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diff --git a/runtime/doc/pattern.txt b/runtime/doc/pattern.txt new file mode 100644 index 0000000..82b4418 --- /dev/null +++ b/runtime/doc/pattern.txt @@ -0,0 +1,1435 @@ +*pattern.txt* For Vim version 8.2. Last change: 2021 Jan 08 + + + VIM REFERENCE MANUAL by Bram Moolenaar + + +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. Magic |/magic| +4. Overview of pattern items |pattern-overview| +5. Multi items |pattern-multi-items| +6. Ordinary atoms |pattern-atoms| +7. Ignoring case in a pattern |/ignorecase| +8. Composing characters |patterns-composing| +9. Compare with Perl patterns |perl-patterns| +10. Highlighting matches |match-highlight| + +============================================================================== +1. Search commands *search-commands* + + */* +/{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 occurrence of the + latest used pattern |last-pattern| with latest used + |{offset}|. + +//{offset}<CR> Search forward for the [count]'th occurrence of the + 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 occurrence of the + latest used pattern |last-pattern| with latest used + |{offset}|. + +??{offset}<CR> Search backward for the [count]'th occurrence of the + latest used pattern |last-pattern| with new + |{offset}|. If {offset} is empty no offset is used. + + *n* +n Repeat the latest "/" or "?" [count] times. + If the cursor doesn't move the search is repeated with + count + 1. + |last-pattern| + + *N* +N Repeat the latest "/" or "?" [count] times in + opposite direction. |last-pattern| + + *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 + variable, this command will jump to its declaration. + First Vim searches for the start of the current + function, just like "[[". If it is not found the + 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 + (see 'comments' option). + Note that this is not guaranteed to work, Vim does not + really check the syntax, it only searches for a match + with the keyword. If included files also need to be + searched use the commands listed in |include-search|. + After this command |n| searches forward for the next + match (not backward). + + *gD* +gD Goto global Declaration. When the cursor is on a + global variable that is defined in the file, this + command will jump to its declaration. This works just + like "gd", except that the search for the keyword + always starts in line 1. + + *1gd* +1gd Like "gd", but ignore matches inside a {} block that + ends before the cursor position. + + *1gD* +1gD Like "gD", but ignore matches inside a {} block that + ends before the cursor position. + + *CTRL-C* +CTRL-C Interrupt current (search) command. Use CTRL-Break on + MS-Windows |dos-CTRL-Break|. + In Normal mode, any pending command is aborted. + + *: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. + This command doesn't work in an autocommand, because + the highlighting state is saved and restored when + executing autocommands |autocmd-searchpat|. + Same thing for when invoking a user function. + +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. + +When 'shortmess' does not include the "S" flag, Vim will automatically show an +index, on which the cursor is. This can look like this: > + + [1/5] Cursor is on first of 5 matches. + [1/>99] Cursor is on first of more than 99 matches. + [>99/>99] Cursor is after 99 match of more than 99 matches. + [?/??] Unknown how many matches exists, generating the + statistics was aborted because of search timeout. + +Note: the count does not take offset into account. + +When no match is found you get the error: *E486* Pattern not found +Note that for the |:global| command this behaves like a normal message, for Vi +compatibility. For the |:s| command the "e" flag can be used to avoid the +error message |:s_flags|. + + *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] identical to s[+num] above (mnemonic: begin) + b[-num] [num] identical to s[-num] above (mnemonic: begin) + ;{pattern} perform another search, see |//;| + +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<CR> change until end of match + bar<Esc> type replacement + //<CR> go to start of next match + c//e<CR> 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. However, if there is no previous search command, a +previous substitute pattern is used, if possible. + +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 usually 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'. See |cpo-c|. + 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. + +When searching backwards, searching starts at the start of the line, using the +'c' flag in 'cpoptions' as described above. Then the last match