l3regex – Reg­u­lar ex­pres­sion fa­cil­i­ties for LaTeX

The pack­age pro­vides reg­u­lar ex­pres­sion test­ing, ex­trac­tion of sub­matches, split­ting, and re­place­ment, all act­ing on to­ken lists. The syn­tax of reg­u­lar ex­pres­sions is mostly a sub­set of the PCRE syn­tax (and is very close to Posix), with some ad­di­tions aris­ing from the fact that TeX ma­nip­u­lates to­kens rather than char­ac­ters.
For per­for­mance rea­sons, only a lim­ited set of fea­tures are im­ple­mented. Notably, back-ref­er­ences are not sup­ported.
The pack­age is cur­rently dis­tributed as part of the LaTeX3 l3­ex­per­i­men­tal bun­dle.