Guix

pcre2el or rxt (RegeXp Translator or RegeXp Tools) is a utility for working with regular expressions in Emacs, based on a recursive-descent parser for regexp syntax. In addition to converting (a subset of) PCRE syntax into its Emacs equivalent, it can do the following:

• convert Emacs syntax to PCRE

• convert either syntax to rx, an S-expression based regexp syntax

• untangle complex regexps by showing the parse tree in rx form and highlighting the corresponding chunks of code

• show the complete list of strings (productions) matching a regexp, provided the list is finite

• provide live font-locking of regexp syntax (so far only for Elisp buffers – other modes on the TODO list).