Extension:AbuseFilter/Rules format/yo

The rules are a custom language. They are formatted similar to conditionals in a C/Java/Perl-like language.

Strings

You can specify a literal by placing it in single or double quotes (for strings), or by typing it in as-is (for numbers, both floating-point and integer). You can get linebreaks with \n, tab characters with \t, and you can also escape the quote character with a backslash.

Use the + (plus) symbol to concatenate two literal strings or the values of two vars with a string value.

Examples

"This is a string"
'This is also a string'
'This string shouldn\'t fail'
"This string\nHas a linebreak"
1234
1.234
-123

User-defined variables

You can define custom variables for ease of understanding with the assign symbol := in a line (closed by ;) within a condition. Such variables may use letters, underscores, and numbers (apart from the first character) and are case-insensitive. Example (from w:Special:AbuseFilter/79):

(
	line1:="(\{\{(r|R)eflist|\{\{(r|R)efs|<references\s?/>|</references\s?>)";
	rcount(line1, removed_lines)
) > (
	rcount(line1, added_lines)
)

Arrays

AbuseFilter has support for non-associative arrays, which can be used like in the following examples.

Caution:

Expressions like page_namespace in [14, 15] may not work as expected. This one will evaluate to true also if page_namespace is 1, 4, or 5. For more information and possible workarounds, please see T181024.

my_array := [ 5, 6, 7, 10 ];
my_array[0] == 5
length(my_array) == 4
int( my_array ) === 4 // Same as length
float( my_array ) === 4.0 // Counts the elements
string(my_array) == "5\n6\n7\n10\n" // Note: the last linebreak could be removed in the future
5 in my_array == true
'5' in my_array == true
'5\n6' in my_array == true // Note: this is due to how arrays are casted to string, i.e. by imploding them with linebreaks
1 in my_array == true // Note: this happens because 'in' casts arguments to strings, so the 1 is caught in '10' and returns true.
my_array[] := 57; // This appends an element at the end of the array
my_array === [ 5, 6, 7, 10, 57 ]
my_array[2] := 42; // And this is for changing an element in the array
my_array === [ 5, 6, 42, 10, 57 ]

Comments

You can specify comments using the following syntax:

/* This is a comment */

Arithmetic

You can use basic arithmetic symbols to do arithmetic on variables and literals with the following syntax:

• - – Subtract the right-hand operand from the left-hand operand.
• + – Add the right-hand operand to the left-hand operand.
• * – Multiply the left-hand operand by the right-hand operand.
• / – Divide the left-hand operand by the right-hand operand.
• ** – Raise the left-hand operand to the exponential power specified by the right-hand operand.
• % – Return the remainder given when the left-hand operand is divided by the right-hand operand.

The type of the returned result is the same that would be returned by PHP, for which a lot of documentation may be found online. More exhaustive examples may be found in this AF parser test.

Example	Result
1 + 1	2
2 * 2	4
1 / 2	0.5
9 ** 2	81
6 % 5	1

Boolean operations

You can match if and only if all of a number of conditions are true, one of a number of conditions are true, or one and only one of all conditions are true.

• x | y — OR – returns true if one or more of the conditions is true.

• x & y — AND – returns true if both of the conditions are true.

• x ^ y — XOR – returns true if one, and only one of the two conditions is true.

• !x — NOT – returns true if the condition is not true.

Examples

Code	Result
1 | 1	true
1 | 0	true
0 | 0	false
1 & 1	true
1 & 0	false
0 & 0	false
1 ^ 1	false
1 ^ 0	true
0 ^ 0	false
!1	false
!0	true

Simple comparisons

You can compare variables with other variables and literals with the following syntax:

• <, > – Return true if the left-hand operand is less than/greater than the right-hand operand respectively. Watch out: operands are casted to strings and, like it happens in PHP, null < any number === true and null > any number === false.
• <=, >= – Return true if the left-hand operand is less than or equal to/greater than or equal to the right-hand operand respectively. Watch out: operands are casted to strings and, like it happens in PHP, null <= any number === true and null >= any number === false.

