865* *E866* *E867* *E869*
424
425Overview of multi items.				*/multi* *E61* *E62*
426More explanation and examples below, follow the links.		*E64* *E871*
427
428	  multi ~
429     'magic' 'nomagic'	matches of the preceding atom ~
430|/star|	*	\*	0 or more	as many as possible
431|/\+|	\+	\+	1 or more	as many as possible (*)
432|/\=|	\=	\=	0 or 1		as many as possible (*)
433|/\?|	\?	\?	0 or 1		as many as possible (*)
434
435|/\{|	\{n,m}	\{n,m}	n to m		as many as possible (*)
436	\{n}	\{n}	n		exactly (*)
437	\{n,}	\{n,}	at least n	as many as possible (*)
438	\{,m}	\{,m}	0 to m		as many as possible (*)
439	\{}	\{}	0 or more	as many as possible (same as *) (*)
440
441|/\{-|	\{-n,m}	\{-n,m}	n to m		as few as possible (*)
442	\{-n}	\{-n}	n		exactly (*)
443	\{-n,}	\{-n,}	at least n	as few as possible (*)
444	\{-,m}	\{-,m}	0 to m		as few as possible (*)
445	\{-}	\{-}	0 or more	as few as possible (*)
446
447							*E59*
448|/\@>|	\@>	\@>	1, like matching a whole pattern (*)
449|/\@=|	\@=	\@=	nothing, requires a match |/zero-width| (*)
450|/\@!|	\@!	\@!	nothing, requires NO match |/zero-width| (*)
451|/\@<=|	\@<=	\@<=	nothing, requires a match behind |/zero-width| (*)
452|/\@<!|	\@<!	\@<!	nothing, requires NO match behind |/zero-width| (*)
453
454(*) {not in Vi}
455
456
457Overview of ordinary atoms.				*/ordinary-atom*
458More explanation and examples below, follow the links.
459
460      ordinary atom ~
461      magic   nomagic	matches ~
462|/^|	^	^	start-of-line (at start of pattern) |/zero-width|
463|/\^|	\^	\^	literal '^'
464|/\_^|	\_^	\_^	start-of-line (used anywhere) |/zero-width|
465|/$|	$	$	end-of-line (at end of pattern) |/zero-width|
466|/\$|	\$	\$	literal '$'
467|/\_$|	\_$	\_$	end-of-line (used anywhere) |/zero-width|
468|/.|	.	\.	any single character (not an end-of-line)
469|/\_.|	\_.	\_.	any single character or end-of-line
470|/\<|	\<	\<	beginning of a word |/zero-width|
471|/\>|	\>	\>	end of a word |/zero-width|
472|/\zs|	\zs	\zs	anything, sets start of match
473|/\ze|	\ze	\ze	anything, sets end of match
474|/\%^|	\%^	\%^	beginning of file |/zero-width|		*E71*
475|/\%$|	\%$	\%$	end of file |/zero-width|
476|/\%V|	\%V	\%V	inside Visual area |/zero-width|
477|/\%#|	\%#	\%#	cursor position |/zero-width|
478|/\%'m|	\%'m	\%'m	mark m position |/zero-width|
479|/\%l|	\%23l	\%23l	in line 23 |/zero-width|
480|/\%c|	\%23c	\%23c	in column 23 |/zero-width|
481|/\%v|	\%23v	\%23v	in virtual column 23 |/zero-width|
482
483Character classes {not in Vi}:				*/character-classes*
484      magic   nomagic	matches ~
485|/\i|	\i	\i	identifier character (see 'isident' option)
486|/\I|	\I	\I	like "\i", but excluding digits
487|/\k|	\k	\k	keyword character (see 'iskeyword' option)
488|/\K|	\K	\K	like "\k", but excluding digits
489|/\f|	\f	\f	file name character (see 'isfname' option)
490|/\F|	\F	\F	like "\f", but excluding digits
491|/\p|	\p	\p	printable character (see 'isprint' option)
492|/\P|	\P	\P	like "\p", but excluding digits
493|/\s|	\s	\s	whitespace character: <Space> and <Tab>
494|/\S|	\S	\S	non-whitespace character; opposite of \s
495|/\d|	\d	\d	digit:				[0-9]
496|/\D|	\D	\D	non-digit:			[^0-9]
497|/\x|	\x	\x	hex digit:			[0-9A-Fa-f]
498|/\X|	\X	\X	non-hex digit:			[^0-9A-Fa-f]
499|/\o|	\o	\o	octal digit:			[0-7]
500|/\O|	\O	\O	non-octal digit:		[^0-7]
501|/\w|	\w	\w	word character:			[0-9A-Za-z_]
502|/\W|	\W	\W	non-word character:		[^0-9A-Za-z_]
503|/\h|	\h	\h	head of word character:		[A-Za-z_]
504|/\H|	\H	\H	non-head of word character:	[^A-Za-z_]
505|/\a|	\a	\a	alphabetic character:		[A-Za-z]
506|/\A|	\A	\A	non-alphabetic character:	[^A-Za-z]
507|/\l|	\l	\l	lowercase character:		[a-z]
508|/\L|	\L	\L	non-lowercase character:	[^a-z]
509|/\u|	\u	\u	uppercase character:		[A-Z]
510|/\U|	\U	\U	non-uppercase character		[^A-Z]
511|/\_|	\_x	\_x	where x is any of the characters above: character
512			class with end-of-line included
513(end of character classes)
514
515      magic   nomagic	matches ~
516|/\e|	\e	\e	<Esc>
517|/\t|	\t	\t	<Tab>
518|/\r|	\r	\r	<CR>
519|/\b|	\b	\b	<BS>
520|/\n|	\n	\n	end-of-line
521|/~|	~	\~	last given substitute string
522|/\1|	\1	\1	same string as matched by first \(\) {not in Vi}
523|/\2|	\2	\2	Like "\1", but uses second \(\)
524	   ...
525|/\9|	\9	\9	Like "\1", but uses ninth \(\)
526								*E68*
527|/\z1|	\z1	\z1	only for syntax highlighting, see |:syn-ext-match|
528	   ...
