Superstring contains a copy of the [PCRE](http://www.pcre.org/) regex engine.

The `10.23` directory contains a subset of the PCRE distribution obtained from [here](https://ftp.pcre.org/pub/pcre/pcre2-10.23.zip).

The file that `superstring` uses to compile PCRE, `pcre.gyp`, was created based on PCRE's `NON-AUTOTOOLS-BUILD` instructions.