Regular Expressions 101

Pro

(?s)applies the following effective flags to the remainder of the pattern: gms

s modifier: single line. Allows a dot to match line terminators

{ifthe literal text {if (case sensitive)

\s+any whitespace character, repeated at least once

!TEST}the literal text !TEST} (case sensitive)

Group 1((?:(?!{(?:if\s+!TEST|\/if)}).|(?R))*)

Non-Capturing Group(?:(?!{(?:if\s+!TEST|\/if)}).|(?R))*

*repeats the group contents below any number of times:

1st Alternative(?!{(?:if\s+!TEST|\/if)}).

Negative Lookahead(?!{(?:if\s+!TEST|\/if)})

{the literal { (123₁₀ / 173₈ / 7B₁₆)

Non-Capturing Group(?:if\s+!TEST|\/if)

1st Alternativeif\s+!TEST

ifthe literal text if (case sensitive)

\s+any whitespace character, repeated at least once

!TESTthe literal text !TEST (case sensitive)

2nd Alternative\/if

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

ifthe literal text if (case sensitive)

}the literal } (125₁₀ / 175₈ / 7D₁₆)

.any character

2nd Alternative(?R)

(?R)recurses into the entire pattern

{the literal { (123₁₀ / 173₈ / 7B₁₆)

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

if}the literal text if} (case sensitive)

Global pattern flags

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

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

Detailed match information will be displayed here automatically.

25 tokens

Regular Expression

(?s){if\s+!TEST}((?:(?!{(?:if\s+!TEST|\/if)}).|(?R))*){\/if}

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    {if !TEST}
      {USERNAME}
      {if !TEST}
        HI
      {/if} 
      klöaksdölsa
    {/if}

    asdas

    {if !TEST}asd{/if}
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