Wikipedia:AutoWikiBrowser/Regular expression#Using look ahead/behind

Used to anchor the search pattern to certain points in the searched text.

Expressions which match any character in a pre-defined set. This list is not exhaustive.

Tokens match a single character from a specified set or range of characters.

Groups match a string of characters (including tokens) in sequence. By default, matches to groups are captured for later reference. Groups may be nested within other groups.

Quantifiers specify how many of the preceding token or group may be matched.

By default, quantifiers are "greedy", meaning they will match as many characters as possible while still allowing the full expression to find a match. Adding a question mark ("?") after a qualifier will make it non-greedy, meaning it will match as few characters as possible while still allowing the full expression to find a match. See #Greed and quantifiers for examples.

Metacharacters are characters with special meaning in regex; to match these characters literally, they must be "escaped" by being preceded with the escape character \.

Used to match a previously captured group again.

Used to check what comes before or after, without consuming or capturing. ("Without consuming" means that matches for look-around assertions do not become part of the string to be replaced. In the following examples, only "abc" is consumed.) In .NET regex, all regex syntax can be used within a look-around assertion.

Comments in the search string do not affect the resulting matches.

Captured groups can be output as part of the replacement string.

Tokens and groups are portions of a regular expression which can be followed by a quantifier to modify the number of consecutive matches. A token is a character, special character, character class, or range (e.g. [m-q]). A group is formed by enclosing tokens or other groups within parentheses. All of these can be modified to match a number of times by a quantifier. For example: a?, \n+, \d{4}, [m-r]*, (a?\n+\d{4}[m-r]*|not){3,7}, and ((?:97[89]-?)?(?:\d[ -]?){9}[\dXx]).

Greed, in regular expression context, describes the number of characters which will be matched (often also stated as "consumed") by a variable length portion of a regular expression{{Snd}} a token or group followed by a quantifier, which specifies a number (or range of numbers) of tokens. If the portion of the regular expression is "greedy", it will match as many characters as possible. If it is not greedy, it will match as few characters as possible.

By default, quantifiers in AWB are greedy. To make a quantifier non-greedy, it must be followed by a question mark. For example:

In this string:

Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.

this expression:

\[\[.*\]\]

will match Lorem ipsum dolor sit amet, consectetur adipisicing.

This expression:

\[\[.*?\]\]

will match {{elc|Lorem ipsum}} and {{elc|consectetur adipisicing}}.

Be careful with expressions like {{code|2=ragel|(\w)(]*>.*?)([,.:;])}}, whose center capture group will span more than one ref group if the outer conditions are met:
sed do eiusmod tempor{{xtag|ref|p|content=reference}} incididunt ut {{xtag|ref|p|content=reference 2}}. labore

|-

! scope="row" |Replace With

| {{code|2=text|new value}}

|-

! scope="row" |Example of text to search

| {{tlx|infobox person|name{{=}}Steveo|occupation{{=}}dancer|nationality{{=}}The moon}}

|-

! scope="row" |Result

| {{tlx|infobox person|name{{=}}Steveo|occupation{{=}}new value|nationality{{=}}The moon}}

|-

! scope="row" |Comments

|

|}

Match inside

Regex: ]*>([^<]|<[^/]|])+

Match inside using a (?! not match) notation

Regex: ]*>([^<]|<(?!/ref>))+

Match template {{...}} possibly with templates inside it, but no templates inside those

Regex: {{([^{]|{[^{]|{{[^{}]+}})+}}

Match words and spaces

Regex: [\w\s]+

Match bracketed URLs

Regex: \[(https?://[^\]\[<>\s"]+) *((?<= )[^\n\]]*|)\]

Regex offers several options to change the default behavior.{{Cite web |last=adegeo |date=29 June 2022 |title=Options for regular expression |url=https://learn.microsoft.com/en-us/dotnet/standard/base-types/regular-expression-options |url-status=live |archive-url=https://archive.ph/Rz3CM |archive-date=2023-02-05 |access-date=2023-02-05 |website=learn.microsoft.com |language=en-us}} Five of these options can be controlled with inline expressions, as described below. Four of these options can also be applied to the entire search pattern with check boxes in the AWB "Find-and-replace" tools. By default, all options are off.