• == (or =), != – Return true if the left-hand operand is equal to/not equal to the right-hand operand respectively.

• ===, !== – Return true if the left-hand operand is equal to/not equal to the right-hand operand AND the left-hand operand is the same/not the same data type to the right-hand operand respectively.

Example	Result
1 == 2	false
1 <= 2	true
1 >= 2	false
1 != 2	true
1 < 2	true
1 > 2	false
2 = 2	true
'' == false	true
'' === false	false
1 == true	true
1 === true	false
['1','2','3'] == ['1','2','3']	true
[1,2,3] === [1,2,3]	true
['1','2','3'] == [1,2,3]	true
['1','2','3'] === [1,2,3]	false
[1,1,''] == [true, true, false]	true
[] == false & [] == null	true
['1'] == '1'	false

Built-in variables

The abuse filter passes various variables by name into the parser. These variables can be accessed by typing their name in, in a place where a literal would work. You can view the variables associated with each request in the abuse log.

Variables from AbuseFilter

Variables always available

Caution:

User-related variables are always available, except for one case: account creation when the creator is not logged in. All variables starting with user_ are affected, except user_type.

Description	Name	Data type	Notes
Action	action	string	One of the following: edit, move, createaccount, autocreateaccount, delete, upload, stashupload
Unix timestamp of change	timestamp	string	int(timestamp) gives you a number with which you can calculate the date, time, day of week, etc.
Database name of the wiki ($1)	wiki_name	string	For instance, this is "enwiki" on the English Wikipedia, and "itwikiquote" on the Italian Wikiquote.
Language code of the wiki ($1)	wiki_language	string	For instance, this is "en" on the English Wikipedia, and "it" on the Italian Wikiquote. Multi-lingual wikis like Commons, Meta, and Wikidata will also report as "en".
Edit count of the user ($1)	user_editcount	integer/null	Null only for unregistered users.
Name of the user account ($1) (IP in case the user is not registered)	user_name	string	For "createaccount" and "autocreateaccount" actions, use accountname if you want the name of the account being created. Caution: On wikis where temporary accounts are enabled, IPs are not returned for unregistered users. Use user_unnamed_ip instead if the IP is needed. More context is available here .
Type of the user account ($1)	user_type	string	The type of the user, which will be one of ip, temp (if the user is using a temporary account ), named, external, or unknown.
Time email address was confirmed ($1)	user_emailconfirm	string/null	In the format: YYYYMMDDHHMMSS. Null if the email wasn't confirmed.
Age of the user account ($1)	user_age	integer	In seconds. 0 for unregistered users.
Whether the user is blocked ($1)	user_blocked	boolean	True for blocked registered users. Also true for edits from blocked IP addresses, even if the editor is a registered user who is not blocked. False otherwise. This doesn't differentiate between partial and sitewide blocks.
Groups (including implicit) the user is in ($1)	user_groups	array of strings	see Special:ListGroupRights
Rights that the user has ($1)	user_rights	array of strings	see Special:ListGroupRights
Nọ́mbà Ìdámọ̀ Ojúewé	article_articleid	integer	(deprecated) Use page_id instead.
Nọ́mbà Ìdámọ̀ Ojúewé (can be seen via "page information" link in sidebar)	page_id	integer	This is 0 for new pages, but it is unreliable when inspecting past hits. If you need an exact result when inspecting past hits, use "page_age == 0" to identify new page creation. (note that it is slower, though.) This issue has been fixed in 9369d08, merged on September 11th 2023.
Page namespace ($1)	article_namespace	integer	(deprecated) Use page_namespace instead.
Page namespace ($1)	page_namespace	integer	refers to namespace index . Check for namespace(s) using expressions like "page_namespace == 2" or "equals_to_any(page_namespace, 1, 3)"
Page age in seconds ($1)	page_age	integer	the number of seconds since the first edit (or 0 for new pages). This is reliable, but it tends to be slow; consider using page_id if you don't need much precision.
Page title without namespace ($1)	article_text	string	(deprecated) Use page_title instead.
Page title without namespace ($1)	page_title	string
Full page title ($1)	article_prefixedtext	string	(deprecated) Use page_prefixedtitle instead.
Full page title ($1)	page_prefixedtitle	string
Edit protection level of the page ($1)	article_restrictions_edit	string	(deprecated) Use page_restrictions_edit instead.
Edit protection level of the page ($1)	page_restrictions_edit	array of strings
Move protection level of the page ($1)	article_restrictions_move	string	(deprecated) Use page_restrictions_move instead.
Move protection level of the page ($1)	page_restrictions_move	array of strings
Upload protection of the file ($1)	article_restrictions_upload	string	(deprecated) Use page_restrictions_upload instead.
Upload protection of the file ($1)	page_restrictions_upload	array of strings
Create protection of the page ($1)	article_restrictions_create	string	(deprecated) Use page_restrictions_create instead.
Create protection of the page ($1)	page_restrictions_create	array of strings
Last ten users to contribute to the page ($1)	article_recent_contributors	array of strings	(deprecated) Use page_recent_contributors instead.
Last ten users to contribute to the page ($1)	page_recent_contributors	array of strings	This tends to be slow (see #Performance). Try to put conditions more likely evaluate to false before this one, to avoid unnecessarily running the query. This value is empty if the user is the only contributor to the page(?), and only scans the last 100 revisions
First user to contribute to the page ($1)	article_first_contributor	string	(deprecated) Use page_first_contributor instead.
First user to contribute to the page ($1)	page_first_contributor	string	This tends to be slow (see #Performance). Try to put conditions more likely evaluate to false before this one, to avoid unnecessarily running the query.