529|/\z1|	\z9	\z9	only for syntax highlighting, see |:syn-ext-match|
530
531	x	x	a character with no special meaning matches itself
532
533|/[]|	[]	\[]	any character specified inside the []
534|/\%[]|	\%[]	\%[]	a sequence of optionally matched atoms
535
536|/\c|	\c	\c	ignore case, do not use the 'ignorecase' option
537|/\C|	\C	\C	match case, do not use the 'ignorecase' option
538|/\Z|	\Z	\Z	ignore differences in Unicode "combining characters".
539			Useful when searching voweled Hebrew or Arabic text.
540
541      magic   nomagic	matches ~
542|/\m|	\m	\m	'magic' on for the following chars in the pattern
543|/\M|	\M	\M	'magic' off for the following chars in the pattern
544|/\v|	\v	\v	the following chars in the pattern are "very magic"
545|/\V|	\V	\V	the following chars in the pattern are "very nomagic"
546|/\%#=|   \%#=1   \%#=1   select regexp engine |/zero-width|
547
548|/\%d|	\%d	\%d	match specified decimal character (eg \%d123)
549|/\%x|	\%x	\%x	match specified hex character (eg \%x2a)
550|/\%o|	\%o	\%o	match specified octal character (eg \%o040)
551|/\%u|	\%u	\%u	match specified multibyte character (eg \%u20ac)
552|/\%U|	\%U	\%U	match specified large multibyte character (eg
553			\%U12345678)
554|/\%C|	\%C	\%C	match any composing characters
555
556Example			matches ~
557\<\I\i*		or
558\<\h\w*
559\<[a-zA-Z_][a-zA-Z0-9_]*
560			An identifier (e.g., in a C program).
561
562\(\.$\|\. \)		A period followed by <EOL> or a space.
563
564[.!?][])"']*\($\|[ ]\)	A search pattern that finds the end of a sentence,
565			with almost the same definition as the ")" command.
566
567cat\Z			Both "cat" and "càt" ("a" followed by 0x0300)
568			Does not match "càt" (character 0x00e0), even
569			though it may look the same.
570
571
572==============================================================================
5735. Multi items						*pattern-multi-items*
574
575An atom can be followed by an indication of how many times the atom can be
576matched and in what way.  This is called a multi.  See |/multi| for an
577overview.
578
579							*/star* */\star*
580*	(use \* when 'magic' is not set)
581	Matches 0 or more of the preceding atom, as many as possible.
582	Example  'nomagic'	matches ~
583	a*	   a\*		"", "a", "aa", "aaa", etc.
584	.*	   \.\*		anything, also an empty string, no end-of-line
585	\_.*	   \_.\*	everything up to the end of the buffer
586	\_.*END	   \_.\*END	everything up to and including the last "END"
587				in the buffer
588
589	Exception: When "*" is used at the start of the pattern or just after
590	"^" it matches the star character.
591
592	Be aware that repeating "\_." can match a lot of text and take a long
593	time.  For example, "\_.*END" matches all text from the current
594	position to the last occurrence of "END" in the file.  Since the "*"
595	will match as many as possible, this first skips over all lines until
596	the end of the file and then tries matching "END", backing up one
597	character at a time.
598
599							*/\+*
600\+	Matches 1 or more of the preceding atom, as many as possible. {not in
601	Vi}
602	Example		matches ~
603	^.\+$		any non-empty line
604	\s\+		white space of at least one character
605
606							*/\=*
607\=	Matches 0 or 1 of the preceding atom, as many as possible. {not in Vi}
608	Example		matches ~
609	foo\=		"fo" and "foo"
610
611							*/\?*
612\?	Just like \=.  Cannot be used when searching backwards with the "?"
613	command. {not in Vi}
614
615					*/\{* *E60* *E554* *E870*
616\{n,m}	Matches n to m of the preceding atom, as many as possible
617\{n}	Matches n of the preceding atom
618\{n,}	Matches at least n of the preceding atom, as many as possible
619\{,m}	Matches 0 to m of the preceding atom, as many as possible
620\{}	Matches 0 or more of the preceding atom, as many as possible (like *)
621							*/\{-*
622\{-n,m}	matches n to m of the preceding atom, as few as possible
623\{-n}	matches n of the preceding atom
624\{-n,}	matches at least n of the preceding atom, as few as possible
625\{-,m}	matches 0 to m of the preceding atom, as few as possible
626\{-}	matches 0 or more of the preceding atom, as few as possible
627	{Vi does not have any of these}
628
629	n and m are positive decimal numbers or zero
630								*non-greedy*
631	If a "-" appears immediately after the "{", then a shortest match
632	first algorithm is used (see example below).  In particular, "\{-}" is
633	the same as "*" but uses the shortest match first algorithm.  BUT: A
634	match that starts earlier is preferred over a shorter match: "a\{-}b"
635	matches "aaab" in "xaaab".
636
637	Example			matches ~
638	ab\{2,3}c		"abbc" or "abbbc"
639	a\{5}			"aaaaa"
640	ab\{2,}c		"abbc", "abbbc", "abbbbc", etc.
641	ab\{,3}c		"ac", "abc", "abbc" or "abbbc"
642	a[bc]\{3}d		"abbbd", "abbcd", "acbcd", "acccd", etc.
643	a\(bc\)\{1,2}d		"abcd" or "abcbcd"
644	a[bc]\{-}[cd]		"abc" in "abcd"
645	a[bc]*[cd]		"abcd" in "abcd"
646
647	The } may optionally be preceded with a backslash: \{n,m\}.
648
649							*/\@=*
650\@=	Matches the preceding atom with zero width. {not in Vi}
651	Like "(?=pattern)" in Perl.
652	Example			matches ~
653	foo\(bar\)\@=		"foo" in "foobar"
654	foo\(bar\)\@=foo	nothing
655							*/zero-width*
656	When using "\@=" (or "^", "$", "\<", "\>") no characters are included
657	in the match.  These items are only used to check if a match can be
658	made.  This can be tricky, because a match with following items will
659	be done in the same position.  The last example above will not match
660	"foobarfoo", because it tries match "foo" in the same position where
661	"bar" matched.
