A short discussion of the basics of Edi Weitz's Portable Perl Compatible Regular Expression library. Assumes you're familiar with regular expressions in general.
I haven't used Edi's cl-ppcre package before, so this article was partly just a learning experience for me. It's documentation is quite complete, so I could just say "Go read http://www.weitz.de/cl-ppcre/"; and be done. :) All the examples are copied from that file. Where to get it: - naked: http://weitz.de/files/cl-ppcre.tar.gz - Debian: apt-get install cl-ppcre - The doc says "There's also a port for Gentoo Linux thanks to Matthew Kennedy and a FreeBSD port thanks to Henrik Motakef. Installation via asdf-install should as well be possible." Where to read the docs: http://www.weitz.de/cl-ppcre/ How to load it: - naked: (load "load.lisp") will compile and load everything. - Debian: (clc:clc-require :cl-ppcre) Interesting points: - many of the functions have a flag, sharedp, which tells the function that the various substrings it generates can share structure with the string matched against. So you could do multiple megabytes of matching, but only actually allocate a few displaced arrays. Nifty. - "CL-PPCRE uses a compiler macro and LOAD-TIME-VALUE to make sure that the scanner is only built once if the first argument to SCAN, SCAN-TO-STRINGS, SPLIT, REGEX-REPLACE, or REGEX-REPLACE-ALL is a constant form." So if you pass it a constant form, it's smart enough to realize that and pre-compile the regex parser. Also very nifty. Basics: - scan regex target-string &key start end => match-start, match-end, reg-starts, reg-ends Search a string for a regular expression. Returns the start of the match, the end of the match, and two arrays denoting the beginnings and ends of register matches. On failure returns NIL. (cl-ppcre:scan "a*b" "xaaabd") ; no register matches => 1, 5, #(), #() (cl-ppcre:scan "(a)*b" "xaaabd") ; 1 register match => 1, 5, #(3), #(4) (subseq "xaaabd" 1 5) => "aaab" (subseq "xaaabd" 3 4) => "a" (cl-ppcre:scan "(a*)b" "xaaabd") ; 1 register match, in different place => 1, 5, #(1), #(4) (subseq "xaaabd" 1 4) => "aaa" - scan-to-strings regex target-string &key start end sharedp => match, regs Like SCAN but returns substrings of target-string instead of positions. (cl-ppcre:scan-to-strings "(([^b])*)b" "aaabd") => "aaab", #("aaa" "a") - split regex target-string &key start end limit with-registers-p omit-unmatched-p sharedp => list Matches regex against target-string as often as possible and returns a list of substrings between the matches. (cl-ppcre:split "\\s+" "foo bar baz frob") => ("foo" "bar" "baz" "frob") (cl-ppcre:split "\\s+" "foo bar baz frob") => ("foo" "bar" "baz" "frob") (cl-ppcre:split "\\s*" "foo bar baz frob") => ("f" "o" "o" "b" "a" "r" "b" "a" "z" "f" "r" "o" "b") - regex-replace regex target-string replacement &key start end preserve-case simple-calls => list Try to match target-string between start and end against regex and replace the first match with replacement. (cl-ppcre:regex-replace "fo+" "foo bar" "frob") => "frob bar" See the documentation for other functions and other examples. -- Larry _______________________________________________ Gardeners mailing list [email protected] http://www.lispniks.com/mailman/listinfo/gardeners