Variables available for some actions

Caution:

Always check that the variables you want to use are available for the current action being filtered, e.g. by using the action variable. Failing to do so (for instance using accountname for an edit, or edit_delta for a deletion) will make any code using the variable in question return false.

Edit variables are not available when examining past uploads. (T345896)

Description	Name	Data type	Notes
Edit summary/reason ($1)	summary	string	Summaries automatically created by MediaWiki ("New section", "Blanked the page", etc.) are created after the filter checks the edit, so they will never actually catch, even if the debugger shows that they should. The variable contains whatever the user sees in the edit summary window, which may include MediaWiki preloaded section titles.
Whether or not the edit is marked as minor (no longer in use)	minor_edit	string	Disabled, and set to false for all entries between 2016 and 2018.
Old page wikitext, before the edit ($1)	old_wikitext	string	This variable can be very large. Consider using removed_lines if possible to improve performance.
New page wikitext, after the edit ($1)	new_wikitext	string	This variable can be very large. Consider using added_lines if possible to improve performance.
Unified diff of changes made by edit ($1)	edit_diff	string
Unified diff of changes made by edit, pre-save transformed ($1)	edit_diff_pst	string	This tends to be slow (see #Performance). Checking both added_lines and removed_lines is probably more efficient.
Ìtóbi ojúewé tuntun	new_size	integer
Old page size ($1)	old_size	integer
Size change in edit ($1)	edit_delta	integer
Lines added in edit, pre-save transformed ($1)	added_lines_pst	array of strings	Use added_lines if possible, which is more efficient.
Lines added in edit ($1)	added_lines	array of strings	includes all lines in the final diff that begin with +
Àwọn ìlà tó jẹ́ yíyọkúrò nínú àtúnṣe	removed_lines	array of strings
All external links in the new text ($1)	all_links	array of strings	This tends to be slow (see #Performance).
Links in the page, before the edit ($1)	old_links	array of strings	This tends to be slow (see #Performance).
All external links added in the edit ($1)	added_links	array of strings	This tends to be slow (see #Performance). Consider checking against added_lines first, then check added_links so that fewer edits are slowed down. This follows MediaWiki's rules for external links . Only unique links are added to the array. Changing a link will count as 1 added and 1 removed link.
All external links removed in the edit ($1)	removed_links	array of strings	This tends to be slow (see #Performance). Consider checking against removed_lines first, then check removed_links so that fewer edits are slowed down. This follows MediaWiki's rules for external links . Only unique links are added to the array. Changing a link will count as 1 added and 1 removed link.
New page wikitext, pre-save transformed ($1)	new_pst	string	This variable can be very large.
Parsed HTML source of the new revision ($1)	new_html	string	This variable can be very large. Consider using added_lines if possible to improve performance.
New page text, stripped of any markup ($1)	new_text	string	This variable can be very large. Consider using added_lines if possible to improve performance.
Old page wikitext, parsed into HTML (no longer in use)	old_html	string	Disabled for performance reasons.
Old page text, stripped of any markup (no longer in use)	old_text	string	Disabled for performance reasons.
Time since last page edit in seconds ($1)	page_last_edit_age	integer or null	null when the page does not exist
SHA1 hash of file contents ($1)	file_sha1	string
Size of the file in bytes ($1)	file_size	integer	The file size in bytes
Width of the file in pixels ($1)	file_width	integer	The width in pixels
Height of the file in pixels ($1)	file_height	integer	The height in pixels
