PCRE is a nice library. I read (on its site, IIRC) that it is used for the regex support in Python and some other languages.
I once worked - as part of new product work in an enterprise company - on building the PCRE library as an object file on multiple Unixes from different vendors (like IBM AIX, HP-UX, Solaris, DEC Ultrix, etc.) and also on Windows (including on both 32-bit and 64-bit variants of some of those OSes), using the C compiler toolchain on each of those platforms. I was a bit surprised to see the amount of variation in the toolchain commands and flags (command-line options) across the tools on all those Unixes. But on further thought, knowing about the Unix wars [1] and configure [2], maybe I should not have been surprised.
Regex facilities for text processing were first implemented by Ken Thompson, long before Perl.
On the topic of implementations, this is important: https://swtch.com/~rsc/regexp/regexp1.html