XS functions to assist in parsing keyword syntax

 XS::Parse::Keywords provides some XS functions to assist in writing syntax
 modules that provide new perl-visible syntax, primarily for authors of
 keyword plugins using the PL_keyword_plugin hook mechanism. It is unlikely to
 be of much use to anyone else; and highly unlikely to be any use when writing
 perl code using these. Unless you are writing a keyword plugin using XS, this
 module is not for you.