/
(?x:#sds
)
(?#sdsa)
#sda
(?x) # extended mode)
(?<!\\) # no escape in before paren)
(?: # begine or end alternation noncap group)
(?<begin>\( # begining pattern paren)
(?: # name/index/noncap alternation noncap group)
(?<named>\?\< # named ?<name>)
(?<name>[\w][\w\d_]+) # capture name)
>)| # end of name >)
(?<indexed>(?!\?))| # indexed capture group no following ? after paren)
(?<nonecap>\?[^<]) # other groups that dont capture no following < after paren)
) # name/index/noncap alternation noncap group)
)| # begining pattern end)
(?<end>\)) # ending paren ends group scope)
)
/
gm