before the +cursor position is used. + +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 can limit the search command "/" to a certain range of lines by including +\%>l items. For example, to match the word "limit" below line 199 and above +line 300: > + /\%>199l\%<300llimit +Also see |/\%>l|. + +Another way 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). + + *E956* +In very rare cases a regular expression is used recursively. This can happen +when executing a pattern takes a long time and when checking for messages on +channels a callback is invoked that also uses a pattern or an autocommand is +triggered. In most cases this should be fine, but if a pattern is in use when +it's used again it fails. Usually this means there is something wrong with +the pattern. + +============================================================================== +2. The definition of a pattern *search-pattern* *pattern* *[pattern]* + *regular-expression* *regexp* *Pattern* + *E76* *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. + Parentheses 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(| + + + */\%#=* *two-engines* *NFA* +Vim includes two regexp engines: +1. An old, backtracking engine that supports everything. +2. A new, NFA engine that works much faster on some patterns, possibly slower + on some patterns. + +Vim will automatically select the right engine for you. However, if you run +into a problem or want to specifically select one engine or the other, you can +prepend one of the following to the pattern: + + \%#=0 Force automatic selection. Only has an effect when + 'regexpengine' has been set to a non-zero value. + \%#=1 Force using the old engine. + \%#=2 Force using the NFA engine. + +You can also use the 'regexpengine' option to change the default. + + *E864* *E868* *E874* *E875* *E876* *E877* *E878* +If selecting the NFA engine and it runs into something that is not implemented +the pattern will not match. This is only useful when debugging Vim. + +============================================================================== +3. Magic */magic* + +Some characters in the pattern, such as letters, are taken literally. They +match exactly the same character in the text. When preceded with a backslash +however, these characters may get a special meaning. For example, "a" matches +the letter "a", while "\a" matches any alphabetic character. + +Other characters have a special meaning without a backslash. They need to be +preceded with a backslash to match literally. For example "." matches any +character while "\." matches a dot. + +If a character is taken literally or not depends on the 'magic' option and the +items in the pattern mentioned next. The 'magic' option should always be set, +but it can be switched off for Vi compatibility. We mention the effect of +'nomagic' here for completeness, but we recommend against using that. + */\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 after it, all ASCII characters except '0'-'9', 'a'-'z', +'A'-'Z' and '_' have special meaning: "very magic" + +Use of "\V" means that after it, only a backslash and the terminating +character (usually / or ?) have special meaning: "very nomagic" + +Examples: +after: \v \m \M \V matches ~ + 'magic' 'nomagic' + a a a a literal 'a' + \a \a \a \a any alphabetic character + . . \. \. any character + \. \. . . literal dot + $ $ $ \$ end-of-line + * * \* \* any number of the previous atom + ~ ~ \~ \~ latest substitute string + () \(\) \(\) \(\) group as an atom + | \| \| \| nothing: separates alternatives + \\ \\ \\ \\ literal backslash + \{ { { { literal curly brace + +{only Vim supports \m, \M, \v and \V} + +If you want to you can make a pattern immune to the 'magic' option being set +or not by putting "\m" or "\M" at the start of the pattern. + +============================================================================== +4. Overview of pattern items *pattern-overview* + *E865* *E866* *E867* *E869* + +Overview of multi items. */multi* *E61* *E62* +More explanation and examples below, follow the links. *E64* *E871* + + 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* +More explanation and examples below, follow the links. + + 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| +|/\%V| \%V \%V inside Visual area |/zero-width| +|/\%#| \%# \%# cursor position |/zero-width| +|/\%'m| \%'m \%'m mark m 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: */character-classes* + magic nomagic matches ~ +|/\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) + + magic nomagic matches ~ +|/\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 \(\) + *E68* +|/\z1| \z1 \z1 only for syntax highlighting, see |:syn-ext-match| + ... +|/\z1| \z9 \z9 only for syntax highlighting, see |:syn-ext-match| + + x x a character with no special meaning matches itself + +|/[]| [] \[] any character specified inside the [] +|/\%[]| \%[] \%[] a sequence of optionally matched atoms + +|/\c| \c \c ignore case, do not use the 'ignorecase' option +|/\C| \C \C match case, do not use the 'ignorecase' option +|/\Z| \Z \Z ignore differences in Unicode "combining characters". + Useful when searching voweled Hebrew or Arabic text. + + magic nomagic matches ~ +|/\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" +|/\%#=| \%#=1 \%#=1 select regexp engine |/zero-width| + +|/\%d| \%d \%d match specified decimal character (eg \%d123) +|/\%x| \%x \%x match specified hex character (eg \%x2a) +|/\%o| \%o \%o match specified octal character (eg \%o040) +|/\%u| \%u \%u match specified multibyte character (eg \%u20ac) +|/\%U| \%U \%U match specified large multibyte character (eg + \%U12345678) +|/\%C| \%C \%C match any composing characters + +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. + + +============================================================================== +5. 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. + + */star* */\star* +* (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. + + */\+* +\+ Matches 1 or more of the preceding atom, as many as possible. + 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. + + */\{* *E60* *E554* *E870* +\{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 + + n and m are positive decimal numbers or zero + *non-greedy* + 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 + parentheses. + + + */\@!* +\@! 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", "appp", etc. not immediately + followed by a "p" + if \(\(then\)\@!.\)*$ "if " not followed by "then" + + 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", "app", 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". + + Useful example: to find "foo" in a line that does not contain "bar": > + /^\%(.*bar\)\@!.*\zsfoo +< This pattern first checks that there is not a single position in the + line where "bar" matches. If ".*bar" matches somewhere the \@! will + reject the pattern. When there is no match any "foo" will be found. + The "\zs" is to have the match start just before "foo". + + */\@<=* +\@<= 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 + At least set a limit for the look-behind, see below. + + "\@<=" 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. + + In the old regexp engine 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: + Bad example matches ~ + \%#=1\1\@<=,\([a-z]\+\) ",abc" in "abc,abc" + + However, the new regexp engine works differently, it is better to not + rely on this behavior, do not use \@<= if it can be avoided: + Example matches ~ + \([a-z]\+\)\zs,\1 ",abc" in "abc,abc" + +\@123<= + Like "\@<=" but only look back 123 bytes. This avoids trying lots + of matches that are known to fail and make executing the pattern very + slow. Example, check if there is a "<" just before "span": + /<\@1<=span + This will try matching "<" only one byte before "span", which is the + only place that works anyway. + After crossing a line boundary, the limit is relative to the end of + the line. Thus the characters at the start of the line with the match + are not counted (this is just to keep it simple). + The number zero is the same as no limit. + + */\@<!* +\@<! 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). Use a limit if you can, see below. + Example matches ~ + \(foo\)\@<!bar any "bar" that's not in "foobar" + \(\/\/.*\)\@<!in "in" which is not after "//" + +\@123<! + Like "\@<!" but only look back 123 bytes. This avoids trying lots of + matches that are known to fail and make executing the pattern very + slow. + + */\@>* +\@> 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. + + +============================================================================== +6. Ordinary atoms *pattern-atoms* + +An ordinary atom can be: + + */^* +^ At beginning of pattern or after "\|", "\(", "\%(" or "\n": matches + start-of-line; at other positions, matches literal '^'. |/zero-width| + Example matches ~ + ^beep( the start of the C function "beep" (probably). + + */\^* +\^ Matches literal '^'. Can be used at any position in the pattern, but + not inside []. + + */\_^* +\_^ Matches start-of-line. |/zero-width| Can be used at any position in + the pattern, but not inside []. + Example matches ~ + \_s*\_^foo white space and blank lines and then "foo" at + start-of-line + + */$* +$ At end of pattern or in front of "\|", "\)" or "\n" ('magic' on): + matches end-of-line <EOL>; at other positions, matches literal '$'. + |/zero-width| + + */\$* +\$ Matches literal '$'. Can be used at any position in the pattern, but + not inside []. + + */\_$* +\_$ Matches end-of-line. |/zero-width| Can be used at any position in the + pattern, but not inside []. Note that "a\_$b" never matches, since + "b" cannot match an end-of-line. Use "a\nb" instead |/\n|. + Example matches ~ + foo\_$\_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, but not inside [], and sets the start of the + match there: The next char is the first char of the whole match. + |/zero-width| + Example: > + /^\s*\zsif +< matches an "if" at the start of a line, ignoring white space. + Can be used multiple times, the last one encountered in a matching + branch is used. Example: > + /\(.\{-}\zsFab\)\{3} +< Finds the third occurrence of "Fab". + This cannot be followed by a multi. *E888* + {not available when compiled without the |+syntax| feature} + */\ze* +\ze Matches at any position, but not inside [], 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". + This cannot be followed by a multi. |E888| + {not available when compiled without the |+syntax| feature} + + */\%^* *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! + + */\%V* +\%V Match inside the Visual area. When Visual mode has already been + stopped match in the area that |gv| would reselect. + This is a |/zero-width| match. To make sure the whole pattern is + inside the Visual area put it at the start and just before the end of + the pattern, e.g.: > + /\%Vfoo.*ba\%Vr +< This also works if only "foo bar" was Visually selected. This: > + /\%Vfoo.*bar\%V +< would match "foo bar" if the Visual selection continues after the "r". + Only works for the current buffer. + + */\%#* *cursor-position* +\%# Matches with the cursor position. Only works when matching in a + buffer displayed in a window. + WARNING: When the cursor is moved after the pattern was used, the + result becomes invalid. Vim doesn't automatically update the matches. + This is especially relevant for syntax highlighting and 'hlsearch'. + In other words: When the cursor moves the display isn't updated for + this change. An update is done for lines which are changed (the whole + line is updated) or when using the |CTRL-L| command (the whole screen + is updated). Example, to highlight the word under the cursor: > + /\k*\%#\k* +< When 'hlsearch' is set and you move the cursor around and make changes + this will clearly show when the match is updated or not. + + */\%'m* */\%<'m* */\%>'m* +\%'m Matches with the position of mark m. +\%<'m Matches before the position of mark m. +\%>'m Matches after the position of mark m. + Example, to highlight the text from mark 's to 'e: > + /.\%>'s.*\%<'e.. +< Note that two dots are required to include mark 'e in the match. That + is because "\%<'e" matches at the character before the 'e mark, and + since it's a |/zero-width| match it doesn't include that character. + WARNING: When the mark is moved after the pattern was used, the result + becomes invalid. Vim doesn't automatically update the matches. + Similar to moving the cursor for "\%#" |/\%#|. + + */\%l* */\%>l* */\%<l* *E951* +\%23l Matches in a specific line. +\%<23l Matches above a specific line (lower line number). +\%>23l Matches below a specific line (higher line number). + 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 multibyte 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. + Example for matching a single byte in column 44: > + /\%>43c.\%<46c +< Note that "\%<46c" matches in column 45 when the "." matches a byte in + column 44. + */\%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 through a tab or other character that occupies more than + one screen character. + WARNING: When inserting or deleting text Vim does not automatically + update highlighted matches. This means Syntax highlighting quickly + becomes wrong. + Example, to highlight all the 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 this is a |/zero-width| match. To + include the column use: > + /^.*\%17v. +< This command does the same thing, but also matches when there is no + character in column 17: > + /^.*\%<18v. +< Note that without the "^" to anchor the match in the first column, + this will also highlight column 17: > + /.*\%17v +< Column 17 is highlighted by 'hlsearch' because there is another match + where ".