662
663	Note that using "\&" works the same as using "\@=": "foo\&.." is the
664	same as "\(foo\)\@=..".  But using "\&" is easier, you don't need the
665	braces.
666
667
668							*/\@!*
669\@!	Matches with zero width if the preceding atom does NOT match at the
670	current position. |/zero-width| {not in Vi}
671	Like "(?!pattern)" in Perl.
672	Example			matches ~
673	foo\(bar\)\@!		any "foo" not followed by "bar"
674	a.\{-}p\@!		"a", "ap", "app", "appp", etc. not immediately
675				followed by a "p"
676	if \(\(then\)\@!.\)*$	"if " not followed by "then"
677
678	Using "\@!" is tricky, because there are many places where a pattern
679	does not match.  "a.*p\@!" will match from an "a" to the end of the
680	line, because ".*" can match all characters in the line and the "p"
681	doesn't match at the end of the line.  "a.\{-}p\@!" will match any
682	"a", "ap", "app", etc. that isn't followed by a "p", because the "."
683	can match a "p" and "p\@!" doesn't match after that.
684
685	You can't use "\@!" to look for a non-match before the matching
686	position: "\(foo\)\@!bar" will match "bar" in "foobar", because at the
687	position where "bar" matches, "foo" does not match.  To avoid matching
688	"foobar" you could use "\(foo\)\@!...bar", but that doesn't match a
689	bar at the start of a line.  Use "\(foo\)\@<!bar".
690
691	Useful example: to find "foo" in a line that does not contain "bar": >
692		/^\%(.*bar\)\@!.*\zsfoo
693<	This pattern first checks that there is not a single position in the
694	line where "bar" matches.  If ".*bar" matches somewhere the \@! will
695	reject the pattern.  When there is no match any "foo" will be found.
696	The "\zs" is to have the match start just before "foo".
697
698							*/\@<=*
699\@<=	Matches with zero width if the preceding atom matches just before what
700	follows. |/zero-width| {not in Vi}
701	Like "(?<=pattern)" in Perl, but Vim allows non-fixed-width patterns.
702	Example			matches ~
703	\(an\_s\+\)\@<=file	"file" after "an" and white space or an
704				end-of-line
705	For speed it's often much better to avoid this multi.  Try using "\zs"
706	instead |/\zs|.  To match the same as the above example:
707		an\_s\+\zsfile
708	At least set a limit for the look-behind, see below.
709
710	"\@<=" and "\@<!" check for matches just before what follows.
711	Theoretically these matches could start anywhere before this position.
712	But to limit the time needed, only the line where what follows matches
713	is searched, and one line before that (if there is one).  This should
714	be sufficient to match most things and not be too slow.
715
716	In the old regexp engine the part of the pattern after "\@<=" and
717	"\@<!" are checked for a match first, thus things like "\1" don't work
718	to reference \(\) inside the preceding atom.  It does work the other
719	way around:
720	Bad example			matches ~
721	\%#=1\1\@<=,\([a-z]\+\)		",abc" in "abc,abc"
722
723	However, the new regexp engine works differently, it is better to not
724	rely on this behavior, do not use \@<= if it can be avoided:
725	Example				matches ~
726	\([a-z]\+\)\zs,\1		",abc" in "abc,abc"
727
728\@123<=
729	Like "\@<=" but only look back 123 bytes. This avoids trying lots
730	of matches that are known to fail and make executing the pattern very
731	slow.  Example, check if there is a "<" just before "span":
732		/<\@1<=span
733	This will try matching "<" only one byte before "span", which is the
734	only place that works anyway.
735	After crossing a line boundary, the limit is relative to the end of
736	the line.  Thus the characters at the start of the line with the match
737	are not counted (this is just to keep it simple).
738	The number zero is the same as no limit.
739
740							*/\@<!*
741\@<!	Matches with zero width if the preceding atom does NOT match just
742	before what follows.  Thus this matches if there is no position in the
743	current or previous line where the atom matches such that it ends just
744	before what follows.  |/zero-width| {not in Vi}
745	Like "(?<!pattern)" in Perl, but Vim allows non-fixed-width patterns.
746	The match with the preceding atom is made to end just before the match
747	with what follows, thus an atom that ends in ".*" will work.
748	Warning: This can be slow (because many positions need to be checked
749	for a match).  Use a limit if you can, see below.
750	Example			matches ~
751	\(foo\)\@<!bar		any "bar" that's not in "foobar"
752	\(\/\/.*\)\@<!in	"in" which is not after "//"
753
754\@123<!
755	Like "\@<!" but only look back 123 bytes. This avoids trying lots of
756	matches that are known to fail and make executing the pattern very
757	slow.
758
759							*/\@>*
760\@>	Matches the preceding atom like matching a whole pattern. {not in Vi}
761	Like "(?>pattern)" in Perl.
762	Example		matches ~
763	\(a*\)\@>a	nothing (the "a*" takes all the "a"'s, there can't be
764			another one following)
765
766	This matches the preceding atom as if it was a pattern by itself.  If
767	it doesn't match, there is no retry with shorter sub-matches or
768	anything.  Observe this difference: "a*b" and "a*ab" both match
769	"aaab", but in the second case the "a*" matches only the first two
770	"a"s.  "\(a*\)\@>ab" will not match "aaab", because the "a*" matches
771	the "aaa" (as many "a"s as possible), thus the "ab" can't match.
772
773
774==============================================================================
7756.  Ordinary atoms					*pattern-atoms*
776
777An ordinary atom can be:
778
779							*/^*
780^	At beginning of pattern or after "\|", "\(", "\%(" or "\n": matches
781	start-of-line; at other positions, matches literal '^'. |/zero-width|
782	Example		matches ~
783	^beep(		the start of the C function "beep" (probably).
784
785							*/\^*
786\^	Matches literal '^'.  Can be used at any position in the pattern.
787
788							*/\_^*
789\_^	Matches start-of-line. |/zero-width|  Can be used at any position in
790	the pattern.
