\[the literal [ (9110 / 1338 / 5B16)
ifthe literal text if (case sensitive) \s+any whitespace character, repeated at least once
Negated Character Class[^\]]*+ *+matches any number of characters outside the set below:
\]the literal ] (9310 / 1358 / 5D16)
\]the literal ] (9310 / 1358 / 5D16)
Group 3((?>(?!\[(?:end)?if\b).|(?R))*) Atomic Group(?>(?!\[(?:end)?if\b).|(?R))* *repeats the group contents below any number of times:
1st Alternative(?!\[(?:end)?if\b). Negative Lookahead(?!\[(?:end)?if\b) \[the literal [ (9110 / 1338 / 5B16)
Non-Capturing Group(?:end)? ?repeats the group contents below at most once:
endthe literal text end (case sensitive) ifthe literal text if (case sensitive) \ban ASCII word boundary
.any character
(?R)recurses into the entire pattern
\[the literal [ (9110 / 1338 / 5B16)
endifthe literal text endif (case sensitive) \]the literal ] (9310 / 1358 / 5D16)
s modifier: single line. Allows a dot to match line terminators
x modifier: extended. Ignores unescaped whitespace and comments outside character classes