User:松/Drafts/Extension:AbuseFilter/Rules format

Format of rules

The rules are formatted much as conditionals in a C/Java/Perl-like language.

Variables and literals

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.

Examples

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

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.

Examples

USER_EDITCOUNT
ARTICLE_RECENT_CONTRIBUTORS

Simple comparisons

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

< and > — Return true if the left-hand operand is less than/greater than the right-hand operand respectively.
<= and >= — Return true if the left-hand operand is less than or equal to/greater than or equal to the right-hand operand respectively.
== and != — Return true if the left-hand operand is equal to/not equal to the right-hand operand respectively.

Examples

1 == 2

Result: False

1 <= 2

Result: True

1 >= 2

Result: False

1 != 2

Result: True

1 < 2

Result: True

1 > 2

Result: False

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 index specified by the left-hand operand.
% — Return the remainder given when the left-hand operand is divided by the right-hand operand.

Examples

1 + 1

Result: 2

2 * 2

Result: 4

1 / 2

Result: 0.5

9 ** 2

Result: 81

6 % 5

Result: 1

Keywords

Two special keywords are included for often-used functionality

like 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.
rlike and regex return true if the left-hand operand matches the regex pattern in the right-hand operand.

Examples

"1234" like "12?4"

Result: True

"1234" like "12*"

Result: True

"foo" in "foobar"

Result: True

"foo" regex "\w+"

Result: 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.

length returns the length of the string given as the first argument.
lcase returns the first argument converted to lower case.
ccnorm normalises confusable/similar characters in the argument, and returns a canonical form.
rmdoubles removes repeated characters in the argument, and returns the result.
specialratio returns the number of non-alphanumeric characters divided by the total number of characters in the first argument.
norm is equivalent to rmspecials(rmdoubles(ccnorm(arg1))).
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.
rmspecials removes any special characters in the first argument, and returns the result.

Examples

length("Wikipedia")

Result: 9

lcase("Wikipedia")

Result: wikipedia

ccnorm("ωɨƙɩᑭƐƉlα")

Result: W1K1PED1A

rmdoubles( "foobybboo" )

Result: fobybo

specialratio("Wikipedia!")

Result: 0.1

norm( "!!ω..ɨ..ƙ..ɩ..ᑭᑭ..Ɛ.Ɖ@@l%%α!!" )

Result: W1K1PED1A

count( "foo", "foofooboofoo" )

Result: 3

count( "foo,bar,baz" )

Result: 3

rmspecials( "FOOBAR!!1" )

Result: FOOBAR1

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

1 | 1

Result: True

1 | 0

Result: True

0 | 0

Result: False

1 & 1

Result: True

1 & 0

Result: False

0 & 0

Result: False

1 ^ 1

Result: False

1 ^ 0

Result: True

0 ^ 0

Result: False

!1

Result: False

Order of operations

Operations are generally done right-to-left, but there is an order to which they are resolved. This is:

Anything surrounded by parentheses (( and )) is evaluated as a single unit.
Turning variables/literals into their respective data.
Function calls
Unary + and - (i.e. -1234, +1234)
Keywords
Boolean inversion (!x)
Exponentiation
Multiplication-related (multiplication, division, modulo)
Comparisons.
Boolean operations.