## PATTERN

*pattern.txt*   For IdeaVIM version 0.12.0.  Last change: 2006 Nov 12

IdeaVIM REFERENCE MANUAL    by Rick Maddy

Patterns and search commands                            *pattern-searches*

The very basics can be found in section |03.9| of the user manual.  A few more
explanations are in chapter 27 |usr_27.txt|.

1. Search commands              |search-commands|
2. The definition of a pattern  |search-pattern|
3. Overview of pattern items    |pattern-overview|
4. Multi items                  |pattern-multi-items|
5. Ordinary atoms               |pattern-atoms|
6. Ignoring case in a pattern   |/ignorecase|
7. Compare with Perl patterns   |perl-patterns|
8. Highlighting matches         |match-highlight|



1. Search commands                              *search-commands* *E486*

*/*
/{pattern}[/]<CR>       Search forward for the [count]'th occurrence of
{pattern} (exclusive).

/{pattern}/{offset}<CR> Search forward for the [count]'th occurrence of
{pattern} and go |{offset}| lines up or down.
(linewise).

*/<CR>*
/<CR>                   Search forward for the [count]'th latest used
pattern |last-pattern| with latest used |{offset}|.

//{offset}<CR>          Search forward for the [count]'th latest used
pattern |last-pattern| with new |{offset}|.  If
{offset} is empty no offset is used.

*?*
?{pattern}[?]<CR>       Search backward for the [count]'th previous
occurrence of {pattern} (exclusive).

?{pattern}?{offset}<CR> Search backward for the [count]'th previous
occurrence of {pattern} and go |{offset}| lines up or
down (linewise).

*?<CR>*
?<CR>                   Search backward for the [count]'th latest used
pattern |last-pattern| with latest used |{offset}|.

??{offset}<CR>          Search backward for the [count]'th latest used
pattern |last-pattern| with new |{offset}|.  If
{offset} is empty no offset is used.

*n*
n                       Repeat the latest "/" or "?" [count] times.
|last-pattern| {Vi: no count}

*N*
N                       Repeat the latest "/" or "?" [count] times in
opposite direction. |last-pattern| {Vi: no count}

*star* *E348* *E349*
*                       Search forward for the [count]'th occurrence of the
word nearest to the cursor.  The word used for the
search is the first of:
1. the keyword under the cursor |'iskeyword'|
2. the first keyword after the cursor, in the
current line
3. the non-blank word under the cursor
4. the first non-blank word after the cursor,
in the current line
Only whole keywords are searched for, like with the
command "/\<keyword\>".  (exclusive)
'ignorecase' is used, 'smartcase' is not.

*#*
#                       Same as "*", but search backward.  The pound sign
(character 163) also works.  If the "#" key works as
backspace, try using "stty erase <BS>" before starting
Vim (<BS> is CTRL-H or a real backspace).

*gstar*
g*                      Like "*", but don't put "\<" and "\>" around the word.
This makes the search also find matches that are not a
whole word.

*g#*
g#                      Like "#", but don't put "\<" and "\>" around the word.
This makes the search also find matches that are not a
whole word.

*gd*
gd                      Goto local Declaration.  When the cursor is on a local
First Vim searches for the start of the current
search stops in line 1.  If it is found, Vim goes back
until a blank line is found.  From this position Vim
searches for the keyword under the cursor, like with
"*", but lines that look like a comment are ignored

*gD*
gD                      Goto global Declaration.  When the cursor is on a
global variable that is defined in the file, this
like "gd", except that the search for the keyword
always starts in line 1.

*:noh* *:nohlsearch*
:noh[lsearch]           Stop the highlighting for the 'hlsearch' option.  It
is automatically turned back on when using a search
command, or setting the 'hlsearch' option.

While typing the search pattern the current match will be shown if the
'incsearch' option is on.  Remember that you still have to finish the search
command with <CR> to actually position the cursor at the displayed match.  Or
use <Esc> to abandon the search.

All matches for the last used search pattern will be highlighted if you set
the 'hlsearch' option.  This can be suspended with the |:nohlsearch| command.

*search-offset* *{offset}*
These commands search for the specified pattern.  With "/" and "?" an
additional offset may be given.  There are two types of offsets: line offsets
and character offsets.

The offset gives the cursor position relative to the found match:
[num]       [num] lines downwards, in column 1
+[num]      [num] lines downwards, in column 1
-[num]      [num] lines upwards, in column 1
e[+num]     [num] characters to the right of the end of the match
e[-num]     [num] characters to the left of the end of the match
s[+num]     [num] characters to the right of the start of the match
s[-num]     [num] characters to the left of the start of the match
b[+num]     [num] characters to the right of the start (begin) of the match
b[-num]     [num] characters to the left of the start (begin) of the match

If a '-' or '+' is given but [num] is omitted, a count of one will be used.
When including an offset with 'e', the search becomes inclusive (the
character the cursor lands on is included in operations).

Examples:

pattern                 cursor position 
/test/+1                one line below "test", in column 1
/test/e                 on the last t of "test"
/test/s+2               on the 's' of "test"
/test/b-3               three characters before "test"

If one of these commands is used after an operator, the characters between
the cursor position before and after the search is affected.  However, if a
line offset is given, the whole lines between the two cursor positions are
affected.