*" matches zero characters. +< + +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 multibyte 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* */\_i* */\_I* */\_k* */\_K* */\_f* */\_F* + */\_p* */\_P* */\_s* */\_S* */\_d* */\_D* */\_x* */\_X* + */\_o* */\_O* */\_w* */\_W* */\_h* */\_H* */\_a* */\_A* + */\_l* */\_L* */\_u* */\_U* +\_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* *E872* *E873* + +\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 square + 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 + [А-яЁё] Russian alphabet (with utf-8 and cp1251) + + */[\n]* + 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. + *E769* + When the ']' is not there Vim will not give an error message but + assume no collection is used. Useful to search for '['. However, you + do get E769 for internal searching. And be aware that in a + `:substitute` command the whole command becomes the pattern. E.g. + ":s/[/x/" searches for "[/x" and replaces it with nothing. It does + not search for "[" and replaces it with "x"! + + *E944* *E945* + 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. If the starting character exceeds + the ending character, e.g. [c-a], E944 occurs. Non-ASCII characters + can be used, but the character values must not be more than 256 apart + in the old regexp engine. For example, searching by [\u3000-\u4000] + after setting re=1 emits a E945 error. Prepending \%#=2 will fix it. + - A character class expression is evaluated to the set of characters + belonging to that character class. The following character classes + are supported: + Name Func Contents ~ +*[:alnum:]* [:alnum:] isalnum ASCII letters and digits +*[:alpha:]* [:alpha:] isalpha ASCII letters +*[:blank:]* [:blank:] space and tab +*[:cntrl:]* [:cntrl:] iscntrl ASCII control characters +*[:digit:]* [:digit:] decimal digits '0' to '9' +*[:graph:]* [:graph:] isgraph ASCII printable characters excluding + space +*[:lower:]* [:lower:] (1) lowercase letters (all letters when + 'ignorecase' is used) +*[:print:]* [:print:] (2) printable characters including space +*[:punct:]* [:punct:] ispunct ASCII punctuation characters +*[:space:]* [:space:] whitespace characters: space, tab, CR, + NL, vertical tab, form feed +*[:upper:]* [:upper:] (3) uppercase letters (all letters when + 'ignorecase' is used) +*[:xdigit:]* [:xdigit:] hexadecimal digits: 0-9, a-f, A-F +*[:return:]* [:return:] the <CR> character +*[:tab:]* [:tab:] the <Tab> character +*[:escape:]* [:escape:] the <Esc> character +*[:backspace:]* [:backspace:] the <BS> character +*[:ident:]* [:ident:] identifier character (same as "\i") +*[:keyword:]* [:keyword:] keyword character (same as "\k") +*[:fname:]* [:fname:] file name character (same as "\f") + The square brackets in character class expressions are additional to + the square 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, except [:lower:] and + [:upper:] also work for multibyte characters when using the new + regexp engine. See |two-engines|. In the future these items may + work for multibyte characters. For now, to get all "alpha" + characters you can use: [[:lower:][:upper:]]. + + The "Func" column shows what library function is used. The + implementation depends on the system. Otherwise: + (1) Uses islower() for ASCII and Vim builtin rules for other + characters. + (2) Uses Vim builtin rules + (3) As with (1) but using isupper() + */[[=* *[==]* + - An equivalence class. This means that characters are matched that + have almost the same meaning, e.g., when ignoring accents. This + only works for Unicode, latin1 and latin9. The form is: + [=a=] + */[[.* *[..]* + - A collation element. This currently simply accepts a single + character in the form: + [.a.] + */\]* + - 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 "^]-\bdertnoUux". "[\xyz]" matches '\', + 'x', 'y' and 'z'. It's better to use "\\" though, future expansions + may use other characters after '\'. + - Omitting the trailing ] is not considered an error. "[]" works like + "[]]", it matches the ']' character. + - 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> + \n line break, see above |/[\n]| + \d123 decimal number of character + \o40 octal number of character up to 0o377 + \x20 hexadecimal number of character up to 0xff + \u20AC hex. number of multibyte character up to 0xffff + \U1234 hex. number of multibyte character up to 0xffffffff + 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. However, + the new |NFA| regexp engine deals with this better than the old one. + + */\%[]* *E69* *E70* *E369* +\%[] A sequence 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". + There can be no \(\), \%(\) or \z(\) items inside the [] and \%[] does + not nest. + To include a "[" use "[[]" and for "]" use []]", e.g.,: > + /index\%[[[]0[]]] +< matches "index" "index[", "index[0" and "index[0]". + {not available when compiled without the |+syntax| feature} + + */\%d* */\%x* */\%o* */\%u* */\%U* *E678* + +\%d123 Matches the character specified with a decimal number. Must be + followed by a non-digit. +\%o40 Matches the character specified with an octal number up to 0377. + Numbers below 0o40 must be followed by a non-octal digit or a + non-digit. +\%x2a Matches the character specified with up to two hexadecimal characters. +\%u20AC Matches the character specified with up to four hexadecimal + characters. +\%U1234abcd Matches the character specified with up to eight hexadecimal + characters, up to 0x7fffffff + +============================================================================== +7. 