I am trying to write a regular expression to aid in the parsing of a configuration file and I want to allow the users of the configuration file to specify any character in their directive including the special characters for the file format (comment (#), equivalance (=), etc.) and I have been trying to write an appropriate regex with no success. I am new at this and I have tried: 
s/([^(?:([^\\]|\A)\\(\\{2})*\#)]*)(.*)/$1/

[download]
which represents a # not followed by an odd number of \'s (since \\# is the \ character metaquoted followed by a comment) but that didn't work becasue ^ only represents single characters and not sets of characters. I then tried the perl 5.005 negative lookbehind (?<!) but it only allows fixed width lookbehinds and I want to allow any number of \'s. Currently I am doing: 
split /\Q#\E/;
$_ = $_[0];
if(/\A\s*\Z/) {
  next;
}
$string = $_;
for($i = 1; $i <= $#_; $i++) {
  $_ = $_[$i - 1];
  m/(.)((\\){2})*\Z/;
  if("$1" eq "\\") {
    $string .= "\#" . $_[$i];
  } else {
   last;
  }
}

[download]
Can anyone suggest a regex to do all that work? I remember seeing one to correctly parse a C string somewhere which would deal with these same issues, but hard as I look I cannot find it.

Will

Originally posted as a Categorized Question.

In reply to How do I write a regex which allows meta-quoting? by WHolcomb

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.