An example of how to search for matches with a pattern and change the match
with another word:
        /foo<CR>        find "foo"
        c//e            change until end of match
        bar<Esc>        type replacement
        //<CR>          go to start of next match
        c//e            change until end of match
        beep<Esc>       type another replacement
                        etc.

*//;* *E386*
A very special offset is ';' followed by another search command.  For example:

   /test 1/;/test
   /test.*/+1;?ing?

The first one first finds the next occurrence of "test 1", and then the first
occurrence of "test" after that.

This is like executing two search commands after each other, except that:
- It can be used as a single motion command after an operator.
- The direction for a following "n" or "N" command comes from the first
search command.
- When an error occurs the cursor is not moved at all.

*last-pattern*
The last used pattern and offset are remembered.  They can be used to repeat
the search, possibly in another direction or with another count.  Note that
two patterns are remembered: One for 'normal' search commands and one for the
substitute command ":s".  Each time an empty pattern is given, the previously
used pattern is used.

The 'magic' option sticks with the last used pattern.  If you change 'magic',
this will not change how the last used pattern will be interpreted.
The 'ignorecase' option does not do this.  When 'ignorecase' is changed, it
will result in the pattern to match other text.

All matches for the last used search pattern will be highlighted if you set
the 'hlsearch' option.

To clear the last used search pattern:
        :let @/ = ""
This will not set the pattern to an empty string, because that would match
everywhere.  The pattern is really cleared, like when starting Vim.

The search usual skips matches that don't move the cursor.  Whether the next
match is found at the next character or after the skipped match depends on the
'c' flag in 'cpoptions'.
with 'c' flag:   "/..." advances 1 to 3 characters
without 'c' flag:   "/..." advances 1 character
The unpredictability with the 'c' flag is caused by starting the search in the
first column, skipping matches until one is found past the cursor position.

In Vi the ":tag" command sets the last search pattern when the tag is searched
for.  In Vim this is not done, the previous search pattern is still remembered,
unless the 't' flag is present in 'cpoptions'.  The search pattern is always
put in the search history.

If the 'wrapscan' option is on (which is the default), searches wrap around
the end of the buffer.  If 'wrapscan' is not set, the backward search stops
at the beginning and the forward search stops at the end of the buffer.  If
'wrapscan' is set and the pattern was not found the error message "pattern
not found" is given, and the cursor will not be moved.  If 'wrapscan' is not
set the message becomes "search hit BOTTOM without match" when searching
forward, or "search hit TOP without match" when searching backward.  If
wrapscan is set and the search wraps around the end of the file the message
"search hit TOP, continuing at BOTTOM" or "search hit BOTTOM, continuing at
TOP" is given when searching backwards or forwards respectively.  This can be
switched off by setting the 's' flag in the 'shortmess' option.  The highlight
method 'w' is used for this message (default: standout).

*search-range*
You cannot limit the search command "/" to a certain range of lines.  A trick
to do this anyway is to use the ":substitute" command with the 'c' flag.
Example:
   :.,300s/Pattern//gc
This command will search from the cursor position until line 300 for
"Pattern".  At the match, you will be asked to type a character.  Type 'q' to
stop at this match, type 'n' to find the next match.

The "*", "#", "g*" and "g#" commands look for a word near the cursor in this
order, the first one that is found is used:
- The keyword currently under the cursor.
- The first keyword to the right of the cursor, in the same line.
- The WORD currently under the cursor.
- The first WORD to the right of the cursor, in the same line.
The keyword may only contain letters and characters in 'iskeyword'.
The WORD may contain any non-blanks (<Tab>s and/or <Space>s).
Note that if you type with ten fingers, the characters are easy to remember:
the "#" is under your left hand middle finger (search to the left and up) and
the "*" is under your right hand middle finger (search to the right and down).
(this depends on your keyboard layout though).



2. The definition of a pattern          *search-pattern* *pattern* *[pattern]*
*regular-expression* *regexp* *Pattern*
*E76* *E361* *E363* *E383* *E476*

For starters, read chapter 27 of the user manual |usr_27.txt|.

*/bar* */\bar* */pattern*
1. A pattern is one or more branches, separated by "\|".  It matches anything
that matches one of the branches.  Example: "foo\|beep" matches "foo" and
matches "beep".  If more than one branch matches, the first one is used.

pattern ::=      branch
or  branch \| branch
or  branch \| branch \| branch
etc.

*/branch* */\&*
2. A branch is one or more concats, separated by "\&".  It matches the last
concat, but only if all the preceding concats also match at the same
position.  Examples:
"foobeep\&..." matches "foo" in "foobeep".
".*Peter\&.*Bob" matches in a line containing both "Peter" and "Bob"

branch ::=       concat
or  concat \& concat
or  concat \& concat \& concat
etc.

*/concat*
3. A concat is one or more pieces, concatenated.  It matches a match for the
first piece, followed by a match for the second piece, etc.  Example:
"f[0-9]b", first matches "f", then a digit and then "b".

concat  ::=      piece
or  piece piece
or  piece piece piece
etc.