791	Example		matches ~
792	\_s*\_^foo	white space and blank lines and then "foo" at
793			start-of-line
794
795							*/$*
796$	At end of pattern or in front of "\|", "\)" or "\n" ('magic' on):
797	matches end-of-line <EOL>; at other positions, matches literal '$'.
798	|/zero-width|
799
800							*/\$*
801\$	Matches literal '$'.  Can be used at any position in the pattern.
802
803							*/\_$*
804\_$	Matches end-of-line. |/zero-width|  Can be used at any position in the
805	pattern.  Note that "a\_$b" never matches, since "b" cannot match an
806	end-of-line.  Use "a\nb" instead |/\n|.
807	Example		matches ~
808	foo\_$\_s*	"foo" at end-of-line and following white space and
809			blank lines
810
811.	(with 'nomagic': \.)				*/.* */\.*
812	Matches any single character, but not an end-of-line.
813
814							*/\_.*
815\_.	Matches any single character or end-of-line.
816	Careful: "\_.*" matches all text to the end of the buffer!
817
818							*/\<*
819\<	Matches the beginning of a word: The next char is the first char of a
820	word.  The 'iskeyword' option specifies what is a word character.
821	|/zero-width|
822
823							*/\>*
824\>	Matches the end of a word: The previous char is the last char of a
825	word.  The 'iskeyword' option specifies what is a word character.
826	|/zero-width|
827
828							*/\zs*
829\zs	Matches at any position, and sets the start of the match there: The
830	next char is the first char of the whole match. |/zero-width|
831	Example: >
832		/^\s*\zsif
833<	matches an "if" at the start of a line, ignoring white space.
834	Can be used multiple times, the last one encountered in a matching
835	branch is used.  Example: >
836		/\(.\{-}\zsFab\)\{3}
837<	Finds the third occurrence of "Fab".
838	This cannot be followed by a multi. *E888*
839	{not in Vi} {not available when compiled without the |+syntax| feature}
840							*/\ze*
841\ze	Matches at any position, and sets the end of the match there: The
842	previous char is the last char of the whole match. |/zero-width|
843	Can be used multiple times, the last one encountered in a matching
844	branch is used.
845	Example: "end\ze\(if\|for\)" matches the "end" in "endif" and
846	"endfor".
847	This cannot be followed by a multi. |E888|
848	{not in Vi} {not available when compiled without the |+syntax| feature}
849
850						*/\%^* *start-of-file*
851\%^	Matches start of the file.  When matching with a string, matches the
852	start of the string. {not in Vi}
853	For example, to find the first "VIM" in a file: >
854		/\%^\_.\{-}\zsVIM
855<
856						*/\%$* *end-of-file*
857\%$	Matches end of the file.  When matching with a string, matches the
858	end of the string. {not in Vi}
859	Note that this does NOT find the last "VIM" in a file: >
860		/VIM\_.\{-}\%$
861<	It will find the next VIM, because the part after it will always
862	match.  This one will find the last "VIM" in the file: >
863		/VIM\ze\(\(VIM\)\@!\_.\)*\%$
864<	This uses |/\@!| to ascertain that "VIM" does NOT match in any
865	position after the first "VIM".
866	Searching from the end of the file backwards is easier!
867
868						*/\%V*
869\%V	Match inside the Visual area.  When Visual mode has already been
870	stopped match in the area that |gv| would reselect.
871	This is a |/zero-width| match.  To make sure the whole pattern is
872	inside the Visual area put it at the start and just before the end of
873	the pattern, e.g.: >
874		/\%Vfoo.*ba\%Vr
875<	This also works if only "foo bar" was Visually selected. This: >
876		/\%Vfoo.*bar\%V
877<	would match "foo bar" if the Visual selection continues after the "r".
878	Only works for the current buffer.
879
880						*/\%#* *cursor-position*
881\%#	Matches with the cursor position.  Only works when matching in a
882	buffer displayed in a window. {not in Vi}
883	WARNING: When the cursor is moved after the pattern was used, the
884	result becomes invalid.  Vim doesn't automatically update the matches.
885	This is especially relevant for syntax highlighting and 'hlsearch'.
886	In other words: When the cursor moves the display isn't updated for
887	this change.  An update is done for lines which are changed (the whole
888	line is updated) or when using the |CTRL-L| command (the whole screen
889	is updated).  Example, to highlight the word under the cursor: >
890		/\k*\%#\k*
891<	When 'hlsearch' is set and you move the cursor around and make changes
892	this will clearly show when the match is updated or not.
893
894						*/\%'m* */\%<'m* */\%>'m*
895\%'m	Matches with the position of mark m.
896\%<'m	Matches before the position of mark m.
897\%>'m	Matches after the position of mark m.
898	Example, to highlight the text from mark 's to 'e: >
899		/.\%>'s.*\%<'e..
900<	Note that two dots are required to include mark 'e in the match.  That
901	is because "\%<'e" matches at the character before the 'e mark, and
902	since it's a |/zero-width| match it doesn't include that character.
903	{not in Vi}
904	WARNING: When the mark is moved after the pattern was used, the result
905	becomes invalid.  Vim doesn't automatically update the matches.
906	Similar to moving the cursor for "\%#" |/\%#|.
907
908						*/\%l* */\%>l* */\%<l*
909\%23l	Matches in a specific line.
910\%<23l	Matches above a specific line (lower line number).
911\%>23l	Matches below a specific line (higher line number).
912	These three can be used to match specific lines in a buffer.  The "23"
913	can be any line number.  The first line is 1. {not in Vi}
914	WARNING: When inserting or deleting lines Vim does not automatically
915	update the matches.  This means Syntax highlighting quickly becomes
916	wrong.
917	Example, to highlight the line where the cursor currently is: >
918		:exe '/\%' . line(".") . 'l.*'
919<	When 'hlsearch' is set and you move the cursor around and make changes
920	this will clearly show when the match is updated or not.
921
922						*/\%c* */\%>c* */\%<c*
923\%23c	Matches in a specific column.
924\%<23c	Matches before a specific column.
925\%>23c	Matches after a specific column.
