2015-06-10 16:44:30 +00:00
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#+TITLE: RegeXp Translator Mode
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* Table of Contents :TOC@4:
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- [[#what-is-this][What is this?]]
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- [[#generate-all-matching-strings-productions][Generate all matching strings (productions)]]
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- [[#re-builder-support][RE-Builder support]]
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- [[#use-from-lisp][Use from Lisp]]
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- [[#keybindings][Keybindings]]
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* What is this?
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This contrib layer sets up pcre2el or rxt (RegeXp Translator or RegeXp Tools)
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which is a utility for working with regular expressions in Emacs, to parse,
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convert, and font-lock PCRE, Emacs and rx regexps.
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Using pcre2el you can convert an Emacs Regexp to pcre (and back) (oh and output
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as rx too.)
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* Generate all matching strings (productions)
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Occasionally you come across a regexp which is designed to match a finite set of
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strings, e.g. a set of keywords, and it would be useful to recover the original
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set. (In Emacs you can generate such regexps using =regexp-opt=). The commands
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2015-06-12 01:23:07 +00:00
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=rxt-convert-to-strings= (~C-c /′~), =rxt-pcre-to-strings= (~C-c / p ′~) or
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=rxt-elisp-to-strings= (~C-c / e ′~) accomplish this by generating all the
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2015-06-10 16:44:30 +00:00
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matching strings ("productions") of a regexp. (The productions are copied to the
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kill ring as a Lisp list).
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An example in Lisp code:
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#+begin_src emacs-lisp
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(regexp-opt =("cat" "caterpillar" "catatonic"))
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;; => "\\(?:cat\\(?:atonic\\|erpillar\\)?\\)"
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(rxt-elisp-to-strings "\\(?:cat\\(?:atonic\\|erpillar\\)?\\)")
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;; => =("cat" "caterpillar" "catatonic")
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#+end_src
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** RE-Builder support
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The Emacs RE-Builder is a useful visual tool which allows using several
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2015-06-10 21:16:01 +00:00
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different built-in syntaxes via =reb-change-syntax= (~C-c TAB~). It supports
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2015-06-10 16:44:30 +00:00
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Elisp read and literal syntax and =rx=, but it can only convert from the
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symbolic forms to Elisp, not the other way. This package hacks the RE-Builder to
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also work with emulated PCRE syntax, and to convert transparently between Elisp,
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PCRE and rx syntaxes. PCRE mode reads a delimited Perl-like literal of the form
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=/ ... /=, and it should correctly support using the =x= and =s= flags.
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** Use from Lisp
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Example of using the conversion functions:
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#+begin_src emacs-lisp
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(rxt-pcre-to-elisp "(abc|def)\\w+\\d+")
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;; => "\\(\\(?:abc\\|def\\)\\)[_[:alnum:]]+[[:digit:]]+"
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#+end_src
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* Keybindings
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2015-06-10 21:16:01 +00:00
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=pcre2el= defines keybindings under ~C-c /~ so we'll define them under ~<SPC> R~.
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2015-06-10 16:44:30 +00:00
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