*/piece*
4. A piece is an atom, possibly followed by a multi, an indication of how many
times the atom can be matched.  Example: "a*" matches any sequence of "a"
characters: "", "a", "aa", etc.  See |/multi|.

piece   ::=      atom
or  atom  multi

*/atom*
5. An atom can be one of a long list of items.  Many atoms match one character
in the text.  It is often an ordinary character or a character class.
Braces can be used to make a pattern into an atom.  The "\z(\)" construct
is only for syntax highlighting.

atom    ::=      ordinary-atom               |/ordinary-atom|
or  $$pattern$$               |/$$| or \%( pattern$$              |/\%(|
or  \z( pattern \)              |/\z(|



3. Overview of pattern items                            *pattern-overview*

Overview of multi items.                                */multi* *E61* *E62*

          multi 
     'magic' 'nomagic'  matches of the preceding atom 
|/star| *       \*      0 or more       as many as possible
|/\+|   \+      \+      1 or more       as many as possible
|/\=|   \=      \=      0 or 1          as many as possible
|/\?|   \?      \?      0 or 1          as many as possible

|/\{|   \{n,m}  \{n,m}  n to m          as many as possible
\{n}    \{n}    n               exactly
\{n,}   \{n,}   at least n      as many as possible
\{,m}   \{,m}   0 to m          as many as possible
\{}     \{}     0 or more       as many as possible (same as *)

|/\{-|  \{-n,m} \{-n,m} n to m          as few as possible
\{-n}   \{-n}   n               exactly
\{-n,}  \{-n,}  at least n      as few as possible
\{-,m}  \{-,m}  0 to m          as few as possible
\{-}    \{-}    0 or more       as few as possible

*E59*
|/\@>|  \@>     \@>     1, like matching a whole pattern
|/\@=|  \@=     \@=     nothing, requires a match |/zero-width|
|/\@!|  \@!     \@!     nothing, requires NO match |/zero-width|
|/\@<=| \@<=    \@<=    nothing, requires a match behind |/zero-width|
|/\@<!| \@<!    \@<!    nothing, requires NO match behind |/zero-width|

