You're right, the (corrected) code won't find palindromes. It wasn't intended to. It was the first step in finding a palindrome candidate.

OK, fair enough. So what did you want it to do? Did you just want to check for repeated characters at the proper end of word boundaries?

[Insert "Lightbulb Over Head" graphic here ]

You just want a filter to grab candidates, then strip whitespace, then test for palindrome-ness.

I think you'd do us a favor by coming up with an appropriate regex with ??{code}, something near:

/(\b
  (([a-z])                        # at least one char
   ?{local @suffix; push @suffix, $^N}) # build up suffix
  (([a-z)
   ?{local @suffix; push @suffix, $^N}
   | \S+)+
  [a-z]?                             # possible odd char
  (([a-z])
   (?{if ($^N eq $suffix[-1]) {pop @suffix}})
   | \S+)+)
  (([a-z])
   (?{if ($^N eq $suffix[-1]) {pop @suffix}})
 \b)
/x
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Though I don't think that works, and it's untested. (Hey, I have to leave something up to you.) Besides, there's a lot left out of the perlre with ?{code} and ??{code}, so please come back and tell us what it should say :)