Bits per color channel of the file ($1)	file_bits_per_channel	integer	The amount of bits per color channel
MIME type of the file ($1)	file_mime	string	The file MIME type.
Media type of the file ($1)	file_mediatype	string	The file media type.
Page ID of move destination page ($1)	moved_to_articleid	integer	(deprecated) Use moved_to_id instead.
Page ID of move destination page ($1)	moved_to_id	integer
Title of move destination page ($1)	moved_to_text	string	(deprecated) Use moved_to_title instead.
Title of move destination page ($1)	moved_to_title	string
Full title of move destination page ($1)	moved_to_prefixedtext	string	(deprecated) Use moved_to_prefixedtitle instead.
Full title of move destination page ($1)	moved_to_prefixedtitle	string
Namespace of move destination page ($1)	moved_to_namespace	integer
Move destination page age in seconds ($1)	moved_to_age	integer
Time since last move destination page edit in seconds ($1)	moved_to_last_edit_age	integer or null	null when the target page does not exist
Edit protection level of move destination page ($1)	moved_to_restrictions_edit	array of string	Same as page_restrictions_edit, but for the target of the move.
Move protection level of move destination page ($1)	moved_to_restrictions_move	array of string	Same as page_restrictions_move, but for the target of the move.
Upload protection of move destination file ($1)	moved_to_restrictions_upload	array of string	Same as page_restrictions_upload, but for the target of the move.
Create protection of move destination page ($1)	moved_to_restrictions_create	array of string	Same as page_restrictions_create, but for the target of the move.
Last ten users to contribute to move destination page ($1)	moved_to_recent_contributors	array of strings	Same as page_recent_contributors, but for the target of the move.
First user to contribute to move destination page ($1)	moved_to_first_contributor	string	Same as page_first_contributor, but for the target of the move.
Namespace of move source page ($1)	moved_from_namespace	integer
Title of move source page ($1)	moved_from_text	string	(deprecated) Use moved_from_title instead.
Title of move source page ($1)	moved_from_title	string
Full title of move source page ($1)	moved_from_prefixedtext	string	(deprecated) Use moved_from_prefixedtitle instead.
Full title of move source page ($1)	moved_from_prefixedtitle	string
Page ID of move source page ($1)	moved_from_articleid	integer	(deprecated) Use moved_from_id instead.
Page ID of move source page ($1)	moved_from_id	integer
Move source page age in seconds ($1)	moved_from_age	integer
Time since last move source page edit in seconds ($1)	moved_from_last_edit_age	integer
Edit protection level of move source page ($1)	moved_from_restrictions_edit	array of string	Same as page_restrictions_edit, but for the page being moved.
Move protection level of move source page ($1)	moved_from_restrictions_move	array of string	Same as page_restrictions_move, but for the page being moved.
Upload protection of move source file ($1)	moved_from_restrictions_upload	array of string	Same as page_restrictions_upload, but for the page being moved.
Create protection of move source page ($1)	moved_from_restrictions_create	array of string	Same as page_restrictions_create, but for the page being moved.
Last ten users to contribute to move source page ($1)	moved_from_recent_contributors	array of strings	Same as page_recent_contributors, but for the page being moved.
First user to contribute to move source page ($1)	moved_from_first_contributor	string	Same as page_first_contributor, but for the page being moved.
Orúkọ ìforúkọpamọ́ (nígbà ìdá ìforúkọpamọ́)	accountname	string
Content model of the old revision	old_content_model	string	See Help:ChangeContentModel for information about content model changes
Content model of the new revision	new_content_model	string	See Help:ChangeContentModel for information about content model changes

