http://www.perlmonks.org?node_id=1028265


in reply to Re^2: Help with regex - find captured pattern twice
in thread Help with regex - find captured pattern twice

You might read it as this:

s/ (?<! # 2. NOT preceded by \pL # a letter ) ( # 1. Capture \pL # a letter ) ( # 3. Capture \( # open paren; [\d+-]+ # one or more digits, plus, minus; \) # close paren )? # (Zero or one time) (?! # 4. NOT followed by \pL # a letter ) /(${1}SS*exp($1$2))/gx;