Overview of ordinary atoms.                             */ordinary-atom*

      ordinary atom 
      magic   nomagic   matches 
|/^|    ^       ^       start-of-line (at start of pattern) |/zero-width|
|/\^|   \^      \^      literal '^'
|/\_^|  \_^     \_^     start-of-line (used anywhere) |/zero-width|
|/$|$       $end-of-line (at end of pattern) |/zero-width| |/\$|   \$\$      literal '$' |/\_$|  \_$\_$     end-of-line (used anywhere) |/zero-width|
|/.|    .       \.      any single character (not an end-of-line)
|/\_.|  \_.     \_.     any single character or end-of-line
|/\<|   \<      \<      beginning of a word |/zero-width|
|/\>|   \>      \>      end of a word |/zero-width|
|/\zs|  \zs     \zs     anything, sets start of match
|/\ze|  \ze     \ze     anything, sets end of match
|/\%^|  \%^     \%^     beginning of file |/zero-width|         *E71*
|/\%$| \%$     \%$end of file |/zero-width| |/\%#| \%# \%# cursor position |/zero-width| |/\%l| \%23l \%23l in line 23 |/zero-width| |/\%c| \%23c \%23c in column 23 |/zero-width| |/\%v| \%23v \%23v in virtual column 23 |/zero-width| Character classes: |/\i| \i \i identifier character (see 'isident' option) |/\I| \I \I like "\i", but excluding digits |/\k| \k \k keyword character (see 'iskeyword' option) |/\K| \K \K like "\k", but excluding digits |/\f| \f \f file name character (see 'isfname' option) |/\F| \F \F like "\f", but excluding digits |/\p| \p \p printable character (see 'isprint' option) |/\P| \P \P like "\p", but excluding digits |/\s| \s \s whitespace character: <Space> and <Tab> |/\S| \S \S non-whitespace character; opposite of \s |/\d| \d \d digit: [0-9] |/\D| \D \D non-digit: [^0-9] |/\x| \x \x hex digit: [0-9A-Fa-f] |/\X| \X \X non-hex digit: [^0-9A-Fa-f] |/\o| \o \o octal digit: [0-7] |/\O| \O \O non-octal digit: [^0-7] |/\w| \w \w word character: [0-9A-Za-z_] |/\W| \W \W non-word character: [^0-9A-Za-z_] |/\h| \h \h head of word character: [A-Za-z_] |/\H| \H \H non-head of word character: [^A-Za-z_] |/\a| \a \a alphabetic character: [A-Za-z] |/\A| \A \A non-alphabetic character: [^A-Za-z] |/\l| \l \l lowercase character: [a-z] |/\L| \L \L non-lowercase character: [^a-z] |/\u| \u \u uppercase character: [A-Z] |/\U| \U \U non-uppercase character [^A-Z] |/\_| \_x \_x where x is any of the characters above: character class with end-of-line included (end of character classes) |/\e| \e \e <Esc> |/\t| \t \t <Tab> |/\r| \r \r <CR> |/\b| \b \b <BS> |/\n| \n \n end-of-line |/~| ~ \~ last given substitute string |/\1| \1 \1 same string as matched by first  |/\2| \2 \2 Like "\1", but uses second  ... |/\9| \9 \9 Like "\1", but uses ninth  x x a character with no special meaning matches itself |/[]| [] $] any character specified inside the [] |/\%[]| \%[] \%[] a list of optionally matched atoms |/\c| \c \c ignore case |/\C| \C \C match case |/\m| \m \m 'magic' on for the following chars in the pattern |/\M| \M \M 'magic' off for the following chars in the pattern |/\v| \v \v the following chars in the pattern are "very magic" |/\V| \V \V the following chars in the pattern are "very nomagic" |/\Z| \Z \Z ignore differences in Unicode "combining characters". Useful when searching voweled Hebrew or Arabic text. Example matches  \<\I\i* or \<\h\w* \<[a-zA-Z_][a-zA-Z0-9_]* An identifier (e.g., in a C program). $$\.\|\.$$ A period followed by <EOL> or a space. [.!?][])"']*$$\|[ ]$$ A search pattern that finds the end of a sentence, with almost the same definition as the ")" command. cat\Z Both "cat" and "càt" ("a" followed by 0x0300) Does not match "càt" (character 0x00e0), even though it may look the same.  3. Magic */magic* Some characters in the pattern are taken literally. They match with the same character in the text. When preceded with a backslash however, these characters get a special meaning. Other characters have a special meaning without a backslash. They need to be preceded with a backslash to match literally. If a character is taken literally or not depends on the 'magic' option and the items mentioned next. */\m* */\M* Use of "\m" makes the pattern after it be interpreted as if 'magic' is set, ignoring the actual value of the 'magic' option. Use of "\M" makes the pattern after it be interpreted as if 'nomagic' is used. */\v* */\V* Use of "\v" means that in the pattern after it all ASCII characters except '0'-'9', 'a'-'z', 'A'-'Z' and '_' have a special meaning. "very magic" Use of "\V" means that in the pattern after it only the backslash has a special meaning. "very nomagic" Examples: after: \v \m \M \V matches  'magic' 'nomagic' \ matches end-of-line . . \. \. matches any character * * \* \* any number of the previous atom ()    grouping into an atom | \| \| \| separating alternatives \a \a \a \a alphabetic character \\ \\ \\ \\ literal backslash \. \. . . literal dot \{ { { { literal '{' a a a a literal 'a' {only Vim supports \m, \M, \v and \V} It is recommended to always keep the 'magic' option at the default setting, which is 'magic'. This avoids portability problems. To make a pattern immune to the 'magic' option being set or not, put "\m" or "\M" at the start of the pattern.  4. Multi items *pattern-multi-items* An atom can be followed by an indication of how many times the atom can be matched and in what way. This is called a multi. See |/multi| for an overview. It is not possible to use a multi that can match more than one time after an atom that can match an empty string. That's because this could result in an endless loop. If you try it, you will get this error message:  *, \+ or \{ operand could be empty */star* */\star* *E56* * (use \* when 'magic' is not set) Matches 0 or more of the preceding atom, as many as possible.  Example 'nomagic' matches  a* a\* "", "a", "aa", "aaa", etc. .* \.\* anything, also an empty string, no end-of-line \_.* \_.\* everything up to the end of the buffer \_.*END \_.\*END everything up to and including the last "END" in the buffer Exception: When "*" is used at the start of the pattern or just after "^" it matches the star character. Be aware that repeating "\_." can match a lot of text and take a long time. For example, "\_.*END" matches all text from the current position to the last occurrence of "END" in the file. Since the "*" will match as many as possible, this first skips over all lines until the end of the file and then tries matching "END", backing up one character at a time. */\+* *E57* \+ Matches 1 or more of the preceding atom, as many as possible. {not in Vi}  Example matches  ^.\+ any non-empty line \s\+ white space of at least one character */\=* \= Matches 0 or 1 of the preceding atom, as many as possible.  Example matches  foo\= "fo" and "foo" */\?