From: Simon Strandgaard <neoneye@...>
Date: 2004-06-03T01:57:14+09:00
Subject: [ann] regexp-engine 0.11

Phwew.. regexp now supports unicode ;-)

download as TGZ:
http://rubyforge.org/frs/download.php/706/regexp-engine-0.11.tar.gz

download as ZIP:
http://rubyforge.org/frs/download.php/707/regexp-engine-0.11.zip

demo site:
http://neoneye.dk/regexp.rbx

changelog:
http://rubyforge.org/cgi-bin/viewcvs/cgi/viewcvs.cgi/projects/regexp_engine/CHANGES?rev=1.72&cvsroot=aeditor&content-type=text/vnd.viewcvs-markup


Overview
========

Regexp engine is written entirely in Ruby. It is very compatible
with Ruby's builtin regexp-engine. Carefully tested (+2000 tests).


Features
========

There is at the moment 3 parsers.. perl5, perl6, xml.

Encodings supported: ASCII, UTF8.


Not yet supported stuff
=======================

Send me a mail in case there are something you want, or if 
you are a developer yourself then send me some patches.

* subcaptures inside negative-lookahead/behind.
* grammars.
* UTF16 and other encoding.
* inline-code.
* named captures.
* possesive quantifiers. 
* recursive expression. 


Perl5 syntax
============

  a|b|c         alternation 
  [...] [^...]  character class.. and inverse charclass
  [[:alpha:]]   posix character class
  [[:^alpha:]]  inverse posix character class
  .             dot matches anything except newline, same as [^\n]
  \1 .. \9      backreference . . . . . . . . . . . . . . . . . . . . . . see [3]
  *     *?      loop 0 or more times  greedy/lazy
  +     +?      loop 1 or more times  greedy/lazy
  {n,}  {n,}?   loop n or more times  greedy/lazy
  ?     ??      loop 0..1 times       greedy/lazy
  {n,m} {n,m}?  loop n..m times       greedy/lazy
  {n}   {n}?    loop n times          greedy/lazy 
  ( ... )       capturing group
  (?: ... )     non-capturing group
  (?> ... )     atomic grouping
  (?= ... )     positive-lookahead 
  (?! ... )     negative-lookahead  . . . . . . . . . . . . . . . . . . . see [2]
  (?<= ... )    positive-lookbehind . . . . . . . . . . . . . . . . . . . see [1]
  (?<! ... )    negative-lookbehind . . . . . . . . . . . . . . . . . . . see [1], [2]
  (?# ... )     posix-comment
  (?i)  (?-i)   ignorecase on/off
  (?m)  (?-m)   multiline  on/off
  (?x)  (?-x)   extended   on/off
  ^     \A      begin of line, begin of string
  $     \z \Z   end of line, end of string (excl newline)
  \b    \B      word boundary, nonword boundary
  \d    \D      [[:digit:]] and the inverse [^[:digit:]]
  \s    \S      [[:space:]] and the inverse [^[:space:]]
  \w    \W      [[:word:]]  and the inverse [^[:word:]]
  \x20          hex . . . . . . . . . . . . . . . . . . . . . . . . . . . see [4] 
  \040          octal . . . . . . . . . . . . . . . . . . . . . . . . . . see [3], [4]
  \x{deadbeef}  widechar codepoint specified as hex
  \n            newline
  \a            bell
  \             escape next char

precedens between operators:
  ()            pattern memory
  + * ? {}      number of occurrences
  ^ $ \b \B     pattern anchors
  |             alternatives


1. Variable-width-lookbehind are fairly supported by this engine.
   For instance this (?<=(a.*)g) is a valid expression. 
   Beware that the left-most-longest rule is inversed inside lookbehind,
   and that Backreferences are not possible (yet).

2. Subcaptures inside negative-lookahead/behind are empty
   at the moment.

3. If one tries to backreference a not-existing capture then it
   will be interpreted as an octal symbol.

4. When encoding is ASCII, you can specify hex/octal values in 
   the range 0-255. However when encoding is UTF8 then only the 
   range 0-127 are valid, in this case the range 128-255 is undefined.




Call For Help
=============

etablish contact, if you have interest in perl6 regexp.
etablish contact, if you have knowledge about asian text-encodings.


--
Simon Strandgaard