Protected variables

A variable can be considered protected. For instance, on wikis with temporary accounts enabled, IPs are considered PII and access to them must be restricted. Protected variables and filters that use them are only accessible to maintainers with the abusefilter-access-protected-vars right. Using a protected variable flags the filter as protected as well. The filter subsequently cannot be unprotected, even if it no longer actively uses a protected variable, as its historical logs will remain available.

Logs generated by protected filters can only be viewed by users with the abusefilter-protected-vars-log right.

The default protected variables are defined in AbuseFilterProtectedVariables in extension.json.

user_unnamed_ip is null when examining past edits.

Description	Name	Data type	Notes
IP of the user account (for logged-out users and temporary accounts only) ($1)	user_unnamed_ip	string	User IP for anonymous users/temporary accounts This returns null for registered users.

Variables from other extensions

Most of these variables are always set to false when examinating past edits, and may not reflect their actual value at the time the edit was made. See T102944.

Description	Name	Data type	Values	Added by
Global groups that the user is in ($1)	global_user_groups	array		CentralAuth
Global edit count of the user ($1)	global_user_editcount	integer		CentralAuth
Global groups that the user is in on account creation ($1)	global_account_groups	array	Available only when action is createaccount (then it is always empty) or autocreateaccount.	CentralAuth
Global edit count of the user on account creation ($1)	global_account_editcount	integer	Available only when action is createaccount (then it is always zero) or autocreateaccount.	CentralAuth
OAuth consumer used to perform this change ($1)	oauth_consumer	integer		OAuth
Page ID of Structured Discussions board ($1)	board_articleid	integer	(deprecated) Use board_id instead.	StructuredDiscussions
Page ID of Structured Discussions board ($1)	board_id	integer		StructuredDiscussions
Namespace of Structured Discussions board ($1)	board_namespace	integer	refers to namespace index	StructuredDiscussions
Title (without namespace) of Structured Discussions board ($1)	board_text	string	(deprecated) Use board_title instead.	StructuredDiscussions
Title (without namespace) of Structured Discussions board ($1)	board_title	string		StructuredDiscussions
Full title of Structured Discussions board ($1)	board_prefixedtext	string	(deprecated) Use board_prefixedtitle instead.	StructuredDiscussions
Full title of Structured Discussions board ($1)	board_prefixedtitle	string		StructuredDiscussions
Source text of translation unit	translate_source_text	string		Translate
Target language for translation	translate_target_language	string	This is the language code, like en for English.	Translate
Whether or not the change was made through a Tor exit node ($1)	tor_exit_node	boolean	true if the action comes from a tor exit node.	TorBlock
Whether or not a user is editing through the mobile interface ($1)	user_mobile	boolean	true for mobile users, false otherwise.	MobileFrontend
Whether the user is editing from mobile app ($1)	user_app	boolean	true if the user is editing from the mobile app, false otherwise.	MobileApp
Page views[1]	article_views	integer	(deprecated) Use page_views instead.	HitCounters
Page views[2]	page_views	integer	the amount of page views	HitCounters
Source page views[3]	moved_from_views	integer	the amount of page views of the source page	HitCounters
Target page views[4]	moved_to_views	integer	the amount of page views of the target page	HitCounters
Whether the IP address is blocked using the stopforumspam.com list[5]	sfs_blocked	boolean	Whether the IP address is blocked using the stopforumspam.com list	StopForumSpam

Notes

When action='move', only the summary, action, timestamp and user_* variables are available. The page_* variables are also available, but the prefix is replaced by moved_from_ and moved_to_, that represent the values of the original article name and the destination one, respectively. For example, moved_from_title and moved_to_title instead of page_title.

