GNU grep is based on a fast lazy-state deterministic matcher (about twice as fast as stock Unix egrep) hybridized with a Boyer-Moore-Gosper search for a fixed string that eliminates impossible text from being considered by the full regexp matcher without necessarily having to look at every character. The result is typically many times faster than Unix grep or egrep.
Debian package information is generally stored in files having a special file format, dubbed the Debian control file format (dctrl), a special case of the record jar file format. These tools operate on any files conforming in a general sense to that format, and are therefore widely applicable whenever this format is in play. The tools in this bundle are grep-dctrl, sort-dctrl, join-dctrl, and tbl-dctrl.