private function getColumnChainsRegxp() { return '~ (?(DEFINE) (?P<word> [\\w_]*[a-z][\\w_]* ) (?P<del> [.:] ) (?P<node> (?&del)? (?&word) (\\((?&word)\\))? ) ) (?P<chain> (?!\\.) (?&node)*) \\. (?P<column> (?&word) | \\* ) ~xi'; }