Since MediaWiki 1.28 (gerrit:295254), action='upload' is only used when publishing an upload, and not for uploads to stash. A new action='stashupload' is introduced, which is used for all uploads, including uploads to stash. This behaves like action='upload' used to, and only provides file metadata variables (file_*). Variables related to the page edit, including summary, new_wikitext and several others, are now available for action='upload'. For every file upload, filters may be called with action='stashupload' (for uploads to stash), and are always called with action='upload'; they are not called with action='edit'.

Filter authors should use action='stashupload' | action='upload' in filter code when a file can be checked based only on the file contents – for example, to reject low-resolution files – and action='upload' only when the wikitext parts of the edit need to be examined too – for example, to reject files with no description. This allows tools that separate uploading the file and publishing the file (e.g. UploadWizard or upload dialog ) to inform the user of the failure before they spend the time filling in the upload details.

Performance

As noted in the table above, some of these variables can be very slow. While writing filters, remember that the condition limit is not a good metric of how heavy filters are. For instance, variables like *_recent_contributors or *_links always need a DB query to be computed, while *_pst variables will have to perform parsing of the text, which again is a heavy operation; all these variables should be used very, very carefully. For instance, on Italian Wikipedia it's been observed that, with 135 active filters and an average of 450 used conditions, filters execution time was around 500ms, with peaks reaching 15 seconds. Removing the added_links variable from a single filter, and halving the cases when another filter would use added_lines_pst brought the average execution time to 50ms. More specifically:

• Use _links variables when you need high accuracy and checking for "http://..." in other variables (for instance, added_lines) could lead to heavy malfunctioning;

• Use _pst variables when you're really sure that non-PST variables aren't enough.

You may also conditionally decide which one to check: if, for instance, you want to examine a signature, check first if added_lines contains ~~~;

• In general, when dealing with these variables, it's always much better to consume further conditions but avoid computing heavy stuff.

In order to achieve this, always put heavy variables as last conditions.

Last but not least, note that whenever a variable is computed for a given filter, it'll be saved and any other filter will immediately retrieve it. This means that one single filter computing this variable counts more or less as dozens of filters using it.

Keywords

Where not specifically stated, keywords cast their operands to strings

The following special keywords are included for often-used functionality:

• like (or matches) returns true if the left-hand operand matches the glob pattern in the right-hand operand.
• in returns true if the right-hand operand (a string) contains the left-hand operand. Note: empty strings are not contained in, nor contain, any other string (not even the empty string itself).
• contains works like in, but with the left and right-hand operands switched. Note: empty strings are not contained in, nor contain, any other string (not even the empty string itself).
• rlike (or regex) and irlike return true if the left-hand operand matches (contains) the regex pattern in the right-hand operand (irlike is case insensitive).
  • The system uses PCRE.
  • The only PCRE option enabled is PCRE_UTF8 (modifier u in PHP); for irlike both PCRE_CASELESS and PCRE_UTF8 are enabled (modifier iu).
• if ... then ... end
• if ... then ... else ... end
• ... ? ... : ...
• true, false, null

Examples

Code	Result	Comment
"1234" like "12?4"	True
"1234" like "12*"	True
"foo" in "foobar"	True
"foobar" contains "foo"	True
"o" in ["foo", "bar"]	True	Due to the string cast
"foo" regex "\w+"	True
"a\b" regex "a\\\\b"	True	To look for the escape character backslash using regex you need to use either four backslashes or two \x5C. (Either works fine.)
"a\b" regex "a\x5C\x5Cb"	True

Functions

A number of built-in functions are included to ease some common issues. They are executed in the general format functionName( arg1, arg2, arg3 ), and can be used in place of any literal or variable. Its arguments can be given as literals, variables, or even other functions.