{{notelist}}

The options statement {{code|(?flags-flags)}} turns the options given by "flags" on (or off, for any flags preceded by a minus sign) from the point where the statement appears to the end of the pattern, or to the point where a given option is cancelled by another options statement. For example:

(?im-s) #Turn ON IgnoreCase (i) and MultiLine (m) options, and turn OFF SingleLine (s) option, from here to the end of the pattern or until cancelled

Alternatively, the syntax {{code|(?flags-flags:pattern)}} applies the specified options only to the part of the pattern appearing inside the parentheses:

(?x:pattern1)pattern2 #Apply the IgnorePatternWhitespace (x) option to pattern1, but not to pattern2

You can make your own shortcut editing macros. When you edit a page, you can enter your short-cut macro keys into the page anywhere you want AWB to act upon them.

For example, you are examining a page in the AWB edit box. You see numerous items like adding {{tlx|fact}}, inserting line breaks {{tag|br|void}}, commenting out entire lines {{tag|!--|content=comment}}, inserting state names, {{xtag|ref|p|content=Insert footnote text here}}, insert Level 2,3,or even 4 headlines, etc... This can all be done by creating your short-cut macro keys.

• The process

:# Create a rule. See Find and replace, Advanced settings.

:# Edit your page in the edit box. Insert your short-cut editing macro key(s) anywhere in the page you want AWB to make the change(s) for you.

:# Re-parse the page. Right click on the edit box and select Re-parse from the context pop up menu. AWB will then re-examine your page with your macro short-cut key(s), find your short-cut key(s) and perform the action you specified in the rule.

Naming a short-cut macro key can be any name. But it is best to try and make it unique so that it will not interfere with any other process that AWB may find and suggest. For that reason using {{highlight|///}} followed by a set of lowercase characters that you can easily remember is best (lowercase is used so that you do not have to use the shift key). You can then enter these short-cut macros keys you create into the page manually or by using the edit box context menu paste more function. The reason why we use three '/' is so that AWB will not confuse web addresses/url's in a page when re-parsing.

Examples:

Create a rule as a regular expression.

{{expand section}}

Efficiency is how long the regex engine takes to find matches, which is a function of how many characters the engine has to read, including backtracking. Complex regular expressions can often be constructed in several different ways, all with the same outputs but with greatly varying efficiency. If AWB is taking a long time to generate results because of a regex rule:

• Try constructing the expression a different way. There are several online resources with guidance to creating efficient regex patterns.
• Using the "advanced settings" find-and-replace tool, enter expressions on the "If" tab to filter the pages that an expensive find-and-replace rule is applied to.

{{reflist}}

• [http://regexstorm.net/tester RegEx Storm] (supporting .NET regex flavour);
• [https://regex101.com/ RegEx101] (supporting .NET regex flavour)
• [http://regexpal.com/ RexEx Pal]
• [http://gskinner.com/RegExr/ RegExr]
• [http://rubular.com/ Rubular]

• [http://regexhero.net/tester/ RegEx Hero]

• [http://www.wellho.net/regex/dotnet.html Regular Expressions in .NET] Well House Consultants.
• [http://www.regular-expressions.info/ Regular-Expressions.info]
• [https://perldoc.perl.org/perlre#Regular-Expressions Regular Expressions] perldoc.perl.org.
• [https://docs.python.org/release/2.5.2/lib/re-syntax.html Regular Expression Syntax] docs.python.org.
• [http://msdn.microsoft.com/en-us/library/az24scfc.aspx Regular Expression Language – Quick Reference] MSDN.
• [http://msdn.microsoft.com/en-us/library/hs600312.aspx .NET regular expressions] MSDN.
• [http://www.zytrax.com/tech/web/regex.htm Regular Expressions – User Guide] zytrax.com.

Manual Regular expressions