matches any word character (equal to [a-zA-Z0-9_])
+Quantifier — Matches between one and unlimited times, as many times as possible, giving back as needed (greedy)
\s*
matches any whitespace character (equal to [\r\n\t\f\v ])
*Quantifier — Matches between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\( matches the character ( literally (case sensitive)
\Kresets the starting point of the reported match. Any previously consumed characters are no longer included in the final match
Named Capture Group e
(?<e>[^()]+|[^()]*\((?&e)\)[^()]*)*
*Quantifier — Matches between zero and unlimited times, as many times as possible, giving back as needed (greedy)
A repeated capturing group will only capture the last iteration. Put a capturing group around the repeated group to capture all iterations or use a non-capturing group instead if you're not interested in the data
1st Alternative
[^()]+
Match a single character not present in the list below
[^()]+
2nd Alternative
[^()]*\((?&e)\)[^()]*
Match a single character not present in the list below
[^()]*
\( matches the character ( literally (case sensitive)
(?&e)recurses the subpattern named e
\) matches the character ) literally (case sensitive)
Match a single character not present in the list below
[^()]*
Positive Lookahead
(?=\))
Assert that the Regex below matches
\) matches the character ) literally (case sensitive)
Global pattern flags
g modifier:global. All matches (don't return after first match)
m modifier:multi line. Causes ^ and $ to match the begin/end of each line (not only begin/end of string)
x modifier:extended. Spaces and text after a # in the pattern are ignored