name	description
lcase	Returns the argument converted to lower case.
ucase	Returns the argument converted to upper case.
length	Returns the length of the string given as the argument. If the argument is an array, returns its number of elements.
string	Casts to string data type. If the argument is an array, implodes it with linebreaks.
int	Casts to integer data type.
float	Casts to floating-point data type.
bool	Casts to boolean data type.
norm	Equivalent to rmwhitespace(rmspecials(rmdoubles(ccnorm(arg1)))).
ccnorm	Normalises confusable/similar characters in the argument, and returns a canonical form. A list of characters and their replacements can be found on git, e.g. ccnorm( "Eeèéëēĕėęě3ƐƷ" ) === "EEEEEEEEEEEEE". The output of this function is always uppercase. While not expensive, this function isn't cheap either, and could slow a filter down if called many times.
ccnorm_contains_any	Normalises confusable/similar characters in all its arguments, and returns true if the first string contains any string from the following arguments (unlimited number of arguments, logic OR mode). A list of characters and their replacements can be found on git. Due to the usage of ccnorm, this function can be slow if passed too many arguments.
ccnorm_contains_all	Normalises confusable/similar characters in all its arguments, and returns true if the first string contains every string from the following arguments (unlimited number of arguments, logic AND mode). A list of characters and their replacements can be found on git. Due to the usage of ccnorm, this function can be slow if passed too many arguments.
specialratio	Returns the number of non-alphanumeric characters divided by the total number of characters in the argument.
rmspecials	Removes any special characters in the argument, and returns the result. Does not remove whitespace. (Equivalent to s/[^\p{L}\p{N}\s]//g.)
rmdoubles	Removes repeated characters in the argument, and returns the result.
rmwhitespace	Removes whitespace (spaces, tabs, newlines).
count	Returns the number of times the needle (first string) appears in the haystack (second string). If only one argument is given, splits it by commas and returns the number of segments.
rcount	Similar to count but the needle uses a regular expression instead. Can be made case-insensitive by letting the regular expression start with "(?i)". Please note that, for plain strings, this function can be up to 50 times slower than count, so use that one when possible.
get_matches	MW 1.31+ Looks for matches of the regex needle (first string) in the haystack (second string). Returns an array where the 0 element is the whole match and every [n] element is the match of the n'th capturing group of the needle. Can be made case-insensitive by letting the regular expression start with "(?i)". If a capturing group didn't match, that array position will take value of false.
ip_in_range	Returns true if user's IP (first string) matches the specified IP range (second string, can be in CIDR notation, explicit notation like "1.1.1.1-2.2.2.2", or a single IP). Only works for anonymous users. Supports both IPv4 and IPv6 addresses.
ip_in_ranges	Da true pada ti IP olumulo (okun akọkọ) ba baamu 'eyikeyi ti awọn sakani IP ti a sọ pato (awọn gbolohun ọrọ ti o tẹle ni ọgbọn OR mode, le wa ni CIDR notation, ami akiyesi ti o fojuhan bi "1.1 .1.1-2.2.2.2", tabi IP kan ṣoṣo). Nikan ṣiṣẹ fun awọn olumulo ailorukọ. Atilẹyin mejeeji IPv4 ati IPv6 adirẹsi.
contains_any	Returns true if the first string contains any string from the following arguments (unlimited number of arguments in logic OR mode). If the first argument is an array, it gets casted to string.
contains_all	Returns true if the first string contains every string from the following arguments (unlimited number of arguments in logic AND mode). If the first argument is an array, it gets casted to string.
equals_to_any	Returns true if the first argument is identical (===) to any of the following ones (unlimited number of arguments). Basically, equals_to_any(a, b, c) is the same as a===b | a===c, but more compact and saves conditions.
substr	Returns the portion of the first string, by offset from the second argument (starts at 0) and maximum length from the third argument (optional).
strlen	Same as length.
strpos	Returns the numeric position of the first occurrence of needle (second string) in the haystack (first string), starting from offset from the third argument (optional, default is 0). This function may return 0 when the needle is found at the beginning of the haystack, so it might be misinterpreted as false value by another comparative operator. The better way is to use === or !== for testing whether it is found. Differently from PHP's strpos(), which returns false when the needle is not found, this function returns -1 when the needle is not found.
str_replace	Replaces all occurrences of the search string with the replacement string. The function takes 3 arguments in the following order: text to perform the search on, text to find, replacement text.
str_replace_regexp	Replaces all occurrences of the search string with the replacement string using regular expressions. The function takes 3 arguments in the following order: text to perform the search on, regular expression to match, replacement expression.
rescape	Returns the argument with some characters preceded with the escape character "\", so that the string can be used in a regular expression without those characters having a special meaning.
set	Sets a variable (first string) with a given value (second argument) for further use in the filter. Another syntax: name := value.
set_var	Same as set.

