re2c is a tool for generating C-based recognizers from regular expressions. re2c-based scanners are efficient: for programming languages, given similar specifications, an re2c-based scanner is typically almost twice as fast as a flex-based scanner with little or no increase in size (possibly a decrease on cisc architectures). Indeed, re2c-based scanners are quite competitive with hand-crafted ones. WWW: http://re2c.sourceforge.net/