This has already been done by the regex ninja japhy in the funky YAPE::Regex::Explain module.

use YAPE::Explain::Regex;

my $re = qr/foo*(?<=bar)+?(?:baz)?/;
print YAPE::Regex::Explain->new($re)->explain;

__output__

The regular expression:

(?-imsx:foo*(?<=bar)(?:baz)?)

matches as follows:

NODE                     EXPLANATION
----------------------------------------------------------------------
(?-imsx:                 group, but do not capture (case-sensitive)
                         (with ^ and $ matching normally) (with . not
                         matching \n) (matching whitespace and #
                         normally):
----------------------------------------------------------------------
  fo                       'fo'
----------------------------------------------------------------------
  o*                       'o' (0 or more times (matching the most
                           amount possible))
----------------------------------------------------------------------
  (?<=                     look behind to see if there is (1 or more
                           times (matching the least amount
                           possible)):
----------------------------------------------------------------------
    bar                      'bar'
----------------------------------------------------------------------
  )+?                      end of look-behind
----------------------------------------------------------------------
  (?:                      group, but do not capture (optional
                           (matching the most amount possible)):
----------------------------------------------------------------------
    baz                      'baz'
----------------------------------------------------------------------
  )?                       end of grouping
----------------------------------------------------------------------
)                        end of grouping
----------------------------------------------------------------------
[download]

HTH

_________
broquaint

---

---

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! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

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:
	&		&
	<		&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.