Perl5 Compatible Regular Expressions
The PCRE2 library is a set of functions that implement regular expression pattern matching using the same syntax and semantics as Perl 5. PCRE2 has its own native API, as well as a set of wrapper functions that correspond to the POSIX regular expression API. The PCRE2 library is free, even for building proprietary software.
PCRE2 is a re-working of the original PCRE library to provide an entirely new API.