926	These three can be used to match specific columns in a buffer or
927	string.  The "23" can be any column number.  The first column is 1.
928	Actually, the column is the byte number (thus it's not exactly right
929	for multi-byte characters).  {not in Vi}
930	WARNING: When inserting or deleting text Vim does not automatically
931	update the matches.  This means Syntax highlighting quickly becomes
932	wrong.
933	Example, to highlight the column where the cursor currently is: >
934		:exe '/\%' . col(".") . 'c'
935<	When 'hlsearch' is set and you move the cursor around and make changes
936	this will clearly show when the match is updated or not.
937	Example for matching a single byte in column 44: >
938		/\%>43c.\%<46c
939<	Note that "\%<46c" matches in column 45 when the "." matches a byte in
940	column 44.
941						*/\%v* */\%>v* */\%<v*
942\%23v	Matches in a specific virtual column.
943\%<23v	Matches before a specific virtual column.
944\%>23v	Matches after a specific virtual column.
945	These three can be used to match specific virtual columns in a buffer
946	or string.  When not matching with a buffer in a window, the option
947	values of the current window are used (e.g., 'tabstop').
948	The "23" can be any column number.  The first column is 1.
949	Note that some virtual column positions will never match, because they
950	are halfway through a tab or other character that occupies more than
951	one screen character.  {not in Vi}
952	WARNING: When inserting or deleting text Vim does not automatically
953	update highlighted matches.  This means Syntax highlighting quickly
954	becomes wrong.
955	Example, to highlight all the characters after virtual column 72: >
956		/\%>72v.*
957<	When 'hlsearch' is set and you move the cursor around and make changes
958	this will clearly show when the match is updated or not.
959	To match the text up to column 17: >
960		/^.*\%17v
961<	Column 17 is not included, because this is a |/zero-width| match. To
962	include the column use: >
963		/^.*\%17v.
964<	This command does the same thing, but also matches when there is no
965	character in column 17: >
966		/^.*\%<18v.
967<	Note that without the "^" to anchor the match in the first column,
968	this will also highlight column 17: >
969		/.*\%17v
970<	Column 17 is highlighted by 'hlsearch' because there is another match
971	where ".*" matches zero characters.
972<
973
974Character classes: {not in Vi}
975\i	identifier character (see 'isident' option)	*/\i*
976\I	like "\i", but excluding digits			*/\I*
977\k	keyword character (see 'iskeyword' option)	*/\k*
978\K	like "\k", but excluding digits			*/\K*
979\f	file name character (see 'isfname' option)	*/\f*
980\F	like "\f", but excluding digits			*/\F*
981\p	printable character (see 'isprint' option)	*/\p*
982\P	like "\p", but excluding digits			*/\P*
983
984NOTE: the above also work for multi-byte characters.  The ones below only
985match ASCII characters, as indicated by the range.
986
987						*whitespace* *white-space*
988\s	whitespace character: <Space> and <Tab>		*/\s*
989\S	non-whitespace character; opposite of \s	*/\S*
990\d	digit:				[0-9]		*/\d*
991\D	non-digit:			[^0-9]		*/\D*
992\x	hex digit:			[0-9A-Fa-f]	*/\x*
993\X	non-hex digit:			[^0-9A-Fa-f]	*/\X*
994\o	octal digit:			[0-7]		*/\o*
995\O	non-octal digit:		[^0-7]		*/\O*
996\w	word character:			[0-9A-Za-z_]	*/\w*
997\W	non-word character:		[^0-9A-Za-z_]	*/\W*
998\h	head of word character:		[A-Za-z_]	*/\h*
999\H	non-head of word character:	[^A-Za-z_]	*/\H*
1000\a	alphabetic character:		[A-Za-z]	*/\a*
1001\A	non-alphabetic character:	[^A-Za-z]	*/\A*
1002\l	lowercase character:		[a-z]		*/\l*
1003\L	non-lowercase character:	[^a-z]		*/\L*
1004\u	uppercase character:		[A-Z]		*/\u*
1005\U	non-uppercase character:	[^A-Z]		*/\U*
1006
1007	NOTE: Using the atom is faster than the [] form.
1008
1009	NOTE: 'ignorecase', "\c" and "\C" are not used by character classes.
1010
1011			*/\_* *E63* */\_i* */\_I* */\_k* */\_K* */\_f* */\_F*
1012			*/\_p* */\_P* */\_s* */\_S* */\_d* */\_D* */\_x* */\_X*
1013			*/\_o* */\_O* */\_w* */\_W* */\_h* */\_H* */\_a* */\_A*
1014			*/\_l* */\_L* */\_u* */\_U*
1015\_x	Where "x" is any of the characters above: The character class with
1016	end-of-line added
1017(end of character classes)
1018
1019\e	matches <Esc>					*/\e*
1020\t	matches <Tab>					*/\t*
1021\r	matches <CR>					*/\r*
1022\b	matches <BS>					*/\b*
1023\n	matches an end-of-line				*/\n*
1024	When matching in a string instead of buffer text a literal newline
1025	character is matched.
1026
1027~	matches the last given substitute string	*/~* */\~*
1028
1029\(\)	A pattern enclosed by escaped parentheses.	*/\(* */\(\)* */\)*
1030	E.g., "\(^a\)" matches 'a' at the start of a line.
1031	*E51* *E54* *E55* *E872* *E873*
1032
1033\1      Matches the same string that was matched by	*/\1* *E65*
1034	the first sub-expression in \( and \). {not in Vi}
1035	Example: "\([a-z]\).\1" matches "ata", "ehe", "tot", etc.
1036\2      Like "\1", but uses second sub-expression,	*/\2*
1037   ...							*/\3*
1038\9      Like "\1", but uses ninth sub-expression.	*/\9*
1039	Note: The numbering of groups is done based on which "\(" comes first
1040	in the pattern (going left to right), NOT based on what is matched
1041	first.
1042
1043\%(\)	A pattern enclosed by escaped parentheses.	*/\%(\)* */\%(* *E53*
1044	Just like \(\), but without counting it as a sub-expression.  This
1045	allows using more groups and it's a little bit faster.
