UniversalCodeGrep
UniversalCodeGrep (ucg) is an extremely fast grep-like tool specialized for searching large bodies of source code. It is intended to be largely command-line compatible with Ack, to some extent with ag, and where appropriate with grep. Search patterns are specified as PCRE regexes. ucg is intended to address the impatient programmer's code searching needs. ucg is written in C++11 and takes advantage of the concurrency (and other) support of the language to increase scanning speed while reducing reliance on third-party libraries and increasing portability. Regex scanning is provided by the PCRE library, with its JIT compilation feature providing a huge performance gain on most platforms.
