Regular Expressions 101

Explanation

Pro

(?i)applies the following effective flags to the remainder of the pattern: gxi

i modifier: insensitive. Matches without distinguishing uppercase and lowercase letters

\ban ASCII word boundary

Negative Lookahead(?!.*?\.onion)

.*?any character (except for line terminators), repeated any number of times

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

onionthe literal text onion (case insensitive)

Atomic Group(?> (?: [a-z][\w-]+: (?: /{1,3} | [a-z0-9%] ) | ftp:// | www\d{0,3}[.] | [a-z0-9.\-]+[.][a-z]{2,4}/ ) (?:[^\s()<>]+|\(([^\s()<>]+|(\([^\s()<>]+\)))*\))+?(?:\(([^\s()<>]+|(\([^\s()<>]+\)))*?\)|[^\s`!()\[\]{};:\'".,<>?«»“”‘’]))

Non-Capturing Group(?: [a-z][\w-]+: (?: /{1,3} | [a-z0-9%] ) | ftp:// | www\d{0,3}[.] | [a-z0-9.\-]+[.][a-z]{2,4}/ )

1st Alternative [a-z][\w-]+: (?: /{1,3} | [a-z0-9%] )

Character Class[a-z]

a-zone character from a (97₁₀) to z (122₁₀) (case insensitive)

Character Class[\w-]+

+matches at least one character from the set below:

\wany word character

-the literal - (45₁₀ / 55₈ / 2D₁₆)

: the literal text :

Non-Capturing Group(?: /{1,3} | [a-z0-9%] )

1st Alternative /{1,3}

/{1,3}the literal / (47₁₀ / 57₈ / 2F₁₆) , repeated between 1 and 3 times

2nd Alternative [a-z0-9%]

Character Class[a-z0-9%]

a-zone character from a (97₁₀) to z (122₁₀) (case insensitive)

0-9one character from 0 (48₁₀) to 9 (57₁₀)

%the literal % (37₁₀ / 45₈ / 25₁₆)

2nd Alternative ftp://

ftp:// the literal text ftp:// (case insensitive)

3rd Alternative www\d{0,3}[.]

wwwthe literal text www (case insensitive)

\d{0,3}a digit, repeated between 0 and 3 times

Character Class[.]

.the literal . (46₁₀ / 56₈ / 2E₁₆)

4th Alternative [a-z0-9.\-]+[.][a-z]{2,4}/

Character Class[a-z0-9.\-]+

+matches at least one character from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case insensitive)

0-9one character from 0 (48₁₀) to 9 (57₁₀)

.the literal . (46₁₀ / 56₈ / 2E₁₆)

\-the literal - (45₁₀ / 55₈ / 2D₁₆)

Character Class[.]

.the literal . (46₁₀ / 56₈ / 2E₁₆)

Character Class[a-z]{2,4}

{2,4}matches between 2 and 4 characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case insensitive)

/ the literal text /

Non-Capturing Group(?:[^\s()<>]+|\(([^\s()<>]+|(\([^\s()<>]+\)))*\))+?

+?repeats the group contents below at least once:

1st Alternative[^\s()<>]+

Negated Character Class[^\s()<>]+

+matches at least one character outside the set below:

\sany whitespace character

(the literal ( (40₁₀ / 50₈ / 28₁₆)

)the literal ) (41₁₀ / 51₈ / 29₁₆)

<the literal < (60₁₀ / 74₈ / 3C₁₆)

>the literal > (62₁₀ / 76₈ / 3E₁₆)

2nd Alternative\(([^\s()<>]+|(\([^\s()<>]+\)))*\)

\(the literal ( (40₁₀ / 50₈ / 28₁₆)

Group 1([^\s()<>]+|(\([^\s()<>]+\)))*

*repeats the group contents below any number of times:

1st Alternative[^\s()<>]+

Negated Character Class[^\s()<>]+

+matches at least one character outside the set below:

\sany whitespace character

(the literal ( (40₁₀ / 50₈ / 28₁₆)

)the literal ) (41₁₀ / 51₈ / 29₁₆)

<the literal < (60₁₀ / 74₈ / 3C₁₆)

>the literal > (62₁₀ / 76₈ / 3E₁₆)

2nd Alternative(\([^\s()<>]+\))

\)the literal ) (41₁₀ / 51₈ / 29₁₆)

Non-Capturing Group(?:\(([^\s()<>]+|(\([^\s()<>]+\)))*?\)|[^\s`!()\[\]{};:\'".,<>?«»“”‘’])

\ban ASCII word boundary

Negative Lookahead(?!<<)

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

x modifier: extended. Ignores unescaped whitespace and comments outside character classes

Unit Test Summary

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Quick Reference

25 tokens

Regular Expression

(?i)\b(?!.*?\.onion)
(?>
    (?:
        [a-z][\w-]+:
        (?:
            /{1,3}
          |
            [a-z0-9%]
        )
      |
        ftp://
      |
        www\d{0,3}[.]
      |
        [a-z0-9.\-]+[.][a-z]{2,4}/
    )
    (?:[^\s()<>]+|\(([^\s()<>]+|(\([^\s()<>]+\)))*\))+?(?:\(([^\s()<>]+|(\([^\s()<>]+\)))*?\)|[^\s`!()\[\]{};:\'".,<>?«»“”‘’]))\b(?!<<)

Unit Tests

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