1046	{not in Vi}
1047
1048x	A single character, with no special meaning, matches itself
1049
1050							*/\* */\\*
1051\x	A backslash followed by a single character, with no special meaning,
1052	is reserved for future expansions
1053
1054[]	(with 'nomagic': \[])		*/[]* */\[]* */\_[]* */collection*
1055\_[]
1056	A collection.  This is a sequence of characters enclosed in brackets.
1057	It matches any single character in the collection.
1058	Example		matches ~
1059	[xyz]		any 'x', 'y' or 'z'
1060	[a-zA-Z]$	any alphabetic character at the end of a line
1061	\c[a-z]$	same
1062	[А-яЁё]		Russian alphabet (with utf-8 and cp1251)
1063
1064								*/[\n]*
1065	With "\_" prepended the collection also includes the end-of-line.
1066	The same can be done by including "\n" in the collection.  The
1067	end-of-line is also matched when the collection starts with "^"!  Thus
1068	"\_[^ab]" matches the end-of-line and any character but "a" and "b".
1069	This makes it Vi compatible: Without the "\_" or "\n" the collection
1070	does not match an end-of-line.
1071								*E769*
1072	When the ']' is not there Vim will not give an error message but
1073	assume no collection is used.  Useful to search for '['.  However, you
1074	do get E769 for internal searching.  And be aware that in a
1075	`:substitute` command the whole command becomes the pattern.  E.g.
1076	":s/[/x/" searches for "[/x" and replaces it with nothing.  It does
1077	not search for "[" and replaces it with "x"!
1078
1079								*E944* *E945*
1080	If the sequence begins with "^", it matches any single character NOT
1081	in the collection: "[^xyz]" matches anything but 'x', 'y' and 'z'.
1082	- If two characters in the sequence are separated by '-', this is
1083	  shorthand for the full list of ASCII characters between them.  E.g.,
1084	  "[0-9]" matches any decimal digit. If the starting character exceeds
1085	  the ending character, e.g. [c-a], E944 occurs. Non-ASCII characters
1086	  can be used, but the character values must not be more than 256 apart
1087	  in the old regexp engine. For example, searching by [\u3000-\u4000]
1088	  after setting re=1 emits a E945 error. Prepending \%#=2 will fix it.
1089	- A character class expression is evaluated to the set of characters
1090	  belonging to that character class.  The following character classes
1091	  are supported:
1092		  Name	      Func	Contents ~
1093*[:alnum:]*	  [:alnum:]   isalnum	ASCII letters and digits
1094*[:alpha:]*	  [:alpha:]   isalpha  	ASCII letters
1095*[:blank:]*	  [:blank:]     	space and tab
1096*[:cntrl:]*	  [:cntrl:]   iscntrl 	ASCII control characters
1097*[:digit:]*	  [:digit:]     	decimal digits '0' to '9'
1098*[:graph:]*	  [:graph:]   isgraph	ASCII printable characters excluding
1099					space
1100*[:lower:]*	  [:lower:]   (1)	lowercase letters (all letters when
1101					'ignorecase' is used)
1102*[:print:]*	  [:print:]   (2) 	printable characters including space
1103*[:punct:]*	  [:punct:]   ispunct	ASCII punctuation characters
1104*[:space:]*	  [:space:]     	whitespace characters: space, tab, CR,
1105					NL, vertical tab, form feed
1106*[:upper:]*	  [:upper:]   (3)	uppercase letters (all letters when
1107					'ignorecase' is used)
1108*[:xdigit:]*	  [:xdigit:]    	hexadecimal digits: 0-9, a-f, A-F
1109*[:return:]*	  [:return:]		the <CR> character
1110*[:tab:]*	  [:tab:]		the <Tab> character
1111*[:escape:]*	  [:escape:]		the <Esc> character
1112*[:backspace:]*	  [:backspace:]		the <BS> character
1113	  The brackets in character class expressions are additional to the
1114	  brackets delimiting a collection.  For example, the following is a
1115	  plausible pattern for a UNIX filename: "[-./[:alnum:]_~]\+" That is,
1116	  a list of at least one character, each of which is either '-', '.',
1117	  '/', alphabetic, numeric, '_' or '~'.
1118	  These items only work for 8-bit characters, except [:lower:] and
1119	  [:upper:] also work for multi-byte characters when using the new
1120	  regexp engine.  See |two-engines|.  In the future these items may
1121	  work for multi-byte characters.  For now, to get all "alpha"
1122	  characters you can use: [[:lower:][:upper:]].
1123
1124	  The "Func" column shows what library function is used.  The
1125	  implementation depends on the system.  Otherwise:
1126	  (1) Uses islower() for ASCII and Vim builtin rules for other
1127	  characters when built with the |+multi_byte| feature.
1128	  (2) Uses Vim builtin rules
1129	  (3) As with (1) but using isupper()
1130							*/[[=* *[==]*
1131	- An equivalence class.  This means that characters are matched that
1132	  have almost the same meaning, e.g., when ignoring accents.  This
1133	  only works for Unicode, latin1 and latin9.  The form is:
1134		[=a=]
1135							*/[[.* *[..]*
1136	- A collation element.  This currently simply accepts a single
1137	  character in the form:
1138		[.a.]
1139							  */\]*
1140	- To include a literal ']', '^', '-' or '\' in the collection, put a
1141	  backslash before it: "[xyz\]]", "[\^xyz]", "[xy\-z]" and "[xyz\\]".
1142	  (Note: POSIX does not support the use of a backslash this way).  For
1143	  ']' you can also make it the first character (following a possible
1144	  "^"):  "[]xyz]" or "[^]xyz]" {not in Vi}.
1145	  For '-' you can also make it the first or last character: "[-xyz]",
1146	  "[^-xyz]" or "[xyz-]".  For '\' you can also let it be followed by
1147	  any character that's not in "^]-\bdertnoUux".  "[\xyz]" matches '\',
1148	  'x', 'y' and 'z'.  It's better to use "\\" though, future expansions
1149	  may use other characters after '\'.
