As the comment by tchrist to this [0] downvoted answer says, as soon as back references were used (40 years ago apparently) regexes were not regular anymore. [

As the comment by tchrist to this [0] downvoted answer says, as soon as back references were used (40 years ago apparently) regexes were not regular anymore. [0] http://stackoverflow.com/questions/4231382/regular-expression-pattern-not-matching-anywhere-in-string/4231400#4231400 http://stackoverflow.com/questions/4231382/regular-expressio...