Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. — Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

Global blank

boost::xpressive::blank — Matches a blank (horizonal white-space) character.

unspecified blank;

The regex traits are used to determine which characters are blank characters. To match any character that is not blank, use ~blank.