* \? Just like \=. Cannot be used when searching backwards with the "?" command. */\{* *E58* *E60* *E554* \{n,m} Matches n to m of the preceding atom, as many as possible \{n} Matches n of the preceding atom \{n,} Matches at least n of the preceding atom, as many as possible \{,m} Matches 0 to m of the preceding atom, as many as possible \{} Matches 0 or more of the preceding atom, as many as possible (like *) */\{-* \{-n,m} matches n to m of the preceding atom, as few as possible \{-n} matches n of the preceding atom \{-n,} matches at least n of the preceding atom, as few as possible \{-,m} matches 0 to m of the preceding atom, as few as possible \{-} matches 0 or more of the preceding atom, as few as possible {Vi does not have any of these} n and m are positive decimal numbers If a "-" appears immediately after the "{", then a shortest match first algorithm is used (see example below). In particular, "\{-}" is the same as "*" but uses the shortest match first algorithm. BUT: A match that starts earlier is preferred over a shorter match: "a\{-}b" matches "aaab" in "xaaab".  Example matches  ab\{2,3}c "abbc" or "abbbc" a\{5} "aaaaa". ab\{2,}c "abbc", "abbbc", "abbbbc", etc ab\{,3}c "ac", "abc", "abbc" or "abbbc". a[bc]\{3}d "abbbd", "abbcd", "acbcd", "acccd", etc. a$$bc$$\{1,2}d "abcd" or "abcbcd" a[bc]\{-}[cd] "abc" in "abcd" a[bc]*[cd] "abcd" in "abcd" The } may optionally be preceded with a backslash: \{n,m\}. */\@=* \@= Matches the preceding atom with zero width. Like '(?=pattern)" in Perl.  Example matches  foo$$bar$$\@= "foo" in "foobar" foo$$bar$$\@=foo nothing */zero-width* When using "\@=" (or "^", "", "\<", "\>") no characters are included in the match. These items are only used to check if a match can be made. This can be tricky, because a match with following items will be done in the same position. The last example above will not match "foobarfoo", because it tries match "foo" in the same position where "bar" matched. Note that using "\&" works the same as using "\@=": "foo\&.." is the same as "$$foo$$\@=..". But using "\&" is easier, you don't need the braces. */\@!* \@! Matches with zero width if the preceding atom does NOT match at the current position |/zero-width| Like '(?!pattern)" in Perl.  Example matches  foo$$bar$$\@! any "foo" not followed by "bar" a.\{-}p\@! "a", "ap", "app", etc. not followed by a "p" Using "\@!" is tricky, because there are many places where a pattern does not match. "a.*p\@!" will match from an "a" to the end of the line, because ".*" can match all characters in the line and the "p" doesn't match at the end of the line. "a.\{-}p\@!" will match any "a", "ap", "aap", etc. that isn't followed by a "p", because the "." can match a "p" and "p\@!" doesn't match after that. You can't use "\@!" to look for a non-match before the matching position: "$$foo$$\@!bar" will match "bar" in "foobar", because at the position where "bar" matches, "foo" does not match. To avoid matching "foobar" you could use "$$foo$$\@!...bar", but that doesn't match a bar at the start of a line. Use "$$foo$$\@<!bar". */\@<=* \@<= Matches with zero width if the preceding atom matches just before what follows. |/zero-width| Like '(?<=pattern)" in Perl, but Vim allows non-fixed-width patterns.  Example matches  $$an\_s\+$$\@<=file "file" after "an" and white space or an end-of-line For speed it's often much better to avoid this multi. Try using "\zs" instead |/\zs|. To match the same as the above example: an\_s\+\zsfile "\@<=" and "\@<!" check for matches just before what follows. Theoretically these matches could start anywhere before this position. But to limit the time needed, only the line where what follows matches is searched, and one line before that (if there is one). This should be sufficient to match most things and not be too slow. The part of the pattern after "\@<=" and "\@<!" are checked for a match first, thus things like "\1" don't work to reference  inside the preceding atom. It does work the other way around:  Example matches  \1\@<=,$$[a-z]\+$$ ",abc" in "abc,abc" */\@<!* \@<! Matches with zero width if the preceding atom does NOT match just before what follows. Thus this matches if there is no position in the current or previous line where the atom matches such that it ends just before what follows. |/zero-width| Like '(?<!pattern)" in Perl, but Vim allows non-fixed-width patterns. The match with the preceding atom is made to end just before the match with what follows, thus an atom that ends in ".*" will work. Warning: This can be slow (because many positions need to be checked for a match).  Example matches  $$foo$$\@<!bar any "bar" that's not in "foobar" $$\/\/.*$$\@\<!in "in" which is not after "//" */\@>* \@> Matches the preceding atom like matching a whole pattern. Like '(?>pattern)" in Perl.  Example matches  $$a*$$\@>a nothing (the "a*" takes all the "a"'s, there can't be another one following) This matches the preceding atom as if it was a pattern by itself. If it doesn't match, there is no retry with shorter sub-matches or anything. Observe this difference: "a*b" and "a*ab" both match "aaab", but in the second case the "a*" matches only the first two "a"s. "$$a*$$\@>ab" will not match "aaab", because the "a*" matches the "aaa" (as many "a"s as possible), thus the "ab" can't match.  5. Ordinary atoms *pattern-atoms* An ordinary atom can be: */^* ^ At beginning of pattern or after "\|", "$$", "\%(" or "\n": matches start-of-line; at other positions, matches literal '^'. |/zero-width|  Example matches  ^beep( the start of the C function "beep" (probably). */\^* \^ Matches literal '^'. Can be used at any position in the pattern. */\_^* \_^ Matches start-of-line. |/zero-width| Can be used at any position in the pattern.  Example matches  \_s*\_^foo white space and blank lines and then "foo" at start-of-line */* At end of pattern or in front of "\|" or "$$" ("|" or ")" after "\v"): matches end-of-line <EOL>; at other positions, matches literal ''. |/zero-width| */\* \ Matches literal ''. Can be used at any position in the pattern. */\_* \_ Matches end-of-line. |/zero-width| Can be used at any position in the pattern.  Example matches  foo\_\_s* "foo" at end-of-line and following white space and blank lines . (with 'nomagic': \.) */.* */\.* Matches any single character, but not an end-of-line. */\_.* \_. Matches any single character or end-of-line. Careful: "\_.