PCRE - Perl Compatible Regular Expressions
The PCRE library is a set of functions that implement regular expression pattern matching using the same syntax and semantics as Perl 5. PCRE has its own native API as well as a set of wrapper functions that correspond to the POSIX regular expression API.
http://www.pcre.org/
JRegex
Computers, Programming, Languages, Regular Expressions - JRegex. Regular expression support that offers a superset of Perl5.
https://jregex.sourceforge.net/