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 + +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. + + *CR-used-for-NL* +When 'fileformat' is "mac", <NL> characters in the file are stored as <CR> +characters internally. In the text they are shown as "^J". 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* *pattern-multibyte* +Patterns will also work with multibyte characters, mostly as you would +expect. But invalid bytes may cause trouble, a pattern with an invalid byte +will probably never match. + +============================================================================== +8. Composing characters *patterns-composing* + + */\Z* +When "\Z" appears anywhere in the pattern, all 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". +Exception: If the pattern starts with one or more composing characters, these +must match. + */\%C* +Use "\%C" to skip any composing characters. For example, the pattern "a" does +not match in "càt" (where the a has the composing character 0x0300), but +"a\%C" does. Note that this does not match "cát" (where the á is character +0xe1, it does not have a compositing character). It does match "cat" (where +the a is just an a). + +When a composing character appears at the start of the pattern or after an +item that doesn't include the composing character, a match is found at any +character that includes this composing character. + +When using a dot and a composing character, this works the same as the +composing character by itself, except that it doesn't matter what comes before +this. + +The order of composing characters does not matter. Also, the text may have +more composing characters than the pattern, it still matches. But all +composing characters in the pattern must be found in the text. + +Suppose B is a base character and x and y are composing characters: + pattern text match ~ + Bxy Bxy yes (perfect match) + Bxy Byx yes (order ignored) + Bxy By no (x missing) + Bxy Bx no (y missing) + Bx Bx yes (perfect match) + Bx By no (x missing) + Bx Bxy yes (extra y ignored) + Bx Byx yes (extra y ignored) + +============================================================================== +9. 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 newline characters 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 +- setting the start and end of the match: \zs \ze + +============================================================================== +10. 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 {group} highlighting still applies when a character is + to be highlighted for 'hlsearch', as the highlighting for + matches is given higher priority than that of 'hlsearch'. + Syntax highlighting (see 'syntax') is also overruled by + matches. + + 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. + + 'ignorecase' does not apply, use |/\c| in the pattern to + ignore case. Otherwise case is not ignored. + + 'redrawtime' defines the maximum time searched for pattern + matches. + + When matching end-of-line and Vim redraws only part of the + display you may get unexpected results. That is because Vim + looks for a match in the line where redrawing starts. + + Also see |matcharg()| and |getmatches()|. The former returns + the highlight group and pattern of a previous |:match| + command. The latter returns a list with highlight groups and + patterns defined by both |matchadd()| and |:match|. + + Highlighting matches using |:match| are limited to three + matches (aside from |:match|, |:2match| and |:3match| are + available). |matchadd()| does not have this limitation and in + addition makes it possible to prioritize matches. + + 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. + + +:2mat[ch] {group} /{pattern}/ *:2match* +:2mat[ch] +:2mat[ch] none +:3mat[ch] {group} /{pattern}/ *:3match* +:3mat[ch] +:3mat[ch] none + Just like |:match| above, but set a separate match. Thus + there can be three matches active at the same time. The match + with the lowest number has priority if several match at the + same position. + The ":3match" command is used by the |matchparen| plugin. You + are suggested to use ":match" for manual matching and + ":2match" for another plugin. + + + vim:tw=78:ts=8:noet:ft=help:norl: |