*" matches all text to the end of the buffer! */\<* \< Matches the beginning of a word: The next char is the first char of a word. The 'iskeyword' option specifies what is a word character. |/zero-width| */\>* \> Matches the end of a word: The previous char is the last char of a word. The 'iskeyword' option specifies what is a word character. |/zero-width| */\zs* \zs Matches at any position, and sets the start of the match there: The next char is the first char of the whole match. |/zero-width| Can be used multiple times, the last one encountered in a matching branch is used. Example: "^\s*\zsif" matches an "if" at the start of a line, ignoring white space. */\ze* \ze Matches at any position, and sets the end of the match there: The previous char is the last char of the whole match. |/zero-width| Can be used multiple times, the last one encountered in a matching branch is used. Example: "end\ze$$if\|for$$" matches the "end" in "endif" and "endfor". */\%^* *start-of-file* \%^ Matches start of the file. When matching with a string, matches the start of the string. For example, to find the first "VIM" in a file:  /\%^\_.\{-}\zsVIM */\%* *end-of-file* \% Matches end of the file. When matching with a string, matches the end of the string. Note that this does NOT find the last "VIM" in a file:  /VIM\_.\{-}\% It will find the next VIM, because the part after it will always match. This one will find the last "VIM" in the file:  /VIM\ze$$\(VIM$$\@!\_.\)*\% This uses |/\@!| to ascertain that "VIM" does NOT match in any position after the first "VIM". Searching from the end of the file backwards is easier! */\%l* */\%>l* */\%<l* \%23l Matches in a specific line. \%<23l Matches above a specific line. \%>23l Matches below a specific line. These three can be used to match specific lines in a buffer. The "23" can be any line number. The first line is 1. WARNING: When inserting or deleting lines Vim does not automatically update the matches. This means Syntax highlighting quickly becomes wrong. Example, to highlight the line where the cursor currently is:  :exe '/\%' . line(".") . 'l.*' When 'hlsearch' is set and you move the cursor around and make changes this will clearly show when the match is updated or not. */\%c* */\%>c* */\%<c* \%23c Matches in a specific column. \%<23c Matches before a specific column. \%>23c Matches after a specific column. These three can be used to match specific columns in a buffer or string. The "23" can be any column number. The first column is 1. Actually, the column is the byte number (thus it's not exactly right for multi-byte characters). WARNING: When inserting or deleting text Vim does not automatically update the matches. This means Syntax highlighting quickly becomes wrong. Example, to highlight the column where the cursor currently is:  :exe '/\%' . col(".") . 'c' When 'hlsearch' is set and you move the cursor around and make changes this will clearly show when the match is updated or not. */\%v* */\%>v* */\%<v* \%23v Matches in a specific virtual column. \%<23v Matches before a specific virtual column. \%>23v Matches after a specific virtual column. These three can be used to match specific virtual columns in a buffer or string. When not matching with a buffer in a window, the option values of the current window are used (e.g., 'tabstop'). The "23" can be any column number. The first column is 1. Note that some virtual column positions will never match, because they are halfway a Tab or other character that occupies more than one screen character. WARNING: When inserting or deleting text Vim does not automatically update the matches. This means Syntax highlighting quickly becomes wrong. Example, to highlight the all characters after virtual column 72:  /\%>72v.* When 'hlsearch' is set and you move the cursor around and make changes this will clearly show when the match is updated or not. To match the text up to column 17:  /.*\%17v Column 17 is not included, because that's where the "\%17v" matches, and since this is a |/zero-width| match, column 17 isn't included in the match. This does the same:  /.*\%<18v Character classes: \i identifier character (see 'isident' option) */\i* \I like "\i", but excluding digits */\I* \k keyword character (see 'iskeyword' option) */\k* \K like "\k", but excluding digits */\K* \f file name character (see 'isfname' option) */\f* \F like "\f", but excluding digits */\F* \p printable character (see 'isprint' option) */\p* \P like "\p", but excluding digits */\P* NOTE: the above also work for multi-byte characters. The ones below only match ASCII characters, as indicated by the range. *whitespace* *white-space* \s whitespace character: <Space> and <Tab> */\s* \S non-whitespace character; opposite of \s */\S* \d digit: [0-9] */\d* \D non-digit: [^0-9] */\D* \x hex digit: [0-9A-Fa-f] */\x* \X non-hex digit: [^0-9A-Fa-f] */\X* \o octal digit: [0-7] */\o* \O non-octal digit: [^0-7] */\O* \w word character: [0-9A-Za-z_] */\w* \W non-word character: [^0-9A-Za-z_] */\W* \h head of word character: [A-Za-z_] */\h* \H non-head of word character: [^A-Za-z_] */\H* \a alphabetic character: [A-Za-z] */\a* \A non-alphabetic character: [^A-Za-z] */\A* \l lowercase character: [a-z] */\l* \L non-lowercase character: [^a-z] */\L* \u uppercase character: [A-Z] */\u* \U non-uppercase character [^A-Z] */\U* NOTE: Using the atom is faster than the [] form. NOTE: 'ignorecase', "\c" and "\C" are not used by character classes. */\_* *E63* \_x Where "x" is any of the characters above: The character class with end-of-line added (end of character classes) \e matches <Esc> */\e* \t matches <Tab> */\t* \r matches <CR> */\r* \b matches <BS> */\b* \n matches an end-of-line */\n* When matching in a string instead of buffer text a literal newline character is matched. ~ matches the last given substitute string */~* */\~*  A pattern enclosed by escaped parentheses. */$$* */\($$* */\)* E.g., "$$^a$$" matches 'a' at the start of a line. *E51* *E54* *E55* \1 Matches the same string that was matched by */\1* *E65* the first sub-expression in $$and$$. Example: "$$[a-z]$$.\1" matches "ata", "ehe", "tot", etc. \2 Like "\1", but uses second sub-expression, */\2* ... */\3* \9 Like "\1", but uses ninth sub-expression. */\9* Note: The numbering of groups is done based on which "$$" comes first in the pattern (going left to right), NOT based on what is matched first. \%($$ A pattern enclosed by escaped parentheses. */\%(\)* */\%(* *E53* Just like , but without counting it as a sub-expression. This allows using more groups and it's a little bit faster. x A single character, with no special meaning, matches itself */\* */\\* \x A backslash followed by a single character, with no special meaning, is reserved for future expansions [] (with 'nomagic': \[]) */[]* */\[]* */\_[]* */collection* \_[] A collection. This is a sequence of characters enclosed in brackets. It matches any single character in the collection.  