1150	- Omitting the trailing ] is not considered an error. "[]" works like
1151	  "[]]", it matches the ']' character.
1152	- The following translations are accepted when the 'l' flag is not
1153	  included in 'cpoptions' {not in Vi}:
1154		\e	<Esc>
1155		\t	<Tab>
1156		\r	<CR>	(NOT end-of-line!)
1157		\b	<BS>
1158		\n	line break, see above |/[\n]|
1159		\d123	decimal number of character
1160		\o40	octal number of character up to 0377
1161		\x20	hexadecimal number of character up to 0xff
1162		\u20AC	hex. number of multibyte character up to 0xffff
1163		\U1234	hex. number of multibyte character up to 0xffffffff
1164	  NOTE: The other backslash codes mentioned above do not work inside
1165	  []!
1166	- Matching with a collection can be slow, because each character in
1167	  the text has to be compared with each character in the collection.
1168	  Use one of the other atoms above when possible.  Example: "\d" is
1169	  much faster than "[0-9]" and matches the same characters.
1170
1171						*/\%[]* *E69* *E70* *E369*
1172\%[]	A sequence of optionally matched atoms.  This always matches.
1173	It matches as much of the list of atoms it contains as possible.  Thus
1174	it stops at the first atom that doesn't match.  For example: >
1175		/r\%[ead]
1176<	matches "r", "re", "rea" or "read".  The longest that matches is used.
1177	To match the Ex command "function", where "fu" is required and
1178	"nction" is optional, this would work: >
1179		/\<fu\%[nction]\>
1180<	The end-of-word atom "\>" is used to avoid matching "fu" in "full".
1181	It gets more complicated when the atoms are not ordinary characters.
1182	You don't often have to use it, but it is possible.  Example: >
1183		/\<r\%[[eo]ad]\>
1184<	Matches the words "r", "re", "ro", "rea", "roa", "read" and "road".
1185	There can be no \(\), \%(\) or \z(\) items inside the [] and \%[] does
1186	not nest.
1187	To include a "[" use "[[]" and for "]" use []]", e.g.,: >
1188		/index\%[[[]0[]]]
1189<	matches "index" "index[", "index[0" and "index[0]".
1190	{not available when compiled without the |+syntax| feature}
1191
1192				*/\%d* */\%x* */\%o* */\%u* */\%U* *E678*
1193
1194\%d123	Matches the character specified with a decimal number.  Must be
1195	followed by a non-digit.
1196\%o40	Matches the character specified with an octal number up to 0377.
1197	Numbers below 040 must be followed by a non-octal digit or a non-digit.
1198\%x2a	Matches the character specified with up to two hexadecimal characters.
1199\%u20AC	Matches the character specified with up to four hexadecimal
1200	characters.
1201\%U1234abcd	Matches the character specified with up to eight hexadecimal
1202	characters.
1203
1204==============================================================================
12057. Ignoring case in a pattern					*/ignorecase*
1206
1207If the 'ignorecase' option is on, the case of normal letters is ignored.
1208'smartcase' can be set to ignore case when the pattern contains lowercase
1209letters only.
1210							*/\c* */\C*
1211When "\c" appears anywhere in the pattern, the whole pattern is handled like
1212'ignorecase' is on.  The actual value of 'ignorecase' and 'smartcase' is
1213ignored.  "\C" does the opposite: Force matching case for the whole pattern.
1214{only Vim supports \c and \C}
1215Note that 'ignorecase', "\c" and "\C" are not used for the character classes.
1216
1217Examples:
1218      pattern	'ignorecase'  'smartcase'	matches ~
1219	foo	  off		-		foo
1220	foo	  on		-		foo Foo FOO
1221	Foo	  on		off		foo Foo FOO
1222	Foo	  on		on		    Foo
1223	\cfoo	  -		-		foo Foo FOO
1224	foo\C	  -		-		foo
1225
1226Technical detail:				*NL-used-for-Nul*
1227<Nul> characters in the file are stored as <NL> in memory.  In the display
1228they are shown as "^@".  The translation is done when reading and writing
1229files.  To match a <Nul> with a search pattern you can just enter CTRL-@ or
1230"CTRL-V 000".  This is probably just what you expect.  Internally the
1231character is replaced with a <NL> in the search pattern.  What is unusual is
1232that typing CTRL-V CTRL-J also inserts a <NL>, thus also searches for a <Nul>
1233in the file.  {Vi cannot handle <Nul> characters in the file at all}
1234
1235						*CR-used-for-NL*
1236When 'fileformat' is "mac", <NL> characters in the file are stored as <CR>
1237characters internally.  In the text they are shown as "^J".  Otherwise this
1238works similar to the usage of <NL> for a <Nul>.
1239
1240When working with expression evaluation, a <NL> character in the pattern
1241matches a <NL> in the string.  The use of "\n" (backslash n) to match a <NL>
1242doesn't work there, it only works to match text in the buffer.
1243
1244						*pattern-multi-byte*
1245Patterns will also work with multi-byte characters, mostly as you would
1246expect.  But invalid bytes may cause trouble, a pattern with an invalid byte
1247will probably never match.
1248
1249==============================================================================
12508. Composing characters					*patterns-composing*
1251
1252							*/\Z*
1253When "\Z" appears anywhere in the pattern, all composing characters are
1254ignored.  Thus only the base characters need to match, the composing
1255characters may be different and the number of composing characters may differ.
1256Only relevant when 'encoding' is "utf-8".
1257Exception: If the pattern starts with one or more composing characters, these
1258must match.
1259							*/\%C*
1260Use "\%C" to skip any composing characters.  For example, the pattern "a" does
1261not match in "càt" (where the a has the composing character 0x0300), but
1262"a\%C" does.  Note that this does not match "cát" (where the á is character
12630xe1, it does not have a compositing character).  It does match "cat" (where
1264the a is just an a).
1265
1266When a composing character appears at the start of the pattern of after an
1267item that doesn't include the composing character, a match is found at any
1268character that includes this composing character.
1269
1270When using a dot and a composing character, this works the same as the
1271composing character by itself, except that it doesn't matter what comes before
1272this.
