I see two big bugs.

• One:
You're using <DATA> in list context, which will only ever return anything(everything!) once, but you're using it in a while loop. The second loop iteration will assign an empty list to @lines, then evaluate false and leave the while loop. Just erase the while loop, and leave it's conditional as a non-loop-control statement, and this bug should be fixed.
• Two:
The last foreach is rather borked. You're trying to use strings as hash refs. You should replace @lines with @{ $vars{lines} } I think, but I can't really tell what you're doing so I'm not totally sure.

Also, are you really trying to throw away the reverse_map lines? It isn't clear. You should handle this case like the comment, if you're expecting that data and don't want it. That will make the code more clear. Also, consider starting that regex with ^\s* to speed the program up.
--
Snazzy tagline here

---

---

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.