Example matches  [xyz] any 'x', 'y' or 'z' [a-zA-Z] any alphabetic character at the end of a line \c[a-z] same With "\_" prepended the collection also includes the end-of-line. The same can be done by including "\n" in the collection. The end-of-line is also matched when the collection starts with "^"! Thus "\_[^ab]" matches the end-of-line and any character but "a" and "b". This makes it Vi compatible: Without the "\_" or "\n" the collection does not match an end-of-line. If the sequence begins with "^", it matches any single character NOT in the collection: "[^xyz]" matches anything but 'x', 'y' and 'z'. - If two characters in the sequence are separated by '-', this is shorthand for the full list of ASCII characters between them. E.g., "[0-9]" matches any decimal digit. - A character class expression is evaluated to the set of characters belonging to that character class. The following character classes are supported:  Name Contents  *[:alnum:]* [:alnum:] letters and digits *[:alpha:]* [:alpha:] letters *[:blank:]* [:blank:] space and tab characters *[:cntrl:]* [:cntrl:] control characters *[:digit:]* [:digit:] decimal digits *[:graph:]* [:graph:] printable characters excluding space *[:lower:]* [:lower:] lowercase letters (all letters when 'ignorecase' is used) *[:print:]* [:print:] printable characters including space *[:punct:]* [:punct:] punctuation characters *[:space:]* [:space:] whitespace characters *[:upper:]* [:upper:] uppercase letters (all letters when 'ignorecase' is used) *[:xdigit:]* [:xdigit:] hexadecimal digits *[:return:]* [:return:] the <CR> character *[:tab:]* [:tab:] the <Tab> character *[:escape:]* [:escape:] the <Esc> character *[:backspace:]* [:backspace:] the <BS> character The brackets in character class expressions are additional to the brackets delimiting a collection. For example, the following is a plausible pattern for a UNIX filename: "[-./[:alnum:]_~]\+" That is, a list of at least one character, each of which is either '-', '.', '/', alphabetic, numeric, '_' or '~'. These items only work for 8-bit characters. */$* - To include a literal ']', '^', '-' or '\' in the collection, put a backslash before it: "[xyz\]]", "[\^xyz]", "[xy\-z]" and "[xyz\\]". (Note: POSIX does not support the use of a backslash this way). For ']' you can also make it the first character (following a possible "^"): "[]xyz]" or "[^]xyz]". For '-' you can also make it the first or last character: "[-xyz]", "[^-xyz]" or "[xyz-]". For '\' you can also let it be followed by any character that's not in "^]-\bertn". "[\xyz]" matches '\', 'x', 'y' and 'z'. It's better to use "\\" though, future expansions may use other characters after '\'. - The following translations are accepted when the 'l' flag is not included in 'cpoptions': \e <Esc> \t <Tab> \r <CR> (NOT end-of-line!) \b <BS> NOTE: The other backslash codes mentioned above do not work inside []! - Matching with a collection can be slow, because each character in the text has to be compared with each character in the collection. Use one of the other atoms above when possible. Example: "\d" is much faster than "[0-9]" and matches the same characters. */\%[]* *E69* *E70* *E369* \%[] A list of optionally matched atoms. This always matches. It matches as much of the list of atoms it contains as possible. Thus it stops at the first atom that doesn't match. For example:  /r\%[ead] matches "r", "re", "rea" or "read". The longest that matches is used. To match the Ex command "function", where "fu" is required and "nction" is optional, this would work:  /\<fu\%[nction]\> The end-of-word atom "\>" is used to avoid matching "fu" in "full". It gets more complicated when the atoms are not ordinary characters. You don't often have to use it, but it is possible. Example:  /\<r\%[[eo]ad]\> Matches the words "r", "re", "ro", "rea", "roa", "read" and "road". {not available when compiled without the +syntax feature}  6. Ignoring case in a pattern */ignorecase* If the 'ignorecase' option is on, the case of normal letters is ignored. 'smartcase' can be set to ignore case when the pattern contains lowercase letters only. */\c* */\C* When "\c" appears anywhere in the pattern, the whole pattern is handled like 'ignorecase' is on. The actual value of 'ignorecase' and 'smartcase' is ignored. "\C" does the opposite: Force matching case for the whole pattern. {only Vim supports \c and \C} Note that 'ignorecase', "\c" and "\C" are not used for the character classes. Examples:  pattern 'ignorecase' 'smartcase' matches  foo off - foo foo on - foo Foo FOO Foo on off foo Foo FOO Foo on on Foo \cfoo - - foo Foo FOO foo\C - - foo */\Z* When "\Z" appears anywhere in the pattern, composing characters are ignored. Thus only the base characters need to match, the composing characters may be different and the number of composing characters may differ. Only relevant when 'encoding' is "utf-8". Technical detail: *NL-used-for-Nul* <Nul> characters in the file are stored as <NL> in memory. In the display they are shown as "^@". The translation is done when reading and writing files. To match a <Nul> with a search pattern you can just enter CTRL-@ or "CTRL-V 000". This is probably just what you expect. Internally the character is replaced with a <NL> in the search pattern. What is unusual is that typing CTRL-V CTRL-J also inserts a <NL>, thus also searches for a <Nul> in the file. {Vi cannot handle <Nul> characters in the file at all} *CR-used-for-NL* When 'fileformat' is "mac", <NL> characters in the file are stored as <CR> characters internally. In the display they are shown as "^M". Otherwise this works similar to the usage of <NL> for a <Nul>. When working with expression evaluation, a <NL> character in the pattern matches a <NL> in the string. The use of "\n" (backslash n) to match a <NL> doesn't work there, it only works to match text in the buffer. *pattern-multi-byte* Patters will also work with multi-byte charaters, mostly as you would expect. But invalid bytes may cause trouble, a pattern with an invalid byte will probably never match.  7. Compare with Perl patterns *perl-patterns* Vim's regexes are most similar to Perl's, in terms of what you can do. The difference between them is mostly just notation; here's a summary of where they differ: Capability in Vimspeak in Perlspeak   force case insensitivity \c (?i) force case sensitivity \C (?-i) backref-less grouping \%(atom) (?:atom) conservative quantifiers \{-n,m} *?, +?, ??, {}? 0-width match atom\@= (?=atom) 0-width non-match atom\@! (?!atom) 0-width preceding match atom\@<= (?<=atom) 0-width preceding non-match atom\@<! (?<!atom) match without retry atom\@> (?>atom) Vim and Perl handle newlines inside a string a bit differently: In Perl, ^ and$ only match at the very beginning and end of the text,
by default, but you can set the 'm' flag, which lets them match at
embedded newlines as well.  You can also set the 's' flag, which causes
a . to match newlines as well.  (Both these flags can be changed inside
a pattern using the same syntax used for the i flag above, BTW.)