1273
1274The order of composing characters does not matter.  Also, the text may have
1275more composing characters than the pattern, it still matches.  But all
1276composing characters in the pattern must be found in the text.
1277
1278Suppose B is a base character and x and y are composing characters:
1279	pattern		text		match ~
1280	Bxy		Bxy		yes (perfect match)
1281	Bxy		Byx		yes (order ignored)
1282	Bxy		By		no (x missing)
1283	Bxy		Bx		no (y missing)
1284	Bx		Bx		yes (perfect match)
1285	Bx		By		no (x missing)
1286	Bx		Bxy		yes (extra y ignored)
1287	Bx		Byx		yes (extra y ignored)
1288
1289==============================================================================
12909. Compare with Perl patterns				*perl-patterns*
1291
1292Vim's regexes are most similar to Perl's, in terms of what you can do.  The
1293difference between them is mostly just notation;  here's a summary of where
1294they differ:
1295
1296Capability			in Vimspeak	in Perlspeak ~
1297----------------------------------------------------------------
1298force case insensitivity	\c		(?i)
1299force case sensitivity		\C		(?-i)
1300backref-less grouping		\%(atom\)	(?:atom)
1301conservative quantifiers	\{-n,m}		*?, +?, ??, {}?
13020-width match			atom\@=		(?=atom)
13030-width non-match		atom\@!		(?!atom)
13040-width preceding match		atom\@<=	(?<=atom)
13050-width preceding non-match	atom\@<!	(?<!atom)
1306match without retry		atom\@>		(?>atom)
1307
1308Vim and Perl handle newline characters inside a string a bit differently:
1309
1310In Perl, ^ and $ only match at the very beginning and end of the text,
1311by default, but you can set the 'm' flag, which lets them match at
1312embedded newlines as well.  You can also set the 's' flag, which causes
1313a . to match newlines as well.  (Both these flags can be changed inside
1314a pattern using the same syntax used for the i flag above, BTW.)
1315
1316On the other hand, Vim's ^ and $ always match at embedded newlines, and
1317you get two separate atoms, \%^ and \%$, which only match at the very
1318start and end of the text, respectively.  Vim solves the second problem
1319by giving you the \_ "modifier":  put it in front of a . or a character
1320class, and they will match newlines as well.
1321
1322Finally, these constructs are unique to Perl:
1323- execution of arbitrary code in the regex:  (?{perl code})
1324- conditional expressions:  (?(condition)true-expr|false-expr)
1325
1326...and these are unique to Vim:
1327- changing the magic-ness of a pattern:  \v \V \m \M
1328   (very useful for avoiding backslashitis)
1329- sequence of optionally matching atoms:  \%[atoms]
1330- \& (which is to \| what "and" is to "or";  it forces several branches
1331   to match at one spot)
1332- matching lines/columns by number:  \%5l \%5c \%5v
1333- setting the start and end of the match:  \zs \ze
1334
1335==============================================================================
133610. Highlighting matches				*match-highlight*
1337
1338							*:mat* *:match*
1339:mat[ch] {group} /{pattern}/
1340		Define a pattern to highlight in the current window.  It will
1341		be highlighted with {group}.  Example: >
1342			:highlight MyGroup ctermbg=green guibg=green
1343			:match MyGroup /TODO/
1344<		Instead of // any character can be used to mark the start and
1345		end of the {pattern}.  Watch out for using special characters,
1346		such as '"' and '|'.
1347
1348		{group} must exist at the moment this command is executed.
1349
1350		The {group} highlighting still applies when a character is
1351		to be highlighted for 'hlsearch', as the highlighting for
1352		matches is given higher priority than that of 'hlsearch'.
1353		Syntax highlighting (see 'syntax') is also overruled by
1354		matches.
1355
1356		Note that highlighting the last used search pattern with
1357		'hlsearch' is used in all windows, while the pattern defined
1358		with ":match" only exists in the current window.  It is kept
1359		when switching to another buffer.
1360
1361		'ignorecase' does not apply, use |/\c| in the pattern to
1362		ignore case.  Otherwise case is not ignored.
1363
1364		'redrawtime' defines the maximum time searched for pattern
1365		matches.
1366
1367		When matching end-of-line and Vim redraws only part of the
1368		display you may get unexpected results.  That is because Vim
1369		looks for a match in the line where redrawing starts.
1370
1371		Also see |matcharg()| and |getmatches()|. The former returns
1372		the highlight group and pattern of a previous |:match|
1373		command.  The latter returns a list with highlight groups and
1374		patterns defined by both |matchadd()| and |:match|.
1375
1376		Highlighting matches using |:match| are limited to three
1377		matches (aside from |:match|, |:2match| and |:3match| are
1378		available). |matchadd()| does not have this limitation and in
1379		addition makes it possible to prioritize matches.
1380
1381		Another example, which highlights all characters in virtual
1382		column 72 and more: >
1383			:highlight rightMargin term=bold ctermfg=blue guifg=blue
1384			:match rightMargin /.\%>72v/
1385<		To highlight all character that are in virtual column 7: >
1386			:highlight col8 ctermbg=grey guibg=grey
1387			:match col8 /\%<8v.\%>7v/
1388<		Note the use of two items to also match a character that
1389		occupies more than one virtual column, such as a TAB.
1390
1391:mat[ch]
1392:mat[ch] none
1393		Clear a previously defined match pattern.
1394
1395
1396:2mat[ch] {group} /{pattern}/					*:2match*
1397:2mat[ch]
1398:2mat[ch] none
1399:3mat[ch] {group} /{pattern}/					*:3match*
1400:3mat[ch]
1401:3mat[ch] none
1402		Just like |:match| above, but set a separate match.  Thus
1403		there can be three matches active at the same time.  The match
1404		with the lowest number has priority if several match at the
1405		same position.
1406		The ":3match" command is used by the |matchparen| plugin.  You
1407		are suggested to use ":match" for manual matching and
1408		":2match" for another plugin.
1409
1410
1411 vim:tw=78:ts=8:ft=help:norl:
1412