agcre was not really meant to be a drop-in replacement for grep:
- defaults to extended regexps
- does most (sane/useful) perl extensions
- does utf-8 searching and matching
- is built around a vm style of matching, rather than a dfa, or aho
corasick-style optimizations, so sacrifices performance for protection
against sociopathic expressions
- extends the api to do backwards searching (similar to memrchr in a byte
string, where memchr does the forward searching)
But certainly has none of the production-ready style of matching that would
be necessary for a full grep replacement, to say nothing of atf tests (it
has its own test suite, just not atf)