On the other hand, Vim's ^ and $always match at embedded newlines, and you get two separate atoms, \%^ and \%$, which only match at the very
start and end of the text, respectively.  Vim solves the second problem
by giving you the \_ "modifier":  put it in front of a . or a character
class, and they will match newlines as well.

Finally, these constructs are unique to Perl:
- execution of arbitrary code in the regex:  (?{perl code})
- conditional expressions:  (?(condition)true-expr|false-expr)

...and these are unique to Vim:
- changing the magic-ness of a pattern:  \v \V \m \M
(very useful for avoiding backslashitis)
- sequence of optionally matching atoms:  \%[atoms]
- \& (which is to \| what "and" is to "or";  it forces several branches
to match at one spot)
- matching lines/columns by number:  \%5l \%5c \%5v
- limiting the "return value" of a regex:  \zs \ze



8. Highlighting matches                                 *match-highlight*

*:mat* *:match*
:mat[ch] {group} /{pattern}/
Define a pattern to highlight in the current window.  It will
be highlighted with {group}.  Example:
                        :highlight MyGroup ctermbg=green guibg=green
                        :match MyGroup /TODO/
Instead of // any character can be used to mark the start and
end of the {pattern}.  Watch out for using special characters,
such as '"' and '|'.
{group} must exist at the moment this command is executed.
The match overrides the 'hlsearch' highlighting.
'ignorecase' does not apply, use |/\c| in the pattern to
ignore case.  Otherwise case is not ignored.
Note that highlighting the last used search pattern with
'hlsearch' is used in all windows, while the pattern defined
with ":match" only exists in the current window.  It is kept
when switching to another buffer.
Another example, which highlights all characters in virtual
column 72 and more:
                        :highlight rightMargin term=bold ctermfg=blue guifg=blue
                        :match rightMargin /.\%>72v/
<               To highlight all character that are in virtual column 7:
                        :highlight col8 ctermbg=grey guibg=grey
                        :match col8 /\%<8v.\%>7v/
Note the use of two items to also match a character that
occupies more than one virtual column, such as a TAB.

:mat[ch]
:mat[ch] none
Clear a previously defined match pattern.