cl-ppcre is a portable CL#

Sun Aug 24 07:16:35 2003

cl-ppcre is a portable CL package providing perl-compatible regexps. There are two things I'd like to say about it on the basis of ten minutes use

1. It's asdf-packaged. Although it's not in cclan, which means I can't download it with asdf-install because I haven't got a trust relationship with Edi Wietz' PGP key, I can download it from the page and then painlessly install it from local disk.

   (asdf-install:install "/home/dan/cl-ppcre.tgz")
   Install where?
   1) System-wide install: 
      System in #P"/usr/local/lib/sbcl/site-systems/"
      Files in #P"/usr/local/lib/sbcl/site/" 
   2) Personal installation: 
      System in #P"/home/dan/.sbcl/systems/"
      Files in #P"/home/dan/.sbcl/site/" 
    -> 2
   Installing /home/dan/clppcre.tgz in #P"/home/dan/.sbcl/site/",#P"/home/dan/.sbcl/systems/"
   cl-ppcre-0.5.7/
   [ ... and so it goes ]
   

2. Although billed as perl-compatible, that doesn't mean you have to use the Perl syntax: you can also write regexes as trees. For example

   (defparameter *postcode-p*
     (let ((a '(:CHAR-CLASS (:RANGE #\a #\z)))
   	(n :digit-class)
   	(s '(:GREEDY-REPETITION 0 NIL :WHITESPACE-CHAR-CLASS)))
       (cl-ppcre:create-scanner
        `(:alternation
          (:sequence ,a ,n       ,s  ,N ,A ,A)
          (:sequence ,A ,N ,N    ,s  ,N ,A ,A)
          (:sequence ,A ,A ,N    ,s  ,N ,A ,A)
          (:sequence ,A ,A ,N ,N ,s  ,N ,A ,A)
          (:sequence ,A ,N ,A    ,s  ,N ,A ,A)
          (:sequence ,A ,A ,N ,A ,s  ,N ,A ,A)))))
   
   * (cl-ppcre:scan *postcode-p* "w1y 1ha")
   0
   7
   #()
   #()
   * 
   

   That's a regex for UK postcodes (actually, not quite. I should add the special case for GIR 0AA, which apparently is Alliance & Leicester Girobank Plc in Bootle). Isn't it just much easier to see what it does as a tree?