Examples

Code	Result	Comment
length( "Wikipedia" )	9
lcase( "WikiPedia" )	wikipedia
ccnorm( "w1k1p3d14" )	WIKIPEDIA	ccnorm output is always uppercase
ccnorm( "ωɨƙɩᑭƐƉ1α" )	WIKIPEDIA
ccnorm_contains_any( "w1k1p3d14", "wiKiP3D1A", "foo", "bar" )	true
ccnorm_contains_any( "w1k1p3d14", "foo", "bar", "baz" )	false
ccnorm_contains_any( "w1k1p3d14 is 4w3s0me", "bar", "baz", "some" )	true
ccnorm( "ìíîïĩїį!ľ₤ĺľḷĿ" )	IIIIIII!LLLLLL
norm( "!!ω..ɨ..ƙ..ɩ..ᑭᑭ..Ɛ.Ɖ@@1%%α!!" )	WIKIPEDAIA
norm( "F00 B@rr" )	FOBAR	norm removes whitespace, special characters and duplicates, then uses ccnorm
rmdoubles( "foobybboo" )	fobybo
specialratio( "Wikipedia!" )	0.1
count( "foo", "foofooboofoo" )	3
count( "foo,bar,baz" )	3
rmspecials( "FOOBAR!!1" )	FOOBAR1
rescape( "abc* (def)" )	abc\* \(def\)
str_replace( "foobarbaz", "bar", "-" )	foo-baz
str_replace_regexp( "foobarbaz", "(.)a(.)", "$2a$1" )	foorabzab
ip_in_range( "127.0.10.0", "127.0.0.0/12" )	true
ip_in_ranges( "127.0.10.0", "10.0.0.0/8", "127.0.0.0/12" )	true
contains_any( "foobar", "x", "y", "f" )	true
get_matches( "(foo?ba+r) is (so+ good)", "fobaaar is soooo good to eat" )	['fobaaar is soooo good', 'fobaaar', 'soooo good']

Order of operations

Operations are generally done left-to-right, but there is an order to which they are resolved. As soon as the filter fails one of the conditions, it will stop checking the rest of them (due to short-circuit evaluation) and move on to the next filter. The evaluation order is:

1. Anything surrounded by parentheses (( and )) is evaluated as a single unit.
2. Turning variables/literals into their respective data. (e.g., page_namespace to 0)
3. Function calls (norm, lcase, etc.)
4. Unary + and - (defining positive or negative value, e.g. -1234, +1234)
5. Keywords (in, rlike, etc.)
6. Boolean inversion (!x)
7. Exponentiation (2**3 → 8)
8. Multiplication-related (multiplication, division, modulo)
9. Addition and subtraction (3-2 → 1)
10. Comparisons (<, >, ==)
11. Boolean operations (&, |, ^)
12. Ternary operator (... ? ... : ...)
13. Assignments (:=)

Examples

• A & B | C is equivalent to (A & B) | C, not to A & (B | C). In particular, both false & true | true and false & false | true evaluates to true.
• A | B & C is equivalent to (A | B) & C, not to A | (B & C). In particular, both true | true & false and true | false & false evaluates to false.
• added_lines rlike "foo" + "|bar" is wrong, use added_lines rlike ("foo" + "|bar") instead.

Condition counting

The condition limit is (more or less) tracking the number of comparison operators + number of function calls entered.

Further explanation on how to reduce conditions used can be found at Extension:AbuseFilter/Conditions .

Exclusions

Although the AbuseFilter examine function will identify "rollback" actions as edits, the AbuseFilter will not evaluate rollback actions for matching.

Useful links

• PCRE pattern syntax
• Edit filters of cross-wiki interest
• Extension:AbuseFilter/Conditions

Notes